Oversize ER32 Collets (undersize ones, too)

[ChazzC]

How Do They Do It?

Standard ER32 collet sets are 3mm – 20mm (maximum capacity). Several vendors (I got mine from SHARS) sell 1mm, 1.5mm & 2mm, and I always understood how these could work since they have a smaller clamping range (0.5mm vs. 1mm).

However, I also had 21mm, 22mm, 23mm, 24mm & 25mm ER32 collets that I purchased directly from China on eBay. I figured they got away with these sizes by making the bodies thinner and spec'ing them with a higher TIR (0.0006" vs. 0.0003" for the standard and mini's), but I just received an ER32 26mm collet from Ali (after being pointed to it by @Advil here) and I finally figured out how they get away with making these "impossible" capacity collets:


The 20mm is from my standard set, 21mm through 25mm are from my previous eBay purchase and the 26mm is from Ali. Obviously the larger the capacity the shorter the back end of the collet, and they also play with the number of slots. Mystery Solved!

Once I can do something other than take pictures in the shop I'll do some kind of comparison; don't have any precision ground bars in the 20mm – 26mm range, but I'll figure something out. In the meantime I have to address organization – I don't have room in my Odd-Size ER32 Collets box:

 

[GeneT45]

Even if those weren't great, I think I could find the occasional use for them. I might see what I can find in ER40.

GsT

 

[Advil]

Yes I'm kind of tempted to pick up a $30-something dollar ER40 D1-4 chuck and collets 1" and up. That would really cover most sizes of stock I might turn above what 5C can hold. without having to spin the whole 3 or 4 jaw chuck.

 

[Larry$]

How Do They Do It?

I'll be interested in seeing how true they run.
I only have an inch set of ER40 collets (actually two sets but don't like the one set - Too far between sizes and really difficult to snap into the nut)
I'll use my ER40 chuck when I don't have 5C collets to fit what I'm working on. I've got the internal stop for the 5C collets so doing repeated items is easier as well as not having to work up close to that big ER nut. Occasionally use an R8 to ER40 on the mill when I don't have the correct R8 collet.