Repeatable Z when using collets

[KyleL]

Hi all, long time lurker. I'm in the process of designing a router and I believe I'll be using one of the water cooled Chinese spindles, either ER16, or ER20.

Anyways, right now I have a cnc'd Taig (ER16 spindle) and was wondering if anyone has any ideas for tool changes and maintaining an accurate Z. Right now, I drop out the tool and reset the z-height which requires me to break up operations in to separate programs so I can reset everything between runs. Not exactly quick...

I was thinking about creating an insulated, opto-isolated tool height probe similar to how the Datron mills are setup. Is this even possible while in a program? Judging by Hoss's tool-changer I'd guess that Mach3 can run programmed functions from gcode? Anyone have any idea if this is possible under EMC2?

Thanks,
-K

[Rees Guitars]

I was thinking just a small aluminum ring with allen key as a depth stop on the tool. Think it would imbalance it?

Pretty much like these: http://www.woodshopbits.com/depth-co...ets-p-223.html

And these small mills have pressed on plastic ones: http://www.thinktink.com/stack/volum...ting_rings.htm

[KyleL]

I thought about collars, but the z height would end up becoming a function of the torque applied to the collet nut, I believe. Assuming that though, it would probably be reasonably repeatable as long as you put about the same force on the collet nut each time.

I actually have a few collars sitting around, I'll try one tonight and see how accurate it is, it may still be a good option for my Taig assuming larger bits and slower rpms.

I'd be a bit scared running those at 8-24k though.

[ee_t]

http://www.mail-archive.com/emc-user.../msg17886.html

[Andre' B]

Originally Posted by KyleL I thought about collars, but the z height would end up becoming a function of the torque applied to the collet nut, I believe. Assuming that though, it would probably be reasonably repeatable as long as you put about the same force on the collet nut each time. I actually have a few collars sitting around, I'll try one tonight and see how accurate it is, it may still be a good option for my Taig assuming larger bits and slower rpms. I'd be a bit scared running those at 8-24k though.

Torque wrench, they do wonders for repeatablity on vices too.
http://www.toolprice.com/c=l4cicoL0x...ch_Pounds.html

Maybe just use solid collers (no set screws) and put them on with Loctite 609 retaining compound, you will need a torch if you want to get them off.