Oscillating Motion Type on an Oscillating Spindle Sander

[Bill Webster]

I am making an Oscillating spindle sander. One of the main advantages of oscillating a spindle sander is to reduce sanding scratches. Most OSS's you buy use a constant velocity up and down motion, like a triangle wave. If you move the OSS spindle up and down using a gearmotor and a pitman arm, you will get a sine wave motion, where the velocity is faster in the middle of the strokes and slows down to zero velocity at the ends of the strokes. But I wonder how much difference it really makes if you use the sine wave motion Sine wave motion is much simpler to make on a DIY made OSS.

sine.jpg

triangle.jpg

Don't know why my images don't show up???

[Mike Kees]

Bill I do not see it making that big of a difference. Maybe the sandpaper would wear a little faster in the center ? Try it out and see.

[Randall J Cox]

Normally you are also moving the wood at the same time, so that's kind of another dimension...… Randy

[Matt Day]

I go for the triangular patters I think. Since the pitman arm makes the cylinder essentially pause for a moment, it’s not oscillating and could streak the wood. I’d rather have it moving at all times.

[Mike Kees]

Matt do you think that will actually make a difference ? I was thinking that the spindle is turning all the time anyway . If the up/down oscillations have a pause the only thing I see is it maybe affecting sand paper wear. This is just a guess on my part,I have been wrong a few times before.

[Matt Day]

Would it make a difference, I don’t know. But from a design standpoint it’s supposed to oscillate so keep it moving.