Finish the Base:
After getting the base screwed together and the carriage mounted on it, I decided to go ahead and paint it before installing the motor and getting it wired. I used the same kind of paint as they did in the Woodsmith sander article (Rustoleum Hammered). I got too impatient and should have spent a lot more time sanding. I found that it also takes a ton of paint to achieve the hammered affect and it works best when applied on horizontal surfaces. It might have also helped to prime the plywood first but the paint can said that was only needed on metal. The edges of the plywood did not accept the paint well and the plies that are end grain either sucked in or repelled the paint so they just turned a dull gray instead of the hammered black. It was a mistake to paint some of the surfaces where the belt rollers and belt rub. I eventually had to sand some of the paint off. Next time, I would spend a lot more time with surface prep and prime the plywood. I decide to make the top that divides the carriage from the motor compartment out of hardboard to maximize the clearance between the belt and the base (still needs to be painted). It just slides in place and I may use magnets to hold it in place. It has to removable to be able to get to the underside of the carriage.
I attached some rubber feet designed for large guitar amps and speakers that I hope will help dampen vibration and noise amplified through the work bench this will be sitting on. Once I build the sanding platform, I will put some on the end as well so that it can be used in the vertical position. The end of steel bar that releases the tension on the belt for belt changes was dipped in Plasti-Dip that I bought literally 20 years ago and never opened. It looked like about half of the solvent had evaporated but it still seemed to work okay.
Wiring and Mounting the Motor:
Wiring went as expected—nothing too magical here. I am not sure I like the toggle switches I installed. The are a little too easy to turn on accidentally when moving it around which is a little scary if your hand is near the belt when it happens. I couldn’t find a 3 speed dial switch locally that could handle more than a few amps, at least without spending a lot more money, so I went with these toggle switches instead. I may replace them later.
I had to put some electrical tape on the capacitor because the connectors were ever so slightly exposed which I discovered the hard way. Ouch! I still need to clamp it and the wires down inside the base.
At the the max speed the motor is pretty loud, partially because it is basically sitting in a big plywood resonating chamber. I may trying putting some rubber between the motor and the mount to see if that helps any.
Testing and Tracking:
After putting in the motor, I attached the pulleys and belt , mounted the tension springs and box, put a sanding belt on and gave it a test. Initially everything worked very well. I was able to adjust the tracking with the adjustment screw and everything worked just fine. Success! or so I thought. I turned it off and went inside to eat lunch. When I came back out and turned it on again, I could not keep the belt on the the darned thing.
After removing and replacing the belt and the tension box several times, I finally realized that I had a slight bit of racking in the tension box and that when I adjusted the tracking screw, the head would rack so that it basically didn’t change the roller’s angle. I tried putting some shims in the tension box to reduce the play and that helps some but the belt would not consistently track down the center. It would work for a few minutes and then slowly start moving.
Next, I took out the 2 large springs that were sitting in the pockets and instead put a single spring on the center threaded rod and along with the shims, that seemed to help. This was my original design and the nice thing about this is that I can now adjust the spring tension with a nut on the threaded rod. I found that it worked better with less tension but it still wasn’t perfect. The tension box was still slightly racking to the right (towards the side with doors on the base). What finally worked is to jam a small spring on the right side between the carriage head and body that puts enough tension on it to keep it from racking.
Now, very minor adjustments to the adjustment screw is all it takes to get the belt to track down the middle. Once aligned, it now appears to stay there even after breaking for lunch. We will see if this continues to work. If it does, I may need to figure out a way to keep the spring in place because it is just held in place by the tension of the spring. I may try adding some more shims to see if I can eliminate the racking altogether but for now it is usable. If I were to build another one, I would change the design so that the tension box is about twice as long in hopes that racking would be less of an issue.
Another set of 80 grit belts arrived from Amazon and they are about 1/4” shorter than the ones I have been using to test with—they are actually the correct 48” length. Since the final size of the carriage and tension box was based upon the first set of belts that I bought, this makes the new belts really tight to put on so I may need to make some minor adjustments to fix that. Should not take much to tweak that by sanding off a bit off the end of the the tension box on my new belt sander. Oh wait…
Next, I have to make some slight adjustments to the doors so that they close properly, finish painting and add a latch to the doors. I will build the table/sanding platform and start using it! The sanding platform will incorporate the shop vac connectors for dust collection. I made the mistake of intentionally installing the carriage so that it is not parallel to the base. This means that I will have to tweak my design so that I can make the sanding platform perpendicular to the belt. Doh! I also plan to eventually design some attachments that I can use for sharpening, similar to the Robert Sorby sharpening system.
-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.