this is a frame i made a little while back … just to show what can be done with MDF molds
an inflation bladder was used … pumped to 3 bar … 45 psi
aarg pfft , can a mod move this to the showcase please 
wrong section
Nice piece.
Nice Job! have you any moulding pics?
Looks great!
i sprayed the mold blue , but the hardner was off, so i had to scrape the moulds clean and spray them again
couple pics showing the layup
Seriously badass, good job, and a good documentation on bladder molding. This need to be moved to the correct section (showcase), so that people can easily find it and be inspired to try this method or build something similar.
What is that bladder made out of?
Nice work!
great work !
Agreed that is a badass job you did there! Kudos!
How did you made the bladder ???
ta guys !
the bladder is a garbage bag … i find that the cheaper bags split easily , when you hold the cheaper bag to the light is has a very distinct grain in the plastic a bit like cellulite … lol
the more expensive bags tend to be more consistent with the thickness of the bag … i bought a whole bunch of different bags and found one that works great
i use a soldering iron with a ballnose tip … i sat with an angle grinder and rounded the tip , then went thru different grades of paper polishing the tip to a nice shine
some guys use a flat tip, but i have found the round tip works best for me
lay down two or three sheets of newspaper onto a flat table …
a layer of oven baking paper ( NOT wax paper it cant handle the heat)
then the plastic bag
another layer of the baking paper
template <-- i use a 3mm board cut to shape
then its just a case of running the iron around the template …
i do two laps with the iron … i know when its done properly as the bladder comes loose from the outside
and thats it
a tip … keep the opening small ! 6mm tube works great, when its too big the pressure wants to push the pipe out and it makes it harder to stop the bladder from popping
That is a great job. I have never seen a bladder used yet. Do you pressurize it? How much PSI? So one side in the mold laps the joint and bonds the two halves, is that how it works? Thanks .
blackrat, why didn’t you use a vacuum bag instead of the garbage bag to make the bladder?
the bag needs to have stretch to get around corners etc, it also needs to allow folding onto itself
all the vacuum bags ive ever used are too thick … but if you have a lightweight vacuum bag there is no reason why it wont work … you just gotta experiment a little to find a bladder that works for you
pressure … i would say 1 bar (15psi) works pretty good on most average sized parts , i have pumped to three bar , but your mold has to be pretty strong to handle it , think of a car tyre … thats on average 2 bar
Nice work!