Jens Larsen's small 10.5" bandsawJens Larsen writes:
I've finally gotten around to making a bandsaw.
I have a medium size saw, a decent English one, which I use a lot for rough work. It's mostly fitted with a wide, and often well-worn blade (cutting through bark doesn't do it any good). So having a smaller one with a narrow blade is something I had wanted for some time.
As my saw had to be small enough to stand on a workbench and to be moved easily, one of your plans was not an option. But being much impressed by your bandsaws, I did take the liberty to base my design on yours.
I chose a wheel diameter of 270mm (10½") and a blade speed of about 700 m/min. Using a 1400 rpm motor I had laying around, it ought to be possible to fit the motor inside the frame.
This would, I thought, make the machine more portable. Construction could be made simpler by forming the bottom part of the frame with 3 pieces of plywood, one at each end of the frame, and one between these to give stiffness crosswise.
It worked well on paper. Replacing the front-most board in the lower frame member with a thinner piece of 12 mm plywood, gave room for a slightly thicker hub/pulley on the lower wheel. Letting the trunnions for the table tilt sit directly on the lower frame member didn't leave much room for the bottom blade support, but just enough.
The rest is much like your saws. The frame is of course scaled down. More than adequate for the small saw, even with slightly simpler design.
The finished saw with fence in place. I didn't have enough decent plywood at hand for the table, so it's made from an old veneered MDF tabletop. Works quite well, and the piece of hardwood inserted at the front to keep the parts aligned isn't really necessary.
The upper blade guide is made much like yours, except that it's cut from one block of ply, and that I fastened the guide-blocks with barrel-nuts rather than making slots in the guide-blocks. To ease alignment it has a small ledge for these to rest on (same is done on the lower ones)
I won't win any safety-points for the guard, I'm afraid, but it's safe enough. It's only partly open with the guide in a low position, and I can't see how a jumped-off or broken blade should escape anyway. I made it this small, to avoid having it go through the top of the enclosure.
After glue-up. the frame was cut to size on the table saw, and the plywood end plates forming the bottom frame test fitted. An extra piece was glued on to give a better support to the upper blade-guide column.
The frame is made from five 18x90 mm construction quality pine, with one board in the upper member being 120mm. A further board is added to the upright, and the outer board on the lower member is replaced by 12mm ply + 6 mm infill.
I'm not into CAD design, so mine was done the old fashioned way with pencil and T-square. Quite fast and accurate, and all on one piece of packing paper as seen on the left.
I have a good size lathe and a chuck that can grip inside a 35 mm hole, so I made the wheels by first turning the hub/pulley from 24 mm ply, Then I glued everything up and finished the wheels on the lathe, including the recesses for the 40mm bearings.
Bicycle tubes don't come this small, so I had to use some other tubes and glue them on (with Superglue) to make them stay in place.
I liked your second design for supporting the upper wheel, but had to turn it "upside-down" to fit neatly with my smaller wheels. That is I made one of the boards in the frame 30 mm higher than the rest and cut a slot in the bottom of the block to fit over this. This also brought the "pivot point" much closer to the axle, which should, in principle, be an advantage. And for the same reason, space restraints, I made the block of two parts, the rear-most of which I let pass down behind the frame, allowing the tilt alignment to act directly on the frame. Tilt adjustment is by a hanger-bolt screwed into the frame.
The motor is bolted directly to the side panel, but I got the belt length a bit wrong, so had to lay it a bit into the panel to get enough room for adjustment.
For added stiffness a bracket is added between the trunnion and the table at the rear.
The trunnions were cut on the bandsaw from good quality 12 mm ply, sanded to fit, and test fitted to ensure proper position and function. They are held in position by a 10 mm coach bolt through the frame. The bolt is held in position (if not, it tends to act as a brake ) by the small aluminum plate seen behind the blade guide in the next picture.
There isn't much room for the pulley, belt and cover-plate, but just enough. But getting everything in place with a belt that's too short to go around the main wheel, the limited space, and a tight fitting cover plate is a bit tricky.
Its held to the side by 2 bolts threaded into the holder and running in a slot in the side panel. The arrangement is tight, but does allow for the adjustment needed.
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