Homemade Wooden Bandsaw Mill
The following is a short video and a detailed look of the Homemade Wooden Bandsaw Mill that I built in late 2015 to middle of 2106.
Why make this thing?
I’ve been a hobbyist woodworker for a long time. Most often my woods of choice have been pine, oak, and poplar that can be purchased at home centers. There is absolutely nothing wrong with these, but I have been wanting to use woods with more character. The arrival of Emerald Ash Borer to Indiana was kind of a push to make it happen. I grew tired of seeing so many beautiful trees being cut up into rounds and offered as free firewood on craigslist. I wanted to be able to give these and other trees new life instead of a second death this time by fire.
I began to scour the internet and youtube for mill options, and boy are there options. Bandsaw Mill, chainsaw (Alaskan Mill), swing arm (large circular saw blade), etc each with advantages and disadvantages. I settled on a bandsaw mill style as it is familiar to me and in my searching I had come across several examples of wooden equipment. I found a setup by Geek Woodworker on the Lumberjocks forum that I decided to start from. My mill has several features in common with his, and some other things that make mine unique.
Step #1: The Power Plant
I knew that I wanted to make this bandsaw mill have a gasoline engine as I wanted to be able to mill where there is no electricity. Given that this would be an experimental mill, I didn’t want to spend too much on anything just in case it didn’t work out. In my research it appeared that I would need somewhere in the neighborhood of 5-10 hp depending on cut width, blade speed, tooth angle, etc. I chose to go with a 6.5 hp engine from Harbor Freight as they are “cheap” (inexpensive and replaceable). An additional reason to go with this engine is that these things are widely used by go-kart building enthusiasts. Clutches with pulleys are widely available and I purchased one with a 3″ pulley.
Step #2: Deliver the Power
To distribute the power I decided to use 18″ wheels. The target blade speed is in the neighborhood of 4500 FPM. This puts the wheel RPM at around 1000. The engine turns around 3000 RPM with a 3″ pulley and so I made a 9″ drive pulley for 3:1. I haven’t verified what the actual blade FPM is, but it works for my needs as it currently operates. A 4L-660 v-belt joins the clutch to the drive pulley. I checked online at Woodmizer’s site to see what length blades are standard. I got a 1.25″x0.42’x158″ 9° from them (there is a Woodmizer locally in Indianapolis).
Step #3: Support the Power
The main beam is a box with 2×6 top and bottom with 2×4 on edge front and back. There is no glue, it is only screwed together with 2-1/2″ exterior grade screws (this allowed for me to modify things… which I had to several times since I was designing on the fly). Each end has a 2×6 with a horizontal slot to receive the 5/8″ tension bolt. The ends are not identical, however.
End “A” which is the non-driven end also has a 2×4 behind the 2×6. I had intended for the drive side “B” to have a fixed wheel block. I realized after I had shortened the beam on that end that this wasn’t going to work well (given the slop and inaccuracies between a hole in pine and axle being a cheap bolt). So the driven “B” end has a shortened wheel block and no 2×4, but there is a piece of 1/2 plywood.
The boxes for the legs to go into are made from pieces of 2×6, 2×4, 1×4 (cut to 3″ wide) and some MDF. After using the mill and watching the video, it is apparent that this part of my mill is a weak point. I will have to find a way to reinforce against side to side and twisting.
The gantry legs are pairs of 2x4s. The verticals are mortised into the horizontals and MDF gussets add rigidity. 5″ MDF wheels with 1/4″ bolt axles allow the gantry to roll in the 3/4″ aluminum track on both sides of the log bed.
The top of the legs have MDF caps with a 2×4. The threaded rod for up/down adjustment passes through the 2×4 and MDF.
Originally I had the rod on the back of the leg. The old location for the coupling nut can be seen on the picture above with the engine. This location caused the blade and beam assembly to lean forward. So I turned the caps around, drilled holes through the 2x6s, and added a new 2×4 block under the beam to trap a washer and coupling nut. No more droop, problem solved. I chose to use a coupling nut to have as many threads as possible in contact with the threaded rod. I don’t have a leg lock, so the 2 threaded rods and coupling nuts are holding up the weight of the saw and engine all the time.
The construction of the wheel blocks, how the tension and tracking works, and the blade guides will be covered in another post.