Motor upgrade for lathe

[Raymond Sprouse]

First off, sorry about my ignorance.

I've been doing a lot of research on lathe mods. One thing that I would like to do is upgrade the motor on my lathe. I see that a lot of people online have mentioned using dc motors and pwm's from treadmills. I concidered this method for a while, but I think I want to go with the 3ph 2-3hp 220 vac motor and variable frequency drive. I have spent a lot of time searching for a motor and vfd online and have run into a few questions.

1. Most vfd's advertised say the max hp for the motor that they can run. I am guessing that is the max amps the vfd puts out?
2. If your got a 3hp vfd, I assume you could use say a 2hp motor with it?
3. The output freq for the vfd is a range. I have seen some say 0-60, 0-400, or one that said 5-68. I may be a little off on the numbers. Am I correct in the assumption that the hertz is what determines the rpm on the motor? If so, then a vfd that puts our 0-60hz would have an rpm range from 0-X rpm?
4. Most vfd I have seen have a forward and reverse option. Does this require a certain type of ac motor for both directions?
5. I have read that some motors require a capacitor start. Is that something that a vfd is able to do?

I have many more questions, but I'll leave it at these for now. It seems the more I read, the more questions come up.

If anyone has done an upgrade like this, please let me know what would be a good motor/vfd would be and a possible source. A lot of people talk about ebay and this online surplus store.

Any information would be greatly appreciated.

[Skip Spaulding]

Ray, I converted my Nova 1624, went with 2hp/3phase and 2hp rated vfd. I probably spent more than I needed but I am very happy so far. I used the bowl saver (McNaughton) the other day on some green cherry. Very smooth, did not have to change belt position. So far I have run with the belt in the 1020rpm set up, about middle of my of my pulleys. Rpm on my display reads 0-2700 when running, I very seldom turn at top or bottom end. I feel going from 11/2 to 2hp was well worth it and just turning a dial for speed change is a real pleasure!
I hope to try some large HF's after the holidays. Will try and keep you posted.
Have a great Christmas! or Happy Holiday!
Skip

[Alex Shanku]

Raymond,

I have a Delta 1460 powered with a small 3/4hp 3ph motor controlled by a VFD.

I think that this is probably the best buy in small VFD's today.

http://www.factorymation.com/s.nl/it.A/id.198/.f

Great product and warranty.

Simple to set up. I have a 10K (I think) pot. mounted to control the freq. and vary the lathe speed.

I dont use forward/reverse much while turning, so I still control that manually through the vfd controls on the unit.

In addition to the responses you will get on this forum, you may want to make your way over to OWWM.org and search the forum, there are some very good posts about setting up 3ph motors and freq drives. Included also are some excellent wiring diagrams, which I found helpful.

[Jake Helmboldt]

Ray, I converted my Nova 1624, went with 2hp/3phase and 2hp rated vfd. I probably spent more than I needed but I am very happy so far. I used the bowl saver (McNaughton) the other day on some green cherry. Very smooth, did not have to change belt position. So far I have run with the belt in the 1020rpm set up, about middle of my of my pulleys. Rpm on my display reads 0-2700 when running, I very seldom turn at top or bottom end. I feel going from 11/2 to 2hp was well worth it and just turning a dial for speed change is a real pleasure!
I hope to try some large HF's after the holidays. Will try and keep you posted.
Have a great Christmas! or Happy Holiday!
Skip

Skip, how much did it cost for the conversion? I assume you still have the full functionality of the swivel head and such?

[Paul Atkins]

Thanks Alex. I am about to convert my 9' lathe to variable speed control. This looks like the ticket.

[Reed Gray]

It might be worth talking to Brent English of Robust lathes about the 'Vector' drive he is using. I don't know if he would sell the drive and converter, but he probably knows more than most of us about it. There was a thread about it a few days ago about the Robust Liberty lathe.

robo hippy

[Dennis Ford]

If your got a 3hp vfd, I assume you could use say a 2hp motor with it?
That is correct.
Am I correct in the assumption that the hertz is what determines the rpm on the motor? If so, then a vfd that puts our 0-60hz would have an rpm range from 0-X rpm?
Your assumption is correct, motor speed is roughly proportional to the frequency. The speed range of any particular motor depends on its design. At 60hz, some motors run ~3500 rpm, some run ~1750 and some run ~1160. These are called two pole, four pole or six pole motors. Most lathes use four pole motors (1750 rpm @ 60hz). My homemade lathe has a six pole motor (more torque but less speed).

Select a motor that fits your lathe, consider;
* mounting
* shaft size (if the motor "frame size" is the same, shaft size will match)
* rpm
* a motor that is not "inverter duty" will eventually be damaged by voltage spikes from the VFD. IMHO most of us will turn for years before this is a problem.

Three phase motors are easily reversed, nothing special required.

Some single phase motors are "capacitor start", three phase motors are not. Single phase motors will not work with a VFD.

[Chris Haas]

pay attention to the vfd input requirements.

NOT ALL VFD'S TAKE SINGLE PHASE AND MAKE IT THREE PHASE!!!

a lot of people think this, but that isnt the case. in fact most i've come across take 230v three phase and make it 230v or 460v 3 phase with variable frequency. thats why you see the hz outputs varing sooooo much.

now on to my next point. do you have a vfd yet? i'm working with an electrician that is going to provide and pre program a 3hp single phase to 3 phase vfd for my specific motor and if you pm me, i can supply you with his info. he is not only reasonable in price, but the cheapest you will find periord.

[Raymond Sprouse]

Thanks for all the feedback. That cleared up a lot for me. Alex, thanks for the link. That vfd looks good. I looked through that companies motors too. That be a one stop shop. Thanks again everyone.

[Skip Spaulding]

Jake, to answer your question, conversion was about $575.00. I ordered through FactoryMation. Motor is 2hp WEG premium efficiency cast iron, drive is Teco 7300CV. I also ordered parts to build remote (cost extra) but have found controls on the VFD are working great. Yes I still have full use of all features on the Nova. Used my existing pulleys, but did have motor pulley reamed out to fit new motor shaft. I am sure I probably could have gone with cheaper motor and drive but so far I really enjoy my set up.

[Raymond Sprouse]

I found this motor and this vfd. What do you all think?

[Chris Haas]

this vfd was my second choice, it will work fine for you too. my first choice was a used one so there is no more of them. look for a 3 hp 3 phase motor too. cant beat the prices.

[Bob Bergstrom]

When I was turning outboard up to 24" on my Delta 450. I found the limiting factor was belt slippage more than any lack of power. I used spray belt dressing trying to contend with the slippage. It was a two belt system with a shreve pulley. If you lathe has a good way to tighten the belt it may not be a concern with a 3 hp. motor. My powermatic 3520 has a ribbed belt and a tension lever which really helps delivering the power to the head stock.

[Raymond Sprouse]

Chris, I tried your link but it takes me to ask.com. Sorry. And do you mean my pick for motor/vfd was your second choice?

[Raymond Sprouse]

Bob, thanks for the belt slip tip. That was my first thought too. But my motor sound changes when mine bogs down.