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Need K&T 40 NST dimensions

rke[pler

Diamond
Joined
Feb 19, 2002
Location
Peralta, NM USA
I'm in the process of adapting a 40 NMTB PDQ tool holder to my Autometric and am deciding on whether or not to add the slots for the driving lugs to the toolholders or to make a lug that doesn't need the slots. The lugs are missing, so it's about the same effort either way. Since I'm adapting a quick change to the spindle it's not like I'll be modifying a lot of NMTB tools.

I have a scan from the brochure, but the resolution isn't quite high enough for all the dims. I see .505 width, 1/32 radius in the corners but I just can't make out the depth.

40nst_image.jpg

BTW: if anyone has some 40 NST tooling for sale cheap it might tilt my decision to slotting the NMTB 40 toolholders I have so that standard driving lugs could be used. I think they'd be better for driving anyway as I'll be taking a fair amount of meat for the taper on the modified taper.
 
Depth says .718 / .708 from center - if done to the mean on both sides the bottoms would be .025" higher than the 1.375 OD

..and .324 less than the 1.750 gage line (.162 under each side). I'll have to play with things a bit but it looks like the lug screws are 2.00x apart (so probably exactly 2.000) and with a 1/2" lug that would want a slot .125" deep at the gage line for a tight fit. 1.500 vs 1.426 (from the mean above) - perhaps the 'extra' .074 depth is for sloppy tools? Feels unlikely.

I think I'll make some wonky lugs that float above the tool and see just how bad they look. As long as they engage the NMTB flange I think I'm ok (they'll actually engage a bit more being 1.750 apart). I've got some small head screws coming from McMaster that should help me get this done.

Still, if there's someone with some spare original K&T 40 NST tooling I'd appreciate a shot at it.
 








 
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