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Need some advice on drive shaft for belt grinder


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Ive been trying to source some shafting for the drive wheel on a belt grinder im building. I have a drive wheel that locks on with a nut, it was taken off my old little grinder, but the step up pulleys i need use a keyway shaft, both are the same bore(1/2"), but no where ive found sells a partial keyway with a single threaded end.

 

Id rather not buy another drive wheel since i have one already. Id appreciate any advice!

 

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Well besides having a machine shop or a friend with the right tools to modify a shaft, You could do some simple things to make it work. Mark and center punch the end drill and tap. having the hole perfectly centered will not have a significant effect on balance so it is ok to do this all this with basic power tools and hand taps.

Key ways on shafts are typically done on a mill, but there is not a lot of shear force on a grinder setup so the full strength of a proper key is not really required. One way to make a simple key is to place the pulley on the shaft drill and tap a hole between the two items. 50/50 just like a key, Install a bolt with some locktite. It will do the job just fine. If the pulley has an offset Hub you can install a pair of set screws. If it does not you can sometimes come in at an angle from the side and get your set screw in that way.

There is also a Locktite designed specifically for things like this. It can fill a reasonably gap too. You put it on the shaft and the bore and assemble and let sit for 24 hours.

You can also take a small cut off wheel or dremal tool and cut a key into the shaft. It does not have to be pretty.

Patrick B)

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Its times like this, i wish i hadnt sold my mill. Its not so much as the keyway, but since the drive wheel requires a threaded end to secure, i cant put it on a keyway shaft, i could always thread the end, but i have yet to find a partial keyway shaft so i can thread the opposite end.. The setup i need is a keyway on the motorside for the pulley, and on the belt side, i need a thread, and a nut to secure the drive wheel.

 

Also, what size pulleys are you guys running? I was going to order a 2",3",4" step up, but i dont want to end up with a grinder running too fast.

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A full key way shaft would not deter me from threading the end, but that's me.

Again you can do a partial key way on the shaft with out a mill.

pulley sizes do not matter as much as the relative size between them. Your looking for ratios. A 2" 3" 4" has circumferences of 6.28, 9.42, 12.56. So a 2" to 4" is a 2/1 ratio and would roughly cut your motor RPM in half reverse that and it will double it. what is too fast or too slow is influenced by the circumference of your drive wheel. Bigger wheel more Surface feet per minute.

Patrick B)

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Patrick,

Thanks! my drive wheel is 4", the SFM should be manageable with that step pulley. i cant find the equation to figure that all out, but the motor is only 1725 RPM.

 

I remembered my landlord has a shop thats well set-up, i might be able to convince him to thread and mill a shaft.

 

Im really excited about getting a new grinder set up, im severly limited with my current little grinder.

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McMaster-carr shafting with keyway, TG&P 1045 is the best stuff. If I was building another grinder today, I'd start off with 3/4" shaft.

 

http://www.mcmaster.com/#precision-shafts/=ld2uyz

 

you can get dual-diameter shafts. I'd stick with 3/4" but if you want 1/2" on one side, it's doable.

Also, there are one and two side threaded shafts. McMaster-carr has almost anything.

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