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Hi guys I was just wondering what speed would be optimal for a home made drum sander, I've seen speeds on the net from 910sfpm and 3300 sfpm for sanding my drum is 4 7/8" diameter and I've got either a old lawn mower motor 2HP (no casing) or one off an old cement mixer 1HP so hopefully one of these will be ok.

Cheers Guys

John

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Formerly JJH

I learn more from my mistakes than my successes

John: Not sure what surface speed you would use but too high a speed tends to generate too much heat and cause your paper to gum up from excretions from the wood.I'd rather have it a bit slow then too fast.

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A person who has never made a mistake has never made anything!!!

The commercial ones I can find online run a 5 inch drum at 1500-1750 rpm. Those things definitely generate a lot of heat. I suspect drum material that dissipated heat quickly would be better. Also a larger drum would equal more surface area to spread the heat across as well as dissipate faster. Just making things up, I'd say either motor would work, but I'd use pulleys to gear them down. If I was using a wooden drum, I'd go slower, or take extra light passes.

I assume you already know this if you're building one, but these also make a bunch of dust and require good dust collection to function well.

Mike

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Mike Lindstrom

Hi, John

I made one a few years ago, and ended up making it about 2500 SFM. I've been happy with it, but I've never used another sander to compare it with. It's got a 3450 RPM motor ( old Craftsman table saw motor) , 3 inch drive sheave, 6 inch driven sheave, and a 5 1/2 inch drum.

If you use a v-belt and cheap die-cast sheaves, like I did, you can easily and cheaply change it later on ( or, even use a multi-diameter sheave so you can change it easily from job to job). Grainger's is the place to get that stuff. I based the drum on a 3/4 inch diameter steel shaft that I also got at Grainger's, as well as the pillow blocks.

Phil

Ther is another speed that is important to consider and that is the feed rate

With a home-built sander you may have more vibration problems than with a commercial unit. My home-built has a solid (MDF/ply) drum and it does vibrate a bit.
Vibration can be a funny thing- not necessarily worse at faster speed, but it often seems to be- so having a selection of pulleys is handy for experimenting.
My 5" dia homebuilt is direct-driven with a 1725 rpm motor. 4" dust collector hose to 1HP collector.
Heat buildup and paper gumming depends on airflow and (as Michael points out) feed rate.
I have better luck with lighter cuts and faster feed, rather than the converse.

Cheers
John

The way I worked out how to build mine was to first get a free motor, which turned out to be 3HP 1425 RPM, then buy some off the shelf pullys (a 3.5" and a 2"). I had to get one machined so that would fit the drum shaft (cost about $25). Then looking at the specs for the commercial drum sanders I found that 2800-3000ft/min was what they were using (generally). Then I did the math to determine the drum size I'd need to achieve that rate.

If you get the drum diameter sorted first, then you are making work for yourself by having to match that with pullys and motor speed to get the ft/min of sandpaper required. Makes it tough to make it work cheaply. The drum is the one thing you can make yourself to any diameter the math tells you, everything else costs money. Get the cheap or free motor first, then the off-the-shelf pullys, then do some math to work out the drum diameter.

Oh, and sandpaper gums up, get used to it.