Repairing an old Hardinge lathe chuck

I have an old Hardinge 5" 4-jaw chuck model 36-HC.

Parts are no longer available for the chuck.

3 of the 4 jaw screws look similar to the photo below.

I'm currently using the chuck as a rotary table but I'd like to use it on the lathe.

Does it make sense to fill the chuck key holes with something like JB Weld and rebore them?

Gary

No, dont do that!
I would keep an eye on HGR, they are listing many Hardinge, the chucks end up separated, and listed as chucks, sometimes they know what they fit sometimes not, might find one for parts, or another one.
I have been cherry picking Cushman solid steel chucks, they have pulled from Lodge & Shipley Powerturn lathes.

garyrice said:

I have an old Hardinge 5" 4-jaw chuck model 36-HC.

Parts are no longer available for the chuck.

3 of the 4 jaw screws look similar to the photo below.

I'm currently using the chuck as a rotary table but I'd like to use it on the lathe.

Does it make sense to fill the chuck key holes with something like JB Weld and rebore them?

Gary

View attachment 301189

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Glue is not a valid repair for broken hardened steel.

If you have one good (no cracks around the square hole) screw, I will buy it to repair a chuck with one bad screw. But I suspect if three of yours are badly broken, the other will have cracks.

Larry

It's not that hard to make new screws, .........if I could do it in my mid teens - almost anyone who can half find their way round a lathe can.

Keep an eye on E-bay, a couple years back during house cleaning I auctioned off quite a few surplus Hardinge items, they went a lot cheaper than I thought they would. I think I may have gotten $35 for a 5" 3 jaw, chuck was in great shape, only issue was I made a new key for it, so the key wasn't vintage.

Limy Sami said:

It's not that hard to make new screws, .........if I could do it in my mid teens - almost anyone who can half find their way round a lathe can.

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Your "mid teens"?

He needs guidance from a younger craftsman, then.
Bronze Age chuck screws went out of style when the Iron Age came in.



Meanwhile... 4-jaw independent chuck accuracy being in the hands of the craftsman, rather than at the mercy of a precision - unworn, undamaged - scroll plate - as 3 or 6 jaw chucks are?

Even a cheap 4-J independent lets you get work DONE while searching for a BETTER one.
And "cheap" they surely can be:

Sanou k72 lathe chuck 80/100/125mm 4 jaw independent hardened reversible tool Sale - Banggood.com|Shopping USA

I have one. Fair decent Cast Iron body. NO MATCH for my Hardinge, Cushman, or the forged steel Polish, Japanese, or Swedish made ones, but....

Not half bad for the silly-low price, delivered, brand-new, no wear, no damage, either.

thermite said:

Your "mid teens"?

He needs guidance from a younger craftsman, then.
B.

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You should be making them out of flint then.

Yes I can make them. But I can't harden them. I suspect hardening them is rather important.

Gary

I have a couple Sanou chucks.

I don't really NEED the Hardinge to be a chuck again. I'd just LIKE it to be a chuck again.

Gary

Limy Sami said:

You should be making them out of flint then.

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Nephrite, actually. I kid you not.

Picked up an appreciation for its (pre)historical importance - not as decorations - but as one of the toughest known stones for working wood, bone, shell, leather scraping and drilling, making knives, fishhooks, arrowheads, even musical "bells", whilst averaging nine TONS of it a year, year after year through my Jewelery Manufacturing shop. Ours was imported as drilled beads from "Hoover Hong", Taiwan, ROC.. who got their raw material from.. of all places.. Alaska, USA!

http://archpress.lib.sfu.ca/index.php/archpress/catalog/download/68/38/1903-1?inline=1

The gnarlier structure makes it superior for several types of stone tools, axe heads as need to stand impact, for example. Chisels, even!

Downside is it doesn't take to knapping - a relatively FAST process towards a rather GOOD slicing edge. Two raw flints, one single impact, minimum, and you could be "in bizness" with a sharp edge immediately once you get the hang of flint.

You must "edge" the "industrial" jade OTOH, the patient and SLOW abrasive way.

That teardrop-shaped amulet an Asian woman may wear? Her distant ancestral G'G'mother's version of an ever-handy emergency version of a "Swiss Army knife", ready to scrape an animal hide, tend a wound, make a hole for cordage, or help prepare food if the need arose.

Every young kid should learn to do BOTH at least for one tool. Then the general population is prepared to survive in case Sandalistas or Bidenfistyah's get control of the economy.

I also have a small chuck with this same problem except it is only one screw. I have gotten buy for the last 10 years with it that way but it is a super big pain in the but. I have been racking my brain for years to think of a good way to fix it. I thought of making new but don't have a way of making the square blind hole for the key. I had thought about using a square piece of brass in the hole as a dam/Backer and then trying to build up just around the broken out side using the tig. But it's my only 4 jaw for that lathe and I haven't been willing to risk wrecking it. A chuck came up on kijiji recently for my lathe but 300 for a 6" chuck and drive dog plate was far more than I was willing or allowed to spend. Seems a waste waste to get rid of an otherwise good chuck. I am surprised on a machining forum how often it is said to just replace something instead of fix something.

Gary,
I've got half a dozen of those Hardinge 5" 4 jaws. Seems that the Hardinge vendor (Pratt Burnerd) at one time changed the design of the socket end of the screw. The earlier design (I assume) like yours seems prone to splitting like yours. About half of mine show signs of damage there with no other damage to the chuck. In the later design, the thread extended all the way to the top of the screw, allowing the thread to reinforce the square hole. I've never seen one of those split.

I've got another 5" 3 jaw, also OEM Hardinge but made by Skinner, which has hex sockets in the screws. I really like that arrangement and it certainly would be less prone to splitting.

I have the material and plan to make two new sets of screws to replace my broken ones. I intend to broach the socket for a hex key but haven't gotten around to it yet. Waiting for an excuse to get a rotabroach, I guess.

PM sent.
Jim

Holes in jaw screws for chuck keys.

I cheat, forget the square turn down an allen bolt head and loctite or soft solder it in to a machined recess in the screw head.

I've not wrung one off yet (up to 8'' chucks)

Though I have seen square broached sleeves in various sizes available from some clamping parts etc etc Co's in the US .

Oh yeah, I don't heat treat - just m/c the screws from silver steel (drill rod in the US) and call it good.

Limy Sami said:

It's not that hard to make new screws, .........if I could do it in my mid teens - almost anyone who can half find their way round a lathe can.

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“ It's not that hard to make new screws,”

That’s what she said Limi.

Anyone somewhat skilled can make new screws on a lathe that are as good as the original *for a 4-jaw chuck*.
Why dont You make some ?

Chuck jaws and ways are very difficult to do well.
Very very different animal.

You need to end up with extreme radial precision under high complex cantilever loads.

Fwiw..
I think I might -perhaps- be able to do a 3-jaw chuck and parts.
Well.
I would expect 2-3 attempts and 200-300 work-hours.
If the end result is not equivalent to Schaublin/Weiler/et al it is not worthwhile -- for me -- imo.
Of course a chuck like that from me would cost 15.000$ and up, based on work hours, so no-one would ever buy one.

Independent chuck screws are trivial.

Scroll chucks of high quality are hard to do.
I would look at schunk or similar for an example and disassemble one, for inspiration.

It is perfectly possible to do (much) better than any industrial product ..
as long as someone somewhere pays for it, every now and then.
I´ve made a life and career of doing better than best industrial solutions in numerous fields.

Trueturning said:

“ It's not that hard to make new screws,”

That’s what she said Limi.

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I told you she was a good sport, .......... I hope she made you a nice cup of tea afterwards.

"That teardrop-shaped amulet an Asian woman may wear? Her distant ancestral G'G'mother's version of an ever-handy emergency version of a "Swiss Army knife", ready to scrape an animal hide, tend a wound, make a hole for cordage, or help prepare food if the need arose."

Bill, you have been caught lying again,and again,

Morse taper 2 met you in person and determined you are a pure Bull Shitter.

You have never worked an honest day in your empty little poopy life!