How to wire Stihl USG to be bi-directional??

[walexa07]

Hey guys, I have a USG chain grinder but it only turns one way. The switch has 4 wires coming to it: a black, white, blue, and brown. There is also a green that comes in through the power wire that goes somewhere else. There is also a little power panel or circuit board that has various color wires going to Z2, R, and E.

I would really like to get this grinder to be bi-directional. Any help is greatly appreciated.

Thanks,

Waylan

 

[w8ye]

From the wall plug, if everything is hooked up correctly, the black wire is "hot", the white wire is "Neutral", and the green wire is "Ground".

You are interested in the four wires that come from the motor and how they connect to the black and white wires from the wall plug.

"E" is for earth or ground

The blue and brown are your start winding but there is a light blue and a dark blue? Where do they go?

The ultimate secret is to reverse the power going into the start winding which one side of is currently hooked permanently with the run winding at present?

 

[walexa07]

From the wall plug, if everything is hooked up correctly, the black wire is "hot", the white wire is "Neutral", and the green wire is "Ground".

You are interested in the four wires that come from the motor and how they connect to the black and white wires from the wall plug.

"E" is for earth or ground

The blue and brown are your start winding but there is a light blue and a dark blue? Where do they go?

The ultimate secret is to reverse the power going into the start winding which one side of is currently hooked permanently with the run winding at present?

Thanks for the reply - so I need to figure out what the light blue and dark blue wires go to? I took the switch and photos to Radio Shack to see if they had a switch that would work but I'm not sure they understood what needed to happen. I don't know if a single switch with 4 poles can make the motor bi-directional or if I need to do other rewiring.

Waylan

 

[angelo c]

I thought i remembered you can get the thing started spinning the wrong way with a drill and then hit the switch and it will run backwards .....rednecking run wronging

 

[AKDoug]

Just remember that if it's running backwards you are going to be wearing all that dust and sparks it creates.

 

[walexa07]

Yeah, I am fine with the dust/sparks - I just want it to be putting the burr on the underside of the tooth for both sides of the chain instead of just the 1 side.

 

[w8ye]

Thanks for the reply - so I need to figure out what the light blue and dark blue wires go to? I took the switch and photos to Radio Shack to see if they had a switch that would work but I'm not sure they understood what needed to happen. I don't know if a single switch with 4 poles can make the motor bi-directional or if I need to do other rewiring.

Waylan

You need a TPDT center off switch. You diagonally cross the outer four terminals.

If you don't have a center-off switch you will need to use the existing switch as a start stop and a double pole double throw switch for direction. Wire it up so the toggle is in the direction that the chip fly so there is no confusion. You still have to diagonally cross the outer terminals.

 

[w8ye]

A single phase motor like that has a start winding and a run winding. Each has two wires. The gauge of the individual winding wires are usually different between the run winding and the start winding. Or you could figure it out with a test light or ohm meter?

The motor being a single direction, most likely one side of the run winding is connected to one side of the start winding with a connector or even soldered? This will need to be separated so you have four wires.

 

[w8ye]

There is a thread around here somewhere about reversing a Northern Tools grinder.

Read that thread.

I decided not to reverse my grinder as that burr is gone when the chain hits the wood anyway.

 

[RedneckChainsawRepair]

Thats what I found on my USG, no biggie IMO. Burr gone as soon as it hits the wood.

 

[w8ye]

Here is what I found . . .
http://www.arboristsite.com/community/threads/reversing-a-hf-grinder-3-wire-ac-motor.181620/

http://www.arboristsite.com/community/threads/reversing-chain-grinder.26118/

 

[MCW]

Reversing grinders is one of those things that sounds good in theory but makes zero difference in reality. As mentioned above any burr is gone as soon as the chain hits wood.
I had a MAXX grinder that could grind into both the left and right cutters. It wasn't reversible so to speak but did the same job. I now run a Speed Sharp Auto which only grinds one way. You'll never ever notice the difference in the real world.
You know how some people say "you shouldn't believe everything you read on the internet"? Well this is one of those times

P.S. I've reversed grinders before using the exact same diagram as posted above (in fact I think I originally posted it?). It was an interesting experiment and worked.

 

[walexa07]

Thanks for the info guys - I think I'll just leave it alone for now.

Waylan

 

[AKDoug]

I use the USG exclusively in my business for sharpening chains. Something to learn is that if you get a burr that won't come off easily when it hits the wood, you are taking too big of a bite with the grinder. It's easy to do when you are trying to knock back a rocked out chain. Just take small bites and the burr will be no issue.

 

[MCW]

I use the USG exclusively in my business for sharpening chains. Something to learn is that if you get a burr that won't come off easily when it hits the wood, you are taking too big of a bite with the grinder. It's easy to do when you are trying to knock back a rocked out chain. Just take small bites and the burr will be no issue.

This depends a lot on the wheel type as well. The ABN/CBN type wheels are less likely to cause burrs when pushed hard. Depending on damage to the lead cutter edge you may have to take more off than ideal.

 

[AKDoug]

Oh, I take it off, but in small bites. My attempts to order ABN/CDM wheel for my USG grinder have resulted in backorders that the suppliers don't know when they are going to be filled. I'd love to try one.