Collet systems for lathes

[SmoggyTurnip]

I have a C6 lathe which has an MT4 spindle bore. I also have an X3 mill that has an R8 spindle. I often wish I had a collet system for my lathe, mostly because I want to be able to hold parts without marking them. Is there such a thing as an adapter that would alow me to use R8 collets in my lathe? If not what are some inexpensive options for collet use on my lathe?

 

[mklotz]

I made an R8 collet chuck for my lathe as a practice piece before making my C5 chuck. I made it from aluminum since I never intended to actually use it - it was solely a vehicle for perfecting the techniques I'd need to make the "real" chuck of steel.

That said, it worked quite nicely once finished. The problem, of course, is that one loses the through-chuck capabilities for long stock and, believe me, that's a serious loss you'll ultimately regret. Also, with R8, you can't get square or hex collets (that I know of) and they're both really handy.

Save your R8 collets for the mill and buy/make either a C5 or ER32 collet chuck for the lathe. The former has the advantage of readily available collets while the latter has the advantage of a larger range on each collet and the ability to handle metric sizes.

 

[dwentz]

There are inexpensive mt-2 and mt-3 collets on e-bay, you could get an adapter sleeve and use them for your lathe. Just get some 3/8 all thread for a draw bar. You could also get an adapter to use them in your mill.

MT-4 is too small to put an 5-c adapter in, but you could build a 3c adapter, but the 3c collets are not as easy or as cheap to come by as the 5C. How about a 5C collet chuck, CDCO has one that I have been looking at, its seems like a reasonable price, have heard that it is not too bad either.

Dale

 

[rake60]

The problem with adapters is they add to the extended length from the spindle.
That extra length robs rigidity.

The Import 9 X 20 Lathes have an MT3 taper in the spindle.
I bought an ER32 collet holder for mine because I already owned an R8-ER32
collet holder for my mini-mill along with a full set of collets.
It didn't impress me. It looks like this in the lathe.

And, it is as rigid as it appears. :

Rick

 

[Andrew_D]

The problem with adapters is they add to the extended length from the spindle.
That extra length robs rigidity.

The Import 9 X 20 Lathes have an MT3 taper in the spindle.
I bought an ER32 collet holder for mine because I already owned an R8-ER32
collet holder for my mini-mill along with a full set of collets.
It didn't impress me. It looks like this in the lathe.

And, it is as rigid as it appears. :

Rick

My mini-mill came with an ER-32 -> MT3 collet holder similar to your picture. It ends up with lots of overhang as you've shown.

My to-do list includes making a chuck for ER-32 collets to mount on my 7x12 the same way the 3-jaw/4-jaw/faceplate/etc. does. I can use the collets and ER-32 nut that I already have from the mill holder. This should get me closer to the headstock and also allow passing stock through the spindle.

Thought I had a pic to show what I mean, but I can't seem to find it now...

Andrew

 

[Peter Neill]

The ER32 collet chuck that's made for the Myford looks a lot better, as it screws directly onto the spindle nose and register.
Haven't used it myself, so can't comment on how effective it is.
More details here: http://www.rdgtools.co.uk/acatalog/ER32_SPRING_COLLET_CHUCK_SYSTEMS.html



Peter

 

[Andrew_D]

The ER32 collet chuck that's made for the Myford looks a lot better, as it screws directly onto the spindle nose and register.
Haven't used it myself, so can't comment on how effective it is.
More details here: http://www.rdgtools.co.uk/acatalog/ER32_SPRING_COLLET_CHUCK_SYSTEMS.html

Peter

Yup, that's what I've been thinking of doing... 2nd picture down & 5th picture down

Andrew

 

[bhjones]

There seems to be a huge amount of confusion across all the web forums and email lists related to work holding collets and tool holding collets. This reply I'm quoting here is a good example.

While the ER collets are suitable for both work and tool holding, the method shown here to adapt the collet to the spindle is not suitable for lathe work. This adapter is meant to be used in a milling machine.

A work holding collet will have a couple of features important to use on a lathe. It will be self releasing, or in the case of the ER collets drawn out by the nut, and it will also have an open bore.

The R8 collet for example has neither of these features. Using an R8 collet (or MT taper collet) will limit the length of work to only a few inches because the collets have a blind hole. You'll also have to drive the collet out of the spindle taper after each use. Hammering on the end of your spindle is not a kind thing to do to it.

My own opinion on collets for lathe use is to stick with the 5C style. If your spindle is large enough to run an adapter to go from MT5 (or whatever you spindle taper is) to 5C, then buy or make the adapter and draw tube (note: I sad "tube" and not bar). If it doesn't then get a 5C chuck with an adjustable backing plate. Dial in the taper on the 5C chuck and your all set.

The one advantage to the ER collets is the ability to share them between mills and lathe, but they are no where near a versatile as 5C collets. With 5C you have the option of round, square and hex collets. There are also pot/step collets and E collets that can make life much more enjoyable.

Two things to consider with the pot and e collets that's useful in engine building. You can take a 2" or 3" pot collet and bolt sacrificial jaws on it then cut any size step into them, concentric or offset. Ditto on the e collet. You could take a soft steel e collet and broach a 1/2' square hole, offset by .110 for drilling an offset through hole in 10 parts. Now you could use a 4 jaw to do the same thing, but it would be a pain by comparison.

Lastly, there is no "need" for most of us to have a complete set of 5C collets in 16ths, 32nds and 64ths. Most will never be used and even with import collets, a complete set is a large investment. I recommend a complete set of 16ths, a 3" step and a few E collets to start with. A person can add others as needed.

The problem with adapters is they add to the extended length from the spindle.
That extra length robs rigidity.

The Import 9 X 20 Lathes have an MT3 taper in the spindle.
I bought an ER32 collet holder for mine because I already owned an R8-ER32
collet holder for my mini-mill along with a full set of collets.
It didn't impress me. It looks like this in the lathe.

And, it is as rigid as it appears. :

Rick

 

[shred]

I use my ER-16 collets for small workholding in the lathe with a stubby holder (mine needs less hammering than that to remove a center). Works ok for the small work that fits in an ER-16, there's little need for through-headstock capabilities. For bigger parts I have a 5C-type setup with draw tube, but I always find myself limited on the size range of 5C collets for small work-- ER fixes that. The brits have access to a sweet setup that puts an ER-32 nose on a 5C collet. I keep wanting one of those.

 

[steamer]

"The brits have access to a sweet setup that puts an ER-32 nose on a 5C collet."

That would be really nice to have. I haven't seen one but I will keep my eyes out for one.

Dave

 

[joeby]

I was looking for a good collet setup for the Atlas lathe I have, but the collet setup that was commercially available for them was, I think, 3-C. Not so cheap or easy to find, and the spindle bore is small on these lathes to start with.

So, I drew this up and made one with the nose being 4140 pre-hard. That way, if it gets too badly beaten up on the taper, I can recut it. I finished the taper while it was mounted on the spindle as it would be in use. Runout is generally under .0005".

Kevin

 

[steamer]

OOOOh I like that!

Is that a closer ring inside the body?

Dave

 

[joeby]

Dave,

Yes, the closer ring (nut) is what you see inside the "window". There are grooves cut on either side of the nut and in the nose and backing plate filled with 1/8" bearing balls. The nut spins very easily.

It does extend from the spindle nose a good bit; but it hasn't caused any problems. I use it mainly on small parts anyway.

Back to the OP, the reason I went this route was to use 5-C collets, which were designed for workholding, are easily found, cheap, different shapes available, any size (emergency collet if it's an oddball size, internal collets, and the ability to use collet stops if necessary. As an added benefit, the spindle thread on the Atlas is 1 1/2"-8, and so is the spindle thread on my dividing head.

Kevin

 

[BillH]

I was looking for a good collet setup for the Atlas lathe I have, but the collet setup that was commercially available for them was, I think, 3-C. Not so cheap or easy to find, and the spindle bore is small on these lathes to start with.

So, I drew this up and made one with the nose being 4140 pre-hard. That way, if it gets too badly beaten up on the taper, I can recut it. I finished the taper while it was mounted on the spindle as it would be in use. Runout is generally under .0005".

Kevin

That is a near identical copy of a casting kit you can buy from the same people that sell the Die Filer, T slot cross slide for south bends, and face plates... Whats the URL and name of the company... I cannot remember....

 

[joeby]

Bill,

I have seen pictures of one called a "Loop Collet Chuck", and a fellow by the name of Andy sells a kit, I think it's "Metal Lathe Accessories". I have a boring head I bought from him, very nice fellow to deal with and the castings and drawings were very good.

I liked the looks of the "Loop", and so I made this one similar to it. I'm not certain how the innards are on the "Loop"; but from looking at the pictures, he managed to reduce the overhang a good bit from what I ended up with.

Kevin

 

[Andrew_D]

Is this the site you guys are talking about:

http://www.statecollegecentral.com/metallathe/index.html

Andrew

 

[BillH]

Yes, the Loop chuck, and that is the site!

 

[kvom]

Another collet system is the Jacobs rubberflex. I have used this at school, and my lathe came with a set. Mine is a D1-3 mount, school's is D1-6; not sure if other spindle mounts are available.

I have seen these on eBay sell for around $300.

 

[Andrew_D]

While the ER collets are suitable for both work and tool holding, the method shown here to adapt the collet to the spindle is not suitable for lathe work. This adapter is meant to be used in a milling machine.

Why can't this adapter be used??

Yes, there will be a limit to the length of material that can be used.
Yes, it sticks the material out from the headstock a long ways.
I think we all realize that and agree.

The only other issue I can see is that nobody has mentioned whether this adapter is being used with a drawbar or not. It MUST be used with a drawbar. Unless you like having adapters flying around your head at high speeds!

Andrew

 

[steamer]

Besides overhang, you need to worry about run-out. It can get significant with a large overhang. Other than that, it should be fine.