[GJeff]

I'm starting to put my 8" tilting rotary table to use and quickly finding some clearance issues (spindle and table) when I want to machine a piece close to the chuck with small end mills. I thought Tormach sold special long ER collet holders for this but it seems the long holders on their site are only for threaded insert end mills which won't work for my specific purpose where I need to use 1/8th inch and smaller end mills. I'm currently getting around the issue somewhat by putting a smaller chuck in the jaws of the larger chuck but I'm looking for more robust solution, hopefully one that just uses a longer end mill holder. Any idea how I could get a hold of one or jury rig something that would still be rigid and not add much runout? I really don't want to have to machine several inches away from the chuck and use the tailstock.

[eltejano]

http://www.ebay.com/itm/ER20-3-4-STR...item19dba6eb6b

You can get that ring Tormach sells and epoxy it to the shank for precise repeatability.

[philbur]

Whole bunch of alternatives here:

New C1 ER32-100L Straight Milling Chuck holder -us items in YSTOOL store on eBay!

If you want guaranteed minimum run-out (for small diameter cutters) then you probably need to use the tailstock.

Your chip load per rev needs to be a fraction of the run-out.

Phil

[GJeff]

Thanks guys that's what I was looking for. Tailstock isn't really an option when I'm making full use of the tilting table, but then again like Phil said neither is run-out when using small end mills so long shanks from China scare me a bit. I'll figure it out.

[SpruTormaCam]

I have a standard 8" 4th and did some machining of very small parts and know exactly what you're dealing with. In an effort to keep the setup as short and rigid as possible I found that the standard tool holders were too big to get close (especially for dynamic A axis moves) and long 1/8" carbide end mills were not rigid enough. What worked well for me was a ER11 collet chuck. I bought a bunch of these with a 6" long shaft and cut a retaining ring groove on the 3/4" shaft. I then machined a bushing (1.5 OD, 3/4-.002ish ID, .5 thick) for a slight interference fit so it would work with the TTS. I have some that extend out as short as possible and some that extend out 3" from the bushing (the extra shaft length was cut off).

I got mine from CTC tools on eBay originally but then ordered them directly a little cheaper.
ER11 3/4" x 4" STRAIGHT SHANK CHUCK #C44

I recently bought one from the YS guy on eBay and the shaft was tapered and .002 undersize. It took three emails and threaten bad feedback before he made it right... I'm sure that's an anomaly but I'll stick with the CTC guy who has been great to work with.

I know these are not perfect but for around $25 (plus $7 for the collet) they have worked great for my needs.

Mark...

[Spinnetti]

Above feedback is good. I do lots of small parts close to the chuck too. I'd just get a longer collet chuck off fleabay... look at the ER16 or smaller ones?

[SpruTormaCam]

Thought a picture would be appropriate. This is a standard TTS ER20 with a thread mill (.17dia) and the CTC ER11 with an engraver (1/8" shank). Yes, that is brass that I made the bushing out of because it was easy. I have a 3" machinist vise mounted on my 4th axis and the smaller head on the ER11 has enabled me to get in much closer. As I said before, this has worked well for me.

Mark...

[nitewatchman]

Is it possible to reverse the thinking and use a 5C collet adapter (30294 - 5C Collet Adapter for 8" Table) on the Rotary Table. The nose of this chuck is fairly small and projects out away from the table face. This may give enough clearance to use standard collet chucks or at least reduce the lenght of the chuck to something more reasonable.

nitewatchman