> From: gene heskett [mailto:ghesk...@shentel.net] > It works well John, on the go704. I'd like to come up with a qcth holder > for them on the Sheldon as it has the torque to drive much bigger taps > but haven't quite figured out how to make such a critter, plus the > sheldon has no gibs to constrain the carriage from being lifted clear of > the ways when huge gobs of the torque reaction comes into play. I'd need > to hang another 30 lbs on the back end of the crossfeed to contain that > for say a 3" tap. That in any event even though I have the tap that big, > is a g76 job. But at a 3" size, I'd be longer shaping the boring tool > that doing it, my CBN wheels are quite fine, 2500 grit but fine is also > slow, fragile and expensive.
Hi Gene, I'm mostly using the TTS holders and some of my more expensive tooling is still R8 so I'm not converting over completely. I'm thinking that your approach with 4 set screws to hold the tap might work well with TTS holders. A custom holder with a hole for the tap shank and 4 set screws keeps the tap from turning. Now we're back to the original question I posed. If this TTS holder with a 3/4" shank into the custom R8 holder with say 20 ft-lbs torque on the drawbar won't turn then it's fine for tapping up to the tap size. Since the TTS come with at least 1/2" holes it makes for a reasonably large tap. Up to 7/8" shank which is once again listed as the limit for R8. And it makes the tap holders a lot less expensive than using ER20 collets which are only good up to a certain size. Purchase a TTS for 1/4" shaft, mount in a lathe collet and bore to the size of the target tap. Drill the 4 holes and tap them. Now it's a TTS Tap holder. If one wanted to modify the spindle it would be possible to put a pin hole just outside the diameter of the TTS tool. Then modify the TTS tap holder to have a flange like the pin on your holder that goes into the collet. In fact, modify all the TTS holders to have the flange and it's possible to prevent all TTS tools from spinning in the R8 holders. Not only that but the M66 command can put the pin in the same place so installing TTS indexed tools becomes trivial. John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
