building a clone questions

[little mac]

Ok, so I'm about to start the machine work on my variation of a KMG clone.

first question:
My boss has offered to give the semi-permanent loan of a 1.5 hp 3450 rpm motor. My plans originally called for using a 1725 rpm motor and I worked out the pulley sizes and drive wheel dia as such on the reasoning of one turn equals one surface foot. Now with a motor twice as fast, I am considering a smaller drive wheel to avoid having to use an idler shaft to cut the speed. I need some opinions wheither I can expect good performance with a approx. 2 inch drive wheel or will it be likely to slip too much.

Second question:
How much over size do I need to make the slot where the tension arm fits into the riser peice. Seems to me .005 or less would be desireable, but I've seen pics of alot of clones where this seems alot bigger. (as much as .100) That seems very sloppy to me and might lead to inconsistant tracking. Am I worring too much.

Third question:
Now on to the tracking adjustment itself. I can't decide what thread to use here. The most available to me would be 3/8-16 and 1/2-20. Lets assume the contact point will be at the idler axle.

Forth and final question (for now)
Related to this, is a method of locking the adjustment screw. I'm thinking a cross drilled and tapped hole intersecting the adjustment screw and useing a brass slug pressed by a lock screw against the adjustment screw. Again, am I worrying too much ? Is this even likely to move under operation?

Thanks for the help
Rick

 

[69_knives]

If you use a 3/8" national fine thread (24 pitch) for the tracking adjuster you shouldn't have to worry about the nut backing out. That answers two questions.

A lot of people say 3450 rpm / sfpm is fast, Ideally you'd probably want a 3 step pulley, not sure how a 2" pulley will work on a 3450 motor.

I'd go for as little clearance on the riser/tension arm as possible while still being functional. I made my grinder riser and tension arm out of a 2x4 and plywood and there's probably .075 - .100 clearance if I wiggle it but it works great without tracking issues.