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Our UMC750 was crashed last week by a temp restarting the machine in the middle of a file. Hit hard enough on the tool holder to munch the fixture and shear off one of the 1/2-13 cap screws holding the fixture down with a B/C axis move, and ripped the dovetail off the fixture (mounted on a 5" technigrip).

 

Would you guys thoroughly inspect to be sure axis alignments are all still true, or just re-find COR and go? I re-checked for center of rotation and it is different from what was stored in the control by .03" in x, .01" in y and z.

 

This is the first shop I've been at with UMCs, I've heard they're pretty flimsy. If it were a Mori, I'd just keep going.

But it's a Haas.

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Spindle still good (measured less than .0001" runout on a tool setting gage), but axis of the trunion (B) is out of alignment with Y axis by .007" from front to back of table. Might be a bit of backlash in B axis, got slightly different readings when moving from + vs - (difference of .0025" across 10"), and MRZP mismatches the parameters by .045". We're having a vendor come out to re-align everything.

Thanks for feedback. I've never run a UMC before here. They are about as rigid as a cardboard box.

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1 hour ago, Ewood42 said:

Spindle still good (measured less than .0001" runout on a tool setting gage), but axis of the trunion (B) is out of alignment with Y axis by .007" from front to back of table. Might be a bit of backlash in B axis, got slightly different readings when moving from + vs - (difference of .0025" across 10"), and MRZP mismatches the parameters by .045". We're having a vendor come out to re-align everything.

Thanks for feedback. I've never run a UMC before here. They are about as rigid as a cardboard box.

the problem with mechanical drives is that spot on the gear may never be the same. Not so on a direct drive machine. You could call out a tech with a granite square and whatnot. Might want to run a laser calibration on the rotaries to check for bad spots.

Another $150k on purchase price can get you premium brand's direct drives. add another 50k to that and you could have a whole pallet system. Double the price for one machine? there are no free lunches.

 i don't know how well the Haas calibration routine works on the UMC. I've heard it's pretty bad on a VF trunnion setup. No matter how good it is it's not going to correct geometry errors, only make the best of them.

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4 hours ago, mkd said:

the problem with mechanical drives is that spot on the gear may never be the same. Not so on a direct drive machine. You could call out a tech with a granite square and whatnot. Might want to run a laser calibration on the rotaries to check for bad spots.

Yup. Had an old kafo horizontal at at a previous employer that had a some deformed teeth on the ring gear that drove the B axis. Discrepency between B+ and B- moves was about half a degree. Rather than fix it, they had me modify the post for the machine to output backlash elimination moves any time the B moved, and adjusted the B offset to compensate. 

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4 hours ago, mkd said:

the problem with mechanical drives is that spot on the gear may never be the same.

no worries there

I'm pretty sure that Haas rotary axis are driven by rubber belts on cogged wheels with glass scales for positional feed back

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18 minutes ago, gcode said:

no worries there

I'm pretty sure that Haas rotary axis are driven by rubber belts on cogged wheels with glass scales for positional feed back

The rubber belts and cogged wheels in their table top trunnions, you wouldn't put on your bicycle. Seriously tiny.

 The UMC's have either a worm drive (:shudder:) or a pretty decent cam-drive (or whatever we call 'em) on the SS models. The gear cannot rotate the worm gear so you'd have mechanical damage. Not sure about the cam drive.

 

I believe the big Okumas use a bevel gear. I'd guess a crash would push the pinion and the servo, thus not do direct physical harm.

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Was the Table at "0" or did it hit sideways with the table tilted?

If it was sideways, I bet the outer support bearing was knocked out of place.

There is an adjustment procedure we learned from Hass (it's happened to us twice)

Part of tweaking and leveling the machine to make it square.

One of ours hit so hard sideways in X, it has never been the same.

 

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  • 2 weeks later...

Machine is back running again as of last week. Doesn't seem to be too bad, but we also made some improvements to the fixture we were running the parts on since we were re-making it anyway. So performance doesn't seem to be adversely affected, but no way to know for sure.

Z axis makes some pretty bad noises when moving in rapid, but the decision was made to to not replace the linear guides due to the fact that the part we run on that machine are +/-.02" on the profile. Making 1500 of those little formed Inconel parts a month for the next few years. Should hold up until we're done with the contract for those parts at least, assuming it doesn't get renewed.

 

 

I'm still just a little thrown off by the fact that part of the fine alignment procedure on that machine involves adjusting the pads under the casting. As G said, about as rigid as a wet cardboard box.

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I never understood why the UMC series doesnt use a more traditional trunnion-style setup. It just isnt rigid. WIth that being said, I am glad as hell I havent crashed my 5 axis hurco yet. Vericut comes in handy with that. The three-axis on the other hand, well I had to replace the spindle on that one :)

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and then we have our Okuma MU1000 trunion style horizontal 5X mill

The X axis component with the AB trunion weighs 85,000 pounds.

we bought the automatic probing system for tuning the trunion's pivot distance

To the best of my knowledge the machine has never been crashed, but that doesn't mean

someone hasn't  thumped it and never told anyone.

After 5 years of heavy roughing in steels and Inconel, we ran the tuning software.

The pivot distance has moved 1.5 microns  :rolleyes:

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9 hours ago, Metallic said:

I never understood why the UMC series doesnt use a more traditional trunnion-style setup

The goal with this machine is affordability 

The original  VF-series 30 years ago,  was cheap enough to make NC affordable for thousands of small shops

Back then an entry level Japanese VMC was $100k, an impossible number for many small shops including mine.

I could pick up a VF-1 for $40k. It couldn't hold a candle to a Japanese VMC, but it was a foot in the door to the world of CNC machining.

I think Haas is trying to replicate that success with 5 axis machines by offering an affordable 5X machine.

 

 

 

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