Small Wheel Attachment
A belt grinder with a flat platen is great, but versatility rules in my shop. Thus a way to shape inside curves with any grit I want is priority. After taking a look at some designs, I came up with something that works and doesn't cost an arm and a leg.
The core of this build is a drum sanding kit.
These rubber drums are 2" long and various diameters. The kit that I bought (Big Horn) has 1/2", 3/4", 1" and 1-1/2" diameters. The shanks are 1/4" in diameter, but a A 5/16" rod would make a much better fit inside the rubber.
These are typical (Amazon.com).
For bearings I chose 1603s as they have a 5/16" inside diameter. The outside diameter is 7/8".
Here is the layout for the frame pieces
The 1-1/2" angle is cut to 5-3/4" and drilled to match the holes on the frame pieces. I wanted to keep the wheel as forward as possible so I drilled the front hole 1/2" from the end.
The marks on the bottom are for mounting. I'll make these 5/16 x 5/8" slots.
This is a test fit. I cut the spacers at 3-1/4". The 5/16" ready-rod was cut to 4 -1/2" long and the thread finished on the ends.
Making The WheelsThe wheels consist of three parts. The shaft, the rubber and the bearings.
For a shaft, I used some 5/16" SS 304 round stock cut to 3-3/16" in length for the shaft. Once cut I trued and chamfered the ends.
Once the cement sets the wheel is ready to use.
I let the contact cement dry overnight and so far there have been no problems. Of course you'll need to make sure they are running true. Frame alignment is important.
I will note here that the 1/2" diameter drum was pretty messed up from use on my drill press. I have another kit coming so I can make a full set.
The last step is to align the frame assembly. You will need to adjust the two mounting bolts to get the wheels to run as square as possible. It was fairly quick for me. I had to take the belt off, loosen, adjust and re-tighten. Once it's running true, you shouldn't have to adjust it.
PREMATURE BEARING DEATH WARNINGIt must be noted that these little wheels run at incredible RPMs. In fact, on my grinder the little 1/2" wheel will be eight times the drive wheel RPM. Figure 3500 x 8 and you'll get the idea. You MUST run then slower. If you have a VFD, something like 1000 RPM at the drive wheel would be okay. If you use a pulleys for speed adjustment, use the slowest speed or the bearings will die a premature death.
Best of luck in all your projects!
POST COMMENT: I've had problems with the rubber staying centre. I used two large (14") cable ties on either side of the rubber and cinched them tight. Clip the excess and the rubber has no place to go. Cheers! December 21, 2014.