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plexi glass instead of plywood?
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cadaverchris


Dec 8, 2004, 9:26 AM
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plexi glass instead of plywood?
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I'm going to build a free standing (A-frame style) campus board in my apartment.

I was considering using plexiglass instead of plywood. I have built home climbing walls before. but I don't have any experience in art or construction with this medium. Anyone with construction experience have any comments on this substitute?

my thoughts:
it will be 3 ft wide by 6 feet tall panel.
use 2 sheets (one on top of the other) to get duble the thickness.
decking screws will hold fine. i could get t-nuts that take screws to be held in place rather than the more common hammer-in kind.

will there be too much flex in the campus board?

thanks.


overlord


Dec 8, 2004, 9:32 AM
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Re: plexi glass instead of plywood? [In reply to]
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thats a good idea. itll look really nice if you manage to do it right.

keep the wooden rungs and try to put as much force as possible directly on the frame and use thick plexi and you should be fine.

man, post pics when youre done.

edit: as for my limited (primary school project, very simple) experience with the material, its more like brittle plastic than glass. quite hard to break actually. wouldnt put t nuts in it, but should be fine for a campus board.


gohighgodeep


Dec 8, 2004, 9:51 AM
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Re: plexi glass instead of plywood? [In reply to]
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my only concern is that plexiglass is quite a bit more brittle than plywood... it one of the bolts rips out, it'll crack the plexiglass quite badly, and might make the entire thing useless... whereas in plywood, it'd just rip out. would definetly look pretty sweet tho, and i'd think that thick plexiglass would be able to take the load well enough... and you might want to get some large washers to spread the load over a wide area on the plexiglass.


grayhghost


Dec 8, 2004, 9:56 AM
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We have a small bit of our gym wall
made of plexi-glass. The main problem
is the brittle nature, a crack ran from
one t-nut to another while drilling.
Screws would seem to be a better option
but make sure to space them as far apart
as possible. This idea is cool, post up pics
if it works.


dynosore


Dec 8, 2004, 9:56 AM
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The repeated stress on plexiglass (PMMA) will almost certainly lead to cracking around every hole drilled/bolted into it. I think you will be very dissapointed in the long run if you use this material. It would look cool though. If you're serious about it, use Lexan polycarbonate and it will hold up alot better.


hersh_ml


Dec 8, 2004, 10:08 AM
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I would definitely recommend Lexan over plexiglass. From the testing I have done with Lexan, it holds up exceptionally well. If it stops a .40cal pistol round, its probably ok to use it as a campus board.


jer


Dec 8, 2004, 10:09 AM
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I have done a small ammount of furniture work, and artwork using plexiglass, and unless you have a really good hookup; full sheets especially 1/2" or thicker are ridiculously expensive.
soudns cool, though. good luck.

jer


dynosore


Dec 8, 2004, 10:11 AM
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Even if lexan were to get cracked (doubtful), the crack won't propogate like it does in plexiglass.


dynosore


Dec 8, 2004, 12:21 PM
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In reply to:
http://www.ridoutplastics.com/plasmat.html

You'll pay around 150-200 bucks for a sheet of either plexiglas or lexan thick enough to hold your weight.


stevep


Dec 8, 2004, 12:27 PM
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I would also guess that a thick enough sheet of Lexan or plexiglass may wiegh a chunk more than the equivalent wood, and your anchoring will need to be all that more beefy.


Partner sauron


Dec 8, 2004, 12:34 PM
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In reply to:
I'm going to build a free standing (A-frame style) campus board in my apartment.

I was considering using plexiglass instead of plywood. I have built home climbing walls before. but I don't have any experience in art or construction with this medium. Anyone with construction experience have any comments on this substitute?

If it's purely a campus/hangboard, why not make a plain a-frame and mount the rungs to it - there's no need for the plywood backing if you space everything right.

You can make it out of < $50 in 2x4 's.


- d.


Partner drector


Dec 8, 2004, 12:42 PM
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I've never been able to screw a machine screw, sheet metal screw, wood screw, directly into acrylic without destroying it. It can be tapped for to take a cap screw (bolt) and that might work fine if it's thick. You also don't need t-nuts if you have access to the back side. Just use regular nuts with washers.

You would need cutting fluid to drill since acrylic melts more easily than wood when drilled :shock:.

My experience with this material makes me think it is a bad choice. There is no benefit from it and it weighs more, sosts more, is harder to work with, and is more easily damaged beyond repair. My experience is limited to smaller sizes than a climbing wall so I could be wrong about much of this.

Dave


mingleefu


Dec 8, 2004, 1:03 PM
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If it's purely a campus/hangboard, why not make a plain a-frame and mount the rungs to it - there's no need for the plywood backing if you space everything right.

D'oh. This won't work. First, the rungs of the campus board would likely flex when you pull on them. Keep in mind that campus rungs are generally only around an inch thick, or less. They would flex awfully. It may be possible to back the rungs with 2x4's, but they would certainly need backing of some sort.

The other benefit of the backing is to limit how much of the rung you can grab. If you don't have backing, your fingers will simply fly right past the rung, and you would grab the whole thing like a pullup bar. It would take some sick precision to grab the rungs with just your finger tips.

Use Plywood.


Partner sauron


Dec 8, 2004, 1:41 PM
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In reply to:
In reply to:
If it's purely a campus/hangboard, why not make a plain a-frame and mount the rungs to it - there's no need for the plywood backing if you space everything right.

D'oh. This won't work. First, the rungs of the campus board would likely flex when you pull on them. Keep in mind that campus rungs are generally only around an inch thick, or less. They would flex awfully. It may be possible to back the rungs with 2x4's, but they would certainly need backing of some sort.

You use the 2x4's as rungs. Stand them on end, and they won't flex, even if you weigh as much as me.

In reply to:
The other benefit of the backing is to limit how much of the rung you can grab. If you don't have backing, your fingers will simply fly right past the rung, and you would grab the whole thing like a pullup bar. It would take some sick precision to grab the rungs with just your finger tips.

And precision is bad why?

This method allows you to simply change from a full-hand grab, to a full-finger grab, to a fingertip grab easily. And if you want to be picky, you can put a 1/2" lip on the top edge of the 2x4's, to keep your fingers from going off the back.

Hell, you could even router it into the 2x4, if you're incapable of placing your fingers accurately.


- d.


mingleefu


Dec 8, 2004, 9:10 PM
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In reply to:
In reply to:
In reply to:
If it's purely a campus/hangboard, why not make a plain a-frame and mount the rungs to it - there's no need for the plywood backing if you space everything right.

D'oh. This won't work.

You use the 2x4's as rungs.

Oh. You didn't say that.

In reply to:
In reply to:
The other benefit of the backing is to limit how much of the rung you can grab
And precision is bad why?

It isn't that precision is bad, but it would take an insane amount of precision to strike the campus rung at the right spot, if there was no backing at all.

I must've misunderstood. You didn't define clearly.

whatever.


anykineclimb


Dec 8, 2004, 10:10 PM
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If you're going asthetics, I think thin sheet of Brushed aluminum over the plywood would look pretty slick.
It would be easier to clean the chalk off too.


phxtradrock


Dec 8, 2004, 11:54 PM
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In my experience with materials I would recommend staying away from any acrylic due to its brittle behavior. POLYCARBONATE would do well if you were to purchase it 1/2" thick - I think. I have never built a climbing wall with it. Polycarbonate is drill/saw-able and does fine with bolts. Screws should work fine but I would recommend bolts wherever possible. If you use the wrong type of plastic it will likely fracture like glass at somepoint cutting you up into small nuggets. If this happens contact McDonald's they are always willing to purchase this type of nugget for their 5 and 9 piece meals.


cadaverchris


Dec 9, 2004, 8:20 AM
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thanks everyone for your replies.

if the cost seems to be as high as Dynosore said (150-200 bones) then this project won't happen. But we shall see.

If it gets done i'll definitely post up a pic.

and if anyone else takes up the project let us know how it goes! =)


rokjok


Dec 25, 2004, 6:29 AM
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Another problem with this type of medium is that you will have to glue your holds in place or use a set screw for every handhold. There is not enough friction for the holds to stop from spinning, even if they are cranked down really hard.
I know this, I've tried.

Hope this helps.


irockOscar


Mar 16, 2013, 1:39 PM
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Re: [hersh_ml] plexi glass instead of plywood? [In reply to]
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This is in response t a few posts speaking of Lexan's superiority over plexiglass and I have to wonder if there is anyone who has used both plexiglass as well as Lexan.

A few posts( replies) speak of it's resistance, but I have done online research and have found out that plexiglass actually has 10-15 % more TENSILE STRENGTH as well as FRACTURAL STRENGTH. True LEXAN seems to have more than double the IMPACT strength ( hence its use for bulletproofing) but i would imagine for climbing TENSILE and FRACTURAL are more important, even if not, would it be worth the price ( which , although i have not done the research, double to triple the price)

I still need to do more research , but I am losing hope on using any transparent material for my project. ( which would be the world's first GEODESIC CLIMBING SPHERE)... if I could have used transparent panels, the aesthetics would have been outstanding... but because of the triangular cuts needed the price will be too high. Oh well... back to the drawinf board, ( plywood and fiberglass drawing board)
In reply to:
http://www.hydrosight.com/technology/polycarbonate_vs_acrylic.php
In reply to:
In reply to:


USnavy


Mar 17, 2013, 3:06 AM
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Re: [cadaverchris] plexi glass instead of plywood? [In reply to]
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irockOscar wrote:
This is in response t a few posts speaking of Lexan's superiority over plexiglass and I have to wonder if there is anyone who has used both plexiglass as well as Lexan.

I have. They are quite different. Watch this video for the highlights: http://www.youtube.com/watch?v=h5HM3y8d0NA

I have seen research quote both options. Some say polycarb is stronger and other say that acrylic is stronger. However, the majority of the info I have found says that polycarbonate is stronger. Regardless, polycarb is safer. You can considerably bend polycarb before damaging it. On the other hand, acrylic will break into knife-like shards with little warning.


(This post was edited by USnavy on Mar 17, 2013, 3:23 AM)


dynosore


Mar 17, 2013, 10:15 AM
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Re: [irockOscar] plexi glass instead of plywood? [In reply to]
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OK, there really is no comparison. PC is FAR tougher than PMMA, period. I've worked in polymer research for almost 20 years. I've done thousands of Izod tests on both materials. Lexan is going to give you a notched impact strength of around 700 J/m. Acrylic is less than 50 J/m. I don't know where you read that PMMA has higher "fractural" strength, but it's absurdly untrue. The other problem with PMMA is, once a crack starts, it's going to propagate. Whatever you do, do not waste your money trying to build this out of acrylic.


irockOscar


Mar 17, 2013, 11:42 AM
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Thank you so much for your reply, I need this kind of info , here is the link regarding fractural strength and tensile, I myslef was surprised, but it is not a scientific manual nor are there information on who and where this research is done...

http://www.hydrosight.com/technology/polycarbonate_vs_acrylic.php

as for using the acrylic i do not think it is an option anymore..i do however have some specifications provided by WALLTOPIA if anyone is interested.

1. Weight 12 kg / sq. m
2. Thickness 20 mm
3. Max. space between supports - 1.00-1.20 m
4. Sheets come in 2x3 meters
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irockOscar


Mar 17, 2013, 11:45 AM
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This was the info I got... I would imagine by looking at the credits in the bottom, not a very biased source...would you be able to provide me with something similar?



Polycarbonate - Lexan Acrylic - Plexiglas GS
Density g/cm 1.2 1.19
Max weight gain during immersion % 0.35 2.1
Tensile strength &#963;&#924; at 23C MPa 60-70 80
Flexural strength &#963;bB MPa 90 115
Impact strength acU (Charpy) kJ/m2 35 15
Flexural strength &#963;bB MPa 90 115
Optical Light Transmission % 89 92
Forming Temperature C 185...205 160...175
Vicat B Temperature C 145 115
Velocity of Sound m/min 2270 2750
Attenuation at 5MHz dB/cm 24.9 6.4
Fire Rating German DIN 4102 B2 B2 (*2)
Sources:
Lexan 9030 Sheet Product Datasheet
Plexiglas GS Product Description
(*2): Makrolon AR - Bayer Sheet Europe, October 2004

by Hydrosight
last changed 7th of August 2012


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