# Tailstock mounted pencil grinder for chuck jaw truing?



## expressline99 (Sep 19, 2017)

Is there any reason the tailstock on a lathe couldn't have the ram removed and replaced with a pencil grinder? To me it seems like this would make really good alignment for chuck jaw repair. The movement of the grinder would have to be controlled by the handle in the tailstock of course. The grinder would have to be a tiny pneumatic and It would take some doing to make it work in the place of the tailstock ram. I would think with the lock down of the tailstock it would be stable assuming you could get the grinder mounted properly.  Could be a cheap way of making a "tailstock" grinder. 

(yes I know there shouldn't be any grinding/grit near a lathe.)  

So am I off my rocker again?

Paul


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## richl (Sep 19, 2017)

The jaws and the tailstock would have to be lined up to where you are grinding, with the cross slide you can move the grinder right or left in relation to the ways to hit the jaws of the chuck. With the grinder in the tailstock there is no side to side movement... at least non that I can see...
There might be other uses for that configuration, not sure grinding the jaws on your chuck would be one.

Hth
Rich


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## Bob Korves (Sep 19, 2017)

A standard hand held air die grinder with a 1/4" collet mounted with an adapter in the tool post would be a much betters solution, Paul.  You cannot do accurate work with a skinny shank grinding wheel (flexes too much, cuts too little, and the springiness makes it cut all the way around the work, not just on the high spots) and you could only do center line work using the tailstock unless you offset the tailstock, which is also a PITA getting it back on center again after grinding if lacking the right setup.  Mounting to the tool post allows easily swiveling the die grinder for the angle you need, even if it is zero degrees, and adjusting up and down to be truly on center line.  It is also fairly easy (but slow) to use a sine bar to set an accurate angle.  Even grinding something like a Morse taper requires several orders of magnitude more accuracy than you can get out of the degree markings on the cross slide.


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## expressline99 (Sep 19, 2017)

The reason I'm even considering any of this is for a 3 jaw chuck that I have mounted/bought a while back. But the jaws are completely flat.



Not sure what to do with them?

Paul


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## Bob Korves (Sep 19, 2017)

Use them on triangular or hex stock?  

You could grind them to a radius, but it will not very useful for smaller work unless you also narrow the jaws toward the center so they interlock like how most chucks are made.  I still recommend more rigid tooling than a pencil grinder...


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## expressline99 (Sep 19, 2017)

Bob Korves said:


> Use them on triangular or hex stock?
> 
> You could grind them to a radius, but it will not very useful for smaller work unless you also narrow the jaws toward the center so they interlock like how most chucks are made.  I still recommend more rigid tooling than a pencil grinder...



Oh yes, sorry I meant to say I agree with both of you. The flex would be awful and no easy adjustment while grinding. 
Want a surface grinder project?  It wouldn't fix alignment but seems like it would be difficult otherwise to get that much material off of them. 

Paul


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## BGHansen (Sep 19, 2017)

So I'm guessing you'd advance the cut or grind by tightening the chuck jaws?  Make a pass with the lathe running, back the tool out, shut off the lathe, turn the chuck key a little and repeat?  As Bob mentioned above, you'll be limited in diameter unless you bevel the jaws.  Might be easier to just mount a die grinder on the close slide as Rich mentioned above.  Nice L-W chuck by the way, have one of their dividing heads.  They made great quality stuff.

Bruce


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## JimDawson (Sep 19, 2017)

This is the way I do it.  In this case grinding the 5C taper in a collet chuck.  Harbor Freight air die grinder.


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## richl (Sep 19, 2017)

Not sure this is even a good idea... but... would making a soft jaw to attach to the existing jaws a worth while idea here? From the picture the existing jaws seem a bit short already, and grinding a bevel on them will only decrease that more... I don't see stuff like this mentioned anywhere so I am just tossing out ideas for public consumption...

Nice little diy project. Ever notice that small projects soon become big projects by the time you factor in all the additional steps and tools required...


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## expressline99 (Sep 19, 2017)

BGHansen said:


> So I'm guessing you'd advance the cut or grind by tightening the chuck jaws?  Make a pass with the lathe running, back the tool out, shut off the lathe, turn the chuck key a little and repeat?  As Bob mentioned above, you'll be limited in diameter unless you bevel the jaws.  Might be easier to just mount a die grinder on the close slide as Rich mentioned above.  Nice L-W chuck by the way, have one of their dividing heads.  They made great quality stuff.
> 
> Bruce



That's probably what I'll have to do. I have an HF die grinder somewhere I've never used that I got with a bunch of other stuff.  The Jaws do need a bevel for sure It doesn't tighten down far enough. Not sure how to do that though? 

The chuck was basically new. Whoever had the chuck originally bored it out all the way through to a dimension too large to thread for my lathe. I took it completely apart and the grease was mostly solidified it had sat for so long.  The movement on it is really smooth. I didn't even notice the jaws were flat until I started making the plate for it. 
A dividing head is on my list for sure. So L-W was a good brand? Seems like a quality tool.

Paul


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## expressline99 (Sep 19, 2017)

JimDawson said:


> This is the way I do it.  In this case grinding the 5C taper in a collet chuck.  Harbor Freight air die grinder.
> 
> View attachment 242082


Did you make the attachment or is that commercially available? 



richl said:


> Not sure this is even a good idea... but... would making a soft jaw to attach to the existing jaws a worth while idea here? From the picture the existing jaws seem a bit short already, and grinding a bevel on them will only decrease that more... I don't see stuff like this mentioned anywhere so I am just tossing out ideas for public consumption...
> 
> Nice little diy project. Ever notice that small projects soon become big projects by the time you factor in all the additional steps and tools required...



Wouldn't bother me. Right now it's a chuck I can't use...for much.  Oh my project list... lol  

Paul


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## Silverbullet (Sep 19, 2017)

expressline99 said:


> The reason I'm even considering any of this is for a 3 jaw chuck that I have mounted/bought a while back. But the jaws are completely flat.
> View attachment 242080
> 
> 
> ...


I think I'd braze some 1/2" drill rod with a flat milled on them to each jaw then I'd mill the angle on each jaw . After that I'd grind a shallow curve on the three jaws. Just how I'd approach the problem.


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## Bob Korves (Sep 19, 2017)

JimDawson said:


> This is the way I do it.  In this case grinding the 5C taper in a collet chuck.  Harbor Freight air die grinder.
> 
> View attachment 242082


I have a setup almost exactly like that, picked up in a tool lot, along with many dozens of wheels.


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## Bob Korves (Sep 19, 2017)

expressline99 said:


> Want a surface grinder project?


Come on down!


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## JimDawson (Sep 19, 2017)

expressline99 said:


> Did you make the attachment or is that commercially available?



I made the holder.


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## expressline99 (Sep 19, 2017)

Bob Korves said:


> Come on down!



I know I'm pretty horrible. I need to get over that way...I'm missing a lot of fun I hear.


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## Bob Korves (Sep 19, 2017)

Paul, I also have a Dumore 44-011 tool post grinder with all the extra stuff...


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## expressline99 (Sep 20, 2017)

Bob Korves said:


> Paul, I also have a Dumore 44-011 tool post grinder with all the extra stuff...



Oh yeah I remember that now!  Do you have anything with a 1-1/2"-8 tpi spindle thread?


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## expressline99 (Sep 20, 2017)

JimDawson said:


> I made the holder.



Had I looked at your signature I wouldn't have asked that!  

Paul


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## uncle harry (Sep 20, 2017)

BGHansen said:


> So I'm guessing you'd advance the cut or grind by tightening the chuck jaws?  Make a pass with the lathe running, back the tool out, shut off the lathe, turn the chuck key a little and repeat?  As Bob mentioned above, you'll be limited in diameter unless you bevel the jaws.  Might be easier to just mount a die grinder on the close slide as Rich mentioned above.  Nice L-W chuck by the way, have one of their dividing heads.  They made great quality stuff.
> 
> Bruce



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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## eeler1 (Sep 20, 2017)

Hey Paul, the title made me look.


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## expressline99 (Sep 20, 2017)

eeler1 said:


> Hey Paul, the title made me look.


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)



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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## uncle harry (Sep 20, 2017)

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?
> 
> 
> 
> ...


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.


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## eeler1 (Sep 20, 2017)

Yes, need a picture or it never happened, and you probably never even thought about it except in your dreams.  

Here's a link from the Logan site about the fixture for putting pressure on the jaws when you grind them;

http://lathe.com/tips/chuck-jaw.htm


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## Dabbler (Sep 20, 2017)

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.


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## Kernbigo (Sep 20, 2017)

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 .


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## expressline99 (Sep 21, 2017)

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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## uncle harry (Sep 21, 2017)

expressline99 said:


> I did find a video with the spacer method being used:
> 
> 
> 
> ...




_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._


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## NortonDommi (Nov 1, 2017)

Here's something from an old Popular Science. I'd grind the jaws to the conventional shape and then grind kie this:


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## Kernbigo (Nov 1, 2017)

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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