2 x 72" grinder

[Ruddock]

Making a 2 x 72 belt grinder and the plans say use a 4 inch drive wheel with a 5/8" bore. My question is can I use a bigger bore size but the same outer diameter. What is the difference in using a bigger bore

[swedefiddle]

Bore size is what fits your shaft or Motor.

Outside Diameter of wheel on Motor is what controls belt speed. Variable speed Control will be able to slow it down, not speed it up.

Neil

[Ruddock]

So the bore size has nothing to do with the power of the grinder

[WayneCoeArtistBlacksmith]

The bore size must match the diameter of the shaft on the motor or shaft for the pulleys if you have step pulleys for adjustable speed.  56c face motors have 5/8ths shaft.

[tompdw]

You can buy the parts you need from Beaumont metal works out of Columbus, Ohio.

[WayneCoeArtistBlacksmith]

You can also get parts from www.usaknifemaker.com.

[Kozzy]

Bore size has to do with several factors when designing a machine.  The two main factors are torque to be transmitted and load/bearings that will be used to support the shaft.  High loads require stronger bearings which generally leads to needing a larger shaft.  Lots of torque can twist a shaft (especially a long one) and can strip out a small keyway so again tends to lead to needing a larger shaft.

 

In reality, there is not that much load or torque on something like a belt grinder in the 2 x 72" range.  Even a small-ish shaft is likely adequate in terms of torque and loading.  The decision then tends to lean toward mechanical issues like space, available pulley bores, motor shaft size, and the in's and outs of machine bits.

 

Personally, I lean toward 1" dia shafting on my builds but that's because it's common in stuff I already do.  It's overkill but I'd rather be over than under.