I've made spindle sanders.
When sanding, we basically need disk sanders and spindle sanders.
Disk sanders are used to sand flat surfaces, and spindle sanders are used to sand curved surfaces inside and outside. The most important thing about creating a spindle sander is that it needs a double motion that moves up and down as the spindle rotates.
Due to the small diameter of the spindle, using only one part will shorten the lifespan and reduce sanding efficiency.
First of all, I used a motor and a belt, so that the spindle could rotate. The belt-operated pulley is made by cutting wood into a circular shape, inserting it into a drill, and digging a groove.
Use bearings to reduce frictional force on the spindle.
The next difficult process is to allow the spindle to move up and down throughout its rotation.
It's made with a drawer rail to make a basic guide, a circular pulley attached to the reduction motor, and a pin attached to the end of the circular pulley to allow vertical motion as much as the distance it rotates.
Since the entire body, including the rotating spindle and the motor, has to move up and down, the deceleration motor should be used a little stronger. The deceleration ratio must also be adequate to maximize the power of the motor. If you use a deceleration motor with too much RPM, you will have to force yourself to reduce the number of rotations, which will prevent you from getting the full power.
The spindle is made in several sizes. This is because when sanding the inside of a circle, you also need a small spindle. I also made a nut part to store the spindle, so that unused spindle could be stored.
Two switches are installed so that you can use rotational and vertical movements separately.
If you look closely at the video, you can make it without much difficulty.
I hope it's a good reference. Thank you.

свернуть