I need some thin sheet metal pieces (0.1-0.2mm thickness) that have ‘complex’ shapes and will be a spring mechanism once bent into shape.
My local laser cutting shop has got a big machine that cuts up to 20mm mild steel an dthe smallest parts I have made with them have some ‘jitter’ in the range of 0.2mm which I don’t want there.
Thus I thought, why not use paste stencil material and the service for this.
Now, they are only used to pads and not for contours… so my question, anyone got experience with something ‘out-of-the-box’ like this?
Hehe… laser cutting copper is the hard bit afaik - that’s why they go for something else there.
Those stencils I had in mind are stainless steel and pretty springy - exactly what I want - and the details in the stencils I got so far are pretty good, definitely good enough for that kind of job.
Ah, well… gotta contact the support then I guess.
To answer myself here I didn’t had luck to send a dxf file or some gerber outline for the stencil.
So I went through the trouble and converted the flat shape into a footprint, where the pads are the cut away area and no pad gives me the sheet metal (bend lines are marked with tapered pads).
This looks then something like this:
I then put a couple of these into a ‘layout’ of sorts and have them make me a paste stencil.
Once they come back I can cut them apart with scissors and have what I wanted.
I updated this in case anyone thinks that this might be a way to get EMI-covers for chip assemblies - might need a check for solder-ability though.
That with the not tolerable jitter of 0.2mm and cutting with scissors sounds interesting.
The waterjet is a good solution.
Lasers have no constant beam, they are pulsed. Thus you get overlapping holes (looking like jitter). This depends on the radius of the beam. After that the parts go into a sandbox to clean the edges (a box of sand with an exiter underneath). But that ends up less accurate.
Another way is handling it almost like a pcb. Paint it with light - sensitive paint and the go into an acid bath. But use another type of acid as with pcbs. We do that with pcbs that have magnetic material embedded for miniature transformators.
Yeah, well it’s with them now.
I had some mails back and forth and I understand them now better and they me hopefully as well.
A 20x30 cm 0.2 mm steel sheet which will get me like 20 sets of springs (3 different shapes, 2 of each per set) for about $32… that’s 30 cents a spring, reasonable for a prototype.
Luckily I didn’t had to execute plan B, which would have meant to try 2 other services, from whom I’ve not ordered before.
Use one of these paper cutters (bringing fotos in shape etc.). But a good one.
Place your metal on some sheets of paper and adjust this carefully. The papers prevents the thin metal from being bended instead of cut.
It’s done already and seems to have worked… just got pre-shipping snapshots of my order that included that particular spring (had to adjust some of the pads by their demand to make it work and just wanted to get 'er done for the time being without further messing around):
Will post again once this is here and I made up some springs
The blokes who did it will add some notes to their service from what I went through to make it more clear for other customers.
