How I Refurb Old 3-Jaw Chucks (17 pictures)

If the scroll is worn, or scored from chips getting caught in it, or there is excessive clearance between the hole in the scroll and the central column inside the chuck,or the jaws are too loose in their slots,it cannot be made accurate,regardless of how much it gets prettied up. Generally a beat up looking chuck is not worth trying to rehabilitate. It was never cared for.

Also,I have found that running the lathe backwards in reverse as fast as it will go while grinding produces much the better finish,counterintuitive as it may seem. Running it slow invites harmonic patterns to be made on the metal you are grinding.

Of course,make sure the surface you are grinding is running in the opposite direction from your wheel.
 
I am not trying to say that the steps I have outlined are a fix-all for chucks. I have done 5 or 6 chucks and they have all come out much better than they were before I worked on them. When I started refurbing chucks, it was because I had a young family and could barely afford to have a lathe at my home hobby shop, let alone a new chuck for it. This is what I was able to do at the time and the chucks were MUCH better when done.

Now days I guess I could afford a new chuck but my current lathe has an 8" chuck with a D1-6 mount. When I got it, the original chuck from 1983 was with it. I pretty much did this same process on it. It seems to me to be as good as I would expect from a new chuck and after grinding the outside of it, it now looks nice and doesn't have all the nicks and dings from being used for many years. I spent the time on it and ended up saving myself several hundred dollars by not buying a new chuck.

This process has worked well fo me so I thought I would share my experience.

As for making it look pretty, that is just an added bonus.

Charlie
 
I am all for fixing machines and tools up to make them look nice. Do that myself a lot. But,getting a chuck that has been allowed to get all beat up is not a good candidate for restoring accuracy to.

What lathe was it that could generate a coarse enough cross feed that it could be used to re grind the threads in a scroll? The only one I ever saw was my 1st. lathe-a Sears Atlas. The cross feed fed at the same rate as the leadscrew. Haven't seen another manual lathe that would do that. And,when the scroll threads were resurfaced,what looseness did that cause in the threads on the back of the jaws?

What about repairing the wear between the hole in the scroll,and the central column of the chuck body? If the center hole is worn,how do you accurately center it? It probably is not truly round,and has a worn surface.

I don't mean to run everything down here,but am trying to state facts so guys won't be mislead: I used to make a lot of steel spinning chucks. I'd make a duplicate threaded spindle and never remove it until the chuck was done. However,no matter what I did,there was always some runout in the spinning chuck when it was screwed onto the spindle of the actual lathe it was to be used on. They expected this,and used a hollow front heavy steel ring. The hollow front of the ring was against the back of the chuck,and they would tap on the ring and tilt the chuck a little until it would run true. Thus,I state that a chuck you are grinding should ONLY ever be ground in situ on the lathe it is to be used on. If not,you will very likely have some run out. Grinding the jaws will incorporate this runout into the chuck,and will produce runout in the work you clamp in the chuck when it is placed onto the lathe it will be used on. AT LEAST,grind the inside edges of the jaws on the real lathe you are using the chuck on for best results.

When chuck jaws get bell mouthed,it is because they have been tightened too hard,usually with a "cheater bar". This not only springs the jaws,it may well deform the slots they slide in in a localized spot. Grinding the jaws true may only result in the jaws holding work true in the spot where the slots were deformed,IF you were lucky enough to have had the jaws at the EXACT spot where the slots were deformed in the first place. When you chuck up a different diameter,it may well not run true,since you are not in the deformed area.
 
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Thank you for answering my questions,Rick. But,I spoke with respect to the facilities that a home shop machinist might have. This is,after all,a hobby machinist's forum. Even with the relatively complete shop that I have,I have no such facilities for grinding scrolls in my shop.Nor do I think most others here would also have at home. I know some may.

I have a Hardinge HLVH lathe,a Grizzly 16" X 40",a Bridgeport clone,A Decklel fp1 German mill, A Harrison universal horizontal mill(but not the vertical head,nor a quite complete universal indexing outfit for spiral milling, Deckel 3d pantograph(not yet working), drill press,K.O. Lee tool and cutter grinder,4" x6" horiz/vertical bandsaw,Roll In metal bandsaw,14" vertical contour bandsaw and shaper. But no facility for re cutting scrolls.

So,I have to admit that if you have very advanced machinery,it can be done,though not by me!!:) My shop is strictly manual. I think we need to be realistic about what a hobby machinist might have available.

Sprung by cheater bars,or by crashes,a chuck with jaws bent is still in the same condition,I would think. Perhaps even worse if it was crashed. For the jaws might not only be rendered bell mouthed,but might also have been twisted from having the stock ripped from it. The damage to the slots likely has still been done.

I submit that recutting the backplate on the original lathe once the chuck has been ground all over will not result in those reground surfaces running true. It needs to be done on the user lathe. I rely upon the face of a chuck being true,as I often use it as a datum surface when clamping work in the jaws,when I tap the work back against that face while tightening the jaws.

Sleeving the chuck's central column does not guarantee concentricity,unless you have a way of indicating from the outside diameter of the scroll (or whichever surface suffered the least wear in use),so you could re cut(or grind) the inside hole of the scroll. Chucked in a lathe,that might be difficult. I suppose I might could glue it down to a plate on a rotary table,and thus have the o.d. free for centering up with a dial indicator. But if the scroll is hardened,as most are,these days, grinding it would be necessary. Actually,I could manage that in my vertical mill,though I do not like grinding things in the mill.

My point here is: who has the means to do these things in a home shop? And I am a retired toolmaker. I suppose success might depend upon what performance the operator deems satisfactory in his 3 jaw chuck. My most used chucks for years have been 8" Bison 4 jaw self centering chucks. Properly mounted on back plates turned on the parent lathe,mine have delivered less than .001" runout. I have a never used 12" Cushman that does not deliver that degree of accuracy. When I started out,.003" in a 3 jaw chuck was what I considered good performance from new old stock Union 6" chucks that I managed to find. These days,I am expecting better,and getting it from the moderately priced Bisons. My HLVH uses an adjustable Buck chuck that is quite accurate.
 
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If I had the inclination,and the rest if the parts for my universal index head,o.k.. The real problem is,I just don't have the inclination. I can do a more interesting job and get paid enough to buy several chucks in less time than I could spend refurbishing a worn chuck. There is a point where something isn't practical. Not that I don't spend more than enough time on impractical work. This one just doesn't grab me.

Now,making a miniature milling machine,like the blue one on another thread-that I find more interesting. But,I'd make it large enough to actually be usable.

When I was at Cabin Fever last year,they auctioned off the very beautiful approx. 1/3 scale working model of a HLVH lathe that a German gentleman spent something like 15 yeas off and on working ion. THAT,I'd like to have had to use in my study at night. It was pretty silent. It went for about $16,000.00 dollars. I think it should have gone for many times that. Over my limit,though!

Making the lengthened 18th.C. style door lock was a fairly simple job. Took a few days,and would buy 3 Bison chucks. I just made the case and keeper,and lengthened the internal parts. The old lock was 5/8" too short. It goes into a historic house in Va.. The old lock is the one on the right. The brass keeper is the object above the new lock. The keeper for the old lock had been lost. The new lock was not particularly carefully polished,and has a few dings. They wanted it looking a bit old as it went on an 18th.C. door.

This is not my favorite type of work,nor by any means my best. It puts things in perspective,though.

The surveyor's compass is some of my better work. I was commissioned to make it for David Brinkley,the famous newsman who started in the 1950's . It is about 14"long. The dial is dead silvered and hand engraved. The engraving was filled with black,as was the original from 1802. I'll present it in detail at another time. I made everything on it,even the glass levels,from glass tubing which I put a small amount of bend into.

If a person wants the challenge of making or rebuilding a chuck,I am all for it. Actually,I have thought making a chuck would be interesting. I have made some 18th.C. type lathe chucks for the museum(Williamsburg) where I worked for 39 years,but they were not scroll chucks.

The scale HLVH lathe is seen below. It is about the size of a jeweler's lathe. It will cut all kinds of threads. The maker not only made the standard QC gearbox for it,but a large number of extra gears for cutting threads beyond the range of the normal gearbox,just like the full size HLVH will also do. It was large enough to do some real work on,too,if you were a model maker,or a jeweler.

IMG_0204.JPG new and old lockjpg.jpg brinkley compass.jpg
 
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I certainly did not mean to discourage anyone from rebuilding chucks,or anything else. The fun of doing work is whatever interests the person,and I have done things that made others wonder WHY I just didn't buy it. Like making my own wood carving duplicating machine. I sold that one to Williamsburg when I retired,and am making a smaller one for home shop. My former journeyman just bought his for making gnstocks,and doesn't see the point of making one.

He can carve gunstocks and easily pay for the machine.
 
What would happen if you added weld with a TIG welder to the old jaws rather than grinding them back? Would the TIG-ing soften hardened areas of the jaws? cause them to warp?
 
Thanks Charlie,
The 431, same chuck I now have on my Logan
 
george wilson said:
If I had the inclination,and the rest if the parts for my universal index head,o.k.. The real problem is,I just don't have the inclination. I can do a more interesting job and get paid enough to buy several chucks in less time than I could spend refurbishing a worn chuck. There is a point where something isn't practical. Not that I don't spend more than enough time on impractical work. This one just doesn't grab me.

Now,making a miniature milling machine,like the blue one on another thread-that I find more interesting. But,I'd make it large enough to actually be usable.

When I was at Cabin Fever last year,they auctioned off the very beautiful approx. 1/3 scale working model of a HLVH lathe that a German gentleman spent something like 15 yeas off and on working ion. THAT,I'd like to have had to use in my study at night. It was pretty silent. It went for about $16,000.00 dollars. I think it should have gone for many times that. Over my limit,though!

Making the lengthened 18th.C. style door lock was a fairly simple job. Took a few days,and would buy 3 Bison chucks. I just made the case and keeper,and lengthened the internal parts. The old lock was 5/8" too short. It goes into a historic house in Va.. The old lock is the one on the right. The brass keeper is the object above the new lock. The keeper for the old lock had been lost. The new lock was not particularly carefully polished,and has a few dings. They wanted it looking a bit old as it went on an 18th.C. door.

This is not my favorite type of work,nor by any means my best. It puts things in perspective,though.

The surveyor's compass is some of my better work. I was commissioned to make it for David Brinkley,the famous newsman who started in the 1950's . It is about 14"long. The dial is dead silvered and hand engraved. The engraving was filled with black,as was the original from 1802. I'll present it in detail at another time. I made everything on it,even the glass levels,from glass tubing which I put a small amount of bend into.

If a person wants the challenge of making or rebuilding a chuck,I am all for it. Actually,I have thought making a chuck would be interesting. I have made some 18th.C. type lathe chucks for the museum(Williamsburg) where I worked for 39 years,but they were not scroll chucks.

The scale HLVH lathe is seen below. It is about the size of a jeweler's lathe. It will cut all kinds of threads. The maker not only made the standard QC gearbox for it,but a large number of extra gears for cutting threads beyond the range of the normal gearbox,just like the full size HLVH will also do. It was large enough to do some real work on,too,if you were a model maker,or a jeweler.
Click to expand...


George
This a bit off topic but you reminded me of an old gentleman I once knew, probably 50 years ago. During the second world war he served as an instrument mechanic in northern Africa. When I met him we got to be friends pretty quickly because of my interest in machine tools. He was getting ready to retire to the Rocky Mountain foot hills to spend his days fishing and I was trying to get some knowledge. He had a little shop out in the country and he showed me all the machine tools and accessories he had made/built himself including a small lathe. More like a jewelers lathe. He had made collets for it as well as chucks etc. All his parts/collets had been hardened with cyanide. Believe it or not he built this lathe in a tent in a desert in North Africa with his only tools being a vice, square, hacksaw, drill and files. You wouldn't believe the beautiful job he made of it. He left me a few of the accessories he had made for some of his tools he didn't take with him and from there I received my inspiration to do some of the things I do now.
Nick
 
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