Making your own tools and machines is a big part of the fun of being a Luthier! Either nobody makes what we want, or we can't afford it. So, we figure something out and build it ourselves.
Building your own resawing bandsaw is a good and worthwhile task, but there are a couple of things you should know about resawing:
Horsepower is really important. Specialized resawing bandsaws normally have about a 7 1/2 hp motor, for a reason. Dragging a saw blade through a 8" to 12" thick piece of wood takes a lot of power. The rule of thumb is that it takes a half horsepower for every inch of thickness that you are cutting. An 8" board needs 4 hp and a 12" board needs 6 hp. Most 14" woodworking bandsaws are 1/2 hp or 3/4 hp. And you can't really cheat that lack of power by just going slowly. That heats up the blade and wipes it out.
You've got to get that horsepower to the wood. That means that the belt drive has to be able to take that torque. A single V-belt, done right, is good for 1 1/2 hp max. You are going to need double or triple V-belts between the motor and the wheel pulley. Likewise, there has to be enough traction between the blade and the lower wheel. That means a wide blade, a rubber tire, and a good amount of blade tension. That means a strong frame to take that blade tension load.
Heat buildup is what kills the sharpness of the blade's teeth. The big issue is that the sawdust can pack up inside that long saw slot, dragging on the blade like a brake. The wood smokes, the blade heats up, and the tips of the teeth get red hot and go dull. As they get dull, they get hotter and go duller. Getting a carbide-tipped blade helps, but that only partly solves the problem. And, they are expensive. This heating problem gets worse if you don't have enough horsepower and you try and go slowly, and the blade keeps slowing down.
The way to get the sawdust out is to use a really coarse tooth blade. A blade with fewer, larger teeth gets the chips out of the groove and keeps the teeth cool. It also consumes less horsepower, because there are fewer teeth in the board cutting at the same time. The blade on a good resawing bandsaw has about one tooth per inch, or even less.
In my shop, I have one of my bandsaws set up for ripping and light resawing. It's a 16" Grizzly saw, which has a good strong frame. I've upgraded it to a 1 1/2 hp motor with a better belt drive. The blades I use on it are Lennox carbon steel 1/2" wide x 3 tpi (tooth per inch). That's the coarsest blade I can get in 1/2" wide. I'd have to modify the guides and wheels to use a wider blade. That bandsaw works very well for ripping hard maple neck stock up to 4 1/4" thick. I sometimes use that saw for resawing body boards and tops up to 7" thick, but it's struggling at that thickness.
My buddy Rob Allen has just moved his shop in down the hall from me. One of his machines that has me drooling is a big specialty resawing bandsaw. He paid about $6K for it. It's about 8' tall and 7 1/2 hp. The blade is 1" wide x 1 tpi. I haven't seen it run yet, but he says it works beautifully. That gives you an idea of the machine that's really designed to resaw 12" boards.
I like T-Bone's suggestion of building a specialty resawing bandsaw with the frame as a single straight column. That makes a lot of sense. Take the wheels and parts from a 14" bandsaw and mount them on a single column of 4" x 4" steel tubing....rig it up with a 5 hp motor....That has me thinking...
