Composite mold making questions |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Composite mold making questions |
TonyAKAVW |
Jul 16 2007, 01:48 PM
Post
#1
|
That's my ride. Group: Members Posts: 2,151 Joined: 17-January 03 From: Redondo Beach, CA Member No.: 166 Region Association: None |
I want to make a diffuser/engine pan for my car, and last night I started gluing foam sheets together to make a mold. My plan is to form the foam into the shape I want and then seal it with body filler, and then primer and polish. I have been reading up on making molds for composite work and most seem to talk about making a copmosite piece for the mold rather than what I am planning. If I make my mold as described will my composite part rip the mold apart when I seperate the two? (assuming I use a PVA mold release film).
Also, if I make the part with carbon fiber, how do I finish the edges of the piece when I'm done? I would like to vacuum bag this part because the part will be visible from the top and the bottom... Can I get away not bagging it and get a decent finish? (I'm not super concerned that it has a perfect surface really). -Tony Finished part will look something like this... With the long straight edge meeting up against the firewall and the two tunnels exiting right under the bumper. Attached image(s) |
URY914 |
Jul 17 2007, 08:02 AM
Post
#2
|
I built the lightest 914 in the history of mankind. Group: Members Posts: 120,968 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
Tony,
If I were you I would make this as easy as possible and just lay up some fiberglass mat and use some cheap poly resin. You're spending a lot of time on molds, material and vacuuming when you don't know if this is even going to work. Make the first one simple and cheap and once you get it to the shape you what than use that one for your mold and use the carbon. Everyone here has given great advice but you're jumping in with both feet when maybe you should take smaller steps. Just my $.02. |
andys |
Jul 17 2007, 10:58 AM
Post
#3
|
Advanced Member Group: Members Posts: 2,165 Joined: 21-May 03 From: Valencia, CA Member No.: 721 Region Association: None |
Tony, If I were you I would make this as easy as possible and just lay up some fiberglass mat and use some cheap poly resin. You're spending a lot of time on molds, material and vacuuming when you don't know if this is even going to work. Make the first one simple and cheap and once you get it to the shape you what than use that one for your mold and use the carbon. Everyone here has given great advice but you're jumping in with both feet when maybe you should take smaller steps. Just my $.02. +1 I've built a number of one-off's for race vehicles with the cheap and in-expnsive method. Saves many hours of labor, and in the end it gets dinged-up anyway. A lot depends on the complexity of the shape, but your's seems relatively simple. So, this is how I'd do your part. Construct the simple shape in MDF (positive or negative). Radius the outside corners, and use bondo for the inside radii (use PVC pipe or steel tube of the right size). Knock down the rough areas with sandpaper. If you can get Mylar to lay down flat to your surfaces, then simply do a wet layup with fiberglass/epoxy (cloth and mat combination). BTW, you can buy a two part laminating epoxy (I think they call it "Boat Epoxy") from Home Depot that is plenty adequate for one-off's (and no need to make special trips to a plastics supplier). Finish the top side using a short knap roller to both compress the layers of fiberglass layers together as well as push excess epoxy off the part and discard it. In the event that the Mylar cannot lay flat against your form, then spray several coats of grey primer, and wet sand with 400. Spray with PVA release agent (two coats minimum), then glass over that. For more complex shapes like ducting, I shape the part from urethane foam and use the same process. Yes, it is un-sophisticated, but produces a part quickly and relatively in-expensively by comparrison. Your alternative of course, is to go with "highways" method. Andys |
Lo-Fi Version | Time is now: 2nd June 2024 - 11:12 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |