Thread: 2x72 Grinder concept

I see that you added another mount to the bottom and an L to the top.

Sort of what I was thinking but more of the top arm.

I was thinking more of another side on the top. That would give you an inch + with washers.

I am thinking more in tubes or squares.

your thoughts and design are pretty good but then you asked for opinions!

Since the tension wheel hangs off of center I think that torsion is the load that you want to design for.

3/8" would probably be stiffer torsionally. Oddly, welding or bending flanges on structural members is no stiffer torsionally than the sum of the members. In other words angles and w shapes are not stiff torsionally. For torque you want tubing. The outside of the 3/8" plate will act as a 3/8 X --- tube. It just has a solid center.

I think that I used 1/2" on mine. 1/2" also has the advantage of offering plenty of bearing for tapped holes.

The TW design does incorporate a sprung arm. It is just very short

Good point!

I was thinking more of the torsion at the pivot points than at the length of the arm.

Well, I’m planning on using 1.5”x1.5” aluminum bar stock for tool arms. I guess I could stop screwing around and just use some of that stock for the idler arm.

Originally Posted by jfk742

Well, I’m planning on using 1.5”x1.5” aluminum bar stock for tool arms. I guess I could stop screwing around and just use some of that stock for the idler arm.

From the treadmill, I've got a fair bit of square steel tube. Roughly 1.3"x3.3" with 1/8th thick walls.

This is what I went with: https://www.polarbearforge.com/tools.html

I gave some thought to the GIB as well as any currently available frame, what it really comes down to is the design I’m trying to copy meets all my wants in a grinder and as I can’t afford one I figured I’d make it, looks like all in I’ll be in the $700 neighborhood, which should give me enough material to make 3 frames in total with one being complete with a 1.5hp motor with a vfd, 3 contact wheels, a flat platen and a couple tool rests.