A couple of months ago, Woodsmith magazine had a shop built belt sander on the cover which inspired me to try to build my own. I’ve been using a handheld Dewalt Belt sander with a stand as a bench sander but have been frustrated with the small sanding area. I also had to fix a broken shaft screw using super glue so I know that its days are numbered. The Woodsmith version was designed to take advantage of a lathe to drive the sander when the lathe is not in use but that won’t work for me because one of the purposes I have in mind is lathe chisel sharpening similar to the Sorby sharpening system so I decided to borrow some of Woodsmith’s ideas and design a standalone unit to utilize an old blower motor I have had sitting on a shelf for years. Instead of making a belt sander just for sharpening, I decided to make one that utilizes a 6×48 inch belt so that I can also use it for general sanding duty in the shop.
The material I am using is mostly 3/4” AC grade pine plywood from the local home store. I thought about using Baltic birch plywood but decided that the AC plywood I have on hand was actually pretty good quality and mostly void free and would be much cheaper, especially if I make any mistakes or significant design changes along the way. I thought about using slotted or punched angle steel available at the home store for the carriage/tension mechanism but decided that I do not really have the metal working tools or skills to make all of the components needed. So plywood it is.
Requirements and Design
There are a few You Tube videos of other shop built belt sanders but most of them are either edge sanders, which would not be easy to use for lathe chisel sharpening or narrow belt sharpening sanders which makes them less useful. Most of the DIY sanders that I have seen that are general purpose belt sanders are built so that you have to basically disassemble the sander to change belts. I decided to go big and make one that uses 6×48” belts like the Woodsmith design and my design allows for quick belt changes very similar to the cheap harbor freight sander or the Ryobi sander. Instead of building it so that the belt carriage pivots between vertical and horizontal positions, I decided to make it fixed on the base to simplify the design and make it so that the entire unit base can sit either horizontally or vertically to eliminate the pivoting mechanism but still provide flexibility. I may even try to make it so that in can also be used as an edge sander by later designing a detachable table. and just rolling the whole thing over on its side.
I’ve gotten pretty good at using Sketchup to work through the design process and I drew up a plan. I decided to break it up into 2 parts. First, I designed the belt carriage/tensioning mechanism. I figured that if I can not get this to work, I might as well just go buy a belt sander. Second, I designed a base that would house the motor and provide flexible platform for general sanding as well as mounting jigs for sharpening.
Here is an image of the “final” sketchup design, though I continue to tweak it as I go and discover design issues as I build.
Note that the sanding table and support will be on a hinge and I am going to try using tool box latches to keep it in place so that it can quickly pivot out out of the way for belt changes. The circle drawn on the side of that support is for a dust collection port for the shop vac. I plan to eventually design some sharpening jigs that will either attach to the table or on the left side (far side in the diagram) of the base.
The Build: Belt Carriage
I started by cutting out the pieces for the side rails and tension box and then proceeded to make the rollers out of laminated plywood. Here are the parts ready for assembly:
I initially planned to use a single spring on a central threaded rod to provide tension on the belt but later decided that 2 springs spread apart would reduce torsion and providing better tracking. The tension box basically works like a very tight drawer. The springs are nested in pockets so that they are always trying to push “the drawer” open. If I were starting over, I would make the tension box drawer and pocket longer. This one is only 3.5” long and I am experiencing a little bit of racking that affects tracking. I may need to find some stronger springs to improve that. I would probably drill holes for the spring pockets a little farther apart as well. I may still try that if my tracking issues continue.
Here is a picture of the top of the carriage with the slide and spring assembly:
The rollers were made using the router table jig from Woodsmith Magazine:
The top roller has a slight crown to help keep the belt tracking in the center though I am not sure that it really helps that much on such a wide belt.
The bottom (drive) roller is epoxied onto a 1/2” steel rod with bearings mounted into the sides of the frame. The top roller has the bearings embedded into the ends of the roller. Note that the holes in the rollers were drilled into each of the plywood pieces before gluing them together to avoid needing a 7” long bit. The 1/2 rod was inserted during glue up to make sure that the holes were aligned.
I borrowed the belt tracking adjustment from Woodsmith. A 1” dowel with a 1/2” hole provides a pivot point for the top roller axle and a 1/4” screw threaded through the axle at the other end raises or lowers that side to adjust tracking:
Final Carriage Assembly and Test
After getting everything glued and screwed together it was the moment of truth. I clamped the edged of the carriage frame in my end vice, installed a belt and chucked my cordless drill on the drive shaft and gave it a spin.
I had a little bit of a tracking issue but finally was able to get the belt to track down the middle without constantly tweaking. Very small adjustments in the tracking screw make a huge difference. There is a little bit of racking in the tension box and I may see if some shims or strong springs may help reduce that once I get the base built but for now I am happy with the the way it works.
Next, I’ll build the base and attach the carriage to the base.
Thanks for reading.
-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.