2x72 sander

[Susquatch]

Hmmm might be worth a try one day...

I wanna watch.......... from across the street!

Jk! You could rig it up with a volt or two.......

 

[Susquatch]

You can't do that with the input of the vfd. For single phase to 3 phase VFDs the output could be divided.

I think I am not understanding you. Why do you mention the input? And what does divided output mean?

 

[Chris Cramer]

When you said the VFD wouldn't ne very happy about it, I'm saying that the VFD input would still be wired correctly to single phase power. Then the 3 phase output could be divided to power a single phase motor.

 

[Doggggboy]

Apparently there are single phase output VFDs.

VFD’S for Single Phase Motors?

www.wolfautomation.com

 

[phaxtris]

When you said the VFD wouldn't ne very happy about it, I'm saying that the VFD input would still be wired correctly to single phase power. Then the 3 phase output could be divided to power a single phase motor.

i believe the question is that because the 3 phase is artificially generated in a single to 3 phase vfd that the output stage may not be happy only using 2 of the 3 output phases

single to single vfd i would imagine has some different electronics internally

 

[Chris Cramer]

Yeah, that is why it isn't recommended to use it that way like I said the first time. The single to single phase VFD is different than the single to 3 phase VFD.

 

[Susquatch]

Yeah, that is why it isn't recommended to use it that way like I said the first time. The single to single phase VFD is different than the single to 3 phase VFD.

Sorry for confusing your information. I got it now.

It still seems like a bad thing to do, but I get the idea now. As @Dabbler says, I'd be interested in doing some simple tests. Not doing that with the VFD's I have though. Someday I'll get a cheapo VFD and try it. @Dabbler can hit the go switch.

Yes, a single phase to single phase VFD is the way to go. But I'd still rather use a 3phase motor.

 

[Dabbler]

Ah! not using a single phase VFD to a 3 phase VFD but only on one leg.... Rather using a 1ph to 11ph VFD designed for the purpose.... Now I get also!!!

 

[Former Member]

All I can add to this my motor shop (that I've know for over 30 years), when I suggested the topic answer was DON'T! With a strange look. Short answers like that mean something.

 

[Art M]

I'm a little late to the party here, as usual.
If anyone is interested in a bolt together grinder with side tilt check out Saber opensource grinder project.
Guy (Canadian I believe) named Dan Comeau who is a knife maker posted plans. looks really nice.
Was very good of him to put the time into it to post online.
I'm thinking of building that one or a KMG clone as we have one at work to copy.
The KMG is simpler to build just some flat bar and a bunch of holes to drill, the one we have at work I use for just general shop stuff I actually quite like it. I think a belt grinder of any kind is an extremely useful tool for any home shop.
Art

 

[Dabbler]

@Art M are there any images or videos of a working Saber 2X72 grinder?

[update] I found one myself:

 

[Art M]

OSG the Open Source Grinder project

Link to cut files if you have access or a buddy with a water jet or laser table. I tried with a plasma table at work but the kerf from the plasma torch eats up too much. If someone way smarter than me knew how to modify the cut file you could cut it and drill the holes.
Art

 

[Art M]

SAYBER OPEN SOURCE BELT GRINDER PROJECT - CAD Files, Build Instructions, Schematics BOMs and more for a world class 2" x 72" belt grinder

dcknives.com

I think this is the home page
Art

 

[Chris Cramer]

I'm not sure if I've already shared this, but I've definitely improved my belt grinder both in terms of electrical and mechanical operation. Instead of using multiple square tubes to build the frame, a single large rectangular tube was used to keep everything in line, and the adjustable tensioner was still used. The size of the frame allows me to change the accessory used for contact like the plate and the contact wheel.
In terms of electrical operation the VFD was replaced with a 60hz 3 phase VFD to gain full control of the 3 phase motor up to it's top speed at 60hz instead of 50 hz. This VFD also has more settings t control acceleration, and deceleration; but I'll have to do more research to make use of the other functions.

 

[Doggggboy]

Nice . I was thinking of changing the drive pulley on mine from 5 to 6 inches to gain more fps on the belt speed. I made the mistake of getting a 1725 rpm three phase motor instead of 3500. Then I realized I can run the motor at 90 hz with the vfd. Problem solved. But then again, I'm not making knives and spending hours in front of the grinder.