Jacobs 0JT taper


I need to make a 1/4 hex to 0JT Jacobs chuck adapter. Ive found the
dimensions of this taper , but havnt found anywhere on the net the
angle I need to set my compound slide on my lathe to turn up this simple
part.
Can anyone tell me what this angle is?
I dont think its the same as 0 morse taper.
Hope someone can help
Ted
in
Dorset UK
Reply to
Ted Frater
Loading thread data ...
just use inverse sine
Reply to
Bill Noble
Ted, Even if you knew the taper, it is very difficult to just set the taper attachment to that angle accurately with just the scale and witness marks on the machine. My solution to this dilemma is to chuck an example of the chosen taper and use a dial indicator to trace the tool path across the taper surface. Then adjust the taper attachment for zero change across the sample surface. Once zero change is achieved, you are spot on. Steve
of this taper , but havnt found anywhere on the
Reply to
Steve Lusardi
If you have the dimensions, you can chuck up a piece of drill rod, make sure it's running true, and then adjust it with a dial indicator so that the indicator travels the amount of the dimensions for the length between the dimensions. The dimensions are most likely given in diameter so you need your dial indicator to travel half the difference, or the full difference in 2X the length. For example if they gave you a small diameter of 10mm and a large diameter of 14mm with a distance between the 2 measurements of 25mm, that would be 2mm in 25mm taper on radius, but I would probably mark off 50mm length and adjust for 4mm travel of a dial indicator.
Once you get it close it helps to use some spotting blue to see if it's tight on one end or another test fitting a chuck.
RogerN
Reply to
RogerN
Could you cut the hex on a Jacobs 0 / Morse 0 arbor instead? On this one the largest diameter of the Morse end is ~9mm and there is enough metal for the full hex for about 25mm down the shank. The part is small enough that cutting it down on a surface or cylindrical grinder between centers shouldn't take too long. Or you could anneal and mill it.
jsw
Reply to
Jim Wilkins
What Steve said . . .
Bob Swinney
Ted, Even if you knew the taper, it is very difficult to just set the taper attachment to that angle accurately with just the scale and witness marks on the machine. My solution to this dilemma is to chuck an example of the chosen taper and use a dial indicator to trace the tool path across the taper surface. Then adjust the taper attachment for zero change across the sample surface. Once zero change is achieved, you are spot on. Steve
of this taper , but
Reply to
Robert Swinney
Thanks everyone for all your helpfull sugestions. Ted
Reply to
Ted Frater

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