Hi all, my latest project requires cutting 1/4" and 3/16" diameter steel rods into many small pieces, at various angles. Here’s the model I’m working from:
I’ll be building a full-scale model out of hardboard that I’ll be adhering the metal pieces to with aluminum tape, and then welding them together. Here’s a proof-of-concept I did earlier to give you an idea:
All told there will be a few hundred pieces ranging from 1/2 inch to 3 inches long, cut from rods probably 5 feet long. The cuts don’t need to be super precise as I can weld over gaps and clean it up later.
I can figure out how to get the lengths and angles I need to cut, but I’m not sure how to actually do the cuts in an efficient way. I’m okay with a certain amount of tedium, but I wouldn’t want to (for example) have to unclamp and reclamp the bar after every cut, so something like the chop-saw is probably a no-go. The fiber laser would probably be ideal but it doesn’t seem likely to be available soon. Would the CNC machine be a good candidate for this? Or the plasma cutter, if I made markings directly on the bars as guides? I even thought of making custom miter boxes to use with my portable bandsaw, but that seems a bit over-engineered.
Have you considered using an angle grinder with a cutting disc? That would probably give you more precision than the plasma cutter, and you could clamp a length of bar with a bunch of cuts marked on it, and just work your way down the bar.
That could work! Normally if I was gonna do that I’d clamp the bar in a vice near the cut to reduce vibration, but then I’d have re-clamp after every cut or two. And I can’t check directly to a table because I’d end up damaging the table with the grinder. Maybe if I clamp the bar to a piece of wood or square tube, then clamp that to the table. Then I just have to worry about how popular I’ll be after spending an hour cutting metal with an angle grinder
I think you should maybe consider bending the larger loops where possible. Perhaps bending all the loops and then simply notching them with an angle grinder in order to fit the loops together would be easier.
Organize how many of each cut you’ll need example of out of 100 pieces 15 of them need to be at 5" set up the stop that’s on the right side of the cold saw, screw it in and line up to 5", then feed your rod through 15 times, not having to measure every time but also getting a clean and accurate cut, then cut all your 3" pieces then all 2" pieces etc.
This sounds like a good plan if I can make it work. The challenge is that a lot of the vertices have the bars meeting at interesting angles, for example:
which can leave big (1/4" or more) gaps in those spaces if I don’t cut the rods at angles so they fit together a bit better.
Yesterday I got the idea to fill the vertex gaps using 1/4" or 1/8" carbon steel balls rather than try to get the rods to meet at angles. In that case I can do straight cuts using the technique you suggested, at least on the majority of the spots where 3 or 4 pieces are meeting and the angle isn’t too extreme. Even with clamping / unclamping and moving the stop, this feels like it’d ultimately be less work than figuring out how to mark the bars and cut them by hand.
