Hex Collet for a mill?

[lesrhorer]

The main issue for the hobby milling machine is VERTICAL SPACE. There is never enough, especially for drilling. It definitely does not help a drill chuck takes up at least 4" of an already limited resource, added to the height of the vice. Any drill bit larger than about 3/16" is liable to be too long to be used with a chuck and a vice together. One can hold the work piece directly on the mill table, but access to the top of the piece - especially a small one or an irregular one - can be a real challenge, not to mention a real pain in the tuchas. Of course one great work-around is to use an R-8 or ERxx collet to hold the drill bit, as long as one has over a hundred different collet sizes, of course. But wait! There is a drill bit solution that does not require a variable chuck size. Most drill bit sizes can be had with 1/4" hexagonal shanks.

I looked around, but I could not find any R8 or ER40 hex collets. Does anyone make them? (They should. 5C hex collets are very common.) If so, where can I get one?

Another option would be to make a collet adapter. Does anyone here have a 1/4" hex rotary broach? It would be pretty easy to make an adapter. Take a piece of round stock and slit one side in the mill. Place a close fitting shim in the slot. Put the stock in a collet in the lathe, drill the stock the proper size for the rotary broach, and broach the stock. Viola! A drill bit adapter for 1/4" shank drill bits that takes up only a tiny bit of vertical real estate. If I do the rest, is there anyone out there with a rotary broach who would like to finish the project?

EDIT:

I found another possible solution. Ali Express has an R8 emergency collet that would work perfectly if broached.

R8 Emergency Collet

 

[WobblyHand]

You didn't state what size hex collet? I bought an ER32 1/4" hex collet from Maritools. It appears they also have some in ER40.
hex collets at MariTools

 

[davidpbest]

New ER-40 Hex Collet Block Chuck Holder for CNC Lathe Engraving Machine | eBay

<li> 100% brand new.</li> <li>For fast set-ups on CNC machines.</li> <li>Can be used standing upright.</li> <li>Made of tool steel hardened.</li> <li>High strength and hardness.</li> <li>Durable in use.</li> <li>Through hole allows for long parts to be machined.</li> <li>Material: Hard...

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[WobblyHand]

Well, I think we have it covered. I thought he was talking about collets, David thought it was about collet blocks! Got 'em both!

 

[macardoso]

What is the accuracy of those drills in the hex shank? I thought those were construction grade only and would have unacceptable runout.

 

[RJSakowski]

My experience with the hex shank drill bits is they don't have great concentricity. They are intended for use in drill drivers for easy pop in/pop out where concentricity isn't a real concern.

I have a 24 pc. set of R8 collets by 1/32" that will grip any drill between 1/16" and 3/4". I also have a number of ER20 chucks and 13 collets by 1mm that will grip any drill between .5mm and 13mm

 

[WobblyHand]

Oh, I didn't realize the intent was to use hex shank drills. No, don't do that. Hex shank, not concentric enough. Your holes will always run large. Kind of like bent Harbor Freight drill bits. No, really, it's not a good idea. Once I got rid of HF drills and bought real quality bits, (one at a time) I could hit very close to true hole size.

 

[Weldingrod1]

I have long center drills and drill bits to match many of my R8 collets stored right next to the collets for that exact reason!

Sent from my SM-G892A using Tapatalk

 

[hman]

Of course one great work-around is to use an R-8 or ERxx collet to hold the drill bit, as long as one has over a hundred different collet sizes, of course.

It's not as bad as you think. What you say is true of R-8 collets, because they have very limited grip ranges. But ER collets have a grip range of about 1mm (or 1/32"). So, for instance, with an an ER40 collet chuck, you can cover everything from 1/8" to 1" with a 29 collet set:

https://www.amazon.com/Precision-Drilling-Tapping-Milling-Engraving/dp/B08B5YFDFG/ref=sr_1_3_sspa?crid=33YTRN00R5VE5&dchild=1&keywords=er40+collet+set&qid=1631586277&s=hi&sr=1-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExTFgyS05MVkVMUE5VJmVuY3J5cHRlZElkPUEwNjcyMTcyMjdPUVUwQzA5VzE0TiZlbmNyeXB0ZWRBZElkPUEwODM4ODg1Mlk5SVAyUFBDV0lUVSZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[lesrhorer]

What is the accuracy of those drills in the hex shank? I thought those were construction grade only and would have unacceptable runout.

That is why god made center drills. Some have horrible run-out. Some little or none. Decent ones chucked in the mill can easily do better than the drill press. I can also make them to higher tolerances using good quality drill bits.