Shop built 6in double sleeve drum sander
Posted: Sun Nov 02, 2014 12:18 pm
A drum sander with two different grit sanding sleeves is something I have wanted for a while. I suppose I could of bought one but where is the fun in that. The first picture represents my first attempt. I prefer to use a term Norm uses for his first attempt "prototype".
In the prototype I first turned the cylinder, then drilled the center, next cut the wedge. This caused three problems. First the center hole drifted off center. Second the cylinder was now out of round by the distance of the saw kerf. Third when the sanding sleeves were installed and tightened it was next to impossible to get them apart. The prototype also exposed a inherent flaw with wedge design. As the wedges are drawn together it distorts the round shape. I ignored this and keeping the tolerances close the distortion is negligible.
[ATTACH]26697[/ATTACH]
On my second attempt I cut the wedge while the stock was square. Much safer than cutting the wedge in round stock. Next I drilled the center hole. The next machine operation was to drill spring pockets in the center. The pocket drilling operation made the back hold down to creep. I solved this by putting the light hold down in the track next to the wedge. Compression springs help separate the wedges when removing the sanding sleeves.
[ATTACH]26698[/ATTACH]
[ATTACH]26699[/ATTACH]
The next problem was how to mount the stock with a 3/8 hole in the center. My solution was to grind a point on some thread rod, remove the pointy thingy from the tail stock and mount the other end in the drill chuck. By using the lathe chisel sharping jig and the disk sander I was amazed at the accuracy of the center point. To keep the wedges in place during the turning operation I screwed the wedges together making sure both ends of the screw were below the outside diameter of the cylinder. Looks like I run out of picture space. Post to continue.
[ATTACH]26700[/ATTACH]
[ATTACH]26701[/ATTACH]
In the prototype I first turned the cylinder, then drilled the center, next cut the wedge. This caused three problems. First the center hole drifted off center. Second the cylinder was now out of round by the distance of the saw kerf. Third when the sanding sleeves were installed and tightened it was next to impossible to get them apart. The prototype also exposed a inherent flaw with wedge design. As the wedges are drawn together it distorts the round shape. I ignored this and keeping the tolerances close the distortion is negligible.
[ATTACH]26697[/ATTACH]
On my second attempt I cut the wedge while the stock was square. Much safer than cutting the wedge in round stock. Next I drilled the center hole. The next machine operation was to drill spring pockets in the center. The pocket drilling operation made the back hold down to creep. I solved this by putting the light hold down in the track next to the wedge. Compression springs help separate the wedges when removing the sanding sleeves.
[ATTACH]26698[/ATTACH]
[ATTACH]26699[/ATTACH]
The next problem was how to mount the stock with a 3/8 hole in the center. My solution was to grind a point on some thread rod, remove the pointy thingy from the tail stock and mount the other end in the drill chuck. By using the lathe chisel sharping jig and the disk sander I was amazed at the accuracy of the center point. To keep the wedges in place during the turning operation I screwed the wedges together making sure both ends of the screw were below the outside diameter of the cylinder. Looks like I run out of picture space. Post to continue.
[ATTACH]26700[/ATTACH]
[ATTACH]26701[/ATTACH]