ideas for HDPE sheets?

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himhimself
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ideas for HDPE sheets?

#1 Post by himhimself » Fri Jan 29, 2021 6:37 pm

We get some interesting packaging around items arriving at my work, often from overseas. I hate seeing stuff end up in the landfill, so I always rescue the baltic birch that one supplier builds their crates with. Wonderful 7-ply 3/8" stuff that works great for all kinds of projects, especially speaker cabinets. I've also rescued a bunch of smooth white plastic sheets - pretty sure it's polyethylene, although might be polypropylene. 3/8" thick, approx. 39"x39". Heavy, cool stuff that I have no idea what to do with, but figured I'd come up with some reason to save it. Well, so far I haven't so thought I'd solicit opinions from the forum. Thoughts :?:
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

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Seth
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Re: ideas for HDPE sheets?

#2 Post by Seth » Fri Jan 29, 2021 8:52 pm

If it is HDPE, PL Premium won't stick to it. You can use it as a edge jig or pretty much anywhere it's useful to not have PL stick to it.

Test it out. Put a big smear of PL on it. If it comes off effortlessly, you're good to go.

You can also use it under wherever you set your glue gun down between uses to catch that little bit that always seems to sneak out. Once it's dry, just brush it off into the dust bin.

As far as I know, nothing will stick to it. Might even be able to use it to mix bondo on.
Last edited by Seth on Sat Jan 30, 2021 12:06 am, edited 1 time in total.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Bill Fitzmaurice
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Re: ideas for HDPE sheets?

#3 Post by Bill Fitzmaurice » Fri Jan 29, 2021 10:10 pm

Cut it up for kitchen cutting boards.

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Tom Smit
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Re: ideas for HDPE sheets?

#4 Post by Tom Smit » Fri Jan 29, 2021 11:21 pm

Bill Fitzmaurice wrote:
Fri Jan 29, 2021 10:10 pm
Cut it up for kitchen cutting boards.
.....and mitre guides for jigs on the table saw.
TomS

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Seth
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Re: ideas for HDPE sheets?

#5 Post by Seth » Sat Jan 30, 2021 12:10 am

Make wear rails above the casters on the back of your subs, for going up and down stairs and curbs.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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AntonZ
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Re: ideas for HDPE sheets?

#6 Post by AntonZ » Sat Jan 30, 2021 5:58 am

For identification of the base material: see if there is a stamp somewhere on it. Usually there should be an indication stamped somewhere near an edge or corner that has a symbol indicating the type of the material for recycling purposes. Both PE and PP can be recycled just about endlessly, but they are different materials and should not be mixed in the recycling process. Hence the incentive to mark products with the material type. The symbols for both are a triangle of arrows (standard recycle symbol) with characters indicating the material. Symbols for common types of polyethylene are PE, PET, HDPE. Polypropylene would likely be marked PP.
Example: symbol HDPE for recycling purposes
Example: symbol HDPE for recycling purposes
Symbol_Resin_Code_2_HDPE.png (10.31 KiB) Viewed 250 times

himhimself
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Location: Bloomington IN

Re: ideas for HDPE sheets?

#7 Post by himhimself » Sat Jan 30, 2021 9:56 am

I like the idea of the wear runners on the back of the subs, Seth. Also using in various jigs, especially if PL doesn't stick. No stamps anywhere - I'm assuming they cut them down to size from larger sheets, so maybe that's why. Pretty sure it's HDPE though. Either would work for these kind of projects. If I could figure out how to build with it, I could see making some small, totally weatherproof outdoor speakers...
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

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AntonZ
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Re: ideas for HDPE sheets?

#8 Post by AntonZ » Sat Jan 30, 2021 11:08 am

I don't recall the exact properties of either (material science lessons are quite some time ago :noob: ), but I do seem to remember one of them is just plain impossible to glue. Literally nothing sticks to it. The only way to make a cab out of that material would be to melt the pieces together.

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Seth
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Re: ideas for HDPE sheets?

#9 Post by Seth » Sat Jan 30, 2021 12:43 pm

AntonZ wrote:
Sat Jan 30, 2021 11:08 am
I don't recall the exact properties of either (material science lessons are quite some time ago :noob: ), but I do seem to remember one of them is just plain impossible to glue. Literally nothing sticks to it. The only way to make a cab out of that material would be to melt the pieces together.
That would be the HDPE. A cab could possibly be made, but it would either have to use screws to hold it together and sealer in the joints as a gasket of sorts, or use heat to weld it together.

Ultimately, it wouldn't really be an ideal material to use.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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