slowing down the speed???

larry merlau

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i ran into a question last night from a woodworker that could use some of the forums help..he doesnt do computers so i am caring the ball for him... he has a 5 hp edge sander that he feels runs to fast, its burning up his paper and wood and he wants to have a variable speed or a slower speed for it.. the motor is 220V and single phase.. they make lathes that have variable speed so it must be possible anyone got some solutions as to how he can do this...thanks
 
If it is not direct drive, then just change one of the pulleys to a different size :dunno:

If it is direct drive, then he has a lot larger task ahead of him, what make/brand is it?
 
it is direct drive and i didnt recognize the brand ,,its american though ,,he did mention that its a commercial brand and a small size for commercial work.. cream colored..
 
Larry, in answer to your question you can't do a variable speed drive on a single phase motor. I won't go into the reason why because it's very complicated. Only a three phase motor. Since it's direct drive and since it's a comercial unit I'd say it's the operator.
 
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Side note: So many of us want slower sanders and grinders. You would think there would be a market for this. I too would like to be able to use finer paper on a power sander but slow stock removal and burning risk come along with that. I vote for slower speed or VS on commercial units.
 
...they make lathes that have variable speed so it must be possible anyone got some solutions as to how he can do this...thanks

The variable speed motors on lathes like my PM are three phase. Those can be slowed down, but as Don said, a single phase motor can't be slowed down in a practical manner. (Well, he said they can be slowed down, but I'm pretty sure he meant can't.)
 
The variable speed motors on lathes like my PM are three phase. Those can be slowed down, but as Don said, a single phase motor can't be slowed down in a practical manner. (Well, he said they can be slowed down, but I'm pretty sure he meant can't.)

Vaughn you got 3 phase in your shop? Your lathe also comes in single phase
The speed on both is done with electronic variable speed.:thumb:
If the guy wants to spend the jing he could swap out his old motor for one of these. http://www.dynamotors.com/how-the-motor-works.html?gclid=CNXlp9S6lqICFQ_yDAod4g5NFw
 

Don beat me to it, but yeppers, the speed control (variable frequency drive, or VFD) is also a phase converter. I think pretty much all of the 1.5hp or bigger lathes use the same type of setup. (I think the Nova XP is an exception to that...it's got its own kind of motor.) I believe the smaller variable speed lathes use either a universal AC motor or a DC motor.
 
Larry, the VFD takes single phase in, and puts out three phase. The motor itself is a three phase motor, but the lathe plugs into a 220v single phase outlet.

I'm guessing the easiest way for your friend to make his sander a variable speed machine would be to replace the motor with a three phase motor and VFD phase converter. It'd still probably be easier (and definitely cheaper) to just lighten up his touch when sanding. ;)
 
I have a 80" edge belt sander that I built, I don't have much problem with burning except when sanding pieces that have a large continuous contact area with the belt. For example if I sand the edge of a 3' piece of wood and have the whole edge against the belt then I can get burning because the belt heats since there is no where for the dust to go until it gets to the end of the board. If I'm going to take much off when sanding I use a large grit 40 or 50 grit to start with then change to a fine grit for finishing. If I use 40 or 50 grit paper I can sand the whole piece into a pile of dust before it burns. Its important to keep the belts clean. I keep a belt cleaning block at the sander and use it a lot, it extends the belts life and makes life easier. My sander is direct drive from a 1725 RPM motor to a ~4" drive drum. Hope this helps, maybe its just time for a new belt:dunno:
 
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