Rebuild V-belt shieve

[crawford_d]

Has anyone got experience resurfacing or re-grooving V-belt shivs? My 325D Toro Groundsmaster has 3500 hours on it and has cupped out the two shivs that drive the PTO shaft. The belts are double V’s put together and so now that the groves are cupped out the belts (even new ones) can’t go down deeper in the groves.
What I was wondering is if it is possible to weld up the cupped out part and turn it down again? New pulleys are about $500 so thought it might be cheaper to rebuild. Use the old girl as a snow blowing machine in winter now and it takes lots of power through that drive system.

[Restrorob]

I'm not familiar with this unit but why couldn't you install separate belts of the same length ?

I've never heard of anyone welding cast pulleys because they are made of such porous steel.

[ovalracer44]

You can weld cast iron. Although it is not impossible it is very difficult. You either have to preheat the metal, or keep it relatively cool.

If you preheat it, heat to around 900 degrees. You can preheat as high as 1200 degrees but never higher than 1400 degrees. Weld slowly and turn the current down. Never weld more than 1 inch at a time. Move to another portion of the work and weld there. Allowing the metal to cool is called peening. When you are finished let the piece cool as slowly as possible by burying it in sand or wrapping it in a welding blanket. This will reduce cracking tendencies.

Cold welding is just as effective. Heat the material to 100 degrees. No more. It should not be hotter than you cant touch it. Weld in 1 inch segments and allow the piece to naturally cool. DO NOT accelerate the cooling process in any way. Try to keep the temperature of the piece you are working on cool. Do not let the ends of 2 welds line up parallel with each other.

Either method is acceptable, but for something the size of a pulley I would recommend the preheating method. It is easier to keep a constant temperature.

What ever method you chose you have to continue and can not stop. You also can not change methods half way through.

Use a good mig welder with

Beware also, because you intend to machine the surface, weld material is very hard to machine as it is a lot harder than cast iron or ductile steel. You will need someone with the ability to machine tool steel as cast iron has a rockwell hardness of around 62 HRC, where as a weld can be as strong 20 HRE.

Unless you are really good at welding, have time to piddle on this project and have a connection with a CNC lathe with tool steel cutters, you are better off buying replacement pulleys.

If you decide to repair, good luck.

[Breezmister]

Just wondering, have you looked on line for some after market pulleys ?
Just an off the wall thought, could you have them machined ? Cut the center rib down so the belts are not rideing on it.

[crawford_d]

Thanks for your in put into this project. Really good ideas and you are all right on the money with your help and ideas.
I do have a mig welder and an engine lath but I don't do either professionally any more so would be more difficult then at earlier in my years.
I do like the idea of cutting down the center rib of the pulleys though as it would be very hard to do and even if it didn't work I wouldn't be out much. I have not looked on line for after market pulleys but generally Toro is really big in proprietary type parts and so it is hard to fine.
Sometimes it is just not worth trying to get around paying the price and have it over with. Thanks again guys for your input.