I have some 40x3mm steel flat bar, and I have a need for 5x3 (or thereabouts, havent nailed down the details yet). You cant buy that kind of size, smallest is solid square bar @ 10mm (which I may end up doing).
Basically I have a flat bar frame that I want to mount some glass and or mesh inside and I need to put a bit of a 90º lip on the back to both accommodate/mount that and give rigidity to the frame.
I’d need 16 lengths of 1200mm ish so whatever the method it needs to be pretty reproducable.
I was thinking about making a table and fence for the metal bandsaw but feeding that is going to be a huge pain, plus blade wander on that thing is pretty varied.
Another weird idea would be to clamp it to a table and somehow jig up an angle grinder with cutting disk to make light, straight repeatable passes.
Could a cnc be used somehow? sounds tricky, you’d either have to lose large amounts of material or somehow mount a cutting disk.
Let the ideas flow
rather than cut nearly 20meters of steel with a grinder or bandsaw, why not just get it cut in a hydraulic guillotine at a local metal-workers shop. I’m quite sure that 3mm is thin-enough vertically, and 1.2m is thin enough horizontally for it to fit in one. 16cuts would take them like 5 minutes. ( 4 minutes to set the stops, and 1 minute to do all the cuts )
I’d worry that a guillotine would warp the cut, but if you know of a place i could enquire at I’ll give it a go? Not really aware of any metal fab shops local.
I got steel for my trailer from http://www.aspinalltrailers.com/ . I don’t know if they do one-off jobs, but they certainly have a guillotine there that’s big enough.
If you desperately need to use 5x3 and cannot design around the 10x3, then your best bet for accurate trimming to size is going to be clamping it in a mill and thinning it down.
A guillotine will warp such small pieces of bar due to the forces involved.
Another option would be getting 5x3 laser cut or water jetted from plate.
A jig saw with a metal blade and jig could do it… i recently cut some 5mm plate it wasnt super quick and corners definately weren’t an option but the cut was clean and straight…
My vote would be an angle grinder with a wafer blade and some sort of jig to run the grinder up and down the steel. eg a straight bit of hardwood screwed to a scrap piece of ply and then a runner to guide the grinder along the length of hardwood… oh and and end stop so the flat bar doesn’t get shot out by the grinder.