[ImagineRobots]

Your thoughts please on this crazy adapter idea:

I found this 3/8" shaft to 3/4-16 stainless steel adapter below from High Tech Systems LLC:



Would like to attach my 3" Sherline 3 Jaw Chuck (3/4-16 thread) on one end and a Tormach TTS adapter (3/8" bore set screw holder) on the other end.





Do you think the adapter is strong enough? My mill is an X3 with 2K RPM. I would be machining aluminum and plastic with the chuck.

I'm essentially trying to make this Tormach TTS boring arbor below but with a 3/4-16 thread instead of the stock 7/8-20 thread.



Another thought is maybe buy the Tormach adapter and have someone machine the 7/8-20 thread into a 3/4-16 thread. Is this pratical for some with a lathe to do and how much would it probably cost? Any takers (please PM)?

THanks!

[photomankc]

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[photomankc]

TTS in collet, adapter in TTS, chuck on adapter, and stock in chuck.... sounds like a recipe for problems. I would not be at all comfortable doing any work in a TTS adapted lathe chuck since pull-out becomes an issue on larger tools. Anything beyond 3/4" stock would make me really nervous. Using the set-screw holder would likely make for a horrible cutting experience with AL with the kind of flex that arrangement would look to have


That said, Tormach makes a 'soft' TTS blank that could be machined to the 3/4-16 thread easy enough.

Machinable TTS Blank

[ImagineRobots]

TTS in collet, adapter in TTS, chuck on adapter, and stock in chuck.... sounds like a recipe for problems. I would not be at all comfortable doing any work in a TTS adapted lathe chuck since pull-out becomes an issue on larger tools. Anything beyond 3/4" stock would make me really nervous. Using the set-screw holder would likely make for a horrible cutting experience with AL with the kind of flex that arrangement would look to have


That said, Tormach makes a 'soft' TTS blank that could be machined to the 3/4-16 thread easy enough.

Machinable TTS Blank

Thanks. Machining the TTS blank is the way to go. It would be stronger than using the 3/8" to 3/4-16 adapter kludge that could shear off during something like a machine crash.

[109jb]

I would not even do the chuck mounted directly on the TTS adapter. On top of that, the TTS adapter may be hardened. Even if it isn't, the TTS is $43 and by the time you pay someone to re-machine the threads you will have more into it than the chuck in the picture below. Here is a link to the e-bay ad. It is only $89

4" 3 Jaw R8 Collet Chuck New w Wrench | eBay

Something like that is the only way I would mount a lathe chuck on a mill.

[ImagineRobots]

I would not even do the chuck mounted directly on the TTS adapter. On top of that, the TTS adapter may be hardened. Even if it isn't, the TTS is $43 and by the time you pay someone to re-machine the threads you will have more into it than the chuck in the picture below. Here is a link to the e-bay ad. It is only $89

4" 3 Jaw R8 Collet Chuck New w Wrench | eBay

Something like that is the only way I would mount a lathe chuck on a mill.

Thanks for the link. I was going to buy a similar R8 chuck from Shars with a good TIR (1 thou)

shars.com - 4quot Three Jaw Precision Chuck amp R8 Adaptor

but I converted my mill to use a power drawbar/TTS system and can no longer easily remove the R8 collet.

The power drawbar/TTS system is awesome but now I want a convenient small 3" chuck attachment for it. The Sherline chuck is actually pretty small.

[SCzEngrgGroup]

Using something the size and weight of a chuck, even a small one, with TTS is begging for an accident. Using it with a screw-on adaptor makes the idea aboue 10X crazier - acceleration and deceleration as the spindle changes speed, could easily cause the adaptor to unscrew. Never mind that the cutting forces along, with such a long lever arm, are almost guaranteed to cause pull-out of the TTS shank. I don't think that would EVER be allowed in a real machine shop. Do you really want to see that chuck come off at even a few hundred RPM? JUST ONE TIME, I had a TTS holder pull out - just a set-screw holder with a 1/2" endmill - and it scared the hell out of me, thinking of the damage it could do if it came all the way out.

Regards,
Ray L.

[SCzEngrgGroup]

Using something the size and weight of a chuck, even a small one, with TTS is begging for an accident. Using it with a screw-on adaptor makes the idea aboue 10X crazier - acceleration and deceleration as the spindle changes speed, could easily cause the adaptor to unscrew. Never mind that the cutting forces along, with such a long lever arm, are almost guaranteed to cause pull-out of the TTS shank. I don't think that would EVER be allowed in a real machine shop. Do you really want to see that chuck come off at even a few hundred RPM? JUST ONE TIME, I had a TTS holder pull out - just a set-screw holder with a 1/2" endmill - and it scared the hell out of me, thinking of the damage it could do if it came all the way out.

Regards,
Ray L.