[TraditionalToolworks]

I have a project I need 2 arches out of 1"x1" steel. They need to be 36" in diameter but I only need half of a circle for each one.

This is what I want to build, I want to mount ball bearings around this arch so I can lift and be able to use a cant hook or peavy to turn a log on my sawmill. I can space the ball bearings out, but don't want them any farther than 3-4 inches, and there will be one on each side with an axle welded into the 1"x1" to hold the ball bearings. I have a bunch of ball bearings with 20mm on the inside that I plan to use. My sawmill has a 32" max cut which translates to a 36" diameter log (you have to cut the sides off first). I want to be able to lift each end of a log and be able to spin it in these arches, which would be welded to the top of floor jacks.



Short of buying the material I may need to build a square bender, I've seen some DIY projects on YT, but before I do that I was curious if there is any place I could buy pre-bent stock?

Maybe a local shop could do that, not sure. I haven't checked yet. Anyone know of a place online? Not sure if shipping would prohibit such a purchase. I've seen some small stuff at King Architecture Metals, but nothing in the size I need.

I could also use round thick wall pipe probably. Would that be stronger than 1" square stock?

[LtBadd]

I would check with local shops, or even metal suppliers. I have a local supplier that provides quite a few value added services.

[Spartan]

I don't know of any place that sells bent square stock such as that, but some may. Those curved parts may be good candidates to have CNC plasma cut out of plate and then just weld them together into that final shape.

[v5cvbb]

Alan, what about just notching the square tubing in 7 places, and bending and welding to create 8 straight segments that approximate the curve?

Seems simply enough. Plus you get more hood time.

[TraditionalToolworks]

I would check with local shops, or even metal suppliers. I have a local supplier that provides quite a few value added services.

Yeah, I need to do that, as I mentioned I haven't checked with any local shops at all yet. With this Wuhan crapdemic going on it's put a damper on a lot of stuff.

I don't know of any place that sells bent square stock such as that, but some may. Those curved parts may be good candidates to have CNC plasma cut out of plate and then just weld them together into that final shape.

CNC or plasma might be a decent option. I agree it might be good to weld that together, heavy plate is pretty costly for me locallly, but creating a box tube out of 3/8" plate would be hella strong. I do have a piece of 1" plate that is about 12" wide and 36" long, it was for a different project originally, but the 12" width doesn't allow for too much of the arch. I will most likely need to buy material, so cost is some consideration.

Alan, what about just notching the square tubing in 7 places, and bending and welding to create 8 straight segments that approximate the curve?

Yeah, that might work. Might be doable with 1/4" square tube, so that might be a possibility...gives more opportunity for failure, but if done right it would be strong.

The weight of the logs can reach up to about 5k-6k lbs. The biggest log I've tried to put on the sawmill I estimate weighed about 6k lbs. That would be 3k per end. Keep in mind I only want to turn the log, once in position I will drop it back on the sawmill bed. The idea is to be able to reposition the log how I want to cut it, that's the tricky part when I'm working by myself. The way I do it currently is to use straps, wrap them around and try to lift the forklift to turn the log to cut. It's not ideal and takes a lot of time for one person to do, not to mention it's not very accurate. And it has a tendency to move the bed around as I roll it.

[cj737]

What you need to find is someone with a hydraulic ring roller, capable of bending the square stock. A tube bender won't have the radius you need.

You could make a template from plywood, cut kerfs in the outside of the stock about 3/4 through, then shape and pin the piece. You need a LOT of Kerf cuts.

When you go to re-weld the kerfs, tack at the lowest point (this keeps the kerf open) and skip along. You can clamp and pin the piece into the shape you need, then weld it back solid into a radius. Solid, good as new.

I did this on 3 pieces of angle bar to make a loading ramp for our motorcycle shed. I make a kerf about every 1.5" along the length where I needed the radius. It was damn simple. I tack welded it with my MIG, then came back welded it hot with Flux Core. All 3 pieces were darn near identical (they have angle bar turned on peak for treads).

This is exactly how I'd do it given your resources, time, and no pandemonium keeping you from the shop Plus, its a great exercise to learn a new technique.

[BugHunter]

The only sawmill I have ever used had a hydraulic rig that rotated the log for you. Even held it for the first cut if needed.

I can't imagine 1" square stock being anywhere near big enough to handle a large log. Maybe not even with support all the way around. Surely won't hold anything out 12" away from the support in the center. I can see that being bent almost instantly.

[TraditionalToolworks]

The only sawmill I have ever used had a hydraulic rig that rotated the log for you. Even held it for the first cut if needed.

I can only wish I had hydraulic on my sawmill. It is a project I'd like to take on, maybe one day, it would solve a lot of things other than turning logs, but not in my near term cards.

I can't imagine 1" square stock being anywhere near big enough to handle a large log. Maybe not even with support all the way around. Surely won't hold anything out 12" away from the support in the center. I can see that being bent almost instantly.

You must not have very much experience with ball bearings. Most all of the load will be dispersed to the bottom as the log is turned. This is nothing much more than a toe jack that allows the log to spin. The reason I came up with this design is there was another design that has been done using 2 sprockets and #80 chain which a guy built and worked fine. This is actually a better design, IMO, as I have used ball bearings for machine skates and they are strong.

Just curious, you work with metal more than I do, what do you think the weight/force needed to bend a 1" piece of square stock to be? At 18", which is even questionable if you could get the entire log weight on the outer edge of the arch. I believe the bulk of the weight would still be towards the center due to the diameter of the log. The force is actually momentary as the log spins, after which it would transfer to the bottom center once again.

[Poland308]

Bending sq tube depends on tube diameter, wall thickness and bend radius. Also depends on the dies used. One way or center dies require different pressure. Also the dies that are shaped to collapse or deflect the inside flat surface relive stress and require less force as well.

[cj737]

Just curious, you work with metal more than I do, what do you think the weight/force needed to bend a 1" piece of square stock to be? At 18", which is even questionable if you could get the entire log weight on the outer edge of the arch. I believe the bulk of the weight would still be towards the center due to the diameter of the log. The force is actually momentary as the log spins, after which it would transfer to the bottom center once again.

I don't think load is the largest concern, but rather balance and counterweight of the setup. A log (dead load) at the end of the leg will tend to topple the square stock. As long as you've designed and considered how to restrain the carrier, you'll likely be fine.

[TraditionalToolworks]

I don't think load is the largest concern, but rather balance and counterweight of the setup. A log (dead load) at the end of the leg will tend to topple the square stock. As long as you've designed and considered how to restrain the carrier, you'll likely be fine.

I would probably just weld it to the top of a floor jack, I've seen this work for both log turners and toe jacks.

Worst case I could weld the floor jack mechanism to the sawmill bed, but I would try to keep them separate. Typical wheel spread is pretty decent on most all floor jacks.

Ideally having interchangeable top pieces to swap between turner or toe jack will be ideal.

A toe jack with a conveyor type roller on it, one on each end would allow repositioning the log along the length of the sawmill bed, and the log turner would allow it to reposition the diameter of the log in regard to the edge being cut. Hope that makes sense.

I'm open to tube or solid, or as you suggested above to create my own weldment from cut pieces.

Even if the arch is not perfectly curved, I could compensate for that curve with the placement of the ball bearings.

[BugHunter]

a Just curious, you work with metal more than I do, what do you think the weight/force needed to bend a 1" piece of square stock to be? At 18", which is even questionable if you could get the entire log weight on the outer edge of the arch. I believe the bulk of the weight would still be towards the center due to the diameter of the log. The force is actually momentary as the log spins, after which it would transfer to the bottom center once again.

Imo, if you were using solid stock at 1 in and you use mild Steel, I think you're wasting your time. If you use 4130 it's going to be a lot more difficult to work with but that would certainly hold up better. But you're going to need somebody to Bend it and it will require unfairly nice slip roll or something like that. You would never Fab that on your own in a vise.

If you go up to inch and a half material then I would say maybe the mild steel will work and you could bend it with a torch and it will still be mostly unchanged when it cools back down.

Most of the discussion above centered around Steel Square Tubing and I don't think I would even start the project or something like that. Not unless it was 2 in by 8th in or something like that. Something really heavy but then of course you can't bend it very easily. I think solid stock would be more forgiving for the bending.

[TraditionalToolworks]

One problem with bending square tube is that it needs to crease the inside and outside of the tube. It's doable, just seems more difficult. I think cj's method of either cutting out triangles to bend the pipe and welding the seams back together would be easier, or just do as he also suggested have it cut on CNC/plasma and weld it together as well.

There is no way 1" square of 4130 would be cost effective.

Thanks for your thoughts.

[cj737]

Alan - You don't need to cut triangles, just kerfs on the outside of the radius. As you bend the piece, the kerf opens. Just weld from the bottom of the kerf outward, starting with tacks. And keep it pinned to a template to prevent it from closing down while you weld.

You'll be fine. Worst case? You do it again differently.

[TraditionalToolworks]

Alan - You don't need to cut triangles, just kerfs on the outside of the radius. As you bend the piece, the kerf opens. Just weld from the bottom of the kerf outward, starting with tacks. And keep it pinned to a template to prevent it from closing down while you weld.

You'll be fine. Worst case? You do it again differently.

Ah, got it...so what you're saying is use a lot of cuts, and bend with the cuts on the outside. I was thinking larger pie shapes on the inside and close them up and weld the seam closed. On the style you're talking about do you make a lot of small kerfs? I hadn't thought about the outside of the arch like that...

I have some time to think about it, as I have a couple projects in the meantime. I have a couple mods I need to make to the mechanisms that secure the logs while cutting, but will most likely stick weld those.