jim rozen
Diamond
- Joined
- Feb 26, 2004
- Location
- peekskill, NY
So I spun a drill, bad, in my 14" SB drill press at work - to the point where a dowel pin chucked up showed around 8 thou TIR runout. Easy, right? Just take off the old chuck and put on a new one. Troubles begin:
1) the standard double extractor wedges are NLA at mcmaster carr. Instead they sell you what amounts to a pickle fork sized to slip in the gap between the male jacobs taper on the end of the spindle, and the top of the chuck body with female taper. This does not work so after some wrangling I pull the quill, mount the fork in the vise and slip the assembly over the fork. Copper sheet over the chuck body and a large hammer later, the chuck pops off.
2) at the same time I order the replacement chuck, figure I'll give the machine a nice upgrade -and order a ball bearng super chuck matching the 1/2 inch max of the original. Whoops that's a 3JT size taper! Way big.
3) I then order a 1/2 inch capacity NON ball bearing chuck - and also a JT3 arbor. (Deckel just gets a new chuck)
4) New chuck is JT2. And is way too *small* for the taper in the spindle. ??? Did they make a JT2-1/2 taper??
5) Cursing. I press apart the old worn chuck, and press apart the new chuck. Transplanted the new jaws, split nut, and sleeve onto the old body. Oddy they fit perfectly.
6) clean the original 1940s grease from all the bits, re-lube, re-assemble. Runout not visible anymore. Sigh.
So the mystery remains - did jacobs change their JT standard sizes somewhere along the line?
1) the standard double extractor wedges are NLA at mcmaster carr. Instead they sell you what amounts to a pickle fork sized to slip in the gap between the male jacobs taper on the end of the spindle, and the top of the chuck body with female taper. This does not work so after some wrangling I pull the quill, mount the fork in the vise and slip the assembly over the fork. Copper sheet over the chuck body and a large hammer later, the chuck pops off.
2) at the same time I order the replacement chuck, figure I'll give the machine a nice upgrade -and order a ball bearng super chuck matching the 1/2 inch max of the original. Whoops that's a 3JT size taper! Way big.
3) I then order a 1/2 inch capacity NON ball bearing chuck - and also a JT3 arbor. (Deckel just gets a new chuck)
4) New chuck is JT2. And is way too *small* for the taper in the spindle. ??? Did they make a JT2-1/2 taper??
5) Cursing. I press apart the old worn chuck, and press apart the new chuck. Transplanted the new jaws, split nut, and sleeve onto the old body. Oddy they fit perfectly.
6) clean the original 1940s grease from all the bits, re-lube, re-assemble. Runout not visible anymore. Sigh.
So the mystery remains - did jacobs change their JT standard sizes somewhere along the line?
