Surface Grinder

J

JMJones

Joined
Jul 14, 2010
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I have the opportunity to purchase an older surface grinder with 1hp motor and automatic feed for a decent price. However it is three phase and I dont have that in my shop. Does anyone have any experiance running one of these on a static phase converter?
 
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Thats what I have just check the web and be sure you hook up the converter correctly.... Works just fine thru a 220v line
 
either of the above suggestions will work BARELY. your best bet is to get on ebay and get a rotary phase converter. you get one that will only run your surface grinder or if there is a chance that you may get more equipment that requires three phase power then get a ten or fifteen horse power unit that will run multiple machines. this one,http://cgi.ebay.com/Phoenix-Phase-Converter-3-hp-Rotary-/300521733111?pt=BI_Electrical_Equipment_Tools&hash=item45f87dbbf7 is plenty cheap and is big enough to run a mill also. the problem with a static converter is that it uses a capacitor to start the motor but you are then only running on two legs of the motor so your one horse grinder is now a 2/3rd horse grinder and it is hard on the motor. replacing the motor is fine if you don't have the need to do any precision grinding and/or care about the finish left on the steel.
 
Consider using a vfd instead of an spc or rpc. Because you will not get full power from an spc, and a vfd is a better solution than an rpc: cheaper and more flexible. If you get the vfd you could also use it to give 3ph motors on other machines variable speed, ands 1hp vfds are not that expensive.
 
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There are also super cheap chinese vfd's on ebay that a lot of the cnc guys buy. Lots of user support on cnc forums because of their popularity.
 
I found an old post by Nathan the Machinist which stated that the motors used on a surface grinder are specially balanced and changing the motor is not recommended.


The VFD Salem linked to is the cheapest I have seen.
 
using a vfd for more than one machine seems like it would get to be a real pain in the ass, having to plug and unplug all the time and it will only run one machine at a time. with the rotary you hook it up and run a "three phase circuit all the way around you shop. you cann plug all of you three phase machine into the same circuit and run them all at the same time if you want as long as you don't exceed the horse power or the amperage rating of the converter. Actually you can exceed the horse power rating by turning on other three phase machines and letting them idle in the circuit. for example you have a five horse converter, inyour shop you have a 1 hp grinder a 2hp mill and you get a 7.5 hp hydraulic pump for your new press. though not ideal you can turn on the converter, mill and grinder; 5 hp+2 hp +1 hp = 8hp, you can now run your press off of the combined hp of the idling motors in the circuit. without the right amount of capacitence added to the made up leg you won't have a fully balanced circuit but it will run the hydraulic pump without trouble until you could add more hp to your converter. this can be done in two ways. buy a bigger idler motor (in this case a 10 hp) for the converter and add the proper amount of capacitance to balance the third leg (ideal) or add a second motor ( a three or a five horse) motor and the additional capacitance to what you already have.
 
I ran most of my shop off 3ph statics for a very long time. I ran an old Brown and Sharp surface grinder off one also. I had a VFD that I attempted to hook to the surface grinder but it would not handle the load. Funny the VFD is 3hp and the SG was only 1. Just to darn hard to start. I finally got the rotary and wish I had done it years ago. I got a 10hp delivered for $795. All my 3 phase including the power hammer is now hooked to it. You still need a vfd for variable speed but it is much cleaner power and your performance is not degraded. Just looked at the bay and there is one there for $690 and free shipping. Sounds like a lot of $$ I know but you will have it and be able to use cheaper 3phase motors and your surface grinder.
 
I use the little TECO on my surface grinder too.
I just put it in the cabinet to keep it clean.

Bill, FWIW, I run 4 machines on 2 VFD's.
All you need is a 3 pole, double throw switch.
No need to unplug the machines, you just flip the toggle for one machine or the other.
I can only run one grinder at a time anyhow, so toggling to the second machine is the same motion as turning on another VFD.
Actually it's one less motion, since you don't have to turn the 1st machine off.

I do however run my Bridgeport on a rotary converter.
 
Thanks for all the reply's. Enco said that there 1-3 hp static phase converter was not reccomened for the surface grinder. I dont really see the need for alot of three phase power in my shop because everything else runs off single 110 and 220. i am torn because the surface grinder is a Robot model that I could not find much info on for 600 delivered into my shop and has automatic feed. I have seen it run but am kind of nervous that if anything breaks down I am going to be unable to fix it and have to scrap it. So the risk jumps from 600 plus 100 for the static phase converter to 600 plus two or three hundred for a small rotary converver.
Decisions ...
Decisions ...
 
Fellhoelter said:
I use the little TECO on my surface grinder too.
I just put it in the cabinet to keep it clean.

Bill, FWIW, I run 4 machines on 2 VFD's.
All you need is a 3 pole, double throw switch.
No need to unplug the machines, you just flip the toggle for one machine or the other.
I can only run one grinder at a time anyhow, so toggling to the second machine is the same motion as turning on another VFD.
Actually it's one less motion, since you don't have to turn the 1st machine off.

I do however run my Bridgeport on a rotary converter.
Click to expand...

The switch is a good Idea. but for the price of the two vfds that you are running you could have your whole shop running on one rotary converter.
 
Bill Burke said:
The switch is a good Idea. but for the price of the two vfds that you are running you could have your whole shop running on one rotary converter.
Click to expand...

Spending 2x and giving up the speed control wouldn't work for me, at my hobbyist level.
 
I have a rotary, and use it.

The VFD's are for speed control.
I was just pointing out that you don't have to switch plugs to use a VFD on more than one machine.
 
BTW, I went with a VFD on my surface grinder, and didn't just run a 3 phase line to it because I knew I would be doing a belt conversion on it.

I want speed control for when I do silly things like grind titanium.
I get much better belt life by slowing down the belt speed.
 
Slightly off topic but do you think 600 delivered ( plus the cost of the converter or vfd)is a good deal for a robot surface grinder 6x10 with pope spindel, magnetic chuck and auto feed?
 
6 bills is a GREAT price for a running surface grinder.
Especially one with power feed!
I'd pay $600 more, just for that option.

I am not familiar with the brand though.
Is it an electromagnet, or permanent magnet chuck?
 
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