Need to make a 17mm bore v pulley...

[caveBob]

Hi all,

Found this forum recently, just never posted til now... maybe a little background might help...

Finally picked up my first metal lathe around last Christmas, it's an Atlas 10F H54. No hurries with it as it needed a good cleaning, and since I did that... might as well paint her up too. New timken bearings a few missing parts found on ebay, and she's running now... just need to finish painting the covers and shim the carriage properly (shim stock arrived just yesterday) to sweeten everything up nicely. From what I've read so far, it looks like I need/want a decent ER-40 collet chuck to help me make a bunch of duplicate sized parts. So I talked with Jan this week at tallgrasstools, and he's making up a kit for me that ought to be ready to ship this week, here's a link to his ER-32 Collet Adapter Kit.

This brings me to my question... I need to make a v pulley. Atm I'm using the stock motor w/pulleys and need to make the pulley that will ride on a treadmill motor with a 17mm spindle shaft. ~1" of clean 17mm shaft terminated with a coarse metric pitch thread which originally was used to hold the flywheel in place. Should I just cut off the threaded portion off of the shaft, or remove the spindle from the motor then mount in the lathe and cut the threads down? Second option would mean that the pulley would have to be stepped internally to accept the shaft.

Looking around the net I found MACHINE SHOP TIPS #65 Lathe Project Pulley Part 1 of 3 tubalcain where Tubalcain first drilled to just undersize for the bore, then reamed to final bore size. I reeealy can't see me getting a 17mm reamer for this one-off project and I don't have metric drills that size atm. What if I were to bore a hole as close as I can get to 17mm, just undersize, then make a boring bar of some sort out of some O1 drill rod stock that I have? Could I expect to come away with a "close enough" fit on mounting to the shaft, or should I try something else?

I'm not sure of my abilities to cut accurately right now, especially since I'm new to lathes, and the fact that I'm still fleshing out what needs tweaking/tightening/optimizing for accuracy, etc. I'll eventually figured it out, but for now... any tips?
P.S. if anyone needs a G5523 Triple V-Groove Pulley - 3" Dia., 17mm Bore, I can make you a good deal... (didn't realize that the V wasn't sized for 4L belts , but 3 )

 

[British Steel]

Hi Bob,

No reason at all why you shouldn't drill and bore the pulley - a 5/8" drill bit will get you pretty close to 17mm! A good bored finish - correct surface speed, so RPM should be around 250 - 350, and a fairly fine depth of cut and feed (maybe 0.003" per revolution?) will be close to as good as reamed, if you take a few "spring passes" to allow for flex in the boring bar and have a really *sharp* tool with a slight tip radius.

The boring bar doesn't need to be *all* HSS - the shank can be almost anything steelish, cross-drilled for an HSS toolbit and axially drilled for a locking screw (presume you won't be boring to a blind stop, but right through) - I'd be tempted to keep the threaded section (at a guess it'll be an M16, common thread but there are a couple of variants - 1.5mm pitch is the metric *fine* version!) and "counterbore" the pulley for a locating nut on the end of the shaft.

Cutting a keyway in the pulley bore could be done using the same boring bar with a square-ended tool, racking the carriage back and forth and advancing the tool with the crossfeed a few thou" at a time? It works for me!

Just my ha'pennorth,
Dave H. (the other one)

 

[swatson144]

Unknown lathe.. I think the first thing I'd do is mount the pulley as I wanted to cut it and skim the face a few thou. Right at the machined band. If the band is equal all the way around run a dial indicator from front to back (back being past center) to find out how far out the head to ways alignment is off (probably not much but good to know) or other problems with the setup. If the band isn'r equal it needs fixing. It does not matter if you bore, ream or hone the hole it will only be as good as your setup. It's pretty simple . The pulley needs to run true. The bore can be assumed to be close . But if possible I trust running out the pulley itself. If the pulley is too worn to indicate just do a new one. No one likes a dancing pulley.

Steve