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irving2008
03-06-2008, 04:35 AM
Hi all (is anybody is here... do I hear an echo...)

Anyway, thought I'd use this location as a sometime record of reconditioning a Relmac lathe. Bought for a song a few weeks ago (oops, that should have been a clue) it seemed fine. It lacked a chuck but had a suitable faceplate for a 3.5" one and I had one for another lathe I am recondtioning (eventually, but thats another story) so just had to drill the mounting holes. Also lacked a toolholder but a economy QTC holder, a bit of 1/4 plate and a T-bolt from Chronos (http://www.chronos.ltd.uk/) sorted that Got it all bolted down in its new home on a specially constructed welded angle iron bench but an inability to turn things in a round fashion and a nasty vibration suggested all was not right... see the next post for the story...

Here's how it looked when I got it:
http://www.kisolutionz.com/ttforum/lathe/IMG_2836_1k.JPG

And heres the install with nice new drip-feed oilers from Adams Lubetech (http://www.adamslube.co.uk)
http://www.kisolutionz.com/ttforum/lathe/IMG_2863_1k.JPG

The list of things to do grows daily

Polish the spindle (http://www.mycncuk.com/forums/showthread.php?p=644#post644)
Remove the inside burr on the spindle rear end
Replace main bearings
Fit 3 speed v-pulleys insted of the 2 speed flat pulleys (maybe)
Sort out backlash on cross feed (nasty 0.4mm 'jump')
Sort out backlash on leadscrew (less critical)
Figure out how leadscrew dog clutch should work and sort out

irving2008
03-06-2008, 04:38 AM
This post was copied from the Antique machines forum (http://www.practicalmachinist.com/vb/forumdisplay.php?s=&daysprune=&f=19) on http://www.practicalmachinist.com where I am getting a lot of help from some very knowledgeable guys

Well I went back and did some more measurements, tests, etc. and convinced myself that the spindle wasn't bent. I DTI'd the inside of the spindle and discovered a lump which I previously hadn't noticed when I cleaned it up. Took some removing but eventually it was gone. Retried the taper and the runout was now a much more reasonable 0.04mm (2 thou) average (rotating the taper in the spindle), max .06mm, min 0.02mm. DTI'd the inside of the spindle and got .03mm (1.2thou) runout.

So then went back to the issue of the eccentric cut. Set it all up again, tried bar test for bearing movement and put more effort into it and was getting .2mm (8 thou) movement lifting vertically, but .4mm (16 thou) pressing down. I also discovered 0.4mm end play on the cross-slide (at certain positions of the handle you can physically move the slide - with a clunk!) that will have to be dealt with as well but still felt the problem was in the bearing.

Decided to take the plunge and get the shaft out. In the end it came out surprisingly easily... here are some pics of what I found...

http://www.kisolutionz.com/ttforum/lathe/fbearing1.JPG
http://www.kisolutionz.com/ttforum/lathe/fbearing2.JPG

can you see whats wrong yet :roll:

irving2008
03-06-2008, 04:43 AM
I think I know whats happened... the bullgear is keyed onto the spindle but to get the shaft out you have to turn it so that the mark on the spindle lines up with a mark on the headstock casting, that puts the key at the 3-o-clock position looking into the headstock allowing it to move through the bearing (you can see it out of focus on the left in 1st pic). If you don't line it up and try bashing it out with the bullwheel at the 'normal' position (i.e. the locking pin at 12-o-clock) the key tries to cut through the bearing - hence the partial slot at the 6-o-clock position in the 2nd pic. Sometime in the past someone has tried to remove the spindle and gave up, smashing the bearing in the process... this also probably explains why the back end of the spindle is burred over and wont admit a 3/4" bar (fortunately the thread for the changewheel retainer doesnt run right to the end).

Here are the spindle journals...

Front
http://www.kisolutionz.com/ttforum/lathe/fjournal.JPG

Rear
http://www.kisolutionz.com/ttforum/lathe/rjournal.JPG

irving2008
03-06-2008, 04:45 AM
I think these need regrinding (I would if this was a car crankshaft, but maybe a lathe is different), at least the front one does, its well pitted.

Here's a view of the broken up bearing , note the small pieces of my carefully tapped oiler hole :(, the bearing material went right up through the headstock casting. Does this suggest they might have been poured in situ??

http://www.kisolutionz.com/ttforum/lathe/bearing.JPG

and a view of the headstock with front bearing removed. Is that an oil well in the bottom? If so I dont see how it works as theres no hole in the bearing and it wasn't full of oil. Also I notice the bearing is offset in the headstock - there's considerably more metal to the right where the pinch bolt is than to the left. I have no idea how to specify this or replace it...

http://www.kisolutionz.com/ttforum/lathe/headstock.JPG

Finally, the rear bearing. Its intact, but do I need to replace this? Its a bit scored but otherwise doesn't look too bad.

http://www.kisolutionz.com/ttforum/lathe/rearheadstock.JPG

The last pic shows clearly how offset these bearings are... would these have been manufactured/bored in place? How would I go about specifying or making new ones? have I bitten off more than I can chew? All answers gratefully received...

irving2008
05-06-2008, 12:26 AM
Wel I've decided to pour new bearings and have read up all about it in various places and I am now collecting what I'll need. I have some white metal bearing alloy coming, as well as a ladle and some fire-cement. Watch this space :)

I've rigged up a temporary arrangement to polish the spindle as a precursor to pouring the new bearings

http://www.kisolutionz.com/ttforum/lathe/IMG_2887_1k.JPG

After a few minutes with 80, 120, 150 and 360 grade abrasives it looks like this for the front journal

http://www.kisolutionz.com/ttforum/lathe/IMG_2888_1k.JPG

compared to
http://www.kisolutionz.com/ttforum/lathe/fjournal.JPG

Clearly some way to go but improving...

my concern is whether I can take too much off this way? Currently the spindle is 31.62mm - 31.72mm dia (about 4 thou variation) and there are some noticable hills and valleys on the front jounal through wear. Where the bullwheel sits, just inboard of the front bearing is where is measures 31.72mm as this would have had the least wear (nothing turning at that point). Nominally its a 1.25" - 31.75mm - shaft. The rear journal and where the backgeared pulley runs are about 31.68mm. If i don't even it all out this means that the front bearing must be able to open up to 31.72mm+ from 31.62mm to allow the spindle out. My theory is that if I don't shim the front bearing and lock it down when I pour it then 0.15mm - 0.2mm shims will give suitable clearance on the bearing and they will open up to maybe 0.5mm overall which will give clearance to remove the spindle in the future.

Should I just aim to get the worst of the scoring out (that pitting is quite deep), or should I aim for a mirror finish?

Is wet n dry the right way to go, or should I be using something more esoteric like an abrasive paste (in which case with what and how do I apply it?)

irving2008
05-06-2008, 08:27 AM
Hi, If you're pouring new bearings why not have the shaft reground and re hardened for a few quid? Failing that I'd try and make sure there were no high spots rather than using w&d to gain the appearance of smooth/round/ground etc.

Are you going to use the lathe or is it ornamental?
Hi Kip, Oh definitely for use... got several projects planned... including the restoration of two other lathes...

My original thought was to get it reground but was advised by others with greater knowledge that this wasn't a good idea as it would increase the play in the bearing surfaces for the pulleys and back- and bull-gears which could introduce chatter... and that a good polish was sufficient with white metal bearings as long as they were well scraped after... a regrind would take at least 10thou off and this would mean the pulleys running with the backgear would have >15thou bearing clearance which is not good for a oiled bronze bearing IMHO

Lee Roberts
05-06-2008, 01:24 PM
Log is looking good keep it up, also if you have a look at the link below we do have Bronze bushings for sale and can source alot of diffrent sizes.

If you wanted to take it down more i could have a look for you and see if we can get the right size bushings to fit.

Link: Bronze Bearings
http://stores.ebay.co.uk/MYCNCUK_Oilite-Bearings_W0QQcolZ4QQdirZ1QQfsubZ19734347QQftidZ2QQ tZkm

irving2008
05-06-2008, 04:33 PM
Log is looking good keep it up, also if you have a look at the link below we do have Bronze bushings for sale and can source alot of diffrent sizes.

If you wanted to take it down more i could have a look for you and see if we can get the right size bushings to fit.

Link: Bronze Bearings
http://stores.ebay.co.uk/MYCNCUK_Oilite-Bearings_W0QQcolZ4QQdirZ1QQfsubZ19734347QQftidZ2QQ tZkmWell the spindle is 31.75mm OD, 22mm ID so I'd not want to take it down below 30mm OD, which means I'd need to bush the 2 main bearings plus the bullgear plus the small backgear and pulleys so I'd need 4 bushes about 60mm long approx, 30mm ID, 31.75mm OD. To be honest I'd only bush it if the shaft was so bad that it was impossible to get a reasonable life out of white metal bearings, but given its likely workload I think thats a whole lot of pain I dont need right now. Also might be just as cheap to get a new spindle manufactured from 32mm OD, 20mmID stock...

Lee Roberts
05-06-2008, 11:46 PM
Ok well ill bookmark this log and keep an eye on you.

irving2008
06-06-2008, 05:48 PM
How will that help?

Anyway, today I picked up a kilo of V1-A best bearing alloy from GWN (http://www.gwneale.co.uk), a family owned business who were happy to do a small quantity 'cash in hand'. Also today I picked up a 1.5hp 3-phase motor won yesterday on eBay. Chatting to its previous owner (a Myford owner BTW) mentioned I was planning to pour a bearing but was having problems finding a suitable melting ladle. To my surprise he rummaged in his garage and produced an old but servicable 6" dia leading pot with a spout and wooden handle, ideal for the job, so that changed hands for a further £2.50!

Lee Roberts
06-06-2008, 06:36 PM
lol, good job on the bargins £2.50 ! Any chance of some pics of your progress and also you doing your bearings !?!

irving2008
06-06-2008, 07:43 PM
lol, good job on the bargins £2.50 ! Any chance of some pics of your progress and also you doing your bearings !?!Oh I plan to do a complete record of this... failures and all (I expect to have to pour this more than once!)

I've worked out how to locate the spindle correctly for both front and rear bearings and I'll do the front one first, using the rear bearing and tailstock as guides, then before removing it I shall fabricate a locating bracket that can be bolted to the rear banjo to retain the rear of the spindle in correct alignment to the front bearing once the rear bearing is removed. I'll cut this out rather than melt it out to avoid potentially moving the locator (melting it out will require me to put the lathe on its end somehow to catch the melt without it going everywhere) but might use the torch to soften it...

Weather permitting (this has to be done outside and can't be done in the rain, water droplets and molten metal don't mix!) I hope to do the front bearing this weekend...

Lee Roberts
07-06-2008, 02:16 AM
...rear banjo to retain the rear of...


Banjo ? is that the same as a Dodar? or a real name for a part?

irving2008
07-06-2008, 11:53 AM
Banjo ? is that the same as a Dodar? or a real name for a part?Its a real name... old English lathe terminology for the moveable slotted bracket that supports intermediate changewheels for screwcutting as it comprises a large circular boss attached to a long narrow slotted arm. Also known as the 'changewheel quadrant', particularly if it has multiple radial slots.

http://www.kisolutionz.com/ttforum/lathe/IMG_2862_1ka.JPG

Lee Roberts
07-06-2008, 02:48 PM
Ahh right, thanks for showing us that.

I have also added this post to the FAQ Section: What is a Banjo (http://www.mycncuk.com/forums/showthread.php?t=203)

irving2008
08-06-2008, 12:00 AM
So - todays plan was to get up to the point where I was ready to pour the bearing...

That mean preparing the spindle, locating it in the housing and sealing the bearing ends... so here's how I got on..

Firstly I needed to polish up the spindle on my improvised polishing jig (see post #5 above)

I used wet n dry, kept wet initially and grades down to 600 which is pretty fine. I wrapped the paper round an 8" length of 1/4" x 2" steel flat which made it an easy 2-handed operation.

Here's the before and after, after 30min or so of polishing...

http://www.kisolutionz.com/ttforum/lathe/IMG_2878_1k.JPG

http://www.kisolutionz.com/ttforum/lathe/IMG_2899_1k.JPG

I then turned my attention to the bearing housing and degreased that, wirebrushed it, and now it looks like...

http://www.kisolutionz.com/ttforum/lathe/IMG_2900_1k.JPG

irving2008
08-06-2008, 12:12 AM
Now it was time to do trial fit of everything. I planned to locate the spindle using a MT3 taper and the tailstock in which I placed an MT1-JT6 arbor that was already centre-drilled. This worked well...

http://www.kisolutionz.com/ttforum/lathe/IMG_2905_1k.JPG

The clingfilm is just to keep everything clean until I'm ready..

A quick DTI of the spindle showed 0.005mm runout which is fine!

I then experimented with shimming for the pinch-bolt. I've decided that I should shim it with about 30thou then the bearing will be tight enough to allow the pinchbolt to compensate for wear over a wide range. Not having shims to hand I found that 9 folds of heavy-duty roasting foil from the kitchen gave 32thou so I used that. Here you can see it being trialled...

http://www.kisolutionz.com/ttforum/lathe/IMG_2908_1k.JPG


Now we are ready to prepare for pouring the bearing.

Firstly, coat the journal in soot... this is, apparently, one of several ways of preventing the hot metal sticking to the steel shaft and making it easier to remove - we'll see later if that is true :) A candle provides the soot...

http://www.kisolutionz.com/ttforum/lathe/IMG_2912_1k.JPG

irving2008
08-06-2008, 12:19 AM
Now I refitted the spindle into the headstock (it took a couple of attempts to do this without scratching the carbon coating on the journal) and locked everything down.

Now all that is needed is to seal everything with fire-cement. Now i don't know if the proper putty, Babbit-rite, is firmer than the fire-cement I got from B&Q but I just couldn't find a way to stop it getting into the bearing. Eventually i decided to create a 'shield' from ally foil folded 3 times and cut into a ring...

http://www.kisolutionz.com/ttforum/lathe/IMG_2910_1k.JPG

and then cemented up. Same for the rear of the bearing...

http://www.kisolutionz.com/ttforum/lathe/IMG_2914_1k.JPG

and finally we are ready to pour metal, once the fire-cement has dried overnight

http://www.kisolutionz.com/ttforum/lathe/IMG_2915_1k.JPG

irving2008
08-06-2008, 09:48 AM
Is the backgear on an eccentric and driven by a flat belt with a locking pin(flathead screw) to engage half speed? I thought I saw the locking "pin" in your second picture, I had a machine of this "ilk" 15yrs ago and sold it to a grasstracker 4 years ago and learned to speak Mandarin (bought a Chinese lathe) Why would reducing the OD of the shaft and then fitting "sized" bearings increase any other clearance between gears? I could understand if it were a case of replacing central bearings with offset bearings....I'm confused help me out.
It wouldn't... what I said was that if I ground the spindle down I'd have to bush the bullgear and the pulleys and the backgear pinion as they all run on the spindle. I couldn't just grind down the journals as then the centre of the shaft wouldn't pass through the bearings.

And yes the backgear is exactly like that, except the ratio is 6.67:1!

Can't comment on the Chinese as never owned one, but from what I've seen and read give me some serious old iron any day :)

Lee Roberts
08-06-2008, 01:35 PM
So am i right in thinking you will mould around the fire cement or ?

irving2008
08-06-2008, 03:16 PM
So am i right in thinking you will mould around the fire cement or ?The fire-cement is just to seal the holes to retain the metal inside.

Well I tried a pour ths morning - not very successful :(

http://www.kisolutionz.co.uk/ttforum/lathe/IMG_2916_1k.JPG

- couldn't get enough heat into the pan (maybe its a bit big for small amount, but the burner is only 1kW as well), so it starts solidifying as soon as I start to pour
- you're supposed to scrape the 'slag' off the top, but its hard to tell whats slag and what isn't... it doesn't seem to scrape
- you're supposed to heat up the bearing housing/shaft to about 100deg to help the flow, but I found it hard with a blowtorch to get any heat in there...
- I carefully forgot to leave any air holes in the seal. As a result after about a third of the metal went in the pouring hole solidified and clogged up and that was it... no more pour! I need to leave a way for the air to get out at the top of one of the dams

http://www.kisolutionz.com/ttforum/lathe/IMG_2919_1k.JPG

So need to find a larger gas ring and a smaller ladle.

Next job is to clean it all up so i can start again... :( going to try removing the rear dam and melting it out...

Lee Roberts
08-06-2008, 04:21 PM
Ok mate sorry it didnt work out so well, keep going tho you will sort it i'm sure...

Dinner time, SUNDAY ROAST !

irving2008
08-06-2008, 10:42 PM
Removing the remains of the 1st attempt was easy - didnt even have to melt it out as there was hardly anything in there, but what was there showed promise - nice n shiney and clean surfaces

http://www.kisolutionz.com/ttforum/lathe/IMG_2922_1k.JPG

So cleaned it all up and re-assembled with a blowhole this time and left it out in the hot sun for 4 hours while I popped down to Argos for a better burner - the new one is 2300W and a much wider burner so it melts the metal in about 6 minutes against 18 or so before.. so much hotter (and you can buy the canisters for it too!)

So the fire-cement appeared to be set, it was rock hard and the whole lathe was hot to the touch from being sitting in 26degC sunshine for 4 hours so thought I'd try again...

http://www.kisolutionz.com/ttforum/lathe/IMG_2925_1k.JPG
http://www.kisolutionz.com/ttforum/lathe/IMG_2926_1k.JPG
http://www.kisolutionz.com/ttforum/lathe/IMG_2928_1k.JPG

As you can see, not a great success :rolleyes:

Two mistakes... firstly my impatience, I assumed it had set but clearly was only on the surface and not right through - it needs that 24h or so... and secondly, I made the end dams not from ally foil but from pieces cut from an ally foil dish 'cos its thicker and easier to handle. But to get it round the shaft I cut fringes and bent them over. Big mistake, because it prevented the fire-cement sealing to the shaft properly. As a result when the pressure built up the fringes lifted and allowed the hot metal to spurt as you can see - it was quite a loud bang and fortunately I was standing on the other end... The third pic shows the 'hole' where the pressure built up, probably due to water vapour from the fire-cement. the air blow hole worked ok till it blocked up tho :)

irving2008
08-06-2008, 10:57 PM
So we live and learn...

I now had 3/4 of a bearing, but obviously needed to do it again (but hey, I expected this)

Next problem was to get the spindle out to clean up again... now I had a full circle of bearing metal I encountered another problem... the centre section of the spindle is about 2thou bigger than the journals. The soot 'release agent' worked fine, I could turn the spindle OK although it was tight, but I couldnt extract it. It took some serious work with a rubber hammer to get it out. Whether this would damage the bearing surface is hard to say, the pics suggest not (see below).

Next time I might try the oiled paper suggestion instead of soot as this will give more clearance. Also this time I didn't put the foil shim right through to the journal as the first time it seemed to act as dam, but if I did it might allow the bearing to ease when the pinch bolt is undone. Trouble is all the examples I have found on the web are for fully split bearings not side split like these so I don't have any information on this.

Here is a pic of the bearing surface, sooty but smooth, before I chopped it all out again :(.

http://www.kisolutionz.com/ttforum/lathe/IMG_2933_1k.JPG

Here is the bit that goes into the keyway.. a nice impression and shiney too :)

http://www.kisolutionz.com/ttforum/lathe/IMG_2934_1k.JPG


I am wondering whether to put the lathe on end and try pouring into an open well rather than use the pouring hole (if indeed that what it is). It would certainly be less likely to fail. Or maybe I need multiple airholes in both dams that would 'plug' as the level rises so improving the 'venting'. Clearly this is going to take more than a couple of goes :rolleyes:

Oh well... lets hope the weather is good next weekend!

Lee Roberts
09-06-2008, 01:28 AM
Wow, youíre not wrong. I tried having dinner alfresco today with the family but it was just too hot I couldnít stand it.

Iíve just done a wiki on ďwhite metalĒ so now I understand what it is a bit better, now I know youíre going down the route your going down because you are enjoying what youíre doing and so on but would the bronze bushings not offer a better service to you in this situation and get your build along a bit faster? Or is this not a time sensitive build and your happy to take your time with it?

No offense meant and Iím not trying to just sell you some bronze bushing as it doesnít matter to me, Iím just trying to understand if youíre giving yourself more problems than it is worth.

Now Iím also thinking maybe you just want to restore this machine back to how it was originally, if thatís the case then fair-play to that mate. Hopefully next weekend and the rest of the week to come are nice so we can all get lots done!

I think you could be right about turning the whole thing on end though then pouring. Does this mean weíre going to have to wait till next weekend for an update? Cheers, Lee

irving2008
09-06-2008, 08:47 AM
Lee,

No offence. But there is a good mechanical reason why I want to use the right material... when the oiling fails in a Babbitted bearing its the Babbit that wears. When it fails in a bronze bearing its the spindle that gets chewed up... now I know thats unlikely while its running, but lathes are very stop-start and have long gaps between usage where there is the possibility that the oilways dry out. A Babbitted bearing will survive better under those situations.

And there's something about making like the original. While I plan some mods to this lathe, like an adjustable top-slide, nothing will be done that can't be returned to the original.

And time is not a huge criteria (not sure that a bronze bushing will be any quicker, I'd still need to find someone to grind down the spindle and machine the bushings).

Robin Hewitt
09-06-2008, 01:25 PM
If you want to get it hot you will need to lag it :D

Silly question... Are you faffing about casting because you don't have another lathe to cut the new bushing on? Do you need help?

Robin Hewitt
09-06-2008, 01:45 PM
If you want to get it hot you will need to lag it :D

Silly question... Are you faffing about casting because you don't have another lathe to cut the new bushing on? Do you need help?

irving2008
09-06-2008, 02:06 PM
If you want to get it hot you will need to lag it :D

Silly question... Are you faffing about casting because you don't have another lathe to cut the new bushing on? Do you need help?Robin,

Well I wouldnt call it 'faffing' as such... there is an element of learning a new skill here too :) but you are correct in that currently I dont have access to another (working) lathe.

Even if I did, I don't entirely see how to create a bronze bushing as the spindle is offset in the casting. It would need to be turned down from a solid 1.75" round and bored out to 1.25" approximately 3/16" offcentre. But then the castings would need to be line bored to ensure they are concentric and parallel with the bed as the advantage of a poured bearing is that it isn't dependent on the alignment of the external casting as long as the spindle is in line. Thats not true of the bronze bearing.

Irving...

Lee Roberts
09-06-2008, 03:08 PM
when the oiling fails in a Babbitted bearing its the Babbit that wears. When it fails in a bronze bearing its the spindle that gets chewed up... now I know thats unlikely while its running, but lathes are very stop-start and have long gaps between usage where there is the possibility that the oilways dry out. A Babbitted bearing will survive better under those situations.

And time is not a huge criteria (not sure that a bronze bushing will be any quicker, I'd still need to find someone to grind down the spindle and machine the bushings).

Ok thanks for teaching me somthing today!, i see the bronze bushings are not really an option then.

irving2008
09-06-2008, 04:19 PM
Ok thanks for teaching me somthing today!, i see the bronze bushings are not really an option then.Well they are always an option, but need to consider all aspects... see my reply to Robin for another major reason why not...

Robin Hewitt
09-06-2008, 05:30 PM
It would need to be turned down from a solid 1.75" round and bored out to 1.25" approximately 3/16" offcentre. But then the castings would need to be line bored to ensure they are concentric and parallel with the bed

It seems very odd that they would have bored the headstock off centre. If the tail stock does not offset, have you checked for signs of jiggery pokery? It may have a history which can be undone, making the replacement bush easier, but you'd probably want a shoulder to take the end thrust.

irving2008
09-06-2008, 06:42 PM
Robin,

If you look at the picture below you can see how much of an offset it is... the bearing itself is quite thick and is side spilt. The main reason it is thicker on the split side is because the spindle is keyed to retain the bullgear and when you extract the spindle the key has to pass through the bearing. To give a strong positive drive they wanted to use a fairly substantial key and that meant they needed the bearing to be thick enough to allow a slot for the key to pass through (you can see the slot to the left in the pic, just above the split in the bearing, out of focus tho). But to have that thickness all round would have made it difficult to pinch down without straining the casting, so they offset it in the casting. Thats easy to do with a poured bearing and meant the casting didnt need to be too accurate. I suspect they had a jig that clamped to the bed with a long mandrel with a built-in key and this allowed them to pour both bearings at once and in alignment..

http://www.kisolutionz.com/ttforum/lathe/fbearing1.JPG

Robin Hewitt
09-06-2008, 09:42 PM
Why doesn't the metal around that offset bush look like cast iron?

Is this the back end or is there paint on the thrust bearing face?

Why is there paint inside the bearing?

irving2008
09-06-2008, 10:59 PM
Why doesn't the metal around that offset bush look like cast iron?

Is this the back end or is there paint on the thrust bearing face?

Why is there paint inside the bearing?
I don't know, but it is definately cast iron. This is the thrust bearing face and as to the paint... an overzealous repaint job sometime in the past. Obviously the bearing was shot already and I reckon paint got in through the oiler hole and spread around... who knows maybe it made it run smoother for some unsuspecting buyer... I do know that the guy who owned it before me had it 6y and never used it and it was already painted when he got it - this isnt a standard colour BTW, as standard they were painted hi-gloss black like this one:

http://www.lathes.co.uk/relm/img0.gif

It going to be stripped right back and repainted black with gold or red detailing (just cos I fancy it)

Robin Hewitt
09-06-2008, 11:34 PM
Is it possible this is a fixit bushing inside the original bushing? Suggest you remove the paint :D

irving2008
09-06-2008, 11:41 PM
Is it possible this is a fixit bushing inside the original bushing? Suggest you remove the paint :DNope...here's a pic with the white metal bearing removed... and all nicely cleaned up. You can clearly see the anchor which stops the bearing turning in the casting.

http://www.kisolutionz.com/ttforum/lathe/IMG_2900_1k.JPG

Robin Hewitt
10-06-2008, 10:44 AM
Okay :D If they never machined it it has to be cast :D

You can't preheat the cast iron mould because you don want to detemper the spindle. You can't upend it and pour from the front because you can't remove the spindle to clean it up afterwards.

Suggestions :D

Get a lot more heat in the metal before you pour, howsabout barbeque charcoal.

A deep well around the sprue so you can pour faster.

A damp leather pad on a wood backing that you can put over the well. This is an old goldsmith's trick, steam forces the metal in.

Consider cuttle fish bone to seal the mould and make the well. It is very easy to cut, lets the air out and doesn't burn.

irving2008
10-06-2008, 12:56 PM
... You can't preheat the cast iron mould because you don want to detemper the spindle. You can't upend it and pour from the front because you can't remove the spindle to clean it up afterwards...


I wouldnt have thought it would have been hot enough to detemper the spindle... Its been suggested it needs to be at 150degC or so, the bearing metal melts at 380degC-ish, neither of which are hot enough to detemper a steel spindle, agreed?

irving2008
11-06-2008, 01:00 AM
Kip, while I've seen references elsewhere to line boring I don't have the facilities to do that. And I'm sure the old-timers didnt go to that lengths. Also I don't see how you'd ensure the mandrel was aligned correctly with the tailstock if its just a short length of plaster.

Anyway I've found a local company in Watford that'll regrind the shaft by 4thou to bring it parallel and they quoted me £35 so hopefully I'll get that done this week and try again next weekend. I got some 2mm sheet ally and cut with my hole-saws two 2" washers with 1.25" centres and then took a 6mm hole in the top of each to act as air vents. This should be less likely to blow out. I'll seal the edges with fire-cement and clamp them across the bearing with a couple of small G-clamps.

In the meantime I've swapped out the 1.1hp 1-phase Atlas motor I had for a 1.5hp AEI (c1965) 3-phase with a Jaguar VXS-75 VFD courtesy of eBay (£75 the pair, bargain). I've also cleaned up and rewired the 0.5hp motor that came with the 3.5" Gamages lathe. This motor is proudly labelled 'The British Thompson-Houston Motor Co Ltd' and is very British in its heavy cast iron casing and gloss black finish. BTH became AEI in 1959 (and then were taken over by GEC in '67) but this motor dates from the late 40s or maybe early 50's and runs beautifully and silently.

irving2008
12-06-2008, 11:15 AM
I was thinking of a bar of plaster in the tailstock ready shaped and then pushed up to the headstock...Did that make sense?Not really, although i can see where you're coming from. The challenge is that the tailstock is MT1, spindle is 1.25" diameter. You'd have to embed an MT1 arbour into the plaster when casting it in a 1.25"ID tube and how would you ensure its dead central and in line? Seems a lot of hassle to me...

Also a 1.25" reamer is about £70 which is way more than its going to cost to have the spindle reground...

I had a quote from a 'mobile line-boring' company who normally do much bigger jobs but it was silly money. If I had another working lathe and a milling machine I suppose I could make up a line-boring jig using 2 bearings supported on the cross-slide to hold a boring spindle with a small pulley to be driven from my 3phase VFD'd motor and using the tailstock centre to align it... but then if I had another lathe I could take a fine cut off the spindle, although getting an accuracy of 4 - 5thou over a 12" length would probably be tricky.

irving2008
12-06-2008, 11:48 PM
Here's me thinking everyone has lots of reamers and a working lathe ;) (mine was out of action for 2 days waiting on belts and I was beside myself) My previous one made the rivets for the Titanic.....I sure don't miss it :D Although I discovered that a LH thread requires modification to my 1992 Warco! Oh well it's all fun....Or savage amusement lolWell when I get this one up and running a LH thread will be easy.... :) can do either, in imperial or metric....

The spindle is going in to be reground tomorrow AM early and I hope to get it back next week. They reckon it'll be 2h work inc setup as they'll need to make a MT3 arbour to hold the nose end and chamber the inside of the tail end to hold it on the grinder centres - they do all precision grinding between centres.

So this weekend I'll turn my attention to the Gamages lathe and get that set up on a board so I can try it out. At least the motor is running!

Lee Roberts
16-06-2008, 09:35 PM
Well when I get this one up and running a LH thread will be easy.... :) can do either, in imperial or metric....

The spindle is going in to be reground tomorrow AM early and I hope to get it back next week. They reckon it'll be 2h work inc setup as they'll need to make a MT3 arbour to hold the nose end and chamber the inside of the tail end to hold it on the grinder centres - they do all precision grinding between centres.

So this weekend I'll turn my attention to the Gamages lathe and get that set up on a board so I can try it out. At least the motor is running!

Any joy with the Gamages lathe ? how did the regrind go ?

irving2008
16-06-2008, 10:47 PM
Any joy with the Gamages lathe ? how did the regrind go ?

Should get the spindle back on Wednesday....

The Gamages started out well and went downhill.... :(

http://www.kisolutionz.com/ttforum/lathe/IMG_2956_1k.JPG

http://www.kisolutionz.com/ttforum/lathe/IMG_2957_1k.JPG

Working on a strap to repair it... to save repeating myself, look here: http://www.practicalmachinist.com/vb/showthread.php?t=160002

irving2008
18-06-2008, 08:04 PM
Got my spindle back :)

http://www.kisolutionz.com/ttforum/lathe/IMG_2963_1k.JPG

Cost much less than expected cos they did it as a 'homer' for cash as a favour and not through the books. All nice and shiney and smooooooooth :) and good within .0002 thou (well much tighter than I can measure anyway)

So weather permitting its 'pouring time' again this weekend!

BTW, anyone got a mill :rolleyes: I could get access to, as I'm not likely to get a milling setip working any time soon (apart from the lack of space!)

Lee Roberts
18-06-2008, 11:23 PM
What about one of these:
http://www.mycncuk.com/forums/photoplog/images/4/medium/1_DSC04561.JPG

B'n'Q sell one like it for around £50, this one i use and it seems to be the best i have seen for that price range, or do you need a proper "Mill" ?

The spindle looks sweet mate, cant wait to see what this weekend has to offer !

irving2008
19-06-2008, 12:19 AM
A proper mill - something that'll take a couple of cubic inches out of a casting in a relatively short space of time...

It could wait till I get the 'big' lathe running...

Didnt think B&Q sold milling machines, nothing on their website and cant say I've ever seen them. I've got a cheap pillar drill from B&Q - bought in the sale a couple of years back, reduced from £75 to £15 last one and with a damaged box but its not exactly a solid bit of engineering, struggles with 6mm into cast iron or 8mm into steel.... but hey, the drill bits cost more than the drill!

Robin Hewitt
19-06-2008, 12:39 AM
BTW, anyone got a mill :rolleyes: I could get access to, as I'm not likely to get a milling setip working any time soon (apart from the lack of space!)

Rather depends on where you are.

I'm due south of London, stop just before it gets wet.

About ten miles west of Brighton.

irving2008
19-06-2008, 01:53 PM
Anywhere near Yorkshire?

Brighton's a lot nearer... :)

Lee Roberts
22-06-2008, 10:37 AM
Any advancments ?

irving2008
22-06-2008, 02:59 PM
Any advancments ?Not so far, family things got in the way yesterday :( and its too windy outside today to do a pour.. cant even keep the burner alight! And i dont want to do it indoors there's nowhere to run if it goes wrong! So I'm installing the 3phase motor and tidying up wiring...

keebo
23-06-2008, 07:58 PM
A proper mill - something that'll take a couple of cubic inches out of a casting in a relatively short space of time...

Hi I’ve got a mill and travel from north down to Kent fairly regularly M6, M1, M25, A2M2

Would you be interested in me doing some machining?

Kevin

irving2008
23-06-2008, 10:08 PM
Hi Iíve got a mill and travel from north down to Kent fairly regularly M6, M1, M25, A2M2

Would you be interested in me doing some machining?

KevinKevin, Thanks for the offer. I'm going to look at a short term fix first but will come back to the milling out option if that proves unsatisfactory.

Nice mill btw...

regards,
Irving...

irving2008
30-06-2008, 10:11 PM
Well despite my best endeavours nothing got done the last 2 weekends mainly cos of family things but the weekend before last was just too windy.

Anyway, was going to do it this weekend. Got it all set up and then decided to DTI the spindle from the slide and see how parallel to the ways it was. The end result was it was 0.15mm out in 80mm, but I couldnt decide if that was the tailstock being out or something else. As you will recall from a previous post i am holding the chuck end of the spindle in place using an MT3 deadcentre located in the centre hole of a JT6/MT1 arbor held in the tailstock. But the tailstock wouldnt normally be at that end of the bed so i cant tell if the error is due to the tailstock, the centres or something else...

So I decided to order an MT3-MT1 sleeve and an MT1 parallel test bar. The plan is to hold that in the spindle and locate the far end on an MT1 centre in the tailstock. That way the bar will better show the true direction of the spindle over a 300mm length and will allow me to DTI it from the slide more accurately.

The runout on the reground spindle is impressive. It doesnt even move the needle on the DTI so better than 0.0025mm!

Hopefully next weekend!

irving2008
02-07-2008, 01:00 AM
Well i ordered the taper sleeve and test bar from RDG on Sunday eve, shipped out to me Monday, arrived this morning. Test bar wasn't as long as I expected, 100mm not 300mm :( Anyway, I fitted it all up for a trial and with relatively little adjustment was able to get 0.02mm across an 80mm traverse with .01mm runout on the taper sleeve. Quite pleased with that (<0.01degrees taper), so no more than 0.1mm out (4thou) over the full bed traverse. So will set it all up tomorrow night (and try to remember to take some pics) to give it time to dry for the weekend...

irving2008
06-07-2008, 10:48 PM
well sods law prevailed... I decided before I finally did the pour that it might be a good idea to check the tailstock to spindle relationship when the lathe was actually bolted down and level... well suffice to say the relationship was far from level in the horizontal plane and when the lathe was bolted down and the spindle actually level the good parallel I'd measured went out the window. Eventially after much measuring and cursing I discovered that the lathe bed is twisted and needed packing about 3mm on two opposite corners when I bolted it down. This means I will have to pour the bearing with the lathe bolted in place to the bench. Once bolted down and leveled I then found the saddle would stick badly at a couple of points so I removed all that and cleaned it up, refitted and readjusted the horizontal and vertical gib strips. I also tightened up the leadscrew preload to give 4thou clearance and discovered a hitherto unknown screw that tighens the clasp-nut onto the leadscrew, which allows a modicum of backlash removal. Now it all runs much smoother than before if somewhat slightly stiffer than I would like... taper now measures 0.04mm in 80mm but its more consistent and doesnt vary with saddle travel direction. I also discovered that the tailstock has an adjustment underneath so I'll take the final taper out once the lathe is up and running.

By the time I'd done that on Saturday there wasnt time to do much else and today was a washout (literally and metaphorically) as family things got in the way again...

Hopefully next weekend...

irving2008
20-07-2008, 12:42 AM
Well a weekend came and went... but today I managed to get the day to myself, as SWMBO went shopping with daughter...

So rechecked everything, was still as I'd left it 2 weekends ago. I'd already decided that the main problem before, primarily, was not enough heat in the bearing housing so the metal set too quickly. So I wrapped the whole lot in loft insulation and pointed my 500W heat gun into the centre and left it to cook for 30min. That got it nice and hot. Unfortunately I didnt take any pics cos my camera battery was flat and I couldn't find one of the kids. Anyway, melted the metal, skimmed the slag off the top (using a bit of wood, not metal apparently is good practice) and proceeded to pour. Now being on my own (which prabably wasnt a good idea) I was trying to hold the heat gun in one hand and the ladle in the other so as to keep it all hot as it went in... this worked but it was impossible to pour slowly as I had intended and some 'missed' the hole and ended up on the drip tray. But the two vents seemed to work and hot metal bubbled up all three holes at the same time...

Left it to cool, by which time son was home and found me his camera. So banged the spindle out with a rubber mallet... its a tight fit.. i found a quick reheat helped to release it...

took the first 'dam' off...

http://www.kisolutionz.com/ttforum/lathe/DSCN1787_1K.JPG

Well that was looking good... but wait a mo, whats that down in the RH corner... took the other dam off.... :(

http://www.kisolutionz.com/ttforum/lathe/dscn1788_1k.jpg

bu***r, almost got it right... oh well set up for another go...

http://www.kisolutionz.com/ttforum/lathe/dscn1790_1k.jpg

Dont' know if that problem was lack of heat down there, or an airlock. So for next time (tomorrow hopefully) I'll put a couple of additional air vents down there... like this... note I'm only using the firecement to form the vents. Standard bathroom silicone selaer is all thats needed to fix the aluminium sheet 'dams'... it stands 380degC no problem...

http://www.kisolutionz.com/ttforum/lathe/dscn1791_1k.jpg

http://www.kisolutionz.com/ttforum/lathe/dscn1792_1k.jpg

more to come tomorrow hopefully...

irving2008
21-07-2008, 01:03 AM
Looks like a partial fill Irving :(Thanks Keith for that deep insight :D...

Ok, so the story continues...

Here's some pics of the heating arrangements...hot air gun and some rockwool...

http://www.kisolutionz.com/ttforum/lathe/dscn1793_1k.jpg

http://www.kisolutionz.com/ttforum/lathe/dscn1795_1k.jpg

Note the cute funnel (made out of ally) to try and avoid spillage. Oh and did I show you my VFD install on the wall behind (RH side pic 2)

So... heat it all for 30min (till it all too hot to touch) while melting the metal in the ladle and pour slowly using both hands this time...

and leave to cool....

http://www.kisolutionz.com/ttforum/lathe/dscn1796_1k.jpg

Well it clearly filled to the top on both sides and in the centre... and a probe with a scriber in the smaller vents shows there's metal in the bottom of the upper vent... but nothing in the lower :( ... oh well nothing to do but remove the dams and have a look...

http://www.kisolutionz.com/ttforum/lathe/dscn1797_1k.jpg

this side looks OK, note the slot caused by a shim in the bearing housing slot... that worked well and made it much easier to get the spindle out... nice clean bearing surface from this side...

but OMG once again a failure from the other....

http://www.kisolutionz.com/ttforum/lathe/dscn1799_1k.jpg

it can't have been an airlock so I can only assume it wasnt hot enough and the metal solidified too soon - you can see there is a nice curved flow edge. Also note the nice clean edge to what would have been the 'slot'.

Clearly I need to find a way to get the lower half of the cavity hotter, but I'm getting closer and I can see this will work eventually...

just takes a good hour to chop it all out again and another 2 or 3 to line it all up and prepare it and then 24h to leave it to dry (even with a 10min blast from the heat gun)... so next attempt will be next weekend as I wont have time during the week.... :(

Robin Hewitt
21-07-2008, 10:11 AM
What can I say? Nemo repente sapit, your perseverence is amazing :D

The problem may be asking the metal to go all the way around and then rise to fill in below the slot. Perhaps is you added a channel on the ends so it could go around the slot ends so everything flowed downhill, or, up ended it and put a fat sprue over the slot with a diametrically opposed vent?

irving2008
21-07-2008, 10:28 AM
Keith/Robin

Thanks for your comments.

I am not entirely sure I understand your point Keith, I don't think its an airlock issue as there was plenty of room for the air to come out, I am pretty sure its a heating issue, thats the furthest corner from the fill.

You will note in the previous attempt (which didnt have the shim all the way into the spindle) that that side filled OK but the other side failed. I am wondering if the best option is to have two fill points, one through the top and one to the side to fill from the bottom up initially and then from the top.

Keith, your casting experience is far greater than mine and this is clearly a 'casting' problem so I am grateful for your thoughts. I am a little loath to heat the metal a lot more as I have read that overheating causes some of the trace elements such as antimony and bismuth to leach out, but I don't know how hot that means - I cant get anywhere near hot enough to boil it!

I will persevere... it will come right one day...

irving2008
21-07-2008, 11:43 AM
Irving, My thoughts are that the shim (shown in red) needs the ends trimming to the yellow line to allow a fast and full fill, I think with that modification you will have success.

One uninterrupted pour till metal flows out of the vents (funnels?) maybe use a plumbers mat under the work area to catch the excess metal.

You'll know when you have overheated the metal...Fumes and smoke will start to emanate :)

Keep safe and enjoy the experience matey :beer:I think you may be right, but if that was the case why did it work OK at the other end? Maybe something to do with heat distribution... and when I did have the gap in the shim it failed to fill OK on the other side????

Obviously I'm not chanting the right incantations when i do the pour. The main issue with cutting the shim is that it makes the shaft very hard to remove if its solid metal round it. What I might do is taper the shim back towards the outside so that there is a full gap by the shaft and I can get a junior hacksaw blade in the slot to remove the metal where the shim tapers to fully slot the bearing to remove the shaft

I did have one uninterrupted pour... it flowed out four of the 5 vents but not the last one as the pictures show!

Funnily enough I was thinking on the lines of a wooden dam and it would be easier to make into the right shape - what I actually need are two 50mm x 3mm discs with a ~37mm dia x .5mm deep recess and a 32mm central hole with some cutouts for vents... maybe I should make some up...

Robin Hewitt
21-07-2008, 03:42 PM
Cuttlefish bone is clear proof that God does low temperature metal casting. If He didn't why would anything so wonderful exist.

You can sand it flat in a trice, push things in and it takes the shape, doesn't bend, soaks up dross, doesn't melt, doesn't distort when hot, lets trapped air out at the join and has no thermal inertia :D

irving2008
21-07-2008, 06:37 PM
and where would I buy it???

Robin Hewitt
21-07-2008, 10:47 PM
True, budgies trim their beaks on it, but the big ones go to the goldsmiths. Any problems finding it I can get it off the beach, just have to wait for an onshore wind. We have a thriving cuttlefish population. It weighs nothing :D

It has a thin horny rind on one side, the good stuff is in the middle. Pure white.

irving2008
08-08-2008, 12:32 AM
Well its been a while but last weekend I finally managed a further 2 attempts at pouring this bearing (getting a dab hand at setting it all up now)...

Anyway, got what I was fairly sure was a good one - I used a digital temperature probe from Maplins (£19.99, also doubles as a cheap multimeter to keep in the garage to save my very expensive one getting damaged) to measure the temperature inside the spindle and heated everything til that was 220degC. But it takes an hour or more to cool down to be able to be touched and I didnt have time to get the spindle out then. But I was working at home today so took an hour or so out this evening to get the spindle out (blowtorch needed to exapnd things a little to free it off) and start the clean up.

I am mightily impressed with the result....

http://www.kisolutionz.com/ttforum/lathe/dscn1801_1k.jpg

http://www.kisolutionz.com/ttforum/lathe/dscn1802_1k.jpg

This is after I cut and tidied up the slot (which makes it easy to get the spindle in and out now) and about 1/2 way filing down the excess on the bearing ends. The bearing is so close that 1/4 of a turn on the pinch bolt goes from 'mildly stiff to turn' to 'locked spindle' and the play is <.0005" on the DTI...

Next job is to clean up the ends and then do a spot of scraping on the bearing surface (although I am hesitant to do too much of that, in fact I am tempted not to do any right now since its so tight and the journal is freshly ground)

Looks like I'll have a working lathe in a few weeks....

Lee Roberts
19-09-2008, 01:07 AM
Any advances on this mate?

irving2008
20-09-2008, 09:11 PM
Hi Lee,

Been away on hols, just got back tonight.

Had the lathe up and running but got to sort out some vibration which I think is due to the rear bearing . the new front one is fine and run in now. The other prob I have is that the runout on anything held in the chuck is massive - think a new chuck is needed.

Lee Roberts
20-09-2008, 11:25 PM
ahh i c, is a new chuck going to be a problem or are they quite generic?

irving2008
21-09-2008, 11:48 AM
Lee,

The chuck isn't the issue... machining a new backplate may well be because of the non-standard spindle thread (1.25" x 12tpi).... I'll probably need to get it done professionally :(

m_c
21-09-2008, 12:58 PM
Why not remachine the existing back plate?

Unless you need to remove a lot of metal to make it suitable for a new chuck, then it should be fine.

irving2008
21-09-2008, 06:33 PM
Why not remachine the existing back plate?

Unless you need to remove a lot of metal to make it suitable for a new chuck, then it should be fine.Because a modern chuck requires a larger boss. Currently it has a 4" chuck with a 3" recess but modern 100mm chucks have an 80mm recess. Also there is possibly a problem with the backplate itself, but until I can clamp it up on a known good machine to measure both axial and radial runout accurately I can't be sure...

Lee Roberts
21-09-2008, 08:11 PM
i c thabnks for teaching me yet something new i apprecate it. Hope you can get everything sorted out mate.

irving2008
24-01-2010, 08:31 PM
At the risk of resurrecting this thread, I have been asked if its possible to redo the bearings on another similar lathe. Those who followed the original story will know that this was no mean task and not one I really want to revisit. However I was thinking about how to make it easier. I now know that the original lathes were line bored on a huge jig (see pic) but replicating that isnt going to be easy. I was thinking, maybe it would be possible to make a jig to line-bore the bearing insitu once they had been part filled with white metal around a mandrel smaller than the required bore.

The mandrel would be a piece of steel sheet with a tubular steel core (so as not to require too much heating) approx 1" dia. - this would be clamped to one side of the bearing. The lathe would then be clamped to the end of the workbench with the bed vertical and the bearing recess filled with molten metal. Both bearings would be done at the same time (two mandrels needed).

The question then is how to bore them accurately parallel with the bed? I have a round head mill so swinging the head over is an option, but I'm not sure how I would align everything. Some form of powered spindle (poss the original lathe spindle since it has a MT3 taper and pulleys) clamped to the ways is another and more easy to align but I can't see an easy way to move it through the bore unless I use the existng saddle and I am not sure how rigid that would be... or maybe I'd have to create a new saddle... or a base plate that clamped to the bed with linear bearings? Or that overkill?

Any ideas?

Robin Hewitt
25-01-2010, 11:46 AM
Only a suggestion, a ghastly, unauthentic bodge that may cause you to vomit, but here goes :rofl:

Turn and bore the bearings to size.

File the externals so they can fit perfectly in line

Jig up square and all assembled

Inject Loctite (or metal loaded epoxy if slack), in to wherever you poured the molten metal before

Robin

BillTodd
25-01-2010, 04:06 PM
What you need is a portable boring machine that'll go down to your spindle size (Unfortunately my ancient Buma bar is 2" minimum)

The smaller ones used to be common place in motorcycle and scooter dealers (in the days when you could get your machine re-bored for two shillings and tuppence). Any long established dealers in your area? They may have one you could scrounge?

They're still being made, so there's still a use for them somewhere:

http://www.allstates.com/ShanghaiBoringBar.html

1606 (http://www.allstates.com/Shangh1.jpg)

irving2008
25-01-2010, 05:30 PM
Only a suggestion, a ghastly, unauthentic bodge that may cause you to vomit, but here goes :rofl:

Turn and bore the bearings to size.

File the externals so they can fit perfectly in line

Jig up square and all assembled

Inject Loctite (or metal loaded epoxy if slack), in to wherever you poured the molten metal before

Robin


What you need is a portable boring machine that'll go down to your spindle size (Unfortunately my ancient Buma bar is 2" minimum)
...

Robin, I had considered the idea of boring oversize, then fitting bronze bushes which have been lined with white metal and bored to size. But the effort of this outweighs the idea of boring to size since these bearings if done right, will last another 100 years or so.

Bill - interesting but don't see how to get it parallel to ways... these boring machine assume a cylinder block or similar to sit on that is a known perpendicular to the hole to be bored.

My current plan is to make a saddle out of 1/2" ground plate, approx 8" long which will be bolted to the apron in place of the real saddle and will carrry two braced uprights with oilite bearings in which will run the spare spindle from my breaker lathe and this will be driven by a small, 1/4HP AC motor via two pulleys and a v-belt that I have lying around. This needs a cutter rotating at 400 - 500rpm so gear down 3:1 (1450 -> ~500RPM). I will use my existing MT3 boring bar and draw bar The back end of the saddle will have a gib plate cut at 60deg to match the existing dovetail. I'll fit a handle to the leadscrew at the headstock end in place of the gearwheel to allow the boring assembly to be wound into the headstock...

BillTodd
25-01-2010, 07:00 PM
interesting but don't see how to get it parallel to ways... these boring machine assume a cylinder block or similar to sit on that is a known perpendicular to the hole to be bored.You just need to create a known perpendicular with a couple of right-angle plates, referencing the face and edges of the lathe bed - The boring bar has a built-in three point reference to centre itself in the bore.



My current plan is to make a saddle out of 1/2" ground plate, approx 8" long which will be bolted to the apron in place of the real saddle and will carrry two braced uprights with oilite bearingsOk Sound's like a plan, but seems like a lot of effort - you are, after all, making a complete new spindle boring tool. If you have any kind of removable lathe spindle head (e.g. Southbend type) that could carry a long boring bar, it could save you a lot of work.

Are you going to use the existing lathe to line bore the two new bearing holes in the saddle part? (see attached example) (this would ensure the height and alignment of the boring spindle is correct for the lathe).

Just a thought; What about a couple of self-centring bearing blocks and a length of shaft - i.e. cross drill the shaft at one end to hold a cutting tool. Mount the shaft and bearing between centres while you tighten the bearing blocks to ensure everything is in-line.


BTW How big are these Relmacs?

The pictures show the set-up I used to line bore the bearings for a motorcycle headstock.

The 1" steel bar is held in a collet at one end and a revolving centre at the other. It is cross drilled to hold a cutting tool (broken 6mm carbide end mill).

The second picture shows the use of a DTI to set the cut depth.

You could probably use a similar set-up to bore the bearing holes for you spindle boring tool - that way the new holes would be perfectly aligned with the old spindle.

ptjw7uk
25-01-2010, 08:20 PM
How about doing it the hill billy way, use the lathe and tail stock, as long as you can get something throgh the tail stock that is. Next you will need a long shaft to go through the head stock and tail stock. Make a bearing through which the bar will go fitted to one side of the head stock then bore out the other side, when done reverse and do the other similar to line reaming car king pin bearings using a piloted reamer.
Peter

irving2008
25-01-2010, 10:12 PM
Thanks Bill and Peter...

Bill - the Relmac is a 4.5", 16" between centres, the SuperRelm is the same but 20". The headstock is integral to the bed, so we are talking 55kg+ of cast iron to move around! I don't have another headstock of any usefulness available; well I do have the one off the Lorch, but that has no useful taper to attach a boring tool.

Peter... that has given me an idea...

On the back of the headstock is the banjo plus a stud for an intermediate gear. If I was to make something that would bolt to the banjo plus this stud that just cleared the back of the spindle and held a bearing I could pass a 3/4" bar through the spindle with the far end located on the tailstock centre and into the bearing. I could then position the bearing to locate the shaft centrally in the spindle referencing a centre in the tailstock. I can then remove the bar, remove the spindle and replace the bar knowing it was now aligned with the tailstock and therefore with the ways. If the bearing allows the bar to move parallel to the ways then I can use the tailstock ram to push the boring bar into the headstock. All I need is some way to drive the bar round as it moves and to keep it located in the tailstock.. I am wondering about mounting a direct drive motor clamped onto the tailstock ram. I need about 600rpm and if I'm doing a .5mm deep cut at 0.1mm/rev (about 60mm/min, or 30sec to go through the bore), I'll need 80W of cutting power...

Thats a lot less construction effort probably..

ptjw7uk
26-01-2010, 01:35 PM
My idea was even simpler , just reduce the end that goes through the tail stock to fit an electric drill.
If I was doing it I would also only do one bearing at a time and use the other to hold a bearing block to hold the shaft doing the boring.
Only real problem would be getting the bar straight and long enough but at least you could push the tail stock near to the head.

peter

irving2008
26-01-2010, 02:01 PM
Peter,

Yes I understood your thining, but I would prefer to do them at the same time (not bore them simultaneously, but in one session without tearing the fixture down). Since I want to pour both bearings at the same time. Your approach would require two bearing blocks, to fit the unbored bearing as well as the bored one. Unlike kingpins they will be significantly different sizes - the unbored one approx 1" dia, bored it will be 1.25" +0.002/-0.000.

I am planning to use 20mm dia round rail as rhis is cheap to get and guaranted straight. Although it is hardened so I will need to gring some surface off bore milling some flats on it and drilling 3/4 way through for a 6mm cutter and the remainder of the hole 3mm tapped M3 for a pusher screw. There will also be a 3mm locking screw at right angles. The end thread will be used to push the cutter out and so accurately set the boring size (1 turn of screw = 0.5mm)

ptjw7uk
31-01-2010, 09:11 PM
Just seen this on the web http://bbs.homeshopmachinist.net/showthread.php?t=39441&page=2
Doing just what you want todo
Peter

irving2008
31-01-2010, 11:54 PM
Thats exactly it, except i dont have the luxury of moving the headstock, but the idea is the same...

I have three tailstocks, so i was thinking of removing the centres from two of them and fitting then with oilite inserts to act as bearings for the boring bar... this wil allow the bar to turn as well as be fed

I solved the problem of moving the motor by using a snake drive off my electric drill which has a low speed control

Now... how to regrind the vertical bearing face of the bed....

GeorgeD
25-07-2010, 10:06 PM
Wow!,Irving you must have the patience of saint?

The moment I would have come across the cracked bearing and the condition of the spindle shaft,I'd have given up there and then.

By the way what do you gys use for removing rust?

Here's the easiest way and believe me it works a treat,expensive but it can be diluted and used again with adding a bit of new solution to the used liquid.

It does what it says on the tin. :naughty:
http://liquideng.co.uk/component/option,com_virtuemart/page,shop.browse/category_id,12/Itemid,1/

rotorhead
06-05-2012, 07:24 PM
What you need is a portable boring machine that'll go down to your spindle size (Unfortunately my ancient Buma bar is 2" minimum)

The smaller ones used to be common place in motorcycle and scooter dealers (in the days when you could get your machine re-bored for two shillings and tuppence). Any long established dealers in your area? They may have one you could scrounge?

They're still being made, so there's still a use for them somewhere:

http://www.allstates.com/ShanghaiBoringBar.html

1606 (http://www.allstates.com/Shangh1.jpg)

Hello Bill,

I'm new on here, but would appreciate a picture of your Buma bar

Regards,
Chris(rotorhead)

onecut
25-06-2012, 08:01 PM
bill,intresting to hear you have a buma portable borer l worked for them for about 20yrs off and on good little machine although l would say that as l milled all the parts they were first made with power stations in mind we done alot of breakdown parts for them obviously when a power station is having a problem with a part they dont want to stop production of electricity so to avoid stripping down lengthy and expensive procedure they bored part out where it was sleeved it finished bored it only replacing part when it was unsalvagable that mean they could plan a big strip down and have alternate backup whilst replacing it a lot of them went overseas it was only a small outfit but had a good reputation-happy days look after it will be rare in a few yrs time

BillTodd
26-06-2012, 07:03 PM
Chris: Sorry missed your post (email notification not working here) and Sorry but I can't find a picture ATM (I know I have one somewhere)

Onecut: My one is missing a couple of bits and is in need of a service, so I may be quizzing you about them later :)

onecut
26-06-2012, 10:07 PM
bill.dont know if l will be of any help to you but you never know obviously buma,s is no longer there the old man died a true engineer passing on to his son without being rude he knew absolutely zero about engineering quickly sold place first chance he got to a large well known supermarket chain and a large superstore is now there so spare parts will be difficult to get but at least you have an edge, me l know the then works manager was allowed to take the blueprints of buma borer and he does or did supply spares and l have his phone number at worste he might give you a drawing of the part you are after-onecut