jupiteruke
Well-known member
When making a radiused back, the sides must be cut/sanded so that they follow the radius arch. I built a machine to make this easier for my other shop, but that used some old lath parts that are not available, so I decided to build a mechanical sander to sand the radius into the sides from easily available parts for my Florida shop.
This is sized to use 17" sandpaper that is readily available from any tool rental place that rents floor sanders. A piece of 80 grit paper cost me $4.50 and lasts a very long time, as they are heavy paper designed to take a lot of abuse.
You need to get an electric motor. I got mine out of a dishwasher that was put out for the trash, and I'm sure that any appliance dealer that installs washing machines would be an easy source of old motors. Lots to go wrong on an old washing machine that is not the basic motor.
I cut two circles of 1/2" particle board with the edge of each cut at a bevel. These were cut by drilling a 1/2" hole in the center, and then using a temp board clamped to the bandsaw table with a 1/2" dowel pin as a center around which things could rotate as the disk is cut. These disks are glued together so that the bevels face each other, providing a V grove around the edge of the composite disk. Then I cut a radius dish into one side of the disk. (Easy radius cutting jig here http://jupiteruke.com/blog/page/3/).
This disk rotates on a simple setup, using two bearings, a 1/2" bolt, a stop collar, and a couple of fender washers. The two bearings, which have shoulder flanges, are let into two blocks of wood, and a 9/16" hole is drilled the rest of the way through the blocks to allow the 1/2" bolt to pass through but not bind on the blocks. The bolt is threaded through the blocks, and then they are screwed to a backing board. The stop collar is put on the end of the bolt to take play out of the setup. The previously made disk, cut with a 1/2" hole as the pivot point, fits over the end of the bolt and a nut is used to tighten them on, against the stop collar. Total parts at the local hardware store were $22.50
The motor is mounted to a base board, and then this is positioned on the backing board and screwed down when the V belt (from the auto parts store) is tight and aligned correctly.
The sandpaper is glued to the disk (flat on one side, radiused on the other) with spray adhesive.
This makes sanding the radius into the sides very easy, a matter of mere minutes. One side of the disk is flat so that I can flatten the top of the sides as well as radius the back.
This is sized to use 17" sandpaper that is readily available from any tool rental place that rents floor sanders. A piece of 80 grit paper cost me $4.50 and lasts a very long time, as they are heavy paper designed to take a lot of abuse.
You need to get an electric motor. I got mine out of a dishwasher that was put out for the trash, and I'm sure that any appliance dealer that installs washing machines would be an easy source of old motors. Lots to go wrong on an old washing machine that is not the basic motor.
I cut two circles of 1/2" particle board with the edge of each cut at a bevel. These were cut by drilling a 1/2" hole in the center, and then using a temp board clamped to the bandsaw table with a 1/2" dowel pin as a center around which things could rotate as the disk is cut. These disks are glued together so that the bevels face each other, providing a V grove around the edge of the composite disk. Then I cut a radius dish into one side of the disk. (Easy radius cutting jig here http://jupiteruke.com/blog/page/3/).
This disk rotates on a simple setup, using two bearings, a 1/2" bolt, a stop collar, and a couple of fender washers. The two bearings, which have shoulder flanges, are let into two blocks of wood, and a 9/16" hole is drilled the rest of the way through the blocks to allow the 1/2" bolt to pass through but not bind on the blocks. The bolt is threaded through the blocks, and then they are screwed to a backing board. The stop collar is put on the end of the bolt to take play out of the setup. The previously made disk, cut with a 1/2" hole as the pivot point, fits over the end of the bolt and a nut is used to tighten them on, against the stop collar. Total parts at the local hardware store were $22.50
The motor is mounted to a base board, and then this is positioned on the backing board and screwed down when the V belt (from the auto parts store) is tight and aligned correctly.
The sandpaper is glued to the disk (flat on one side, radiused on the other) with spray adhesive.
This makes sanding the radius into the sides very easy, a matter of mere minutes. One side of the disk is flat so that I can flatten the top of the sides as well as radius the back.
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