Slow rpm

[madman]

Whats a cheap simple way of slowing down a buffalo drill press (pulley model) to around 14 rpm for the low end. I need slow speed for large hole sawing if possible. Thanx

[Bruce Griffing]

You can use a three phase motor and a VFD to get lower speed or a DC motor and a DC drive. The link shows someone who added a jackshaft - that would also work.

http://www.frugalmachinist.com/jackshaft.html

[Rustybolt]

The cheap way is to add a jackshaft as was mentioneded. On some drill presses there is room between the existing pulleys to adda shaft and another pulley.
Another alternative is to get a DC treadmill motor and controlls and go that route.

[precisionworks]

I use an old Ettco tapping head (they're always on eBay for $20-$30USD, Model 2B, like this one: http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW ). They seem to reduce spindle speed by 3-1, so 100RPM becomes 33RPM.

Ettco says they aren't supposed to do this but mine does it anyway. Probably doesn't know any better. Also works O.K. for small hole tapping but not nearly as good as TapMatic.

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Barry Milton

[darryl]

Seems to me a jackshaft might be a better way to go, since you just might want a torque increase at the same time as an rpm decrease. Not sure how well motors will handle being speed controlled down to a low rpm, and deliver increased torque at the same time. Just a thought, maybe it's not a problem.

[wierdscience]

Add a chain sprocket and a right angle gear reducer.Alternately a lawn mower tranny would work too.

[jerry sheppard]

i have an old delta drillpress (early 50's model)...had the same problem,it ran too fast for anything over a 3/8ths drill....what i did was a variation on the jackshaft....i added another motor hanging near to the original motor,including the additional on/off switch....using a multi-step pulley, and using the original motor as a jackshaft, i can slow the spindle speed way down,or speed it it up from the original configuration...i hope this discription is clear, as i don'y have any pictures of my arrangement.......

[Mike Burdick]

Jerry,

Your idea is pretty clever!

[pete913]

Somewhere , back in one of the old issues of HSM, was a variable speed reducer/increaser described by someone that consisted of a couple of chain sprockets and a differential gear setup that was infinitely variable between 0 rpm and 1 to 1. It was fairly simple and ingenious in its design. Maybe someone else remembers seeing it and can give you the full info on it.