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Is this unknown plastic even suitable for shielding for a press?


PeteyPyro

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Is this unknown 5/8" thick plastic usable for safety shielding for a hydraulic press? It has great design, being curved perfectly, and being the perfect size. BBs and air rifle pellets at 1300 FPS bounce off of it. I'm just not certain how much blast I would need to contain or mitigate. I would be making the frame out of 1/4" steel stock, welded to the hydraulic cylinder's base support frame. I'd probably never be pressing more than 1 or two ounces of a BP based comp (no whistle mix). An 8oz. Rocket, confined in a tube holder acts like a grenade if it goes off, right? I can use several layers if needed, and probably will, just to be safer, but I don't known the type or characteristics of this clear curved plastic. It's almost inflexible, very hard to scratch, and seems to exhibit a high index of refraction. Any ideas on this, rocket men?

post-21112-0-28383000-1513372216_thumb.jpg

Edited by PeteyPyro
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Looks like polycarbonate. “Bulletproof”. The curve works to your advantage physically. Set a decent vitamin F charge in front of one and check it out. I bet it’s golden. PS... cover in tin foil to mitigate marring of the surface if ya wanna try to reuse it. Bet ya 50 grams don’t touch it other than the marring of the surface.

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Sounds like a suitable test with vitamin F. I'm thinking it's acrylic. I'll consider launching it in the local quarry, with sand bags in case it shatters.. Edited by PeteyPyro
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IF you are going to test it, you don't want to "launch" it. You want it static, and a good size charge set of on the side of it. I'm thinking you want the stuff set up "concave" on the press, so, the bulge facing towards the press, and explosion center. Pushing against a bend takes a lot of force. Collapsing it, pressing from the inside of it, makes it bend with the force a 'lot' easier. Seams think, so a 'lot' easier is probably still a significant amount of force.

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Yes, B, I was thinking that too. While it would look prettier with the concave side facing the press, it would be safer and stronger with the convex side towards it. Like a Roman arch is strong under compression, and not under tension. I will restrain the plastic to closer simulate "in situ" conditions that it will (hopefully never) encounter while in use.
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Burn an edge with a lighter, polycarbonate is self-extinguishing, it will carbonize and produce soot . Acrylic burns slowly with bubbling but no soot or charring. Cd/dvd``s are polycarbonate so you can compare the burn characteristics of those against the unknown plastic if you`re not sure. ;)

Edited by Col
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Have you ever cut acrylic/plexiglass? It has a very distinct smell. And honestly, if you are only pressing small BP motors I would not at all feel uncomfortable pressing them without a shield. Depending on what you're using as a tube support I guess. I generally would just ram anything smaller than 3lb motors.

 

WB

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Pretty thin stuff tho Dag, and the curve. And 500 grams...jeebus.. I’d be interested in testing that hunk he’s got. I’d be willing to put a couple bux on it surviving a pretty good shot.

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Place your bets. I have 2, 60 gram BP charges in 1 & 1/4" x 3", 3/16" walled tube ready to test the curved plastic. I'll cover the plastic's face with tape to protect it from scatches and charring. It will be restrained, and well bunkered. Devestation film footage coming soon...
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Wheeee! I got a QP of beef jerky..anyone in? Uh- US only :D

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I`d try to recreate a test scenario thats as close to the realworld installation as possible ;). Will the shield be open at the top, bottom, sides or back? Will the press be freestanding or fixed to a bench. Any surface like a wall directly behind the press, benchtop, floor, ceiling etc could potentially reflect or redirect shrapnel and especially fire in unexpected directions.

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Rich, it's only a test with 60 grams of BP, cuz vitamin F would be cheating due to its brissance.<grin> I'll use a 3" standoff with 2 layers of the test plastic. I hope this works, as it would make a nice press shield.
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It survived twice. E-matched visco at 3" offset.

post-21112-0-02601900-1513538988_thumb.jpgThe tire caught some air in the video here...

Not a scratch. It might be incorporated into a shield for the 10 ton re-purposed hydraulic log splitter press. post-21112-0-69910800-1513539189_thumb.jpg Now it's time to weld up a steel frame to hold it, concave side outside, to the press's frame.

Edited by PeteyPyro
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Hmm was not really aware of the scale of things. Ain’t that a little small? Stack the pair?

 

I still think it’ll withstand some Vit F :D

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...The tire caught some air in the video here...attachicon.gif20171217_140111.mp4

 

Couldn't help watching that a few times - Looks like you've come up with a satisfying and quick method for tyre removal. :)

Edited by stix
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Post testing image with the green tape wrapped plastic panels..post-21112-0-40397300-1513604220_thumb.jpg The tire was over the plywood which was over the underground test chamberpost-21112-0-49260000-1513604277_thumb.jpg It was well sealed. Edited by PeteyPyro
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Stix, it launched it good. It was on a piece of 3/4" plywood, covering the 2 foot deep BBQ pit. It was well sealed, I'll give it that. Yeah, Rich, it IS a bit small, but it's only for a 'sight glass'... and it was free plastic. It may well survive a moderate dose of 'vitamin F', but I'd hate to destroy it unnecessarily with destructive testing. I'll post pix here of the whole press, as soon it's completed
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Final thoughts : This material is acrylic, and despite its relatively indestructible nature, would shatter if it did fail. I'm opting for a couple of 3/4" marine plywood sheets that I already have. I'll use an old (but free) video camera that I have in conjunction with an old (& free) 15" monitor. I'll be able to fairly safely monitor pressing operations, cowering behind 1&1/2" of shrapnel resistant marine plywood sheeting. I might even attach the acrylic sheets onto the plywood to allow the point-of-view camera mount placement. Final pictures of the finished 10 ton press with the shield, video monitoring, and ptf gauge will be coming.... Edited by PeteyPyro
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I have my press mounted sideways with the shield on the left. I can load it with my right hand and then step to the side to pump it up. I have a mirror on the wall directly behind the press so I can look at my rammers both through the shield and at 90° to make sure I'm not cocking a rammer or anything else expensive. I still figure I'm a goner if a 3# whistle goes high order in the press but at least there'll be something to bury!

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