Laser Cutting

[PJ-27]

I decided to make up some intricate designs for my BW with the intention of getting the pieces cut on a Laser Cutter.
Being a BW I chose Polycarbonate, since it's strong, light and means I can cut each of the pieces in 2D but have the sheet thick enough to assemble a 3D robot afterwards.
Plus polycarb is cheap, readily available and see-through!

Anyway, it didn't work. The cutter, although powerful enough to do the job, just melted and yellowed the polycarb. Is it possible I'm having issues because it's the Excell D kind?
I phoned round a few local laser cutting companies and none of them will touch polycarbonate - bad smell, finish and mess being their complaints.

One of the companies is still happy to do the work but have asked me to pick a different material, so my question to the forum is what should I pick?
Does anyone know how Nylon or HDPE cuts? Any other suggestions?

[Max]

Re: Laser Cutting

I know hdpe cuts very badly, it melts badly.
I don't know what to suggest as an alternative, you can get metal aser cut but that would be heavy.

[blazerbotics]

Re: Laser Cutting

HDPE doesn't laser cut, just melts back together.

[Eventorizon]

Re: Laser Cutting

Nylon and HDPE can't be cut with a laser in a way in which you could actually use the parts at the end. The melting points are just to high.

I wanted to do it for conker 1 at uni but our 120W laser cutter just melted about 2mm down into the sheet even at full power. Made a horrible smell too, and charred the plastic

If you are serious about having it cut you would have to go to a water jet company. This would also mean you could have it done in Aluminium but the cost would go up considerably. The alternative is change materials to something like Polypropylene which can be laser'd. But polyprop is no where near as strong as Polycarb, flexes easily and is easy to cut.

You might be better off tweaking and optimising your design for laser cut ply wood, that way you can cut out 3 chassis at almost no cost and swap parts out when they get totalled.

[adz600]

Re: Laser Cutting

water jet would work very close in price just leaves a slight angle on deep materials

[mightymouse]

Re: Laser Cutting

The only plastics that cut neatly by laser are acrylic but is VERY brittle at 2mm.

Have heard that Acetal Homocopolymer can be laser cut but will be either white or black. Never tried it but maybe someone here has.

Waterjet will cut, but will mark the edge of the profile unless you can find someone to use pure water.....

If you can produce .stl files for the profile then 3d printing is an option.

Trev

[PJ-27]

Re: Laser Cutting

Isn't Acetal Homopolymer, Delrin? Never seen or touched it but sounds like it does some interesting stuff.

I considered 3D printing, but it's expensive and the materials are limited. Some companies will do versions of Nylon but I'm worried they'll prove brittle.

You can 3D print Polycarbonate, but I'm yet to find a company that do it.

[PJ-27]

Re: Laser Cutting

Just total the printed volume and took the price for Strong&Flexible from Shapeways, works out as $886.90 !

[Eventorizon]

Re: Laser Cutting

At my university I have used both out ABS printers and both are very strong; one uses ABS 64 and the other 82 [Don't know what that means].
I have also used the SLA printer. Its clear but is like acrylic in its properties so I would avoid that.
You could easily do an antweight chassis in ABS. While I was watching AWS-40 I asked what thickness people printed to and they said minimum 3mm in Nylon. Go for something like 3mm in ABS and I am sure it will be strong enough against all but the meanest spinners

[Max]

I know this thread is a bit old but I wondered if you could use polypropylene as armour on a beatle weight as it is supposed to be tough and flexible so it soukds like hdpe. I am not sure if it is an option for laser cutting?

[daliad100]

Recently took apart a pressure washer made from polypropylene, took several smashes into a brick wall to break after sawing all the way around the seam didn't open the case.

I then applied hammer thinking this might be some good robot armour like yourself you but ended up punching out quite neat circles of plastic. Might be reasonable armour in thicker pieces but it's still quite brittle so it may not hold up to some of the weaponry.

[PJ-27]

Polypropylene is a bit like a poor mans Polycarb, I found similar issues with laser cutting though.