[martin_05]

Well, not much has been done since I had to deal with motor issues. I went back and forth a couple of times. After rewiring the motor and contactor for 220V operation something went pop in the motor after hours of operation (spindle burn-in).

My original conclusion was that I messed-up the wiring. Still, I took the motor off the machine, took it apart and inspected it. I rewired carefully, double checking everything.

Well, it turns out I didn't screw it up. The motor let out the smoke that makes all electronic things work within 20 minutes of no-load operation on the bench (not even a pulley on it).

So, that's that.

Now the eBay gods seem to have granted me a path. I just bought a 3HP, 3 phase, 1750 RPM motor. The (reputable) seller assures me it is in great condition and will absolutely take it back for any reason whatsoever (always a good sign).

I also purchased a Hitachi WJ200-022SF variable frequency drive. I bought it brand new. Didn't feel like gambling with a used unit and it sure seemed that there were no deals on this unit on eBay at this time.

Everything should be here by the weekend. It all goes well I'll have the machine spinning again by Sunday.

I do have to ream the pulley from ~22 mm (0.866 in) to 0.875 in. Need to find a cheap reamer. I just don't have one of that size. I was thinking of the manual adjustable set Harbor Freight sells. Any good? I could buy a single chuckable reamer as an alternative. Don't have a indexable boring head, that's one of my next purchases.


-Martin

[Bubba]

Martin,
I used an adjustable reamer to bring mine to size and I did it in steps and creaped up on the size. Take it slow and check often to make sure you don't go over size.

[martin_05]

Thanks Art, that's what I'll do.

Trying to figure out how to balance (or check balance) on the pulleys. I've seen pictures of RF-30 pulleys with balancing holes drilled on the bottom. Mine have none. At the very least it'd be nice to get a sense of how far out of balance they might be.


-Martin

[martin_05]

Yes, I figured out that when balancing the rotor on the motor you have to account for the missing "half key" on the shaft. Same for the missing key material on the pulley.

It's amazing how some topics can take you into deep dark crevasses.


-Martin

[109jb]

you can statically balance them by putting a snug fitting shaft through them and then supporting the shaft at both ends on level bars. The heavy side will rotate to the bottom. Remove a little material from the side that rotates down and do it again. When the handle will stay in any position it is statically balanced. The problem with this is that if the bars aren't level it will just keep rolling if close to balanced.

I use a balancer like the one in the picture to balance model airplane props. This one uses wheels to eliminate the need to have the level bars on the end. In the picture you will also note the cone shaped pieces which automatically center the propeller bore on the shaft. You could rig up something like this with some skate bearings. The prop balancer might work, but is pretty delicate and I'm not sure if I would put the weight of a mill handle on it, but it gives you the idea.

[martin_05]

you can statically balance them by putting a snug fitting shaft through them and then supporting the shaft at both ends on level bars. The heavy side will rotate to the bottom. Remove a little material from the side that rotates down and do it again. When the handle will stay in any position it is statically balanced. The problem with this is that if the bars aren't level it will just keep rolling if close to balanced.

I use a balancer like the one in the picture to balance model airplane props. This one uses wheels to eliminate the need to have the level bars on the end. In the picture you will also note the cone shaped pieces which automatically center the propeller bore on the shaft. You could rig up something like this with some skate bearings. The prop balancer might work, but is pretty delicate and I'm not sure if I would put the weight of a mill handle on it, but it gives you the idea.

Yup, 'been flying model airplanes since I was a kid (and helicopters as I got older). I have exactly that prop balancer and have used it many time. I was eyeballing it for ideas. The key, aside from having a balanced shaft and components, are those two centering conical pieces. Or, more generally speaking, having the piece located at the center of rotation.

The other thing is to make a piece that fits into the slot cut out for the key in order to replace missing material.

I am going to wait until I get my 3HP motor and the VFD and use the "If it ain't broke don't fix it method". I'll run the motor without a pulley first. I'll add a half key to the shaft to account fot he keyway material. If that's smooth I'll add the pulley and see what, if anything, changes. If that's smooth, it ain't broke...no need to fix it. I hope I can take the lazy route.

I just want to minimize vibration at the head as it translates into motion at the cutter tip and just isn't a good thing.

-Martin

[martin_05]

Here's an interesting video. Pretty much a big brother version of the hobby propeller balancer with a motor and sensors added:

https://www.youtube.com/watch?v=VKr5RZt6MQo

Gotta love the guy using the side of a drill bit to enlarge a hole.


-Martin

[martin_05]

OK, got my VFD (Hitachi WJ200, 2.2 Kw) and 3HP 3 phase motor (got it for just under $100!).

Attachment 272422

Attachment 272424

Holy cow, that Hitachi manual is a mess. I have to say, typical Japanese cryptic software and clunky user interface. I've dealt with a lot of Japanese-designed industrial and commercial equipment and they never fail to miss the opportunity to make product less than user friendly and manuals that, well, don't make sense. I won't go into examples in the WJ200 manual because that's not what this thread is about. Let's just say they abound.

I bought the little face-place swap-out gizmo that gives you a potentiometer to control speed. My son managed to break the crappy pot the second or third time he used it. He wasn't really trying. We ended up carving the thing up a bit to install a proper Bourns potentiomenter and a beefier knob. Works great.

I also setup the VFD to go up to 120 Hz, doubling the motor speed at max setting. The motor handles it just fine. That means that I get 1,725 RPM at 60 Hz and 3,450 at 120Hz at the shaft. Not sure what I'll end-up with at the spindle once the belts are installed. I'll have to measure it.

I hear some whining and whistling coming from the motor around 20 to 30Hz. Is this normal? Is it because it isn't an "inverter duty motor"?

Tomorrow I'll go grab an adjustable reamer set and ream-out the spindle pulley to fit the 0.875 in diameter motor shaft. Question: In general terms, what class of fit does one go for on something like this? To what diameter should I ream the pulley?


Thanks!

-Martin

[rowbare]

I think there is an adjustment you can make to the VFD to change the carrier frequency. That might help with the whine. Now whether it is possible to decipher the manual to figure that out is a whole other thing...

bob

[martin_05]

I think there is an adjustment you can make to the VFD to change the carrier frequency. That might help with the whine. Now whether it is possible to decipher the manual to figure that out is a whole other thing

OK, thanks, I'll look for that today and report back.


-Martin

[martin_05]

New motor stepped pulley.

Rather than try to ream out the existing pulley I bought a balanced 7/8 bore pulley from these guys:

Beaumont Metal Works : 4-3-2" Step pulley with a 7/8" bore : KMG Belt Grinder Parts Knife Knives Industrial Commercial Metal Belt Grinders Sander USA

Should have it in a couple of days.

I also like the fact that I can mount it in two different orientations. This gives me more reduction ratio choices between the motor pulley and the middle tensioner pulley.


-Martin

[martin_05]

It's been going slow due to a few stumbles and not having time. I finally got the new 3 HP 3 phase motor and WJ200 VFD installed and running.



That VFD manual sure is a bear to go through. I tried working with it as a PDF but it was just not practical. I printed it and ended-up with a thick binder with a full ream of paper in it.

I decided to start by limiting the motor to 60 Hz max frequency. With the current belt setup I am getting 3,600 RPM at the spindle at full throttle. The motor is rated at 1725 RPM @ 60Hz.

I could go for 120 Hz operation (tested on the bench) but I am not sure. Would this dual belt setup stand up to operating the spindle at 7,200 RPM? I know the bearings are good for it. I rebuilt the spindle and installed brand new bearings. I also replaced the bearings in the pulley stacks. My guess is that I could probably do 7.200 RPM for short stints but I should avoid it as a standard mode of operation. If I rebuild the head to go with a single serpentine belt maybe I can count on higher speeds for every day use.

I am now reading through the manual to see about fine tuning. I would like quick starts and stops. It looks like I need to add an external power resistor to get quick stops. Right now it will error out with an over-voltage condition if I set my deceleration time below about 2 seconds. I want quick stops for tapping. To be fair, at low RPM I it probably stops just fine. I can program a tapping speed setting to be activated on a toggle switch connected to one of the digital inputs in order to avoid the possibility of bumping a potentiometer and going high speed by accident. Once the spindle is controlled by software this should not be an issue at all.


-Martin

[109jb]

If you don't mind my asking, how much did you pay for the new motor and VFD?

[martin_05]

If you don't mind my asking, how much did you pay for the new motor and VFD?

The motor was $100 on eBay. It's a blower motor. Not inverter rated.
I got the WJ200 here:

https://www.driveswarehouse.com/p-2527-wj200-022sf.aspx

7/8 shaft. I had to buy a new stepped pulley (link in a prior note).

Also bought this:

https://www.driveswarehouse.com/p-2591-wj-vl.aspx

The latter broke right away. I just replaced the pot with a beefier version I had laying around. A standard 1/4 inch shaft fit just fine in the same hole.


-Martin