Not CNC but....

[QSIMDO]

Finished mounting a VFD and it's fantastic!
(I can see how you guys with CNC must pee your pants with glee!)

The only bug is a vibration half way up the rpm scale, but I can work around that until just knowing it's there drives me insane!

Thanks to all here and in the VFD section for your help.

[epineh]

VF drives certainly are a good thing to have

I am not too sure about your drive, but most that I have worked with have a "skip frequency" setting, that will do just that, jump over the frequency range that causes that resonating vibration as the motor is running up to speed.

Have a look through your manual and see if your drive does this, it may smooth it out even more, the tricky part is finding the frequency the motor resonates at.

Good luck.

Russell.

[Geof]

..... most that I have worked with have a "skip frequency" setting, that will do just that, jump over the frequency range that causes that resonating vibration as the motor is running up to speed....

I looked at this and thought; how about changing or damping the resonant frequency of the system. Automobile engines have crankshaft dampers sometimes; maybe you could use a similar system on a motor driven by a VFD. The damper is just a ring of metal mounted on a hub with a rubbery material between. I think sometimes it is built into one of the pulleys that drives things like the fan or water pump. You might even be able to adapt a damper from an automibile engine onto the motor on your VFD.

[philbur]

It might be worth using the gearbox to determine if the vibration is at a particular motor speed or spindle speed.

Phil

Finished mounting a VFD and it's fantastic!
(I can see how you guys with CNC must pee your pants with glee!)

The only bug is a vibration half way up the rpm scale, but I can work around that until just knowing it's there drives me insane!

Thanks to all here and in the VFD section for your help.
]

[QSIMDO]

"Skip frequency" sounds interesting, but first things being first I'll pull the motor tonight and run it disconnected from the machine.
See if a bearing is going, listen for noises, check shaft runout, etc.
Then I'll get my big drill out and drive the machine to see if I can replicate that rpm setting.
I'm pretty much thinking it's the motor-to-mill fit though. Running eccentric around a tight key or something.

[BobWarfield]

Quas, looking good. Was thinking it was the adaptor somehow myself. I'm gonna make a similar adapter (couldn't pass up a $50 3HP brand new Baldor off eBay) myself, so I'll be watching closely.

Seems like VFD's are cheaper last time I looked too. Now they're Chinese instead of Japanese.

Next you'll be wanting a belt drive!

Best,

BW

[QSIMDO]

Thanks Bob.
(Good to see you back around too!)

I just posted some questions over in the VFD room but the upshot is I didn't do a great job cutting the keyway when I turned the motor shaft down to D80 so the key was binding a tad.
May still be a part of the problem though because at extremely low RPM setting on the VFD it "lopes".
Sort of a "rrER, rrER, rrER" at tick over.
I won't be cutting down there no matter but I'd still like to debug this.

I've been thinking if I use the bolt holes in the middle and rear of the gear box lid with longer bolts I'll mount the motor directly to a .375" plate without spacers and sink the shaft farther down in the sleeve.
OR...not be such a cheap skate and buy a B5 motor for it.
Hate to give up on the Baldor though.

Is yours the VM3559T that was on eBay? I was thinking of snagging that as a backup for mine.

[BobWarfield]

Yep, that's exactly the motor. I had a 2.5HP B5, but decided to stuff that into a belt grinder project. If I get into a hassle with the 3 HP, I suppose I could always swap back.

Best,

BW

[QSIMDO]

Nice motor indeed but when you open it up the first thought is "there are motors made cheaper than this?"
Not that I'm suggesting the Baldor is shoddy by any means but...maybe I was expecting to be impressed somehow.

As for the Hitachi VFD, if it's made in China I truly am impressed.
I know nothing from circuits but fit/finish/detail are tops.

[BobWarfield]

Nice motor indeed but when you open it up the first thought is "there are motors made cheaper than this?"
Not that I'm suggesting the Baldor is shoddy by any means but...maybe I was expecting to be impressed somehow.

As for the Hitachi VFD, if it's made in China I truly am impressed.
I know nothing from circuits but fit/finish/detail are tops.

Yeah, motors is motors as far as I've seen. They aren't exactly high tech a this end.

RE Chinese VFD's, not Hitachi, but other brands. I have a Hitachi, and it is a nice unit. But folks seems to be just about as happy with a lot cheaper VFD's that weren't available when I got my Hitachi.

Best,

BW

[QSIMDO]

But folks seems to be just about as happy with a lot cheaper VFD's that weren't available when I got my Hitachi.

Best,

BW

I'll definitely remember that for my next re-motoring project...my lathe.
Darn tired of changing belts all the time.

Len

[blighty]

Hi QSIMDO

Bit OT, but that mill you have looks a lot like this one http://www.chesteruk.net/store/lux_mill.htm


if it is, could you give me a little rundown of what it's like.... i have my eye's on one.