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50mm HDPE or 54mm Hole saw?

Posted: Wed Sep 09, 2009 1:45 am
by tghhs
Well i've finally just found a place where i can get HDPE rod (AUS, Vic, profile plastics in bayswater) This is after an email and the 50mm rod comes in meter lenghts of $44 (AUS, btw)

but after goining into bunnings (australian version of Lowes) and fiddling with pvc parts and bushings i decided to go and have a good ol' look in the tool section where i came across a nice 54mm hole saw with a depth of cut of ~57mm for ~$42

this got me thinking, i'll only be wanting ~6-10cm of the 1 meter $44 HDPE rod but if i get the hole saw i'll be able to make as many 2" pistons as i want.

Anyway i hope you see my deilemma, what should i get? i'm going to o-ring the piston as well so do o-rings work well with wood pistons?

Posted: Wed Sep 09, 2009 1:49 am
by jackssmirkingrevenge
Wood is an organic substance and is therefore sensitive to moisture and prone to swelling and deforming.

Assuming you get the rod, one metre will give you at least 20 pistons, are you really going to need more than that?

Posted: Wed Sep 09, 2009 2:30 am
by Technician1002
Maybe it's time to save for both so you can use the piston in a steel tank like one of these.
Image

Posted: Wed Sep 09, 2009 3:23 am
by tghhs
jackssmirkingrevenge wrote:Wood is an organic substance and is therefore sensitive to moisture and prone to swelling and deforming.

Assuming you get the rod, one metre will give you at least 20 pistons, are you really going to need more than that?
yeh, i guess that will also mean i'll be able to lubricate the piston as well if it needs it.

@ Technician: Yeh!!! i totaly agree that will be a future dream because i'm very envious of that cannon

Posted: Wed Sep 09, 2009 3:29 am
by inonickname
Get the HDPE. No contest.

If you have any of the other aussie spudders near you it could be possible to share the rod (and prices) around. Unfortunately I'm in WA.

Posted: Wed Sep 09, 2009 3:51 am
by MrCrowley
I use wood in my 2" housed piston but i'd take HDPE anyday. I also used a hole saw to get my piston and then turned it down on a lathe and added an o-ring groove. Though I used a finish to seal the wood up and stop it from absorbing moisture.

Posted: Wed Sep 09, 2009 5:35 am
by jmadden91
Im in QLD mate, and coincidentally just finished a 50mm Piston Cannon :D Ill split it with ya

Posted: Wed Sep 09, 2009 11:17 am
by THUNDERLORD
I'd go with the rod of HDPE at similar price.
But using the hole saw and flat sheets of plastic,
you could cut out a bunch of layers,
and with cyanoacrylate(sp.?) type normal clear super-glue,
Using a vise and wood blocks OR C clamps and wood, once glue is dry part remains clear and nearly (if not as) strong as a solid piece.
Sort of a plastic plywood.
Leave it in the vice or clamps overnight. 8)

BTW, for a smaller diameter piston, I've been working on a scredriver handle. Just cut the metal shaft shorter, put it in a chuck like a bit and turn it to diameter against a file and sand paper.
Odd Coincedence, in middle school shop class we made screwdrivers with four flat layers of clear plastic, superglued...in vise overnight...belt-sanded, polished clear again with auto-wax and buffer wheel...

Posted: Thu Sep 10, 2009 2:31 am
by tghhs
yeh ok cool thanks guys, i'll go with the HDPE :) should make a sexy piston.

Posted: Fri Sep 11, 2009 8:46 pm
by THUNDERLORD
After replying,
I realized if the hole saw was used,
And sheet polycarbonate was cut out,
There would be a hole in center of each piece that a bolt could be added through,
With a washer each side and a nut,
Superglue could be applied to each layer and the nut and bolt simply tightened (atleast overnight).
The same bolt/nut/washer could be used for attaching sealing face to front of piston. :roll: 8)

Posted: Fri Sep 11, 2009 9:02 pm
by jmadden91
Yeh perhaps sheet HDPE as opposed to 50mm rod