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Maximum RPM for 1.5" dia aluminum bar stock on Daewoo Puma

Now that I have a working program (thanks guys), I'm trying to reduce my cycle time.

I'm running about 1000 fpm for my tools (all carbide, indexable or solid drills) and flood coolant.

The machine has a 6" chuck with aluminum soft jaws and a urethane spindle liner (about 0.015" clearance on each side).

I can only run the machine up to about 2500rpm when the bar is at full lengh, 48". About 10-12" is hanging out the backside of the headstock, unsupported. The part hangs out about 4" from the jaws during machining.

Without the bar (though with the chuck, jaws, and liner) I can reasonably get 4000+ (the machine starts resonating at about

3000-3500rpm, and stops just above that) but with the bar, 2500 is a low rumble, and it gets quite a bit worse after that. The jaws are bored on the ID and turned on the OD.

Any recommendations about how to get this thing up to the 4-5k mark? Once I'm done babysitting it, an operator will be running the machine so I'm a bit wary of ramping the rpm as the bar gets shorter.

Thanks for any thoughts.

Regards,

Robin

Reply to
Robin S.
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Robin, If your Daewoo is like mine there is a flange with a bolt circle on the actuator end of the draw tube. I've seen people make a flanged piece with a thru hole and bolt it up to the draw tube flange to get a little extra bar length.

I just did a spindle rebuild on mine and the low rumble and the resonating that you describe I wonder if your machine is due for a spindle rebuild?

Best, Steve

Reply to
Garlicdude

Steve,

We had the machine inspected by two Daewoo techs (one before it was purchased, one at our shop) so hopefully the bearings are OK. Neither myself or my boss would be able to tell if the bearings were going funky though.

Good idea with extending the spindle tube. There is a bolt hole circle on the flange, currently being used by the spindle liner. I'm sure we could come up with something. It would make change overs a bit more involved, but that's not a huge deal.

Regards,

Robin

Reply to
Robin S.

Robin, I buy steel liners here:

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No idea which is better or cheaper. I just got started with them and have continued.

You also might try wrapping a piece of shim stock say 2" wide around the bar to take up some of the slop in the existing liner. I've used various size "O" rings and made split bushings to bridge sizes of the spindle liners that I have in the shop. They can get kind of pricey to have a big selection.

Best, Steve

Reply to
Garlicdude

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