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Reconditioning a Relmac lathe
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 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/l...MG_2836_1k.JPG
And heres the install with nice new drip-feed oilers from Adams Lubetech
http://www.kisolutionz.com/ttforum/l...MG_2863_1k.JPG
The list of things to do grows daily
- Remove the inside burr on the spindle rear end
- 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
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Re: Reconditioning a Relmac lathe
This post was copied from the Antique machines forum 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:
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Re: Reconditioning a Relmac lathe
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
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Re: Reconditioning a Relmac lathe
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/l...rheadstock.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...
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Re: Reconditioning a Relmac lathe
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/l...MG_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/l...MG_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?)
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
Kip
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
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Re: Reconditioning a Relmac lathe
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_Oil...QQftidZ2QQtZkm
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
CNCUK
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_Oil...QQftidZ2QQtZkm
Well 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...
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Re: Reconditioning a Relmac lathe
Ok well ill bookmark this log and keep an eye on you.
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Re: Reconditioning a Relmac lathe
How will that help?
Anyway, today I picked up a kilo of V1-A best bearing alloy from GWN, 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!
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Re: Reconditioning a Relmac lathe
lol, good job on the bargins £2.50 ! Any chance of some pics of your progress and also you doing your bearings !?!
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
CNCUK
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...
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
irving2008
...rear banjo to retain the rear of...
Banjo ? is that the same as a Dodar? or a real name for a part?
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
CNCUK
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/l...G_2862_1ka.JPG
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Re: Reconditioning a Relmac lathe
Ahh right, thanks for showing us that.
I have also added this post to the FAQ Section: What is a Banjo
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Re: Reconditioning a Relmac lathe
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/l...MG_2878_1k.JPG
http://www.kisolutionz.com/ttforum/l...MG_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/l...MG_2900_1k.JPG
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Re: Reconditioning a Relmac lathe
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/l...MG_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/l...MG_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/l...MG_2912_1k.JPG
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Re: Reconditioning a Relmac lathe
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/l...MG_2910_1k.JPG
and then cemented up. Same for the rear of the bearing...
http://www.kisolutionz.com/ttforum/l...MG_2914_1k.JPG
and finally we are ready to pour metal, once the fire-cement has dried overnight
http://www.kisolutionz.com/ttforum/l...MG_2915_1k.JPG
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
Kip
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 :)
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Re: Reconditioning a Relmac lathe
So am i right in thinking you will mould around the fire cement or ?
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
CNCUK
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...MG_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/l...MG_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...
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Re: Reconditioning a Relmac lathe
Ok mate sorry it didnt work out so well, keep going tho you will sort it i'm sure...
Dinner time, SUNDAY ROAST !
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Re: Reconditioning a Relmac lathe
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/l...MG_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/l...MG_2925_1k.JPG
http://www.kisolutionz.com/ttforum/l...MG_2926_1k.JPG
http://www.kisolutionz.com/ttforum/l...MG_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 :)
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Re: Reconditioning a Relmac lathe
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/l...MG_2933_1k.JPG
Here is the bit that goes into the keyway.. a nice impression and shiney too :)
http://www.kisolutionz.com/ttforum/l...MG_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!
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Re: Reconditioning a Relmac lathe
Wow, you’re not wrong. I tried having dinner alfresco today with the family but it was just too hot I couldn’t stand it.
I’ve just done a wiki on “white metal” so now I understand what it is a bit better, now I know you’re going down the route your going down because you are enjoying what you’re 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 I’m not trying to just sell you some bronze bushing as it doesn’t matter to me, I’m just trying to understand if you’re giving yourself more problems than it is worth.
Now I’m also thinking maybe you just want to restore this machine back to how it was originally, if that’s 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 we’re going to have to wait till next weekend for an update? Cheers, Lee
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Re: Reconditioning a Relmac lathe
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).
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Re: Reconditioning a Relmac lathe
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?
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Re: Reconditioning a Relmac lathe
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?
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
Robin Hewitt
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...
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
irving2008
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.
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
CNCUK
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...
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
irving2008
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.
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Re: Reconditioning a Relmac lathe
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
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Re: Reconditioning a Relmac lathe
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?
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
Robin Hewitt
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)
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Re: Reconditioning a Relmac lathe
Is it possible this is a fixit bushing inside the original bushing? Suggest you remove the paint :D
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
Robin Hewitt
Is it possible this is a fixit bushing inside the original bushing? Suggest you remove the paint :D
Nope...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/l...MG_2900_1k.JPG
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Re: Reconditioning a Relmac lathe
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.
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Re: Reconditioning a Relmac lathe
Quote:
Originally Posted by
Robin Hewitt
... 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?
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Re: Reconditioning a Relmac lathe
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.