Plastic Sheet recommendation

NWCCTV

I have decided to change the base of my robot project from aluminum to plastic. I have found a local supplier that sells 1/4" sheets cut to order. Which would be better for strength and durability plus not chip when cutting or drilling, ABS or PVC?

Erik Friesen

1/4" pvc is fairly floppy. Delrin/Acetal would be stronger, I don't know about abs. 1/2" pvc would be ok probably. Amazon has white pvc sheet. PVC cuts and drills fine in my experience.

idbruce

NWCCTV

I am curious. Why the sudden desire to change? However, if you are determined to change, please consider this. For several years, I have been planning a special purpose robot inside the old noggin. Additionally, I have drawn up various plans that utilize stock aluminum materials. In all instances, the weight of the chassis and batteries have caused me to scrap these plans.

Although I have not spent much time thinking about the design in the last couple of years, I did have sort of an epiphany concerning the base platform, upon which all things will be built. Instead of building the base from stock aluminum materials, which results in some serious weight, machining, and other time and finance consuming issues, I have decided to use a premade base. And for this premade base, I will be utilizing some type of aluminum baking sheet, such as a cookie sheet. The cookie sheet is light weight and strong. Of course, the cookie sheet is made from some fairly thin material, but the sides make it very rigid.

Whatever material you decide to use, metal or plastic, consider using a premade form that is lightweight and has sides to increase rigidity.

Bruce

Lawson

I'd use ABS. It's pretty tough, decent strength, and glues easily. Btw, Lego and a lot of motorized toys are made of ABS.

I also like to avoid PVC when I can. PVC is ~57% chlorine by weight and starts making HCl if heated much over 70C. It also requires lots plasticizers to be molded/extruded as it's melting point when pure is 83C.

Lawson

ajward

I've used PVC for several 'bot designs, both 1/8" and 1/4". The thinner sheet is pretty flexible, but I can get around that adding reinforcements where needed. I've used the 1/4" sheet for a couple of wheeled 'bots without problems, but those haven't had a lot of weight to trundle around. If flex becomes a problem, I'll just add a bit of reinforcement... either aluminum angle or strips of PVC attached with PVC cement.

Plastic has been my choice for several reasons... 'tis lightweight, easy to work with and *cheap*! I go to a local distributor/fabricator (Tap Plastics) and rummage their cut-off bin where I can almost always find something very close to the size I need for less than $2 per pound. Once in a while, they'll just give me a piece or two because I shop there so much.
I can get PVC, ABS, Styrene, Acetal, Delrin and Nylon. It comes in white, black, red, green, blue, mirrored, transparent, translucent and "crinkly". :-)

The pile in the picture cost me about 15 bucks.

Amanda

Phil Pilgrim (PhiPi)

For stiffness vs. weight, it's hard to be glass-reinforced epoxy laminate (e.g. G10, the stuff printed circuit boards are made from).

-Phil

Mark_T

Correx or equivalent is lightweight and stiff - its the plastic equivalent of corrugated cardboard, as used in advertising signs.

W9GFO

I like the expanded PVC sheet. It bonds well using hot glue. I don't like that I can't cut it with the laser.

If the only choices are ABS and PVC I would choose PVC for its light weight and easy workability. If other materials are possible I would choose cast acrylic because it lasers really well and is quite durable. I would choose aircraft ply because it is easy to work with and very strong. MDF is also easy to work with and quite strong, it is what I made my Mecanum robot out of.

Phil Pilgrim (PhiPi)

Some of the strongest, stiffest material by weight I've ever used is Nomex honeycomb-core laminate. It isn't cheap, but my business partner at the time and I were able to score some scraps from the Aurora A (n

GordonMcComb

You didn't say, and so far no one has asked, what size robot you're intending to build. So your question really can't be answered with any margin of assurance. Given the right size and weight of the robot, even cardboard works.

-- Gordon

NWCCTV

OK. I think I have it pretty much narrowed down. The Bot will be 21" x 14". I currently have some 3/8" PVC that seems pretty strong. They are not large enough for the base but I am going to visit a couple plastic distributors today to see what I can get for cheap. One of the main reasons for the change to plastic is costs. Although I have a lot of scrap aluminum, it seems that plastic is easier to work with and repair if I screw up. I have used epoxy on aluminum but I do not like the workability of it. Plus, since the bot will be outside a lot of the time I decided that I need the base enclosed and with aluminum it would be heavier than I want it to be. I have some 1/2" and 3/4" aluminum angle pieces that I can place on the outside edges if need be for reinforcement. My pillow blocks are also aluminum so it will end up being a mix of both unless I decide I do not like the look. I am going to mark this thread solved. Thanks for all the input.

Edit:: So i just returned from a couple different plastic distributors. It some times amazes me as to how generous some people are when you tell them what you are doing. I went to Calsak Plastics in Kent, WA. and the lady there gave me a piece of Makrolon AR 14" x 36". Then, I went to Interstate Plastics in Kent, WA. I picked up a sheet of PVC14" x 30" and a piece of ABS 18" x 21", both pieces for $5.00. I think I will end up using the Makrolon because of its strength and the fact that it is clear will make a really cool looking base for my bot!!!! I also have enough material now to be able to build project boxes to enclose my electronics in!!!! What a deal!