SkullandBonesSkateboards.com Forum Index » MANUFACTURERS FORUM » concrete molds |
Page 1 of 1 |
|
Author |
Message |
shawn |
Posted: Thu Jan 31, 2008 9:11 pm |
|
|
Joined: 26 Mar 2006
Posts: 5
|
i've tried to switch from wood molds to concrete but ended up throwing money out the window! has anybody had success with concrete molds in conjunction with hydrolic presses. because i need some advice because all of my nmolds have cracked .! |
|
|
Back to top |
|
|
pennswood |
Posted: Fri Feb 01, 2008 9:52 am |
|
|
Joined: 14 Sep 2003
Posts: 213
|
concrete molds,
cheap, but it takes about 30 days for the concrete to cure,
if you jump the gun and use them to soon,
they will crack, almost explode under pressure.
we have used polyurethane casting media,
cures overnight, lasts forever.
but it costs around 400.00 per set.
now the bigger problem is why are your molds cracking?
wooden molds, what type of wood?
how did you get them properly offset?
the top and bottom molds should not be the same. |
|
|
Back to top |
|
cortex |
Posted: Fri Feb 01, 2008 1:24 pm |
|
|
Joined: 12 Aug 2006
Posts: 17
Location: Belgium
|
I use concrete molds too and the trick to prevent cracks is to put the molds in an iron case that holds them together and keeps the pressure inside the concrete. I do get minor cracks but I can do at least 500 decks per mold. |
_________________ Cortex Skateboards
www.cortexskateboards.be |
|
Back to top |
|
|
boss |
Posted: Fri Feb 01, 2008 8:36 pm |
|
|
Joined: 19 Nov 2007
Posts: 227
|
this is one of my concrete molds, be sure to use plenty of rebar and wire screen.
|
|
|
Back to top |
|
sk8bones |
Posted: Sun Feb 10, 2008 6:04 pm |
|
|
Joined: 28 Sep 2004
Posts: 540
Location: Oklahoma City
|
It has to be uneven pressure. Concrete does well under compression, but if the pressure is uneven it undergoes sheer stress and cracks. The iron case sounds good. You could also prestress the molds. Stretch cables inside the mold in a mesh pattern. Probably much easier to make a box though. |
|
|
Back to top |
|
looess kroose |
Posted: Fri Mar 07, 2008 1:03 am |
|
|
Joined: 05 Mar 2008
Posts: 1
Location: Toronto
|
could anyone PM me with photos or tips?
this is the only thing im a little sketchy on in my head (worked out alot of the logistics in my head, good to find this place and verify which will work best) |
|
|
Back to top |
|
|
|