Pulley sizes / drum speed for drum sander?

[Lons]

Hi
I'm progressing with my drum sander build but not sure what speed the drum should be running at. I note that the Jet 10-20 specs are 1700 rpm and drum size of 5", i assume they are quoting motor rpm and not speed at the drum peripheral :? .

My motor is 1 ph running at 1425 rpm and drum is not finished yet but should finish about 110 mm made from solid MDF disks so pretty heavy. Will 1425 rpm be about right for the drum shaft or still too fast bearing in mind it may not be perfectly balanced. Probably use a 50mm pulley on the motor but will need to calculate the drum pulley size if I need to change the speed.

Any input will be more than appreciated.

Bob

 

[sploo]

AC induction motors run at a speed that's governed by the supply frequency and number of motor poles (http://www.engineeringtoolbox.com/synch ... d_649.html). As 2 and 4 pole motors seem to be most common, a 50Hz supply will give ~3000rpm or ~1500rpm; so your ~1400rpm motor (which is the same as the specs for most of the Jet models I could find) should be perfect.

Most modern drum sanders appear to be an open ended type, with the motor directly connected to the drum (via a vibration dampening coupler). I.e. 1400rpm is the speed for the motor and therefore the drum.

Some machines, such as the Axy ST-480, measure the load on the main motor, and if it's struggling, it'll slow the motor driving the feed belt; but I assume it's still always trying to run the drum at full rpm.

EDIT: This design http://woodgears.ca/sander/plans/index.html apparently uses a 5" and 2" pulley pair (a 5:2 reduction). Assuming a US 60Hz supply, and a 2 pole motor of around 3600rpm, that would give a drum speed of 1440rpm. It also has a ~5" drum, so again that looks to be in the same ballpark.

 

[Phil Pascoe]

http://www.blocklayer.com/pulley-belteng.aspx

 

[Lons]

Thanks guys

That's a comprehensive answer Sploo and a very useful link Phil

Much appreciated, just need to order a couple of pulleys and a belt , plenty around with 5/8 shaft.

Bob