Laser cutting a spring - choice of material?
I have a scheme that requires a flat, non-conducting spring.
Acrylic it too brittle for my needs, but I know that some plastics can, when cut with a laser, give off fumes and gases that will damage the laser cutter (eg PVC gives off gases that will cloud the mirrors).
What materials would you recommend?
(I've attached a quick sketch of the general shape of the planned spring.)
EDIT: I've added a rough sketch of the project - a torch, cut from acrylic. The four projections are to bind it together with an elastic band. The switch operates like a syringe.
Discussions
Best Answer 7 years ago
I see what you're after, I don't think it will work as you've drawn it. Try this design instead.
Answer 7 years ago
Oh, that makes much more sense (I had a mental image of a 2d sponge), thanks.
If that will work in acrylic, I could make it part of the middle layer...
Answer 7 years ago
It'll work fine in Acrylic - give me some working dimensions.
Answer 7 years ago
The CR2032 is 20mm x 3.2mm, so something around that?
It's not vital at this stage, I'm just trying to make a laser-cut version of a demo model that my boss made on a CNC machine in two layers (we don't have a CNC machine).
Answer 7 years ago
Well it works.
Answer 7 years ago
Oh, my word, you are a star!
7 years ago
This might work a little better.
You will have to make the case a little wider to accommodate the wider spring and push button.
Answer 7 years ago
I see what you're doing, but the plan is to make everything in that middle layer - the spring, plunger, & acrylic - all the same thickness as the battery.
Answer 7 years ago
You could do away with the spring if you make a push /pull plunger
like this. It could be the same thickness as the middle layer,
but you will have to widen the middle layer to accommodate the wider
plunger.
7 years ago
Incidentally, this is a parametric model, you say how wide the spring is, how thick and how many turns there are and it renders it for you.
Answer 7 years ago
Alibre - there are similar facilities though in most modern CAD packages.
Alibre PE's about 140 quid. Mine's the 1400 quid version, with all the bells and whistles.
Answer 7 years ago
£1400?
0_o
Answer 7 years ago
Yeah, well you only buy it once, and I can use it on three computers for the same licence. The top version includes CAM, FEA and sheetmetal working toolsets as well.
Answer 7 years ago
Haha, school would need it on at least 30 computers...
Answer 7 years ago
Well, you could always ask Alibre about academic discounts - Solidworks and Autocad do it, to sucker you into their 20,000 pound offerings
Answer 7 years ago
No point, the HoD has already paid out for something called Techsoft 2D
We'll see...
Answer 7 years ago
Oh god, that's an AWFUL package - its one of the ones the boys use at school.
Have fun/
Answer 7 years ago
Uh-oh
Answer 7 years ago
Oh?
What software is this in?
7 years ago
What plane is it springing in ?
Answer 7 years ago
Flat - in the first sketch, compression would be left-to-right. In the second (just added), it would be from below. I want it to push a watch cell out from a pair of LED legs.
Answer 7 years ago
Steveastro's drawing is almost exactly what we have working as a working spring inside a 'fake transistor' valve :)
Answer 7 years ago
travel ?
Answer 7 years ago
Unsure right now - 50-75% of the uncompressed spring? ~5-10mm?
7 years ago
I don't know which is cooler, laser cut stuff or that Steve jumped on this so fast and did it.
7 years ago
Why not use a bit of sponge?
Answer 7 years ago
I need to retain the "cool, it's all been lasercut" factor - this is going to be a demonstration piece for a class.
Answer 7 years ago
! :-) Cool + expensive
Answer 7 years ago
Steve's modification actually makes it cheaper - the spring will be formed from the acrylic that is already there, and would otherwise be discarded.
7 years ago
I've personally cut springs out of 2mm acrylic and used them as compression springs - but again it all depends on how much force it has to withstand, and in what direction.
Answer 7 years ago
It's not the amount of force, it's the amount of deformation I need it to survive.
I've added another diagram to the question.
7 years ago
1 mm ply or polypropylene
7 years ago
Yeah, Delrin should cut very well - no nasties in the fume.
But what's wrong with plywood ?
7 years ago
Delrin is supposed to laser cut nicely and be more sturdy than acrylic. I never got a chance to try it though.