This Instructable will show you how I built a bench-top edge-sanding jig to hold my hand-held belt sander on its side and allow me to precisely and carefully sand the edges of workpieces.
I built this because I do not have a permanent workspace to house a dedicated stationary tool (and those are expensive). Also, I already had a handheld belt sander, and quite a few belts for it.
This Instructable is broken down into the following steps:
Step 1: Goals, materials, & tools
Step 2: Build a support plate for your sander
Step 3. Tilt the support plate
Step 4: Build a base for the jig
Step 5: Build the work table
Step 6: Putting it together
Step 7: Final thoughts and possible improvements
And as always, the requisite disclaimer:
Caveat emptor. My advice is worth what you paid for it, and may be dangerous to your health and sanity. Read on at your own risk. Don't try this at home.
Step 1: Goals, Materials, & Tools
The first image is a stationary tool of the type whose function I needed to duplicate. The second image is what I had to work with (ok, I had some wood too).
I had read a set of instructions on Rockler's website detailing this idea, however I saw a few improvements that I could make, and needed to make some changes so that the design could be applied to my sander.
Materials are fairly simple:
~ belt sander
~ scrap plywood
~ scrap blocks of wood
~ tempered hard-board, melamine or some other slick table surface
~ screws (I used a combination of 1" and 1 1/4" coarse-thread drywall screws)
~ wood glue
~ tape measure
~ saw(s) (I used a circular saw, a table saw, and a jig saw, but you could work with just about anything)
~ appropriate personal protective equipment (eye protection, ear protection, respiratory protection)
Step 2: Build a Support Plate for Your Sander
Place your sander on its side on a board or piece of plywood, with the belt completely off the side of the wood. This is important so that the belt doesn't tear itself up against the board.
Now trace the portions of your sander's body that are in contact with the board. Using your jigsaw, cut out some plywood shapes that will fit tightly around your sander, and dry-fit them to be sure. Once you're sure of the fit, screw and glue the pieces to the board around the sander, as seen in the picture.
Step 3: Tilt the Sander's Support Plate
With the sander lying on the support plate that you just built, start stacking blocks of scrap wood under the front edge of the plate to place the plate and sander on an angle. Keep adding blocks until the sander is angled enough that a horizontal line could be drawn on the belt and stay mostly over the sander's platen (the platen being the flat metal part under the center of the belt that keeps it flat and presses it against the work).
A note about my project: I wonder if I should have placed my sander at a higher angle. Because the pieces that I'm sanding are mostly 1/2" thick, I can't put wear on the outer ~3/4" of the belt because I can only press work pieces against the portion of the belt that's running across the platen. See Step 7 for more thoughts on this.
Aaaanyhow, once you have chosen your angle, stand up a block of scrap next to the angled support plate, and draw the plate's angle onto it. This block will become the first of the support plate's legs.
Using the angle that you've drawn as a guide, cut some legs for the plate, and attach them to it with screws and glue. Make sure that the plate will stand steady on a flat surface without too much coaxing (you don't want to force it to be stable with screws and glue, because then you're creating unrelieved tension in the body of your jig, which will eventually cause warping).
Step 4: Build a Base for the Jig
Use the size of the table plus the space taken up by the sander when sitting on the angled support plate to determine the overall size of the jig's base.
I could probably have gotten away with just using a piece of plywood for the base, but I opted to give it a short lip out of plywood on the underside for additional strength and to prevent the main piece of ply from warping over time. I used 1/2" ply, which is more than strong enough when reinforced as you see in the picture.
As usual, I glued and screwed this lip into place (in this case, I also pre-drilled the holes, because the edges of 1/2" plywood do not take screws all that well).
Given that I had a belt sander handy, I also took a moment with the base to sand all of the edges and corners. Nobody likes a jig that gives them splinters, and it looks better this way, too.
Step 5: Build the Work Table
So, at this point, your edge-sanding jig should look pretty much like the first picture in this step.
Take your sheet of tempered hard board (or whatever material you're planning to make the table out of) and lay it down on the jig's base, slightly underlapping the sander's position on the support plate. Look straight down at the sander and sight along the belt to draw a rough outline of the cut-out that will be needed to accommodate the belt. For now, err on the side of leaving too much material behind--the belt sander is perfectly capable of enlarging the cut-out as it sees fit.
With the size of your table roughly set, it's time to construct the support pieces. First, measure from the surface of the jig's base to the level at which you want to work table to sit. Subtract the thickness of the table's surface from that measurement and then cut a set of slats (at least four or five) of that width. I used a table saw to be sure that the slats were precisely the same width.
Next, stand the slats on edge on the underside of your table top, placing one slat near each edge of the table for support and at least one towards the middle to support the center of the table. I opted to mate two of the slats together to create an "X", but that really wasn't necessary. Once you've decided where the support slats will stand, trace their edges with a pencil, then remove the slats and use those tracings to drill holes in your tabletop for screws. Don't drill any closer than 1.5" or 2" from the end of each slat to avoid splitting it.
Once you've drilled the holes you can flip the table top over, countersink all of those holes, and then clamp the support slats into place on the underside of the table (using your traced outlines). Now you can pre-drill the edges of the slats through the existing holes in the table top. Lastly, screw the table top to the slats, and be sure that all of the screw heads are below the surface of your table.
Now that you have the table constructed, place it on the jig's base, turn the sander on, and slide the tabletop into position. The sander will create a perfectly-fitted zero-clearance edge between the table and the belt.
To attach the table to the jig's base, trace the slats onto the top of the base by reaching under the table with a pencil. When you remove the table, you can use the outlines to drill holes that will help you locate the screws. Then, just clamp the table into position, flip the entire jig over, pre-drill the edges of the slats through your holes in the base, and then add screws to hold the table on. Be careful about where you put your screws when attaching the finished table to the base. If you put those screws in exactly the same vertical place that you put the screws that hold the table to the slats, they may collide inside the slat and split it, or they may just create a weak spot that's prone to splitting.
Step 6: Putting It Together
At this point, you're pretty much done. You've already used the sanding jig for the first time, to put the finishing touches on the jig's table. The final step is to use a square to make sure that the sander is sitting at 90 degrees in relation to the table. If it is (and seems stable that way), then go ahead and clamp it down. You're done.
If it's not quite 90, then figure out where you need to glue shims under the sander's body to get it to 90. Typically, you'll want to shim the sander very close to where it's clamped, so that you get the most secure connection.
About clamping the sander down (which you should absolutely do): In my case, I had originally considered using two long bolts and a piece of wood the length of the sander's body to create a clamping bar that would hold it down. That design would have put a lot of pressure on the plastic drive-belt cover on the side of the sander, though, and probably would either have broken the cover, or put undue stresses on the drive-train. After shimming under the sander's front handle, I tried clamping it down just at the front handle as shown, and found it to be quick, convenient, and stable. I glued the shim in place for stability, and soaked the other side of it in glue to make it less compressible (it was an off-cut from the end of a board, so it had a lot of springy end-grain).
It should be noted that some sanders may also have removable knobs or grips that screw off, which you could use as attachment points to bolt the sander to the jig. Ultimately, it's whatever works for your particular sander.
Step 7: Final Thoughts and Possible Improvements
If I had the skills and resources to build the table's supports out of metal, I might consider trying to make the height of the table adjustable in relation to the sander (possibly using a super-cool mechanism with multiple threaded rods, turned by a central crank). That would allow me to put more even wear across the entire width of the belt, without needing to change the angle of the sander. I avoided even trying to do that because of how important it is to this project that the edges be sanded at a perfect right angle. I couldn't think of an easy way to build an adjustable table that would stay at 90 degrees to the sander's belt, without having to be re-squared after each adjustment (or each time I dropped the jig). My current version of an adjustable-height table is just clamping an extra piece of plywood to the tabletop to add some height (thanks for the suggestion, flavrt).
Adding a stop-block for safety towards the rear of the sander is also a reasonable consideration. I opted not to add a block, mostly because of the size of the workpieces that I'm sanding. Also, given that my sander is variable speed, I tend to run it slowly, which reduces the violence with which a workpiece will be shot off the table if it catches on the moving belt.
As shown and notated in the last picture, I would also consider adding a dust-collection shroud of some type near the front of the sander, to grab whatever dust doesn't get sucked up by the vacuum cleaner that's connected to the sander's dust port. Of course, that might require a bigger shop vac (or a shop with a dust-collection system), given that my current vac doesn't have the CFM to effectively suck on the tool's dust port and an additional shroud at the same time.
Overall, I'm quite happy with this edge-sanding jig. As you can see in the pictures, it's done its job quite well. I hope that this Instructable has given you some ideas about how to start making your belt sander a lot more useful around the shop.