My "New" Old Lathe

[woodtryer]

Some time ago I was looking at upgrading the old MC1100 to something better. At the time I was looking at maybe getting a VL200BM and making a standing and adding a motor as I can not afford a full on VL200 EVS at well over $4K :(. Anyway I looked around and decided to speed just $400 and add EVS to my old lathe. Sure it's not a 200kg beast but after bolting to the concrete floor of the garage it's pretty steady.
I bought a 2hp 1440rpm 3 phase motor, added a 5 step pulley (which I only use the first 3 steps for extra torque) and a VFD to control everything.
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The first pulley gives me a 3:1 speed ratio so I get 0 to 1000 rpm (and a lot of torque). The second pulley gives me 0 to 2500 rpm and the 3rd speed is 0 to 4000 rpm. I get this range by running the VFD up at 100hz max so i get the higher speed range with just 3 steps on the pulley.
Most of the time i seem to work on the middle range as it seems to have plenty of power and good speed range.

One day I still hope to upgrade to a Vicmarc but for now this will do.

Your feedback is most welcome.

Thanks,

Peter

[dai sensei]

I was thinking of one day doing the same to my JET. So have you removed the cone pulleys from inside?

[woodtryer]

Hi Neil, Initially i didn't but it kept making a rattling sound that was really driving me mad.... so last week it came out. Its a bit of work to remove it but now it is so quiet. :U

Pete.

[BobL]

The first pulley gives me a 3:1 speed ratio so I get 0 to 1000 rpm (and a lot of torque). The second pulley gives me 0 to 2500 rpm and the 3rd speed is 0 to 4000 rpm. I get this range by running the VFD up at 100hz max so i get the higher speed range with just 3 steps on the pulley.
Most of the time i seem to work on the middle range as it seems to have plenty of power and good speed range.

VFDs have very low power/torque at low frequencies so to say you have Zero - X RPM is misleading as you simply won't be able to operate at low RPM.
You also risk over heating the motor if you run at high loads continuously at low frequencies.

Have you turned on and tuned up the Vector control for the VFD?
That will enable the motor to generate improved power/Torque at low RPM but it won't solve teh overheating g

This means that if on your first pulley 1000 rpm = 100 Hz then the VFD/motor won't be able to deliver much useful power/torque at less than ~10Hz and you shouldn't operate below 10Hz anyway so the real range is 100 to 1000 RPM.
The second is 250 to 2500, and the third is 400 to 4000.

However, if the lathe/motor is well balanced you should be able to run a 1440 rpm motor up to at least 120 Hz and maybe even higher.

[woodtryer]

Hi, No i haven't played with the vector control as you have suggested. Sounds like it would be a good idea. As for the speeds, yes i do realise that the motor will no a lack of power at low rpm which is why i used the 3 step pulley system. I also agree with you that to say 0-1000 rpm really means a usable range of probably 200 rpm and up but i don't think i have very used less than that.
How much increase in torque would i achieve playing with the vector control on the vfd?

Cheers

Peter

[BobL]

Hi, No i haven't played with the vector control as you have suggested. Sounds like it would be a good idea. As for the speeds, yes i do realise that the motor will no a lack of power at low rpm which is why i used the 3 step pulley system. I also agree with you that to say 0-1000 rpm really means a usable range of probably 200 rpm and up but i don't think i have very used less than that.
How much increase in torque would i achieve playing with the vector control on the vfd?

It depends on the quality of the VFD and how much time you are prepared to spend tuning it up as it's not just a matter of turning it on.
All the motor parameters have to be entered correctly into the VFD and the autotune function activated. Usually the autotune is run with no motor load and the VFD automatically runs the motor up and down the speed range for a couple of minutes to determine what it needs - sometimes the VFD does not pick up the motor characteristics the first time and you have to rerun it again. Unless you have the test gear to test if the vector drive is working you may not know if it has been turned on or not. About all you can then do is run the auto time a couple of times.

The gain in torque varies from "nothing" at 50Hz down to about twice as much as you otherwise have without vector control at say 15Hz.
At 5Hz its can be as much as 5 or even 10 times more than you would have without the vector control - but don't forget that without vector control, at 5Hz you have "stuff all" , and 5x or even 10x stuff all = "not much".

It really comes down to how much "low speed" / "high load" work you intend doing. If it's not much then I would not bother and just drop down a pulley size.

You also have to keep an eye on low speed/high load from a motor heating port of view.
If it's only light loads you should be fine.

[Optimark]

For $400 or around that figure for other bits and pieces, that sounds like a pretty good compromise to me. I note that there is no hand brake on the left side, was there one originally?

I have access to a variety of Vicmarc lathes at my wood turning club, plus a couple of others, they being Stubby lathes and some Taiwanese units, one with a swivel head, one with a solid head. For some time now I have wondered about the value and ideals of new Vicmarc lathes compared to other higher end lathes that are in similar, or lower price brackets.

I like the agility of the Stubby lathes, plus, it is possible to work on the rear and front of a large bowl without needing to rotate the head by adding the 500mm extension at the side and to the rear of the work. Nice lathes and extremely versatile. I'm sure there are quite a few other things about Stubby lathes that are unique, with the limited use I have had (about 10 times) I have really liked them. The size of the Stubby lathes, as their name implies, is also good as the real estate they need is pretty much smaller than anything else out there.

One lathe that has appeared on the scene recently, has been the Laguna in two versions; reachable, pocket wise and almost unreachable, pocket wise. I saw one of these and went over it really well at the last wood show in Melbourne, the 18-36 model. That lathe is quite different to almost anything I have used; except the Stubby lathes. It seemed to me that the designers, had pretty much thought of most things that are important to turners and applied their minds for better ways to refine the features most of us like or would like on a lathe. Once you add some of the very well thought out extras, the price does climb though.

I was dead set on a Vicmarc lathe and they are very good, but now I'm not so sure any more.

Meanwhile, my Nova 1624 lathe trundles along...

Mick.

[woodtryer]

Hi BobL. I think all that might be a bit too much for me and my brain. I think you lost me just after asking if i had "turned it on" :? I looked in the 500 page manual that came with the VFD and found the section on vector control and then decided to close it...... it's way too much for me to understand.

I guess i'll just run it as is.

Thanks anyway.

Peter

[woodtryer]

Hi Mick. No, there was never a hand break/wheel on this lathe. I have always thought it was a bit of a negative not having one but then again these lathe are pretty basic in what you get. I also forgot to mention that i did only pay $500 for the lathe and then with my additions i have spent under a $1K.

[woodtryer]

Hi BobL, just a quick question. I have found the setting to turn on Dynamic learning of the motor in the VFD. Do you think it's worth me turning that on and letting it go thru its learning process?

Thanks

Peter