Ive had a friend asking me to make some carbon doors, and he wants a rough quote. Any idea on how much it costs to make a mold for a standard sized car door. It would be two molds per door with inner and outer being joined together?
A rough estimate could be $800.
But are you prepared for this? Have you made similar parts?
Is that per mold? and im guessing thats just materials.
Im guessing that it would take 2 or 3 weeks to flange/ duratec/sand/polish/wax each plug ready for mold layup.
And its for a two door car so thats 4 molds all up.
So looking at for four molds $3200 + labour costs?
Dont think he relises just how much work is involved in mold making and the total cost of it.
Im not sure if i want to take it on? Could be a headach
Ive never done doors but have done a few other parts/ molds so yes im set up to do it. Am quilfied in wooden and composite boatbuilding.
The $800 is a very rough estimate for materials to make the 4 molds. Epoxy and glass construction.
Does he want an exact replica of the stock doors, or just lightweight replacements? Huge difference in quality, weight, tooling, and the way they’re made.
if its just one off parts I would just make the molds from chopped mat and vinylester resin, only flange it if your going to infuse it, because otherwise you can just throw the doors in to a bag, its a lot quicker and cheaper this way. material cost would only be a few hundred dollars plus your labor rate for the molds.
The doors will be for a race car so just race car quality, light weight replacemants , and he wants a few more sets to sell off.
Why build the molds out of epoxy?
Epoxy in molds for less shrinkage, stiffer, and more resistant to distortion from exotherm of parts made in it.
Make outer skins, with a core. I wouldn’t bother with an inner frame.
What most people don’t realize is that designing composite parts is very different than stamped sheetmetal. Just duplicating is pointless. Use just the outer skin for its shape, but inside you just need enough to make it strong and have a place to mount.
you wont get any noticable shrinkage using a decent vinylester, it will be faster and cheaper than epoxy. spray gelcoat, let tack and do 2 layers of 1oz, let cure then 4 sets of 3oz letting cure between each set. this will make little over 1/4" thick mold that will be plenty stiff for door molds. I agree with coring the door fronts with closed cell foam core, but having a frame on the back is nice for mounting and adding more stiffness.
hey whale… keep us updated on the progress if you decide to go through with it… ive been wondering how to do this for a while… but im no where ready to take this on… mostly $$$ good luck man:D
Adding a frame to the backside is the wrong way to go about adding stiffness. It only attaches around the perimeter. So what about the entire surface of the outer panel?
A core will stiffen the whole thing, and is much lighter.
And did you mean 4 plies of 3oz fabric? You must be talking about CSM, because 2 plies of 1oz and 4 plies of 3oz woven glass will make a very floppy mold! Might as well lay up on some wet noodles. 
thats why you make the frame also attach along the middle of the door. we make race car doors here everyday, having a frame does make the door stiffer, noticably more torsionally stiff. But I do agree with you, it isnt necessary . yes, I ment 3oz CSM.
Im going to have to agree with both of you.
I would core the outside panel, and also add a frame to hold my window/motor in place. Hell if Im going to drive around with lexan windows!
JRL, you go to flush mounted PC windows…
Fiberglass VW Bug doors…
Insides…
Dang…it is position the correct way on photobucket but …?
That thing must weigh nothing!