SAE drill size to ER collet size

I got a straight arbor for my keyless chuck to fit into an ER collet but never really use it as it takes too much room and I would need to raise/lower the head. I rarely drill on the mill, mostly use the drill press for that.
 
I inherited a drill chuck with MT2 shank from an inlaw. I turned the MT2 down to a short 3/4" straight shank and it makes for a quick change to a drill chuck without messing with the drawbar. I just stick it in an ER 32 collet. The head has to be raised but my powered head lift makes that easy.
 
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mickri said:
My ER32 metric collets sit face up in their holder. When I need a collet I just keep sticking the drill/end mill/whatever in the collets until I find the one that fits. I use the 10mm and 13mm collets the most. They have their own collet nuts. I only use the ER32 collets on the mill/drill. Too much trouble to switch between the collet chuck and the drill chuck. I have to get a stool to stand on. Loosen the drawbar. Wack it with something to get the chuck to break free. Switch the chucks and tighten up the drawbar. I stopped using the ER32 collets to hold drills on the lathe tailstock after I got a drill chuck for the tailstock. I still use the ER32 collets for work holding on the lathe with the collet chuck that I made for the spindle. No gaps in coverage with metric collets.
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ditto what this ^ guy said. A full set of metric collets will hold any drill safely and within it's collapsable range (1mm I think), no harm to the collet whatsoever. To be honest I'm not sure I could even close a collet more than it is able to be closed - I'd run out of threads on the chuck before I tightened the collet. I often drill with my ER25 collet chuck - it's more accurate than a drill chuck, has less stack height than a straight shank chuck held in a collet, saves me changing between collet chuck and R8 shank drill chuck and also has far better grip on the drill than a drill chuck has (= no spun large drills). Look at industry - ever see a drill chuck in a CNC mill tool changer? Nope, all the drills are held in ER collet chucks.

Admittedly it does take more time to drill, chamfer and tap with a collet chuck than a drill chuck, but that's the only downside I can think of for using a collet chuck to drill with.

To David - get a full set of metric ER collets. They're not that much and it'll also make holding SAE drills (if you have metric collets) easier.
 
DavidR8 said:
Is there a reasonable facsimile?
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Get some 4140 Half hard, and make your own. I bought No. 11 ER Collets and nuts, Have about 15 now, It just takes patience to make the holders, and keep each end concentric.

Edit: correct typo.
 
I just checked my TTS holders.
I have:
two 1/4”
Two 3/8”
Four 1/2”
A 1/64-1/4” drill chuck
An ER20 chuck
2e23d2e920c0450e2876ab20c32d82a7.jpg
 
DavidR8 said:
On my mill I use an ER32 collet chuck with 11 collets. A recent project revealed that I am missing collet sizes to hold some SAE drill sizes.
To figure out what I collets I was missing I made this chart showing the SAE drill size up to 1/2" and their corresponding ER collet size.
Hope this is useful to others.
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Thanks for posting that David. Saved.

This is somewhat timely as I ran into a situation where only this 1/2” pencil/extension chuck could have gotten into where I wanted to drill. But the drill was a #29/.136 and the pencil chuck only has three collets, 1/8, 3/16 and 1/4”. So the drill was .010 too big for the 1/8”. I’ve tried to see if other collets are available for the chuck and they don’t seem to be. I hate to incur the wrath of the gods but seeing how most are fairly tolerant of the ignorant....what about this?

I thought about making I guess I’d call an emergency blank that the OD was 1/4” and cut it the length of mini collet and cross drill it about half the length for the relief at the end of slits in preparation for the next time I have the same situation. Then put it in the collet chuck on the lathe and drill it to the exact ID. Then slit to to the cross drills and clean up the internal burrs.

Then I could put my random odd size number drill in my extension chuck with the 1/4” collet?
Please don’t terminate my existence.........
 
That seems like it work @C-Bag.
 
DavidR8 said:
@mikey @benmychree
The situation I'm trying to avoid by using drill bits in ER collets is having to swap out the collet chuck for a drill chuck.
But that doesn't sound like a good approach.
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So long as the drills shanks are within the clamping range of the ER32 collet, there is surely no problem. The collets normally hold milling tools with side loads. Holding a drill, only loaded axially, should be a doddle. Perhaps avoid the extremes of the clamping range.
 
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