Mock fabrication of 1/4" steel with some other cheaper, more accessable material

I'm starting to prototype and fabricate 4x4 parts. I'm doing all the design and having a fab shop produce certain items. Instead of waiting for their turnaround time and paying full price on steel, I'd like to fabricate mock up parts at home, finalize my design, and then send them the drawings.

I'm thinking some kind of acrylic.

I need something I can cut on a CNC router or laser cutter, that will take a bend similarly to steel in a brake, that can be joined via weld or glue.

Any thoughts on how I can simulate the metal bending process with another material?

Also, the problem with acrylic is that it seems to cost quite a bit.

I use cardboard from boxes and lots of tape.

Doesn't lexan form like metal on a sheet metal brake?

I can't use cardboard unless there is some variant that holds a bend well, this stuff needs to hold it's form so I can get accurate measurements back from it.

In reply to Taiden:

The plasticardboard found in political signs will hold its shape if you heat the bended area

Oh that corrugated plastic crap? I wonder where I can find some.... It's not election season!

I would think that you would have to heat the plastic to get it to form without cracking.

I don't know what thickness you are forming, but you need to check with your shop to see what the bend radius needs to be. No sense making plans if they can not bend it like you want.

Lots of people use cardboard to mock up parts. If you want to make it stiff, how about using some fiberglass cloth and resin or even wood glue to hold it.

In reply to Taiden:

Lowes carries it in 2' X 4' sheets.

As far as bending it goes, I don't mind making a hot wire bender!

And yes, I have the shops bending radius.

I do use cardboard for a lot of things, it's a valuable tool... but I want something I can use to make doppelgangers. I'd like to be able to run bolts through various parts to check for fitment. I also have free use of a 4x8 CNC router with vacuum hold down, so that makes the choice to seek out a reasonably priced material worthwhile for me.

Aluminum composite panel material? It's not cheap, but it is workable if you have a router to make bend ing grooves and it definitely meets your other needs.

I cant recall the material name right now, but there is a lightweight plastic board (not corrugated) that is used for real estate signs and the like. Probably 3/16" thick. It melts at (high) heat gun temps, so bending it to form will not be a chore. It also can be drilled/tapped/shaped like metal...sorta.

itsarebuild wrote: Aluminum composite panel material? It's not cheap, but it is workable if you have a router to make bend ing grooves and it definitely meets your other needs.

Whoa! Neat material. Where does someone usually source this stuff, and any thoughts on pricing?

Right now LDPE from McMaster or even Amazon is looking the best.

Acrylic cracks and shatters, lexan bends with heat. Coroplast is just like corrugated cardboard but made of plastic, and other than being waterproof, less flammable and much stronger, has similar characteristics.

Why not a chunk of 6x6 wood. Throw it in the cnc and machine it to shape.

foamcore

Road signs are cheap and plentiful.

3D Solid Modeler, Inventor, Solidworks, etc.

The problem I'm seeing is the thickness.

There are sheet plastics that will fold in a brake, but I don't think you can bend 1/4" in a brake.

If you are trying to do exact fitments, the thickness will matter, especially in your radii, etc.

Corrugated products will not bend similar to steel.

At the hand-forming level, cardboard or foamcore work great. If you are machining with a CNC, it's not going to replicate your final methods very well.

You can copy cutting lines done with a CNC to a laser cutter or water jet, but the machining part is more like a milling machine.

I just don't think your data is going to translate quite as accurately as you seem to be thinking.

Maybe I should detail the workflow.

I currently get best measurements from the car with a variety of measuring methods. Then I draw up the part in SolidEdge. Then I print out 1:1 ratio draft sheets of key parts, especially items with awkward bolt placement, and check those on the car a few times until I'm happy.

At this point, I'd like to make a prototype out of cheap material to check basic fitment. Any huge errors should be obvious at this stage.

After this check, I'd send the drawings / files out to the fab shop and pay full price to have the part made. I'd take the chance to go over fitment with a fine tooth comb and make any additional changes to the part files. Then I'd do a one off, just triple check, and get it ready for market.

Does foamcore hold a bend? I think that's probably the roughest part of the whole thing.

3d printer?

I'm not going to 3d print offroading parts, they tend to be quite large. I'd probably spend as much on a spool as I would on the final steel part.

Coroplast will hold a bend a little better than foamcore, but its corrugated

Find a local steel shop that has an HD plasma burn table or even better, a laser. They can burn everything out in a flat panel for cheap and you can weld it together yourself to prototype the design. Once you have things where you want them, convert your fabricated part into sheetmetal in your cad software and then you can create a finished flat with bend lines to send to your fabricator with a press brake. For onesey twosey parts that need to get fabricated quickly, its tough to beat getting flats cut to size and welding them up at home. Once production volume goes up, the setup time on a press brake will even it out and its way cheaper to get a single piece bent up than multiple panels welded together.

Or just ask your fab shop really nice to run one part when they are slow so you can demo it. Tough to beat the real thing.

That is AWESOME advice 93gsxturbo.

Kenny_McCormic wrote: 3D Solid Modeler, Inventor, Solidworks, etc.

Inventor is over $10k for a single seat now, I'm thinking that's not likely going to happen.

I just bought a copy of Alibre pro (pro = minimum for sheet metal capability) for just under $1k.

Or you could go to your local job shop, and pay them their hourly rate to have an engineer draw it up for you. We do that all day long where I work- they have 2 guys doing nothing but walk-in projects for small companies and guys with hobbies. You will come out ahead doing this compared to having the shop draw all of it up for you twice (once for flats, then once again as sheetmetal models).