Doesn't exist? -- 8 TPI threaded chuck to fit an 80mm HF faceplate (w/ picture)

[DavidR8]

I expect that you need a 1.5x8 thread to fit threaded back chucks. That said, those are not all that common in sizes that will fit a 7X lathe.

 

[bcrimmins]

Ok, now we can see the motivation! Presuming that your lathe has a taper. Aren't there similar ring mandrels that use a taper instead? Perhaps you could make one? Or use a straight shank mandrel in a MT2 chuck?

Indeed there are taper-based ring mandrels. Pretty sure I've looked at every mandrel on the market. For design, functionality and price... this one just happens to be my choice. I was shocked that I couldn't just go to ebay and buy a threaded spindle chuck! There are a ton of faceplate-mountable threaded spindle chucks... that are the female type -- but no male type!!

BTW, I considered just throwing the ring chuck in the jaws but I suspect precision alignment will be a hassle... every single time I use it.

I also considered mounting a spindle adapter like this in the jaws. But same concern.

 

[WobblyHand]

Indeed there are taper-based ring mandrels. Pretty sure I've looked at every mandrel on the market. For design, functionality and price... this one just happens to be my choice. I was shocked that I couldn't just go to ebay and buy a threaded spindle chuck! There are a ton of faceplate-mountable threaded spindle chucks... that are the female type -- but no male type!!

BTW, I considered just throwing the ring chuck in the jaws but I suspect precision alignment will be a hassle... every single time I use it.

I also considered mounting a spindle adapter like this in the jaws. But same concern.

View attachment 393862

The morse taper mandrels will run true. Remove your chuck and seat the mandrel tool into the taper. No fiddling, no adjustment. Works every time. You will have to drive out the taper when you are done, just use a soft metal rod, like aluminum. A tap ought to do it.

Or you could make a super mandrel of your own. If I was you, I'd try the taper one first.

 

[Aaron_W]

I expect that you need a 1.5x8 thread to fit threaded back chucks. That said, those are not all that common in sizes that will fit a 7X lathe.

No but it could be useful on a 10x22" which also commonly uses a flange. Apparently the flange adaptor for plain back chucks can be hard to obtain, and not that cheap. Somebody was recently going to a lot of effort to get one for a PM1022. A 1.5"-8 adaptor would open up a huge range of new and used tooling.

 

[DavidR8]

I don't believe that lathe has a MT spindle so not sure how an MT taper rink mandrel would be.
Unless I'm lost in translation which is entirely possible!

 

[RandyWilson]

The Sieg 7" Minila The series does have an MT3 spindle.

 

[DavidR8]

The Sieg 7" Minila The series does have an MT3 spindle.

Classic!
I looked at the specs and saw the tailstock is MT2 but there's no mention of headstock taper only the bore of 5/8"

 

[bcrimmins]

The morse taper mandrels will run true. Remove your chuck and seat the mandrel tool into the taper. No fiddling, no adjustment. Works every time. You will have to drive out the taper when you are done, just use a soft metal rod, like aluminum. A tap ought to do it.

Or you could make a super mandrel of your own. If I was you, I'd try the taper one first.

Thanks, yeah, I've looked at all (I think) of those but I don't like them as much. They are really common for pen turning and often just an adapted pen mandrel. If necessary, I might end up there... but I really like the design of the spindle version.

 

[WobblyHand]

Classic!
I looked at the specs and saw the tailstock is MT2 but there's no mention of headstock taper only the bore of 5/8"

Just looked at the docs on the lathe, no mention of spindle taper!

My mini-lathe is from Little Machine Shop and made by Sieg (for LMS). It has a MT3 taper in the spindle and a 20mm spindle bore. I'd check the spindle for evidence of a taper.

 

[RandyWilson]

Classic!
I looked at the specs and saw the tailstock is MT2 but there's no mention of headstock taper only the bore of 5/8"

Yeah, I don't see it in the specs. My HF 7x12 spindle is MT3. Littlemachineshop shows that 7x10 to also use a MT3 spindle. But the 5/8" through-bore is the specs is very odd.