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GeorgeD
29-07-2010, 02:14 AM
this how I intend to add the lathe chuck to a 4th axis,I just love this guys vids,every thing related to his CNC build has been casted,machined and built from scratch except the newly added chuck.


http://www.youtube.com/watch?v=W-Gk_OewtD8&feature=related

Robin Hewitt
29-07-2010, 12:11 PM
Presume he's going to add an index pin because without it that belt is going to stretch and add all kinds of finish destroying vibrations. This is only a suggestion and a worm sprung gently down onto it's wheel may be more complicated to implement, but it could save you a lot of future problems if you want to cut anything harder than cheese.

GeorgeD
29-07-2010, 02:22 PM
You'll have to educate me here,Robin

Where does the index pin actually reside,I know I think youmean bracing the turret and orientating?

Robin Hewitt
29-07-2010, 03:05 PM
Oops! I was thinking indexing, as you would for gear cutting, this looks more like rotary tables. I suppose the word is detente. Although a good friction brake with a hard pad might do the trick :smile:

GeorgeD
29-07-2010, 03:26 PM
Hah,thats better,how about like this?


http://www.youtube.com/watch?v=o-9J4KsXYwU&feature=related

GeorgeD
29-07-2010, 03:31 PM
Where does one get drive belts of this calibre without paying a kings ransom fo it?

irving2008
29-07-2010, 03:59 PM
Hah,thats better,how about like this?

Except thats a tool changer so has very few fixed positions. That one doesnt use a friction brake but a rigid locating pin. A true rotary 4th axis needs positive low-backlash locking such as a worm drive. Like this conversion (similar to mine) using the rotary controller documented elsewehre on this forum....


http://www.youtube.com/watch?v=dzERyy58ckI

GeorgeD
29-07-2010, 05:03 PM
Yeah,but you're using an off the shelf poduct here which is adapted to suit the needs,Irving...I'm talking about making and constucting the parts ourselves to reduce overall cost which has been shown in the two previous vids I posted..

phill05
29-07-2010, 05:28 PM
George, thats what life's about making use of what you can, to achieve what you want!! before you can build something on the quality in the vid you need some basic understanding of materials and how to build, and then some form of making the parts, a lathe, a drill press some hand tools and a lot of spare time.

Phill

Wobblybootie
29-07-2010, 05:33 PM
The other thing to bear in mind is ... making parts yourself does not always work out cheaper ... and here speaks the voice of experience :redface:

irving2008
29-07-2010, 05:47 PM
Yeah,but you're using an off the shelf poduct here which is adapted to suit the needs,Irving...I'm talking about making and constucting the parts ourselves to reduce overall cost which has been shown in the two previous vids I posted..

Ignoring the cost of the stepper/control/chuck which are roughly common, the aluminium to construct that axis would be about 30, the steel spindle about another 15, the bearings about 15 and the pulleys/belt about 18 and machine screws etc about 10... you might do marginally better, but by my calculations the parts alone are 88, my rotary table was 40, the conversion parts about 10; it took me a lot less time to convert and only needed the lathe, no CNC milling machine....

Sometimes cheaper is illusionary.......

ecat
29-07-2010, 05:52 PM
The other thing to bear in mind is ... making parts yourself does not always work out cheaper ... and here speaks the voice of experience :redface:

... and then you figure in not only the build time but also the time spent learning how to build the device, how to spec the parts etc..

GeorgeD
29-07-2010, 07:17 PM
You shop dear there,Irving :wink:

You have only to enter a scrap metal yard and you will pick up a couple of bars of metal for a fiver,Aluminium well its debatable whether this is an expensive matrial considering it can be gained for nothing in terms of collecting it in bits here bits there and then casting it.

Any aluminium fabication/machine shop will let you have unusable(off cuts)for a few quid,enough to melt down for a component.

Bearings,well yeah it pays to aquire new...just sent off on ebay for 2x 67x30x17mm roller bearings at 8 inc P&P

Its just me,I like to construct more than buy stock items as I get more pleasure out of it.

It is true that its sometimes cheaper to buy already built and assembled products but if we do the pricing up of components and put alongside the shop bought component then that is the decider before shelling out.

John S
29-07-2010, 07:44 PM
George,
Why do you ask so many questions when it appears you know all the answers ?

.

GeorgeD
29-07-2010, 08:01 PM
Why do you ask so many questions when it appears you know all the answers ?Gotta keep the foums alive somehow,and I don't have all the answers. :rolleyes:

A visit to a scrapyard can reap benefits particulary if its one that deals in industrial maching scrap and there's plenty of those down south,not many in this neck of the woods.

irving2008
30-07-2010, 01:30 AM
You shop dear there,Irving :wink:

You have only to enter a scrap metal yard and you will pick up a couple of bars of metal for a fiver,Aluminium well its debatable whether this is an expensive matrial considering it can be gained for nothing in terms of collecting it in bits here bits there and then casting it.

Any aluminium fabication/machine shop will let you have unusable(off cuts)for a few quid,enough to melt down for a component.

Bearings,well yeah it pays to aquire new...just sent off on ebay for 2x 67x30x17mm roller bearings at 8 inc P&P

Its just me,I like to construct more than buy stock items as I get more pleasure out of it.

It is true that its sometimes cheaper to buy already built and assembled products but if we do the pricing up of components and put alongside the shop bought component then that is the decider before shelling out.You must be very lucky then George...

Well all the scrap dealers around here and fabrication shops seem to know the value of their scrap... 'cos they wont give it away and they charge about the same as eBay sellers.. about 5-7/kilo. To make that you arent looking at scrap but some quality tooling plate I doubt you'd easily find that in a scrap yard. And do you know what form of aluminium you are getting from a scrap yard, will it be machinable?

I hope the bearings you bought arent those advertised as 'transmission' or 'wheel' bearings... their tolerances aren't anywhere good enough... then again with only a ruler and no DTI you'd never know how bad they really are....:smile: :rolleyes:

GeorgeD
30-07-2010, 01:59 AM
I hope the bearings you bought arent those advertised as 'transmission' or 'wheel' bearings... their tolerances aren't anywhere good enough... then again with only a ruler and no DTI you'd never know how bad they really are....:smile: :rolleyes:Now,now Irving just because you lot can't sort the 24 power supply out,no need to take it out on us gentle folk.

I've had bearings off this blokey before and the tolerence was within their bore diameter ie they were a tight fit and had to be pressed on with tube and rubber mallet

Its a well known fact that the further south you go the higher the prices get.

ps I do have a Micrometer and I know how to use it.:whistling:

irving2008
30-07-2010, 08:29 AM
....the tolerence was within their bore diameter ie they were a tight fit and had to be pressed on with tube and rubber mallet...

That wasn't what I was refering to.... there's more than one tolerance spec on a bearing and the one one the central bore diameter is one of the least important...

GeorgeD
30-07-2010, 01:14 PM
That wasn't what I was refering to.... there's more than one tolerance spec on a bearing

Axial forces or Friction? :rolleyes:

Ross77
30-07-2010, 02:39 PM
That wasn't what I was refering to.... there's more than one tolerance spec on a bearing


Its the race to ball tolerance that Irving is talking about, both the inner and outer diameters can to a tight fit(not always recomended) and there can still be axial and radial play if the accuracy is poor.

I'm just looking at the z axis and spindle design for mine and the design of spindles is very complex, It seems to boil down to tapered bearings for high load, low speed (10000rpm or less) and angular contact for every thing above.

There is the option of using deep groove bearings as they are capable of the highest speeds and stacking them in 4 or 5 deep to regain the load and ridigity, but the precision might not be there.

But I guess you knew that :tongue:

GeorgeD
30-07-2010, 03:01 PM
Deep groove ball bearings are intended to work only with radial forces and not with axial forces.

Metal shielded bearings are more efficient over rubber sealed as rubber sealed has more friction.

GeorgeD
30-07-2010, 03:20 PM
Hi Irving,Ross

These tapered roller bearings are for the Lathe spindle as I'm aware the Deepgroove are not satisfactory for the lathe spindle.
This is common to the Mini lathes and the deepgroove come standard with the mini lathes.

Smiler
30-07-2010, 05:25 PM
Got to admit here that I have built this very 4th axis. I use it on a router and have cut oak, beech and Iroko, it works perfectly well with a 6:1 reduction and a 3Nm stepper. Although the materials I have cut are a little harder than cheese, and I intend to try PVC an HDPE soon, you'd be mad to think of using it to cut metals.

It cost more to build than buying a rotary table and converting it; even given I am in the happy position of getting the main shaft, backplate and ally plates etc for free. I used my router to machine the plates and the lathe at work to bore the backplate for the chuck and it STILL cost more than a bought solution but I'm happy as it was a good excersise.

Jeff.

Tom
30-07-2010, 06:37 PM
Axial forces or Friction? :rolleyes:

I fancy a "Friday night pub quiz"....

George, the question is in two parts:

1) What is the difference between these two identically sized bearings? The answer I'm looking for is not 12.03
http://simplybearings.co.uk/shop/p170111/6305+Budget+Open+Type+Deep+Groove+Ball+Bearing+25x 62x17mm/product_info.html
http://simplybearings.co.uk/shop/p5137/SKF+6305C4+Open+Deep+Groove+Ball+Bearing+25x62x17m m/product_info.html

2) Assuming it was suitable for the task, which one would you install into your (hypothetical):
a) Moon lander
b) Nuclear submarine
c) Power station
d) Gantry crane
e) Precision 4th axis
f) Miscellaneous 23.5hr/day, production critical machinery
g) Front car hub
h) Rear car hub
i) Shonky 4th axis built as a learning exercise

Winner gets a pint. *In true pub quiz style, I reserve the right to fall asleep before the end of the discussion and not notice it's all finished until I see that all but one table is looking depressed.

By the way, it's not a loaded question. I haven't built my first shonky 4th axis yet, but when I do, it WILL be shonky.

GeorgeD
30-07-2010, 06:53 PM
We'll see how we get on with my shonky 4th axis.

PS its a tapered roller bearing and it wasn't from Simply bearings/these bearings are specifically for the Mini lathe spindles ie they're the replacement for the deep groove bearings.

Smiler
30-07-2010, 07:27 PM
I fancy a "Friday night pub quiz"....

George, the question is in two parts:

1) What is the difference between these two identically sized bearings? The answer I'm looking for is not 12.03
http://simplybearings.co.uk/shop/p170111/6305+Budget+Open+Type+Deep+Groove+Ball+Bearing+25x 62x17mm/product_info.html
http://simplybearings.co.uk/shop/p5137/SKF+6305C4+Open+Deep+Groove+Ball+Bearing+25x62x17m m/product_info.html

2) Assuming it was suitable for the task, which one would you install into your (hypothetical):
a) Moon lander
b) Nuclear submarine
c) Power station
d) Gantry crane
e) Precision 4th axis
f) Miscellaneous 23.5hr/day, production critical machinery
g) Front car hub
h) Rear car hub
i) Shonky 4th axis built as a learning exercise

Winner gets a pint. *In true pub quiz style, I reserve the right to fall asleep before the end of the discussion and not notice it's all finished until I see that all but one table is looking depressed.

By the way, it's not a loaded question. I haven't built my first shonky 4th axis yet, but when I do, it WILL be shonky.

Me ME MEEE!!!!

One is photographed from the left and the other from the right! I CLAIM MY PINT!

BTW, anything wrong with using angular contacts like the guy in the video did?

Jeff.

Wobblybootie
30-07-2010, 07:54 PM
Trick question!! Bearings are things you Yomp along to get to the next check point/Pub and you use Mils!! (much better than silly degrees 'cos there's lots of them, In fact 6400 if what's left of my grey cell filing system is still operational!!)

Tom
30-07-2010, 08:00 PM
I CLAIM MY PINT!

Jeff, the pint's yours! :beer: You may have to remind me, but don't be shy! :smile:

Ref the angular contact bearings, I'm not really sure. I think the way the big boys do it is to pair a set of single row angular contact bearings opposite each other, and preload them, either next to each other at the chuck end (as a matched pair, with a simple roller at the other end of the shaft), or preloaded along the whole length of the shaft (a non-matched pair, one at each end). I reserve the right to be proven wrong.

As george says, the mini-lathes ship with deep-groove bearings, and the upgrade is to replace them with taper roller bearings. This mod works quite nicely (I've done it), but I don't think you'll see taper rollers in this application on much bigger equipment. I think the mini-lathes get away with it because the loads are low. Which is lucky because the larger angular contact bearings, especially in matched pairs are not cheap.

routercnc
30-07-2010, 08:27 PM
Hi George,

I think that without meaning to you are upsetting alot of people on this forum :exclaim:

You certainly are looking at alot of new things - making a cnc machine, learning how to cast ali at home, making a 4th axis, learning how to weld. If it was me I'd tackle these skills one at a time, and take some of the advice offered along the way on this forum, but I think that you are one of those people who only learns when he has tried it out with his own hands. I hope it all turns out how you want it to.

I think you can put some axial load on a deep groove bearing, and using a ramp cut rather than plunge when milling/routing where possible should help a bit, so for Ross's application it's worth a look. If you've found a source which says no axial load I'd be interested in a link.

Another factor with bearing quality is inclusions (impurities) in the race way. Less inclusions should give a longer life. Got this info at a Timken presentation, so bit of a sales pitch but sounds plausible.

With regards to your machine, can I ask what it is that you intend to make on this new cnc machine with the 4th axis? That might generate some helpful comments.


Ross,
When you've got some more info it would make a good post to see your spindle design (post#20). I cheated and bought ready made, but would be interested to see where you're at. To make it accurate, well balanced, smooth, quiet, durable, and run at very high speed has it's challenges!

Ross77
30-07-2010, 09:31 PM
If you've found a source which says no axial load I'd be interested in a link.

Me too. Ive been looking at the info from the bearing manufactures SFK,NSK etc and they all say the same thing, I wasnt going to get in to here but what the Hell. deep groove are the fastest but provide low axial resistance (when compared to tapered or AC), if they couldnt take any axial load then the shaft and housing would move independantly No.....



Ross,
When you've got some more info it would make a good post to see your spindle design (post#20). I cheated and bought ready made, but would be interested to see where you're at. To make it accurate, well balanced, smooth, quiet, durable, and run at very high speed has it's challenges!


I plan to, just got a bit more research to do. Making it accurate and smooth seems to mean throwing at it ( mulitple angular contact with different contact angles, correct Diameter and spacing for ridigity with oil/air mist lubrication, easy) :whistling: so thats why I was looking at a modified deep groove set up to reduce cost as after all it would be a low use DIY spindle:smile:

GeorgeD
01-08-2010, 01:31 AM
This guy shouldn't be allowed in a machine shop...eck! he's lethal.:eek:


http://www.youtube.com/watch?v=8y-C59aF-ac&feature=related

John S
01-08-2010, 02:00 AM
??????????

I saw nothing wrong with that, everyday machining operation.

Ross77
01-08-2010, 02:53 AM
Using a fly cutter to get a good suface finnish, " how dare he, some one call the HSE......."

George
Why are you posting random S**T, It had nothing to do with the original or previous posts...

Smiler
01-08-2010, 04:44 PM
Ref the angular contact bearings, I'm not really sure. I think the way the big boys do it is to pair a set of single row angular contact bearings opposite each other, and preload them, either next to each other at the chuck end (as a matched pair, with a simple roller at the other end of the shaft), or preloaded along the whole length of the shaft (a non-matched pair, one at each end). I reserve the right to be proven wrong.


I've done it pretty much as per the video to be honest i.e. an angular contact bearing behind the chuck with a thrust bearing the other side of the plate and preloaded them, a simple bearing holds the other end of the shaft. Works really well for router use and I suppose it would work for light engraving on Aluminium but I'd never try machining, I'd convert a rotary table for that (Mr Kip was kind enough to donate a stepper adaptor for such use).

I'll tell you what was REALLY nice about this project. The fact I designed the plates and cut them on my macine and all the bits, bearings, stepper etc. just fit first time, no filing, no drilling larger holes because one was .25 of a mil out because the dot punch slipped, everything just fit and lined up. I know it SHOULD do that anyway but I still find it all amazing and it was worth doing just for that glow you feel when it all goes to plan. My mate at work Kenny has been doing CNC lathe for many years, most at RR, and he says he still gets the same kick when the bits all just slot together first time every time. Wonder if others do :)

GeorgeD
01-08-2010, 04:50 PM
Why are you posting random S**T, It had nothing to do with the original or previous posts...

Its my post is it not?

I find this idea of what he's done there highly dangerous and certainly wouldn't attempt that piece of contraption.

Smiler
01-08-2010, 05:16 PM
But George,

Flycutting has been done for many years, probably as long as there have been machine shops, safely and successfully. If there is any danger it's the fact the guard isn't in place so he could film the operation but that's all. You wouldn't think anything of mounting that part in a lathe and machining it, it's the same thing except the tool is moving not the piece (I'd say the fly cutter was safer IMO)

routercnc
01-08-2010, 05:48 PM
. . . still gets the same kick when the bits all just slot together first time every time. Wonder if others do :)

Definitely. Made a small box for my Wife's sewing kit some time back. Box jointed all the corners, slipped together a treat, gentle sand - hey presto! Still amazing when it all comes together.

George,
What are you thinking of making with your new machine and 4th axis?

GeorgeD
01-08-2010, 06:09 PM
George,
What are you thinking of making with your new machine and 4th axis?Keeping it simple now,decided to use the chuck and spindleon a home made lathe.

Got the motor(2500rpm),got the pullys...one 50mm V type for motor shaft,one 4" for the spindle...will worry about gearing when its up and running? the speed contoller is a simple one for now ie it came off a defunctn router.
The bed will be 25x25x3mm box section,Ifigured its not worth making it big ie 600x250x250mm should do it.
Ordering the toolpost and tail stock from www.littlemachineshop.com (http://www.littlemachineshop.com)

Why is it that you can get anything and everything under the sun from the states and you try here in the UK and its like looking for a needle in a haystack...really pi**es me off trying to buy stuff over here.

Smiler
01-08-2010, 06:48 PM
Why is it that you can get anything and everything under the sun from the states and you try here in the UK and its like looking for a needle in a haystack...really pi**es me off trying to buy stuff over here.

Amen to that George, I suppose it's just the vast market out there that means every niche can be filled by someone simply because the demand exists. It always makes me smile when I see people from the states say they went down to their local DIY shed and bought 10 feet of trapezoidal thread, try that at B&Q or Wickes!

Jeff.

John S
01-08-2010, 09:33 PM
Amen to that George, I suppose it's just the vast market out there that means every niche can be filled by someone simply because the demand exists. It always makes me smile when I see people from the states say they went down to their local DIY shed and bought 10 feet of trapezoidal thread, try that at B&Q or Wickes!

Jeff.

But have you seen the quality of their DIY gear ?
Our local fastners outlet keeps trapezoidal on the shelf and they can get it in if it's a non stocked size but you need a reasonable order.