Hardinge HVL tool breakage issue

I'm having an issue where when parting or grooving only, the tool will tip downwards, catch and snap the tool off. It's happens so quickly I can't see where the movement is coming from, compound, cross slide, or at the tool Post.
There is some cracking in the T slot for the tool post where previous idiot employees have crashed it, but I'm not entirely convinced it's flexing there.
The cam bolt I've replaced twice, as idiots some how sheared it off, but it has been fine since in my care.
I can't feel any excessive looseness in any of the possible places for movement.
Anyone run across this issue before, maybe it's a common thing on these?

NSPowerlifter said:

I'm having an issue where when parting or grooving only, the tool will tip downwards, catch and snap the tool off. It's happens so quickly I can't see where the movement is coming from, compound, cross slide, or at the tool Post.
There is some cracking in the T slot for the tool post where previous idiot employees have crashed it, but I'm not entirely convinced it's flexing there.
The cam bolt I've replaced twice, as idiots some how sheared it off, but it has been fine since in my care.
I can't feel any excessive looseness in any of the possible places for movement.
Anyone run across this issue before, maybe it's a common thing on these?

Click to expand...

Ermmm "some cracking".. "sheared off"?

I'd call that machine a survivor of ABUSE even from the distance of my keyboard!

Always thot Hardinge was being REALISTIC, not just brilliant or lazy, to have developed their HS-mounted swing-arm parting-off rig.

A(ny) light, high precision lathe is both. High-precision.
and LIGHT

A Hardinge "block" type toolholder might be better than a commodity "QCTP".. in case that is what is attempting to hold a parting-off tool?

Hardinge swing arm HS mount parting rig - if you can find and fit one - could be miles better. Hardinge knew full-well what their lathes were good at. Or not so good..

If not? How about a "back" parting tool monoblock? Near-zero flex to it. Mounts right on the topslide-not-compound.

Hardinge always DID have more than one way to get the BBQ meat out of a cat-fur bag. Not new. Put what they already have to work and enjoy saner tasking.

NSPowerlifter said:

Anyone run across this issue before, maybe it's a common thing on these?

Click to expand...

When speed/depth-of-cut is too high.

rons said:

When speed/depth-of-cut is too high.

Click to expand...

No fear. Just pull the breaker and go use the saw.

Hardinge tribe must have parted-off multiple TRILLIONS of parts by now.

Some few were even over a whole US INCH in diameter.

Go figure it was any flavour of "difficult" at HALF that and below?

Horses for courses.

NSPowerlifter said:

I'm having an issue where when parting or grooving only, the tool will tip downwards, catch and snap the tool off. It's happens so quickly I can't see where the movement is coming from, compound, cross slide, or at the tool Post.
There is some cracking in the T slot for the tool post where previous idiot employees have crashed it, but I'm not entirely convinced it's flexing there.
The cam bolt I've replaced twice, as idiots some how sheared it off, but it has been fine since in my care.
I can't feel any excessive looseness in any of the possible places for movement.
Anyone run across this issue before, maybe it's a common thing on these?

Click to expand...

Yes indeed the bottom of the compound slide tends to bow like a banana causing the tool post to rock and the compound clamping to be reduced to the point that it will rotate under load. This in turn causes the operator to over-tighten the cam bolt causing it to shear.

The remedy is to remove the compound slide and machine/grind/scrape the base flat.

Peter. said:

Yes indeed the bottom of the compound slide tends to bow like a banana causing the tool post to rock and the compound clamping to be reduced to the point that it will rotate under load. This in turn causes the operator to over-tighten the cam bolt causing it to shear.

The remedy is to remove the compound slide and machine/grind/scrape the base flat.

Click to expand...

Why... is the "compound".... still ON the topslide ...at all.. when parting-off?

Simple, stout direct mount was always "there". ANY lathe ever built. It was the compound that was an extra-cost OPTION, and for a very long time.

Industrial work, the "compound" might not be seen mounted for a week at a go. Not until one had short, steep, tapers to cut. "Production" Hardinge it might never have been purchased. And no, I do not mean "speed" lathes nor second op. More likely to find a monoblock, more than one, gang tooling, even a swappable turret plate, each plate mounting tool blocks arranged for a specific tasking.

Hardinge "system" had a myriad of choices, more than a few hard to even grok the "why" of.. unless and until you NEEDED that "why?

A "compound" surely was a pain in the anatomy for single-point threading when straight in was faster and less prone to error. They taught you 29 degress whilst at school?

You are no longer at school.

Prolly not running a whimp-ass spaghetti bed training lathe with Iron deficiency anemia, either!

Let alone a Hardinge thread CHASER rig.

Machine-tool designers have to make it hard to screw up if money is to be coined.
So they did exactly that. Made it VERY hard to screw up! Each chaser set cuts exactly one thread. Gearbox, leadscrew, and half-nuts not involved. So it "gets it right" every go.

Mind, we are a mighty INVENTIVE lot as to finding work-arounds, but still...

Take a mag base and the smallest dial indicator . A .0005 would do if you don't have a .0001. Put the mag base on the compound top behind the T slot and indicator on the top of the front of the T slot and test a parting tool into a shaft a little bit and se if it is bending. You could check the compound to the cross-slide too. Those cam locks crack too, so pull it out and look at it. I have a couple of other idea's too. I am a Journeyman Machine Rebuilder and will help. If you get tired of the BS. email me [email protected] I have rebuilt several Hardinges over the years.

Most lathes have a lock on the compound to stop it moving under load, this a jam screw pushing on the gib strip.I put a grub screw in line with the gib adjusting screws and tightened it for forming and parting work.I later made a little lever to replace the grub screw. It is very discrete and it does mean that you can run the compound a little looser for general machining and threading.