So, he told me to come get the darn thing out of his garage... Big Ole Arn!

[wmesquite]

Great read. I just ran through the basics of the Cowern Papers for the last hour and learned quite a bit. Thanks.

Now, I have to choose a VFD. I suppose just fitting it to the proper HP and phase is an oversimplification???

Yep, All you really need to do is match amps, but simplest to get a sensorless vector (SV) drive with single phase input with 2 hp or 3 hp output(assume the 1.5 hp 6 pole motor is a 2 hp).  2hp is smaller physically, so a little easier to mount. I'd mount it under the bed on tailstock end, out of chips way but visible. If you plan on using a fan, I'd ask seller if it has a relay output for it- you still need a relay, but simplifies wiring. If it wasn't SV, probably wouldn't have this kind of output.

Might as well get your remote switches/housing from seller as well- I prefer momentary but no big deal. A speed dial and knob for the potentiometer nice to have as well.  Everything can be found on the auction site, with premium goods for less, that is where I got my supplies. Pic of my VFD and switch setup for grinder/buffer- not pretty, but compact and very nice in use (has reverse and speed pot on top) http://wmesquite.eml.cc/OWWM/CinciNControlsBig.jpg
and better shot of top http://wmesquite.eml.cc/CincyControlTop.jpg

[Gregory of Sherwood Forest]

Yet another detail I hadn't considered... potentiometer...

Jeeze...I think I'll contact the seller by phone and see if they can put together a package for me. They may have some experience in putting together a package that will all work well together.

Thanks again. I'm not just getting fish here, I'm learning to fish.

[TDKPE]

If I were you, I'd source a 2 hp or 3 hp VFD (make sure it's single-phase input for full output), but try the 3-phase motor you already have. There's no risk to it, and you can change out to a larger, slower motor when you find one with the right shaft and that isn't too long to fit the space. Fitting a remote control panel with potentiometer and on/off plus reversing switch even isn't difficult, but if you pay someone else, it may become rather expensive. My remote is made from a Radio Shack 'project' box and stock parts.

[MichaelMouse]

Why not just go DC at the outset?  Simple PWM should provide good torque at half-rated draw of 900rpm, and with a setup made for 1725, the 1800 rpm full should be a good match.

[Gregory of Sherwood Forest]

Tom, I think that's what I'll do. I'm going to get a VFD that will handle a motor up to 3hp, and run my 1 HP 3ph motor with it for a bit. When and IF I need more HP, then I'll upgrade.

So, which VFD? I'd really like one with a knob for controlling speed, as opposed to buttons.


MM - thanks for the recommendation, but I'm already over my head here....

[iclark]

The previous owner of my Woodfast lathe swapped the original DC motor for a 3-phase motor and VFD. Instead of mounting the VFD to the lathe, he made up a post on a base that the VFD is mounted to. That way the VFD and controls can be moved around on the floor to where you want it. It is a bit more awkward than the pivoting control stalk on some Oneways, but it is very convenient.

FWIW, he converted the original DC motor into a grinder on a pedestal.

[Gregory of Sherwood Forest]

Good idea. I'll keep that in mind when it comes time to put together a control box.

I think this FM50 VFD from FactoryMation has been recommended here several times;
http://www.factorymation.com/FM50-203-C

I'll start with that (unless there are any objections?), and a potentiometer, switch for forward/reverse, and a large on/off button. I guess I'll grab a box from them also.

Any suggestions on the potentiometer and switches??

[wmesquite]

FM-50s are v/Hz models, full torque to 15 hz, then mostly ok to 10 hz where torque craters. You need a sensorless vector model to get full torque down to 6 hz. Not sure what your current minimum speed is, but if 20-25% is slow enough, a good choice. If you need 10% of current minimum, then only a sensorless vector will do- but harder to program.

[TDKPE]

I believe the 260 with Reeves drive goes to 410 rpm with an 1800 rpm motor. Since you need to get to 100 rpm or less, per your original post, that's 15 Hz of course. Half that for 50 rpm.

With a 1200 rpm motor, things are a little better with about 270 rpm at 60Hz, and 68 rpm at 15 Hz. You need a vector drive if you want much more than to check the balance or do light sanding (which is how I use mine) at such slow speeds.

The issue of the ability of the belt drive to deliver such torque is a question mark, as much depends on the belt and on the smallest diameter of the driving sheave. But that's something that can be tested with the existing motor by pushing it hard - if it starts slipping and you can't overcome that, then there's not much point in moving to a larger motor.

Really high torque from a really small drive is the bailiwick of chain and, more appropriate to a wood lathe perhaps, cogged belt drives, like timing belts and Harley final drives.

[Gregory of Sherwood Forest]

So I found a user manual download on OWWM, and according to it, the original motor that came with the General 260-1 was capable of turning the workpiece from 3000 RPM all the way down to 410 RPM when the belt was moved to the correct Motor and Headstock pulleys. Now, the manual isn't real clear about the specs, so I'm hoping to find someone who has already gone through all this and perhaps has the answers to get maximum performance of torque at the slowest speeds. Yes, I really want to get under 100 rpms.

The issue, according to the manual, is that torque is lost at those very low ranges, and I'm trying to overcome that as much as possible.

I'm trying to find out what the RPM and HP of the ORIGINAL motors were on the General 260V models. The 1hp 3ph motor I have is 1725 rpm, and the 1.5hp single phase is 1720 (IIRC).

If I'm going to end up getting belt slippage using a VFD at low rpm's anyway, regardless of the motor, then gaining torque doesn't really matter, and that's what you guys have been telling me.

Here's a screen shot of the page in the manual, the shaded area (difficult to see) is the range that torque is lost:




Here's the specs on the 260-1, which is my model (I think, not the 260VD). It indicates the speed range is from 410-3000 RPM.



Of course, that range is with the ORIGINAL motor, which I do not have. I'd like to find out what motor came with it, and the specs, including HP and RPM, so that I figure out what I'll get with the motors that I currently own for it.

Any one know where to find that info? I checked OWWM, but didn't see it.