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I Forge Iron

Surface grinder advice needed

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So I've kinda dove in the deep end here & need some advice / help. 

I bought a DoAll D-6 hydraulic surface grinder from a local machine shop acquaintance of mine. I know that it used to run. I've used it in the past. But its been sitting the better of a year, so it does need some love. 


It's set up for 440v on a 1 horse 3 phase motor. I've only got 220v single phase at the house, so I've got to up the juice. Which is where my first issue is. I've been reading like a fool to learn what I can about VFD controllers & Rotary phase converters so that I can run this puppy & figure out what the next issue will be. However, I'm not real certain of what the differences between the two are. Nor which would be preferable for this application. I would like to be to power the hydraulics as well. The coolant pump is seperat & runs off standard 110v. 


I'm only into this for $80 USD, so I'm willing to play with it for a while. Any advice & help is much appreciated. The D-6 model isn't as well represented with google-fu as others. 


Please pardon all the crap in the yard. My wife has started spring cleaning early. Its not generally so trashed. 






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Sorry I can't help with the grinder but the vehicle in the background caught my attention.

There is a thread in Everything else titled Jeep & Willys lovers. A place to put pictures of our interesting 4X4s. Would love to see a post & pictures of it there. Is it a Duce & a Half?

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How much HP and torque does the grinder require? Unless you're going to  be using it commercially I doubt you need 440v. It's not that special, IIRC runs motors cooler for the same output or some such. If it's only a couple HP you can get a good one for a couple few hundred $.

Frosty The Lucky.

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JHCC; not any more;   They have been endangered ever since "modern" architecture has eroded their habitat. Frank Lloyd Wright played a major part in driving them out from their cornices.  A few are in still in protected preserves like the National Cathedral in Washington DC, USA. Cathedral of Notre Dame in Paris, France, etc.

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Since that motor appears to be a set up with an integral spindle, I'd leave it alone.  It'd be nice to do a swap to 220 if it was a standard frame motor but I doubt that's possible.  Many of those integral spindle systems get really touchy to keep things balanced and smooth.  Look deeper, though:  It could be labeling hype with no more than a standard frame motor bolted on.

The control is where the questions come in.  Is that transformer being used to drop one leg of the 440 to 110 (as it's marked) and the actual relays are running with that?  If so, you have to consider a little more deeply what your phase converter is actually doing--you might be able to separate the control from the 440 line which would allow the VFD to give you the benefits of variable speed. Otherwise a VFD would be nothing but a glorified phase converter:  It'd be fixed to 60hz to feed that control transformer what it wants instead of being useful for the spindle motor.

YMMV...photos only tell .1% of any machine's story and I'm just another internet "idiot" with opinions.

Oh..and once you go VFD, you'll never want a rotary phase converter again.  Even if you have to throw more money at the VFD, you'll not regret it.

Looking closer..that motor says 550V...is there another transformer hidden in that iron somewhere?

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Kozzy. That 550v isn't a typo. I thought that as well, until I found another data tag reading 550v 60hz. Which if my research is right, would mean this unit was set up for Canadian use, or possibly Swiss. I'm betting Canadian though. 

Another thing that has me curious. The relays are also 110v. Same as the transformer. 

The power panel also looks as if it was added post production. 

I may just geta 220v VFD to wire in & see what happens. If I hadn't physically seen this thing run & used it in the past, I'd say I'd been had. 




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Depends on what you want to do with the surface grinder.  For best results (and most accurate finish) you'll want the power to be true 3-phase, and variable speed shouldn't buy a whole lot on a surface grinder anyhow.   A rotary phase converter would be ideal, with a VFD being second choice.  If run on 220V the motor may not run at the rated speed, and as already identified there may be some issues with the control circuit voltages.

For those wondering why a static phase converter is a bad idea, with one missing leg there are oscillation in the applied power that will actually show up in the surface finish on a surface grinder, it's also why a 3-phase motor is more desired for driving the spindle than a single phase- the applied power is less variable ("smoother"). 

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