There must be a typo in Bob's post as the 12/32" (3/8â€) collet "IS" included in the 18 collet set. I suspect he meant to say 13/32".
I, too, have noticed that the 1/32" 18 piece collet set was missing three sizes of collets. Not for sure why the are missing. Maybe one of our resident machinists can provide an answer. I'm guessing that missing sizes are for sizes of raw stock that are not standard or commonly available in the US.
I just noticed, BTW, that the 18 piece sets (by 1/32") are the same price as the 11 piece sets (by 1/16") but for a couple of extra dollars for shipping. Either this is new pricing or a typo as I am pretty sure the larger sets were more expensive when I purchased mine.
I wish I had paid more attention to the math when I bought my 11 piece set. Because the grip range of each ER32 collet is very nearly 1 mm., there are some gaps in the range since 1/16†equals approximately 1.6mm. This is not a problem, if you are only dealing with Imperial sized stock; but can be a problem if you have metric sized material. An 18 piece set would give you a continuous grip range (metric), but with the three missing Imperial sizes, there would be gaps there as well.
Just out of curiosity, I did the conversion to see which sizes would be a problem.
Collet sizes in 32nds for the 18 piece set.
4 (1/8)..........3mm
5 ....................3mm
6 (3/16).......4mm
7 ....................5mm
8(1/4) ...........6mm
9 ....................7mm
10(5/16).......7mm
11 ....................8mm
12(3/8).........9mm
13 ..................10mm.....(missing)
14 (7/16)......11mm
15 ..................11mm
16 (1/2).........12mm
17 ..................13mm.....(missing
18 (9/16).......14mm
19 ....................15mm
20 (5/16)......15mm
21 ....................16mm.....(missing)
22 (11/16)......17mm
23 ..................18mm
24 (3/4)........19mm
.........................20mm.....(this size would be in an 18 piece metric set)
As you can see there are several metric sizes that could not be accommodated by an Imperial set of collets in 1/32†increments. Might be a problem for a few people but probably not for most of us?
This is probably more than most people want to know about collet sizes so it is about time to put a lid on it; but for two final comments. As an average pencrafter, you are probably going to be purchasing the Beall or the PSI collet chuck with the standard five collet accessory set and will need to purchase an additional 5/16†collet if you want the capacity to use the Berea “B†mandrel. IAP member Joe Collazo sells individual 5/16†ER32 collets for $9.00 plus shipping which is a few dollars cheaper than buying to Beall collet even if you get it when you buy the Beall chuck so as to combine shipping.
If you are considering a “by 32nds†set and want to fill in the gaps, do a search of the IAP threads as I think there are some links posted for sources that are less expensive than what Bob had to pay.
Enjoy your collet chuck…..I certainly enjoy mine!!
