Why would you choose either ER32 or ER40 collet for PM-1022V?

cneuor

cneuor

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The only ER collet chuck that Precision Matthews offers for PM-1022V lathe, at least at this time, is the ER40. They say, if you want ER32, you can custom-fit the back plate and people have done it. Before I knew this, I thought I wanted the ER32. But now I am wondering if I should get myself the available ER40 and be done with it. So, I would like to ask this question: why ER32 and not ER40 or vice versa? Other than the set of ER40 collets will cost not really a significant amount more over ER32, is there anything else?

As a separate subject - I could not find any info about the "V-Flange Collet Chuck". What is that, how to use it, and why to have it if there is the ERxx chuck?
 
I already have ER32 collets (1mm - 25mm) so I would start with them with a custom collet chuck; however, when/if I buy a PM 1022 I would probably include the ER40 chuck allong with a couple of extra back plates for other chucking tooling (my Accusize 5” 3-jaw, Eccentric Engineering Flexi-Chuck and ?
 
I have both. The choice between the two for me boils down to the size of what I want to hold and whether I'm trying to hold a tool or material being cut by a tool. For instance, I prefer the ER32 for holding tools (drill bits, end mills, etc.) in the tailstock of a lathe. I also prefer it for holding the same kinds of tools in the mill spindle. But for holding materials that are being machined, the ER40 will handle larger diameter materials in the lathe spindle, or in a hex-block. This all gets more complicated when you also consider 5C collets/chucks. You might find this paper,which I posted here earlier, helpful in understanding the tradeoffs.
 
The document above is the full answer. To add to that:

This page from LittleMachineShop pretty much sums up the sizes of collet commonly available for ER32 and ER40:

littlemachineshop.com

ER Collet Sizes

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

Note the minimums and maximums.
 
About collets: My personal favorites are 5C. BUT they have some drawbacks compared too the ER collets.
If you have decided on the ER system the advantage of the 40 over the 32 is a bit larger size of work you can get into them.
My ER40 & 5C chucks are both of the adjustable type. They can be dialed in even if the tolerances of the parts isn't great. Useful if you are reversing the work in the chuck. Consider what other collet holding devices you will add in the future.
Collet blocks, Spin Indexer, R8 to ER
ER collets have more adjustment range than 5C But 5C can go about 1/8" larger. I got a 5C adjustable chuck when I bought my PM lathe. What I didn't know at the time was how many collets it takes to cover the full range! 72! But, a 5C collet can hold very short parts that are not advisable in an ER. Working very close to the chuck is easier with the 5C. I'm pretty sure that an ER can hold tighter than a 5C but the work should extend further into an ER.
 
I was trying not to go into the weeds with non-standard thin wall ER collets. But here is a 26mm ER32. It's in the "use at your own risk" range of thin.

26mm ER32 collet

And a 32mm ER40

Personally, I have a full rack of 5C. My main ER collets are ER20 and a few ER16 for my mill but I have not ventured into ER collets on the lathe at this point. When I do I'll probably set up some gang tooling on my cross slide using my existing ER20 collets and tools.
 
You have a 1" spindle bore on the 1022, so ER32 range would be more in keeping with the size machine, the other factor is the spindle mount type limits available chucks. The PM-1130V has a number of more desirable feature including a D1-4 chuck mount and a 1.5" spindle bore. It opens more chuck options, and the ER-40 would work better with the larger lathe/ spindle bore. As other mentioned, ER collets have a wider compressability range, so fewer collets than 5C, but ER collets are limited if holding short stock. I have both 5C, and ER40 chuck mounts, for my work I almost always use 5C collets for stock under 1". If you are planning on using it to hold long stock through the collet than ER collet may be preferable. price difference between ER32/ER40 collets in nominal. Also you can ER collets typically in 1 mm increments or imperial, the latter may have a few sizes missing in their 1/32" collet sets. Quality and consistency collet to collet can be quite variable on the less expensive sets.

Always remember on ER collets that they need to be snapped into the nut before mounting and tightening the nut.
 
I haven't looked at davidpbest's paper yet, but I standardized on ER40 in my shop*. This means all of my collet investments are mutually compatible, I have the greater capacity, and, as you mentioned, the cost difference is pretty small. I certainly wouldn't pay extra to trade to a smaller size...

GsT

*Well, for most things. I do have some very small (ER16 and something just a little larger) for tiny boring bars and my dbit grinder.
 
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