Hardinge Sjogren collet chuck runout

ptross · May 9, 2020

I got a Hardinge Sjogren speed chuck with a recent lathe purchase, D1-4 mount.
A relatively new Hardinge collet mounted in the chuck has a bit more than .003 runout holding a 3/4 dia ground rod, which seems way too much. The chuck body OD has only .0005 runout at the nose, but the internal collet taper is out that much too. Is there an adjustment to set this more true? I haven't used one of these before, and have not had it apart yet, thought I'd ask beforehand so I know what to look for.

Peter

Cole2534 · May 9, 2020

I have the D1-6 version and it look a little fiddling to get the TIR down. I made sure all the studs were properly adjusted and then checked all possible hole selections for best result.

I don't know of a way beyond that, unless you want to get out the TP grinder.

Sent from my SM-G930R4 using Tapatalk

thermite · May 9, 2020

What Cole said. "Some of" the Jacobs Rubberflex have a backplate yah can "bump" to center. None of my Sjogrens have that.

As to the grinder? Get it as stable and repeatable as yah can do FIRST, even if yah have to mark it so the D1 pins are put in the same "most favorable" holes each go. And, of course, you have ALREADY seen to it that the D1 has any burrs stoned off the nose, and out of the backplate socket?

Then it generally IS time for a touch-up with TP grinder. Not just Sjogren. Used collet closers in general.

The buggers "lobe" over time if nothing else.

And we are NOT talking about brand-new "virgin bores" by this late in their working lives, are we?

3 Sjogrens worth 2J 2J 5C

ptross · May 9, 2020

Thanks for the suggestions. sounds like grinder time. Do I pick up the existing taper or try to compensate for any bellmouth or other uneven wear?

daryl bane · May 9, 2020

May I suggest that you double check the front part nose, to the mounting end. I had a 2J that had a fair bit of runout. I separated the the pieces an scraped the parts flat. I did not scrape any sort of correction, just flat. Reassembled the parts and runout was now about .0002 at the nose. I would do everything you can before trying to grind in the taper.

thermite · May 9, 2020

ptross said:
Thanks for the suggestions. sounds like grinder time. Do I pick up the existing taper or try to compensate for any bellmouth or other uneven wear?

Grind it to spec. That HOW you take-out wear.

See also what Daryl said .. and do that FIRST (thanks Daryl!)

Yah can live jest fine with a good deal of "lobing" ... so long as it is evened-out well and yah seat the collets TO it, not against it.

PeteM · May 9, 2020

A good number of the Hardginge-Sjogren collet chucks are mounted to a backplate; including the one I now own and another that went away with a previous lathe. If yours is among them, there's likely enough slop (or some could be made) to get the taper running within tenths.

You've likely checked that the current taper isn't bad - or the collet and rod you tested it with? I've seen one case where the key was messed up and affected seating of the collet.

I've been surprised how well my own H-S chuck has held true despite frequent use, removal and replacement, and a messed cut-off or two.

thermite · May 9, 2020

PeteM said:
A good number of the Hardginge-Sjogren collet chucks are mounted to a backplate; including the one I now own and another that went away with a previous lathe. If yours is among them, there's likely enough slop (or some could be made) to get the taper running within tenths.

That presumes the backplate fit-up had been badly done. Not common. Sjogren's were "premium" goods, so treated.

Wear, burrs, or even crash more likely. Best to try to sort those FIRST, dig deeper only if No Joy.

Backplate fit is more likely to be as good as it ever was.

3 Sjogren's worth. And 2 Rubberflex. "etc,"

sfriedberg · May 9, 2020

thermite said:
TSjogren's were "premium" goods, so treated.

"So treated" is the key. I have one Sjogren D1-6 mount where a previous butcher turned away most of the locating taper. There is only about 0.050" of contact between the chuck internal taper and the chamfer at the very tip of my spindle's external chamfer. Trying to get that chuck to run true is a massively frustrating exercise in selectively torquing the three cam locks. Building up the internal taper with bronze and remachining the internal taper has been on my to-do list for quite a while.

thermite · May 9, 2020

sfriedberg said:
Building up the internal taper with bronze and remachining the internal taper has been on my to-do list for quite a while.

Can't see it worth the effort. Starting over with a different used one and breaking that butchered one up for rim, gears, etc. should net-out not all that costly.

One of mine needs a rim, but as with its owner, off the back of ugliness - still FUNCTIONS OK!

ptross · May 10, 2020

I've had the chuck apart and stoned any possible burrs from chuck body and backplate. The fit between them is pretty good, needing the bolts to pull them together fully, so no adjustment there. As I mentioned earlier, the outside of the chuck nose runs out about .0005 but the inside taper at the nose is about .0035. Farther back inside beyond the collet taper it goes down to about .001
at this point I'm thinking the inside taper is the culprit. Being new to much of this I'm thinking I'll need to touch it up with TP grinder, but wondering what to use to dial in the correct taper on the compound. Unless I'm mistaken, don't the collets themselves only match the taper in the nose when they are squeezed around the part? Otherwise I could set up a collet as the reference to set the compound angle. I have a couple of unused Buck collets if they are ok and a Hardinge.
Peter

sfriedberg · May 10, 2020

ptross, you didn't mention the specific collet series this chuck is for (could be 5C, 2J, 22J, maybe some others). Whichever it is, you can find the nominal collet taper angle. Using that, a freshly turned test bar, a dial indicator and a little high school trigonometry, you can dial in your compound angle. Then mount your Sjogren and have at it. Don't take off more than you need, however. A little bit on shallow taper diameter makes a big difference in axial location.

thermite · May 11, 2020

ptross said:
I've had the chuck apart and stoned any possible burrs from chuck body and backplate. The fit between them is pretty good, needing the bolts to pull them together fully, so no adjustment there. As I mentioned earlier, the outside of the chuck nose runs out about .0005 but the inside taper at the nose is about .0035. Farther back inside beyond the collet taper it goes down to about .001
at this point I'm thinking the inside taper is the culprit. Being new to much of this I'm thinking I'll need to touch it up with TP grinder, but wondering what to use to dial in the correct taper on the compound. Unless I'm mistaken, don't the collets themselves only match the taper in the nose when they are squeezed around the part? Otherwise I could set up a collet as the reference to set the compound angle. I have a couple of unused Buck collets if they are ok and a Hardinge.
Peter

I submit that the NEXT thing you should want to do is build a polar-coordinate chart - or a flat-file of "number @ degree or O'Clock' - by measuring at close-enough intervals to CONFIRM it is lobed (from normal wear, and lots OF it), or TILTED. from a crash.

"Both" is possible.

Bugger has been crashed, I might or might not BOTHER trying to grind it, lest I run out of convenient long-axis range or find it wasn't stable.

I'd just go and find another one that has NOT been as badly treated. Mind - the 2J's I prefer are easier to find than the "popular demand" 5C ones.

As to angle-setting.. use the specs. Use a NEW Hardinge or Crawford collet to test with bluing LATER to confirm you got what you set out to do.

Use something more precise than the degrees stamped for a compound. Test bar, DI, and 1.2.3 blocks with a bit of trig and yer better-off.

ptross · May 13, 2020

thanks for pointing me in the right direction.
One more question before I go too far. I understand that the longer the X travel I use when setting up the compound angle, the more accurate my setting could be. I only have 1" travel indicators and no DRO. Is 1 inch enough carriage travel to verify the setting or should I get a 2" indicator? I guess I could rig up a way to clamp a vernier caliper to the lathe and get 4 or 5 inches?
Peter

sfriedberg · May 13, 2020

The taper on most collets is less than 1" long, and considerably less than 1" change on diameter. I'd say you can use any dial indicator for the radial measurement, and if you have a micrometer dial on your compound, you don't need a long travel indicator for that motion. Just mind the backlash.

As a practical matter, you don't need laboratory-grade precision, and if you err, err toward making the taper shallower rather than steeper.

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