Making bandsaw trunnions
I produced an extensive series of articles and videos on building my 14" bandsaw. For the most part, my 14" bandsaw is a smaller version of the 16" bandsaw, so the videos can also be used as a guide for constructing that one.
However, the 14" bandsaw uses hinges to tilt the tables, and thus lacks trunions. So I figured I'd fill in the gap by writing an article about how to make those.
This article covers a slightly improved method over how I built the trunnions in the 16" bandsaw, but it's still based on the same plans.
I start by cutting out the trunion templates from the 16" bandsaw plans, leaving about 3mm of margin all around the templates.
I added the 3 mm margin so that I don't have to be super precise on gluing. I only cut it to its final shape once all the layers are glued.
If you don't have access to another bandsaw while you are building your bandsaw, you can temporarily clamp a (non-tilting) table onto the saw's frame so that you can still use it to cut out these parts.
The trunnion cradles are made of three layers. The middle layer is 1/4" (6mm) or slightly thicker. 8 mm would work too. If you don't have 1/4" thick plywood, it's ok to use solid hardwood for the middle layer.
Next I use an awl to punch through the centers of the dowel positions. I'll drill these out later, but I'm punching them now just in case I mess up the template. Drilling must be done last, because the drill may catch the template and pull it off the wood.
My bandsaw blade was actually a little dull when I did this. So it cut quite slowly, but that's actually good in a way - forces me to go slowly.
When I built my 16" bandsaw, I finished the trunions with a slippery varnish to make them glide more easily. But that turned out to be a mistake. They slid far too easily, and I had to roughen them up to be able to lock the table effectively.
I experimented with using a washer to fit on the end of the carriage bolt. I started with a washer with a hole just smaller than the carriage bolt's square section and filed the corners so it would fit. Then I bent the washer to fit the curve. This would be an adequate solution, though you have to start with just the right washer. It's important that the washer keeps the carriage bolt's head from turning.
So you could build it this way, but for this example, I'll build it the way I built my bandsaw.
Here I'm cutting the piece of wood that the carriage bolt head fits into. The wood needs to be oriented vertically, so that the template is on the end grain. I clamped the workpiece to a large piece of wood to help stabilize it.
This process works very accurately for closed grain woods. For woods such as ash or oak, the awl will often move to the side as it follows the grain. The same is true for some soft woods, though you should be using hardwood for this part.
There are all kinds of jigs out there for aligning dowel holes, but I have had good results with this method. I have a horizontal boring machine for drilling precisely indexed holes, but it's hard to justify the effort in setting it up considering how well I can do without.
I'm not building another bandsaw right now, so this is as far as I'll take that one, but I hope this makes clear how to make that part.
Homemade bandsaw (2010)
An alternative to trunions: using hinges (2011)
Building my 14" bandsaw (2011)
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