# SB-9 3 JAW CHUCK PROBLEM, no MY stupidness



## 65arboc (Sep 17, 2014)

So I've had this 1937 SB 9" for a few months now and have made quite a few things and have really learned a lot on this forum thanks to a lot of people. I did read about taking chucks apart and how you should mark the jaw slots and the jaws and I have done this in the past. Well last night I took a 3 jaw apart and DID NOT mark the slots:nono:so now my question of course is how do I put the jaws back in without knowing where each one goes. Trial and error maybe? BTW the jaws are marked 1-2-3.

Thank you,

Jim


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## george wilson (Sep 17, 2014)

Rotate the scroll until the last thread on it is about to go across one of the slots that the jaws fit into. Then,insert the #1 jaw. Rotate the scroll till it is about to cross the next slot as you are turning the chuck was handle clockwise. Then put in the #2 jaw.

Same for the #3 jaw.

I hope this is clear enough. It's the best I can do this morning.


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## middle.road (Sep 17, 2014)

If there are no corresponding numbers stamped on the chuck body look for some 'dimples'.
I have one for the Logan that has what looks like center punch'd dimples next to the slot to match the number on the jaws.

_Dan


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## 65arboc (Sep 17, 2014)

george wilson said:


> Rotate the scroll until the last thread on it is about to go across one of the slots that the jaws fit into. Then,insert the #1 jaw. Rotate the scroll till it is about to cross the next slot as you are turning the chuck was handle clockwise. Then put in the #2 jaw.
> 
> Same for the #3 jaw.
> 
> I hope this is clear enough. It's the best I can do this morning.



Thanks George for the quick reply. So you are saying #2 and #3 wont go in the last thread on the scroll, only #1.

Dan,

There are no dimples as this chuck has been cleaned up on the outside with a tool bit. It had been beat on pretty bad before so the outside was turned. There may have been marks but they are machined off now.

Thanks

Jim


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## higgite (Sep 17, 2014)

65arboc said:


> Thanks George for the quick reply. So you are saying #2 and #3 wont go in the last thread on the scroll, only #1.
> 
> Thanks
> 
> Jim



Hi Jim,

What George is saying is that the jaws must be inserted in 1,2,3 order. They all engage at the same spot on the scroll, regardless of which slot or what order they are inserted in. But, if not inserted in 1,2,3 order as the scroll progresses from slot to slot, the jaws won't meet in the middle. Hope this helps.

Tom


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## chips&more (Sep 17, 2014)

You are getting very good advice above. I would also like to add. With the jaws out/removed. Try fitting one jaw at a time in each slot. You might find that each jaw fits a particular slot best for a smooth and least wiggle fit.  Then mark accordingly…Good Luck.


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## 65arboc (Sep 17, 2014)

higgite said:


> Hi Jim,
> 
> What George is saying is that the jaws must be inserted in 1,2,3 order. They all engage at the same spot on the scroll, regardless of which slot or what order they are inserted in. But, if not inserted in 1,2,3 order as the scroll progresses from slot to slot, the jaws won't meet in the middle. Hope this helps.
> 
> Tom



Got it, doesn't matter which jaw goes in which slot as long as I go 1-2-3. I thought each slot had to have the exact same jaw put back in that I took out. Now I'm ok.

Thanks guys!

Jim


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## george wilson (Sep 17, 2014)

It could POSSIBLY be that with the jaws inserted in a particular slot,you might get a tad better concentricity. Stranger things have happened,odd as it might seem.

Why not try putting the jaws into given slots. Mark the slots with a magic marker. Try the chuck for concentricity with an accurate round item,like the shank of an end mill. Then,move the jaws one slot over. IF you fine one set of slots makes the chuck more accurate,then,stamp them 1.2,and 3 so you'll know how to assemble the jaws for best results next time.

This is just an experimental suggestion,but it might bear fruit.


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## 65arboc (Sep 17, 2014)

george wilson said:


> It could POSSIBLY be that with the jaws inserted in a particular slot,you might get a tad better concentricity. Stranger things have happened,odd as it might seem.
> 
> Why not try putting the jaws into given slots. Mark the slots with a magic marker. Try the chuck for concentricity with an accurate round item,like the shank of an end mill. Then,move the jaws one slot over. IF you fine one set of slots makes the chuck more accurate,then,stamp them 1.2,and 3 so you'll know how to assemble the jaws for best results next time.
> 
> This is just an experimental suggestion,but it might bear fruit.



Well by golly George that was exactly what I was planning on doing tonight when I get the rest of it apart and cleaned up. It's been sitting a while so who knows what I'll find inside. I love this forum, you guys are great!:drink2:


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## higgite (Sep 17, 2014)

chips&more said:


> You are getting very good advice above. I would also like to add. With the jaws out/removed. Try fitting one jaw at a time in each slot. You might find that each jaw fits a particular slot best for a smooth and least wiggle fit.  Then mark accordingly…Good Luck.



Good point.




george wilson said:


> It could POSSIBLY be that with the jaws  inserted in a particular slot,you might get a tad better concentricity.  Stranger things have happened,odd as it might seem.
> 
> Why not try putting the jaws into given slots. Mark the slots with a  magic marker. Try the chuck for concentricity with an accurate round  item,like the shank of an end mill. Then,move the jaws one slot over. IF  you fine one set of slots makes the chuck more accurate,then,stamp them  1.2,and 3 so you'll know how to assemble the jaws for best results next  time.
> 
> This is just an experimental suggestion,but it might bear fruit.



Good point, George. I should have mentioned that. Also, what I did with my  cheap Chinese 3-jaw scroll chuck was to number the jaw screws and try  tightening each one a little at a time in various sequences. I was surprised to find that with my chuck it does make a  difference. The best sequence for my chuck is 2-3-1. The TIR of  round stock measured next to the chuck varied from less than .001" for a  .300" diameter rod to .002" for a 1" diameter rod. The best I measured  prior to that when tightening the jaws with just one screw was .003", often more.

Tom


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## Whyemier (Sep 17, 2014)

The slots for the jaws on my Grizzly 3 jaw are factory stamped 1-2-3 for the corresponding jaws1-2-3. It seemed to make a difference in a smoother operation when I closed the jaws after I put the corresponding jaw in the numbered slot.

This is the only 3 jaw chuck I' ve ever seen this on.  Otherwise what was said below, watch the scroll insert the jaws in  order.


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## middle.road (Sep 18, 2014)

65arboc said:


> Dan,
> 
> There are no dimples as this chuck has been cleaned up on the outside with a tool bit. It had been beat on pretty bad before so the outside was turned. There may have been marks but they are machined off now.
> 
> ...



Well that explains the missing markings...


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## Don B (Sep 18, 2014)

As others have suggested trial fit the jaws in each position, it will make it easier if you do this with the scroll out and slide the jaws to their furthest extents, it might be quit obvious where each went, but remember still 123 counterclockwise when doing this, and if the jaws are reversible remember to try them both ways.

When you try the chuck body halves remember to rotate it to the three positions and check for fit, try it with the scroll in and check for binding in all three positions.

When things are back together you'll find one of the three tightening pinions will provide the best and most consistent accuracy, best to mark this one, the better quality chuck usually mark this pinion as 0 (zero)

Don't feel to bad, I don't know anyone who hasn't done this same type of thing at some point, I'd like to say I've only made that mistake once but I'd be lying, LOL, good luck)


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## Charles Spencer (Sep 18, 2014)

Whyemier said:


> The slots for the jaws on my Grizzly 3 jaw are factory stamped 1-2-3 for the corresponding jaws1-2-3. It seemed to make a difference in a smoother operation when I closed the jaws after I put the corresponding jaw in the numbered slot.
> 
> This is the only 3 jaw chuck I' ve ever seen this on.  Otherwise what was said below, watch the scroll insert the jaws in  order.



I have four older three-jaw chucks and all of them are numbered this way.  They are all US made and include Skinner and Union.

Charles


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## tonlin (Sep 18, 2014)

Hey Jim,

I echo all the good advice already given and want to add that I did this very thing with my first chuck (before I learned better). When I put it back together, the concentricity was off by a lot and I was dumbfounded. With much help from more knowledgeable guys, I figured out that the chuck had been reassembled wrong when I got it so somebody ahead of me must have done the same thing and didn't know it or how to fix it. Now, when I get a new chuck, unless its brand new from the factory, I check it and if its not perfect I disassemble it, and reassemble with different jaw order until I get the one that is right. Taught me not to assume that they are correct when I get them! 

Good luck on yours,
TJ


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## Whyemier (Sep 18, 2014)

Charles Spencer said:


> I have four older three-jaw chucks and all of them are numbered this way.  They are all US made and include Skinner and Union.
> 
> Charles



I will have to check the one I use on the SB9C.  Learn something most every time I come on this site.


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## 65arboc (Sep 19, 2014)

I got it all back together last night but had to move 1-2-3 jaws twice before I felt they were in the correct slots. So I put it back on the spindle and tightened up a wrist pin in the chuck. I had .003 runout on the wrist pin. This is a 1937 SB and the chuck jaws are pretty worn on the bearing surface. I think I may make up a jig for my Dremmel and grind the jaws true. Oh well just another project. Never had so much fun in my garage. Thanks for all the advice and comments.

Jim


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## george wilson (Sep 19, 2014)

When I was starting out,I had a nos 5" Union chuck. .003" runout was the best I got with it.It had never been used,and came with both sets of jaws.

I also have a very old USA made 4 jaw universal chuck that has never been used. I discovered its scroll is soft as butter. I think some of the old USA made stuff is just not as good as some of the better brands today,like Bison. My Bison 4 jaw universal can center up stock to .001" or better.


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## 65arboc (Sep 19, 2014)

george wilson said:


> When I was starting out,I had a nos 5" Union chuck. .003" runout was the best I got with it.It had never been used,and came with both sets of jaws.
> 
> I also have a very old USA made 4 jaw universal chuck that has never been used. I discovered its scroll is soft as butter. I think some of the old USA made stuff is just not as good as some of the better brands today,like Bison. My Bison 4 jaw universal can center up stock to .001" or better.



Hey George,

   This happens to be a Union Chuck. Do you  think I could grind the jaws to .000 tolerance or should I just deal with it?

Jim


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