Need help understanding differences between collets: ER32 vs. ER24, ect.

[TacticalAnt]

Need help understanding differences between collets: ER32 vs. ER24, ect. I have a 10x22 Grizzly G0602 lathe with MT4 in the head and would like a collet adapter that wont brake the bank.

 

[Nogoingback]

The differences between the ER collets are size: a bigger number equals a range of collets that are larger.

Adding an ER adapter with an MT taper will require a drawbar to ensure that the tool is secure in the spindle.
This sort of adapter is often found in mills where the collet is used for toolholding.
Using that type on the lathe eliminates one of the advantages of the ER system for workholding, which is the ability to pass
long pieces of stock through the collet. It may cost more, but a better solution is the use of a collet chuck
on a backing plate. Shars sells an "adjust true" style collet chuck that is reasonably priced. I don't know
what spindle mount your Griz has, so can't advise on that.

5" ER40 Zero Set Fine Adjustment Collet Chuck

www.shars.com

 

[mickri]

The difference between the different ER collets is the size of stock/tool that can be held in the collet. I don't know the size range of ER24 collets. My ER32 collets go from 1mm to 20 mm. ER40 collets go up to I believe 26mm.

Your lathe has 1 3/4 x 8 tpi threads on the spindle. Like Nogoing back mentioned you probably don't want a MT4 adapter. The better solution is to either make or buy a collet chuck that fits the spindle on your lathe. Beall tool makes collet chucks. I don't know if they make one to fit your lathe. The Beall Tool Company

I made mine. Not hard to make. One benefit of making one is that it will be concentric with your lathe. Halligan142 has a series of videos on how to make one. Don't have the link handy. Sorry.

 

[RJSakowski]

The differences between the ER collets are size: a bigger number equals a range of collets that are larger.

Adding an ER adapter with an MT taper will require a drawbar to ensure that the tool is secure in the spindle.
This sort of adapter is often found in mills where the collet is used for toolholding.
Using that type on the lathe eliminates one of the advantages of the ER system for workholding, which is the ability to pass
long pieces of stock through the collet. It may cost more, but a better solution is the use of a collet chuck
on a backing plate. Shars sells an "adjust true" style collet chuck that is reasonably priced. I don't know
what spindle mount your Griz has, so can't advise on that.

The thread on the 602 spindle is rather unique. It is a 1-3/4-8 tpi. I ordered a new backing plate as a replacement part from Grizzly. P0606054-2 for the 5" backplate and P0602055-3 for the 6" backplate.

 

[RJSakowski]

I would go with the ER32 for the lathe, The ER25 will be limited to 5/8" stock vs 3/4"+ for the ER32. Better yet would be an ER40 @1".

 

[hman]

Little Machine Shop to the rescue:

ER Collet Sizes

This page shows the size and clamping range of the various size ER collets that we carry.

littlemachineshop.com

Here's a screenshot

Note that the number after the ER designation is (within a millimeter of) the maximum diameter of the collet. The maximum of the clamping range is less than the max diameter.

 

[TacticalAnt]

All good info guys, thanks. I think ill want a 5c collet chuck so I can run stock through the head. Or is that a possibility with the ER types? Also, someone mentioned that 5c are actually designed for work holding where the ER are
for tool holding? Maybe not an issue for benchtop lathe.

 

[NortonDommi]

To expand on the great chart hman posted a manufacturers listing below. Also if you find some DNA collets at a good price don't just pass them by.

 

[Chewy]

Quick and dirty for the ER 32 collets is to get a straight shaft holder. I use mine in a 3J chuck most of the time. Fiddle farting around I get 1-2 Thousand runout. If I need better than that I use the 4J and get around 4-5 tenths runout. The ER collets can be used in a Mill to hold bits and rods. You are limited to a little better than an inch inside the collet.

The 5C collets will need a special chuck. The 5C will pass through up until the ID of your headstock. If you pass through more then so many inches, you will need a spacer or spider to keep the stock from whipping around inside the headstock. The 5C can be used with spin indexers and vertical/horizontal holders on the mill to do lots of special angles and gear teeth. 5C doesn't have the squeeze range of ER so you need more of them. Bought the set of 1/16" collets and now I have to get some in the 32" range.
Watch Joe Pi below. He does a really good job on the differences and how they squeeze and grip.

 

[Nogoingback]

All good info guys, thanks. I think ill want a 5c collet chuck so I can run stock through the head. Or is that a possibility with the ER types? Also, someone mentioned that 5c are actually designed for work holding where the ER are
for tool holding? Maybe not an issue for benchtop lathe.

If you use a collet chuck on your spindle instead of the MT adapter, the stock will pass through the spindle. ER's were
designed for tool holding, but they hold stock just fine.