Intro: Make a Bandsaw Fence From Aluminum Extrusions
I do a lot of resawing on my small bandsaw. I need a fence that is tall enough to support the plank as I cut, and that can be adjusted to correct for drift -- the tendency of the saw blade to move away from the cut line. If a bandsaw comes with a fence, it will have neither of these capabilities.
For several years, I had an adjustable rip fence made of wood for my bandsaw. Then I discovered 8020® aluminum extrusions.
I don't want this to sound like an ad: There are several brands available, but I found what I needed with 8020®. They also have an Ebay store where you can buy assorted lengths of extrusion as well as the other parts needed for the build.
Step 1: Parts You'll Need (parts I Used)
- (1) 2x4" extrusion (2040)
- (1) 1x2" extrusion (1020)
- (2) 1x1" extrusion (1010)
- (2) 2x2" corner brace
- (1) 4" linear bearing to fit 1010 extrusion
- (1) 1-7/8" linear bearing to fit 1010 extrusion
- (1) 1/4-20 fixturing knob + 1/4-20 carriage bolt + 1" spacer
- (2) Linear bearing brake + bolt
- (13-24) 1/4-20 specialty nuts & bolts
- Shim Stock
Step 2: Cut Things to Size Drill Some Holes.
If you order 80/20® stock off of Ebay, you don't necessarily get the lengths you want. So verify that you are ordering an extrusion that is at least as long as you need.
My bandsaw is an older 14" Rockwell (Delta). the table is approximately 12" long by 11" wide. It has two flanges on the near and far end of the table with tapped holes (1/4-20). They are put there for mounting fence rails. These flanges extend beyond the table by about 1/4" each side. (If you don't have mounting holes, then you have some serious work cut out for you, drilling and tapping into the cast iron table.)
Measure the length of the table including these flanges. For me that would be about 12-1/2" (I'M GUESSING! DON'T TAKE MY MEASUREMENTS AS GOSPEL!)
Add 4" to that length. This is the length you need for the 2040 and 1020 extrusions.
Measure from the front of the table to the vertical column. This is the length of each of two 1010 extrusions.
(See image notes for orientation.)
Measure the distance (center to center) between the fence rail mounting holes.
Lay your 1010 extrusion on the table top with the right end in line with the front of the table. (You're facing the near end of the table.) Eyeball about where the right hand mounting hole lines up on the extrusion. Mark the extrusion.
Drill a 1/4" hole through the extrusion: centered in the slot of the extrusion.
Measure from the center of that hole and mark the distance for second mounting hole. You need to be pretty accurate here.
Do the same for the far end rail.
Screw four button head cap screws into the rail mounting flange holes. Slide the 1010 extrusions onto the screws. Align the holes in the extrusions with the screw heads and snug down the screws.
If the holes and screws don't align, you will need to elongate the holes untill you can fit your socket wrench into the screw sockets.
Assemble the 2040 and 1020 extrusions. It's possible to bolt the two together, but that would require drilling some access holes through either the 1020 or the 2040 extrusion similar to how the 1010 holes were drilled.
Instead, I used the angle brackets to connect the extrusions. Fit four of the specialty nuts/bolts to each of the 2" corner braces. Then slide the braces onto the two extrusions as seen in image-2. Snug the capscrews. Position the extrusions and braces then firm up two screws on each brace and check for square. I found I needed to add some shims to get the two extrusions square to each other. If the two are square and level on the bottom, tighten down the rest of the screws.
Step 3: Drill Holes in Your Linear Bearings for Your Bearing Brakes:
Drill one hole each into the two linear bearings (1/4"). These holes must be aligned with the slot in the 1010 extrusion. The screws holding the UHMW-PE (Ultra High Molecular Weight Polyethylene) in place are aligned with the slot. With the 4" bearing you could just drill out one of these screwholes. For the 2" bearing, drill between the two screws.
slip a bottonhead cap screw thru the bearing hole and screw on one of the brakes.
Slide the 4" bearing onto the 1010 extrusion. set the fence on the table. measure the space between the bearing surface and the bottom of the fence. You need to cut a shim to fit this space. It should be just slightly thicker than the measured distance (about 1/64" thicker -- you want the fence to ride just above the table so it doesn't drag.) Cut it about 2"x4"; width x length. Next mark for two holes in line with the first and last holes on the "tang" of the bearing. (See image 5 in first step.) Drill 9/32" holes thru the shim.
Insert two specialty nuts/bolts through the bearing and shim: nuts are facing up. Slide the fence over the nuts; square the fence to the 1010 rail as best you can. Snug up the bolts (capscrews).
On the far end of the table/fence you need to add a shim too. Because you don't have a bearing there, this shim must be thicker than the first. Also, it should be about 1/64" thicker than measured Plus about 1" to 1-1/2" longer. (image-3)
Drill a hole in line with the left hand slot of the 2040, plus another for a fixturing knob/bolt. These holes should be significantly oversize (~5/16"). See notes on image-3. The specialty nut/bolt for attaching the shim to the 2040 should not be snugged very tight. The main purpose of this far-end shim & fixturing nut is to prevent the fence from flexing if you apply a lot of pressure when cutting.
Step 4: Done.
You're pretty much finished.
The capscrews connecting the bearing to the fence allow adjustment for drift when resawing lumber:
- loosen these capscrews so the fence will swivel. (It may help to remove the far end fixture screw.)
- Square up your plank (joint one edge & one face. Plane opposite edge/faces if desired.)
- Using a scribe, mark a line along the edge or face marking the thickness you want to cut. pencil it in so you can see it better.
- Freehand cut the line; turning the plank as needed to keep the blade on the line.
- After cutting about 6", turn off the saw. Hold the plank in this last position.
- Bring up the fence to the plank. Snug up the capscrews and tighten the brake.
- Tighten the rear fixture nut.
- Turn on the saw and continue cutting. The fence should guide your plank on a straight line.
Another nice feature of this fence is that I can add auxiliary fences and/or stops as may be needed.
The second bearing allows me to set the fence and make micro adjustments to the thickness of what I'm cutting. And/or move the fence and then reposition it back to where it was without need of measuring.