Let's Make Robots!

Plastics for robotics

So I'm trying to figure out how to best manage the funds I have for purchasing some construction material. I've decided to go with some plastics and lightweight thin aluminum I can cut by hand.

The issue is, I don't know what the different types of plastics have to offer in terms of machinability and robotics platforms, besides Expanded PVC and Polymorph, which I have worked with in the past and still have some pieces left, but I don't care much for working with those materials at the moment.

I'm going to order through TAP Plastics (http://www.tapplastics.com/product/plastics/cut_to_size_plastic) simply because so far I think they are the best price that I have found so far with the widest selection and they cut to size.

The issue with TAP plastics website is it seems there is a $10 minimum charge for ordering cut to size plastic. I can get away with up to 10 sheets of 1/8th (3mm) 4" x 4" any type of plastic, or 3 sheets of 12" x 12" any type of plastic. Since my issue is I don't know these plastics and what is best suited to constructing durable robot bases or parts (i.e. brackets) and how easy one type of plastic is to cut vs another, I don't know if I should get pre-cut sizes or just go with a 12" x 12" sheet and cut out what I need from there.

Has anyone worked with any of the plastics they offer and could offer me some advice as to which type you feel works best for your robotics? Please include ease of machinability, etc, and keep in mind I don't have any heavy duty power tools besides a crappy dremel (barely any cutting bits) and a drill. I have a small hand saw and that's about it.

My ordering limit is about $20 from TAP plus shipping.

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I almost forgot-you'll want to get some adhesive. For PVC you can use plummer's cement, but I'd recommend a tube of Weld-on 16 or Craftex 33 (I think I spelled that right...) Either of those tube adhesives is great for both PVC and acrylic/polycarbonate plastics. Don't try to use super glue on clear acrylics-voice of experience. It's like trying to clean a mirror with a sandblaster.

This looks pretty intesresting if your in the UK

http://www.ema-models.co.uk/

 

last year some1 posted on something called 'plastruct'
apparently its the material that architects use to make dioramas of their designs.

u can get it on ebay real cheap...

I think plastruct is just polystyrene sheets, plastruct being the brand name. They have all sorts of great shapes like tubes and rods because its made for modelers.

What do you mean "cut by hand"? What tools are you using?

Basically my hands and a small hacksaw lol.

That goes for "Poly" too-Unless you have a CNC handy, you can only cut those in straight lines.  What have you got against expanded PVC?  I'm assuming you mean PVC sheet, like Sintra, Komatex or Azek.  Those are probably the easiest to work and form.  If you're going to have TAP cut the plastics for you to a specific shape (other than rectangular) then acrylic might work out, but if there's even a small flaw in the design then you're stuck with about a dozen coasters.  If you're really dedicated to the idea, I'd chat up CtC and see if he'll help you with routing.

HDPE is strong but harder to work and has a waxy feel too it.  ABS is thin, sort of hard to work and usually too brittle.

If the problem with ePVC is price, I'd recommend going to a local sign shop (FastSigns or SignsNow) and asking if you can buy some "drop."  It's the leftover stuff from their millings and they'll usually let me have an armful for a tenspot.  If it's strength, you might try different weights.  Most of it is in 3-6 mil but I use 12 and even 18 for my bots.  The thicker stuff is handy for most applications.

Do you have any knowledge of styrene?

Just the pink stuff that gets used as insulation in your walls or foam core, which you're probably familiar with as a photographer. Not great for construction the likes of which we get into.

Thanks for the info! That's very helpful; I didn't know those plastics were hard to work with without a CNC. Yes you're right about the Expanded PVC sheet. I'm just looking for something a -little- stronger but still easy to form and work with. Preferrably something that takes hot glue and other adhesives well.

Good idea on the local sign shop suggestion. I'll see if my city has anything!