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Hardinge HLV-H Chuck Jaws not closing parallel

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Plastic
Joined
Jun 27, 2022
I lurk around here a lot, soaking up tip and tidbits of know-how as much as I can, but this is my first post.

I have a Hardinge HLV-H that I mostly use with collets. I have a 5" Hardinge 3-jaw chuck (Buck?) with the integrated taper attachment. Could not find a part number or a serial number but maybe I need to look harder.

Was working with some 1.5" round stock this weekend and I noticed that when I close the jaws on the stock, the jaws make contact with the stock first deep inside the chuck. The stock is then free to wiggle quite a bit! There is a significant gap at the outer tips of the jaws.

I can tighten the jaws lightly, tap the stock until it has a minimal run-out and then clamp down but I don't think that is an acceptable way to work.

I pulled the jaws out, cleaned everything up and checked the fit. The jaws are very snug in their grooves. If I place the jaws face-to-face on a surface plate, they do appear be out of square, but I'm not sure if I trust the teeth as a reference surface.

I was wondering if this was normal?

If not, should I get new jaws or try to re-grind these jaws?

Thanks!
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
If the chuck has a taper mount in one piece with the chuck body, it is rather old, and not made by Buck. Decades ago, Hardinge sold Pratt Burnerd (England) 5" three-jaw chucks marked Hardinge and Made in England and Model AHC. They have one-piece jaws, with two sets included when new. Hardinge also sold one-piece soft jaws for these chucks. Inaccuracy is rather normal in old chucks. I once made a jaw preloader and used a small Dumore toolpost grinder to true the jaws on one of these chucks. The better solution was to get a good quality new adjustable body 3-jaw chuck with two-piece jaws and separate adapter plate. Or use a four-jaw.

After the Pratt Burnerd chucks, Hardinge sold Buck Ajust-Tru chucks with separate adapter plates. There are 5" 3-jaw chucks with one-piece jaws and 6" 3-jaw chucks with two-piece jaws. Some of these chucks have the little round aluminum label that says Hardinge by Buck. But Buck sold the same chucks and adapters with just the Buck label for many years before their deal with Hardinge. I have experienced the out of parallel jaw issue with Buck chucks, so again, inaccuracy is rather normal on old chucks.

Pratt Burnerd America in Kalamazoo, MI will regrind the jaws on chucks, but I have never had one done. As I said, I prefer to get new chucks.

Larry
 

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Plastic
Joined
Jun 27, 2022
I went over the chuck, this time with a flashlight, and I finally spotted the model and serial numbers. Pretty faint!

It is a Model 30AHC. I have both sets of jaws.

I have been thinking about getting an Ajust-Tru chuck as it would seem to be easier then the 4-jaw. I may also set up to re-grind the jaws but I'll see what the cost would be to have it done.

Time to go shopping I guess!!

Thanks!
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
You must have a preloader in order to grind chuck jaws. The preloader has to load the jaws in the same way as the work for which the newly ground jaw surfaces will grip the work. I made one for the 30AHC chuck from one large steel flat washer and three smaller ones, each with a saw cut to create the jaw gripping surfaces. Here are pictures. Yes, I did not take much time to make pretty welds with my wire welder. It worked.

Larry

Chuck jaw preloader 1 small.JPG
Chuck jaw preloader 2 small.JPG
 

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Plastic
Joined
Jun 27, 2022
I knew the jaws needed to be preloaded and I was mentally wrestling with how to do that.

Your design is very smart! Doesn't matter if it's ugly, it will still still work well!
 

Mark Rand

Diamond
Joined
Jul 9, 2007
Location
UK Rugby Warwickshire
Another point about the 30AHC chucks:- New hard jaws are pretty much unobtaiable. I managed to get a set of new-old-stock soft jaws and a new scroll for mine. To be honest, I havent fitted them yet, I just use the import chuck that I mounted on a backplate for when I'm doing rough work that doesn't go in collets or step chucks.
 

car2

Stainless
Joined
Sep 19, 2009
Location
Apex, NC
Another note on the Hardinge AHC chucks; if you don't have the original serial-numbered jaws that go with the same serial-numbered body, all bets are off even if in good condition. Not only were the original serial-numbered jaws ground with the body, there are slight differences in the dimension of jaws and bodies from different runs. Sometimes the jaws will fit easily in the slots, sometimes not, and I have jaws that will fit in the t-slots well, but the seating flats of the jaws are different, etc...(I probably have 12 misc orphaned hardinge AHC chuck jaws (2 of some SN''s, 1 of others)--after a few years finally managed to get some good-condition matched bodies and jaws.
If you can find a good condition ACH chuck (probably getting rare now), probably the only significant advantage to those is they are compact since the spindle taper fits up in the chuck. Otherwise, they have no 2-piece jaws or "set-tru" capability.
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
Another point about the 30AHC chucks:- New hard jaws are pretty much unobtaiable. I managed to get a set of new-old-stock soft jaws and a new scroll for mine. To be honest, I havent fitted them yet, I just use the import chuck that I mounted on a backplate for when I'm doing rough work that doesn't go in collets or step chucks.
Hardinge did sell jaw sets, inside, outside and soft blanks. I have a few still in the box. They are, of course, rare and I do not have a new set of outside jaws.

I have never installed a set of the new jaws, so I cannot comment on how they fit or if they would grip properly and run true. If preloaded correctly, the soft jaws should do OK.

Larry

DSC03028 small.JPG
 

majohnson

Cast Iron
Joined
Jan 3, 2013
Location
Erie, CO
When I bought my lathe the other set of jaws did come with 3 jaw chuck. But I never use it the run out is .003-.005 and that after trying everything to get it down.
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
When I bought my lathe the other set of jaws did come with 3 jaw chuck. But I never use it the run out is .003-.005 and that after trying everything to get it down.
That sounds like a normal runout for a run of the mill used non-adjustable 3-jaw chuck. I do have some very expensive Swiss universal chucks for my watch lathes that are very accurate.

On my Hardinge and Clausing lathes, I use adjustable Pratt Burnerd, Reischauer and Buck universal chucks and 4-jaw independent chucks and dial them in to my desired near-zero runout. I bought a new Bison adjustable 3-jaw chuck years ago and found the adjusting screws were not at 90 degree intervals. It was a bad design and hard to adjust, so I sold it cheap.

Larry
 

cyanidekid

Titanium
Joined
Jun 4, 2016
Location
Brooklyn NYC
Jesus L, nice basic design, but FFS, TIG weld that shit!!!

ok, to the OP, you say the jaws are "snug" but put some numbers on that. on the bench, set up an indicator, and see how much tilt you get on the jaws relative to the body. side to side, and front to back.if you get more than .002-.003' on a chuck in the 5" size range either way, regrinding will improve things at that one size, but I'd consider it shot, and not worth the effort. if its that loose, get a new chuck.

ok, checked a couple of my chucks, and on revision, .003 side to side tilt ("roll" in aviation parlance) at the top of the jaw is fine, but front to back it should be .001 ish. that's tilt on the "pitch" axis, NOT backlash. without moving the jaw in or out, the amount it can pitch forward or back.
 
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car2

Stainless
Joined
Sep 19, 2009
Location
Apex, NC
Hardinge did sell jaw sets, inside, outside and soft blanks. I have a few still in the box. They are, of course, rare and I do not have a new set of outside jaws.

I have never installed a set of the new jaws, so I cannot comment on how they fit or if they would grip properly and run true. If preloaded correctly, the soft jaws should do OK.

Larry

View attachment 367633
I dunno what may or may not be "standardized" for the ACH chucks, maybe the t-slots are supposed to be standardized, so having a new "set" will work in any body. However I know from experience that different like-new jaws have vastly different tightness of fit in the same chuck body, and different sets can have significantly different heights of the horizontal seating surfaces (as in 0.01"+), and different detail features, so they are definitely not an "overall" standard design between all chuck jaws made. I went thru this till I finally found very good condition chucks with bodies and jaws with matching serial numbers. I have a bunch of orphan jaws as a result of this learning experience. Larry, as always, thanks for all your valuable and helpful info and advice!.
 








 
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