Working with Plastics

Tiberius

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Jan 14, 2008
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Location
Rural England
Hi,

Are there any experts on plastic types and adhesives out there?

I just got a length of ventilation duct, thinking it would be just right to make a battery box
http://www.bes.co.uk/products/180.asp
I has assumed it was PVC, like most other building plastics, and that I could glue it with either standard solvent weld or cyano-acrylate. But they don't work; its even resistant to acetone.

Any ideas?

Nick
 
that stuff normally glues fine with Marley pipe cement, though epoxy mixed with some micro balloons would glue it, but you have to roughen up the surfaces a little to provide a key
 
Pvc should work with standard pipe cement, MEK or, god forbid, Methelene chloride. Polyprop and the like gotta be heat welded!
otherDoc
 
When using CA glue I always make sure to roughen the surfaces with sandpaper to increase
the gluing surface. I also use a spray can of 'activator' but that may be more about patients.
 
Full marks to the distributor (who was selling it at half the price of other online places). I emailed them and got this back:

Hi Nick,

We have emailed our supplier who has advised as follows.

"The channel is manufactured from uPVC and the fittings from high impact polystyrene (HIPS) therefore “glue” may not be the best option.
As the sections are quite thin we would not recommend solvent welding either.
We would recommend the use of a suitable proprietary white silicone or acrylic sealant"


-------------
 
You might also consider PVC fence posts as a material to house battery packs. It is built as a structural component and appears strong enough to hold the weight needed, and is waterproof. I am in the process of making two battery packs out of one 4 x4 post I bought at Lowe's. I expect to buy flush recessed plugs for each end, and will mount a flush mount cannon plug connector on one end for charging.
 
Hi Bart,

Good idea, I'll look out for something similar over here.

Actually I gave up on the duct, but I stuck with PVC. I bought a big slab of it and started machining it into pieces; it turns out that its quite nice material to work with. So far I'm joining parts together with screws rather than glues or welds. This is a completely OTT way to make a battery case, I know, but it means I can get the dimensions the way I want them. More importantly, I can build the method of mounting it onto the bike in from the beginning.

Nick
 
Have you tried ABS? I found it pretty easy to deal with, and it's not as brittle as PVC. Got an order of like 2 cubic feet of the stuff coming in, myself. :wink:
 
Link said:
Have you tried ABS? I found it pretty easy to deal with, and it's not as brittle as PVC. Got an order of like 2 cubic feet of the stuff coming in, myself. :wink:

What's a good (online) source for bulk ABS?

Thanks, Eric
 
ebinary said:
Link said:
Have you tried ABS? I found it pretty easy to deal with, and it's not as brittle as PVC. Got an order of like 2 cubic feet of the stuff coming in, myself. :wink:

What's a good (online) source for bulk ABS?

Thanks, Eric

Best prices I could find were from Interstate Plastics. They were having problems with the checkout when I was trying to order stuff, but they got it sorted out a few days ago. Roughly half of what I could find it elsewhere. I figure they can get away with this because they add a $15 "small order fee" for any order under $50. Their shipping was surprisingly cheap, too. Two of the sheets are quite big at 24"x48"x1/8", and it was only like $22 to Cali.

Most of what I ordered was beige ABS 1/8" sheet from their surplus section (30 sheets). Something like $1 for a 12"x24" sheet of the stuff.
 
I'll second the plug for ABS. It's slightly lighter than polycarbonate and much easier to drill, cut, bend, etc,.

On the duct material, if solvent glue is out, perhaps try Gorilla glue. That stuff is pretty amazing, but fairly hard when cured. It also takes 24hrs. for a full cure.
 
Ypedal said:
Lexan or " Polycarbonate " is excellent.. you can heat-bend it , expoxy it, screw it.. and it's shatter proof, scratch resistant.. light weight..

http://www.ypedal.com/Chaos3.htm

Actually, Lexan (Polycarbonate) scratches very easily. You have to specify "AR" (abrasion resistant). AR has a thin layer of acrylic bonded to each side of the Lexan rendering it sctratch resistant. :wink:

Matt
 
chaos-li9.JPG


This looks awfully familiar. :wink:
 
I'd be careful with ABS plastic. It deteriorates in the sun. It works fine if buried in the ground and lasts a long time in that environment, but does not last in sun light.
 
I'm stuffing my box in a bag to make it look like a normal rack pack, so sun won't be an issue for me. You could just paint the stuff, too.
 
Polystyrene(ABS) works fine under the sun as long as temperature doesn't exceed 145F. It is actually a good replacement for fiberglass fairings/casing. Compared to fiberglass, it's much easier to repair and shape.
To stick them, you only need IPS weldon #3 and abs cement. Not advisable to use any kind of epoxy.
If you have the extra dough, you can use polycarbonate(Lexan), more impact-resistant and is good up to 200F.
 
The Weldon cements are great for styrene type plastics and even polycarb, but they do contain MEK and methelene chloride. Definitely use in a well ventilated area! I use them for model building and have to go out of the shop to apply. Maybe respirator w/charcoal might work?????
otherDoc
 
Link said:
Have you tried ABS? I found it pretty easy to deal with, and it's not as brittle as PVC. Got an order of like 2 cubic feet of the stuff coming in, myself. :wink:

Hi Link, and you others

Virtually all the small cases I use for electronics are ABS, of one form or another. I get the impression that there are many types of ABS, PVC, Nylon, etc, in the same way that there are many types of aluminium.

I must check out the polycarbonate too. I rejected that as too hard and brittle, but sheet plastic that can be bent could have a lot of uses.

Its definitely a field worth learning more about. Maybe I've got too hung up on metal and fibre glass.

Nick
 
How about "Coroplast" the stuff they use for making signs. This is what i used for my 48 volt battery pack base plate, which had to be tiered or leveled with 3 pieces stuck together to fit properly on my frame.

Coroplast can be bent, easily drilled, and best of all it has great shock absorbtion properties which is what I especially needed for my battery base plate. I often use my bike on gravel trails, my LIFEPO4 pack also has a built-in "BMS" circuit.
 
Isn't coroplast that corrugated plastic stuff? Yeah, I guess that would work, but I wouldn't trust it with a foil-pouch cell in a fall.

I bet it's nice and cheap, though. :wink:
 
Link said:
Isn't coroplast that corrugated plastic stuff? Yeah, I guess that would work, but I wouldn't trust it with a foil-pouch cell in a fall.

I bet it's nice and cheap, though. :wink:

I'd think it provides better impact and thermal insulation than 1/8" ABS.
Hot glue works for fold and flap construction but I wouldn't trust it without a few layers of nylon packing tape or clear duct tape banding.
I'd not bolt through it without a substantial backing plate.
 
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