Tailstock mounted pencil grinder for chuck jaw truing?

eeler1 said:
Hey Paul, the title made me look.
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Sometimes I'm good at that. Will I need to make one so there is a picture...even if the utility is only for a picture?

uncle harry said:
I've watched a couple of videos on U Tube where an outside ring was held on the jaws so that the backlash was represented when tightening inward. This eliminates backlash floating and assures the jaws are biased in the clamping direction. For non-reversable 1-piece jaws, one could use appropriately sized beam clamps on each jaw since there are no reversing screws normally used with 2-piece jaws. Longer screws with sleeves in the outer holes of 2-piece jaws as well as beam clamps on 1-piece jaws will provide something for a ring to clamp onto when tightened inward. (edited)
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Uncle Harry, I think I saw a mrpete video like that at some point. I'll have to go back and watch it again. I have no idea about the second method.

Paul
 
expressline99 said:
Sometimes I'm good at that. Will I need to make one so there is a picture...even if the utility is only for a picture?



Uncle Harry, I think I saw a mrpete video like that at some point. I'll have to go back and watch it again. I have no idea about the second method.

Paul
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Yes, thank you for reminding me. Basically, on 1-piece jaws there is nothing that would allow tightening the jaws on a ring to eliminate backlash. By installing beam clamps on each jaw, it becomes possible to clamp down on a ring on the outside with the inside of the beam clamps. It wouldn't require a great deal of clamp pressure for the grinding.
 
just a 2 cent addition to eeler1's comment: the hole spacing for the 3 holes in the plate are critical or the pressure is uneven. Th holes should be located and bored very accurately.
 
i had one similar to that not a hard fix set the jaws up on my surface grinder and ground the clearance angles back in, then re ground the jaws in Don't use a external ring wrong approach, i use 3 gage block up against the angles you have to grind in .
 
I did find a video with the spacer method being used:

Still looking for the beam clamp method.

I understand the ring with the holes drilled in it. But my bolt pattern skills are pretty poor. If I had a rotary table for the mill
it wouldn't be a big deal...and dro. Just not to that yet.

Paul
 
expressline99 said:
I did find a video with the spacer method being used:

Still looking for the beam clamp method.

I understand the ring with the holes drilled in it. But my bolt pattern skills are pretty poor. If I had a rotary table for the mill
it wouldn't be a big deal...and dro. Just not to that yet.


Paul
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If you have a disc approx. the diameter of your chuck you could find the center and prick punch it. From there you can scribe a a circle with a dividers and prick punch the resulting circle on its scribed layout line. From there you can layout 6 equally spaced points and drill every other one with reasonable accuracy. After that you can drill the center clearance hole from the laid out center.

The beam clamp method is like a dream as stated earlier. I doubt that anyone has video. Having viewed Tubalcaine's video I commented on my method to Tubalcaine and he responded that it was a good idea. The 3-hole method is a far better approach & I will use it if I need to grind my South bend 9a 3 jaw.
 
Here's something from an old Popular Science. I'd grind the jaws to the conventional shape and then grind kie this:

PopSciMech_2__109.jpg

PopSciMech_2__110.jpg
 
yes i use the spacer method but use square gage blocks instead of steel pieces. Also don't use the tailstock bad idea.
 
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