240Z Front Bumper Fiberglass Molds

[Phlebmaster]

I have been working on making 240Z front bumper fiberglass molds. I need to know a few things. I am a total newb at this so please bear with me. This may turn out to be a very good thing for those who want a fiberglass bumper.

:D

 

1. What foam should I use to fill the mold with that is not too difficult to work with?

 

2. What do I line the mold with to keep the foam from sticking and getting wrinkles while setting up?

 

3. Do I need to do anything to protect the foam from the fiberglass resin?

 

Here is that I have so far.....

 

This is my first attempt, but I only had twine to wrap the molding material with so I got bumps. :(

 

 

Here is my second attempt...much better. No bumpies on the bumper. :)

 

 

Here are the two molds and my template...

 

Please help me with what to do next, I want to do this right.

 

Thanks!! :)

[Phlebmaster]

Progress......

 

I had some copper sheeting, so I lined the fiberglass mold I made with it so I can put carnuba wax and releasing agent inside of the mold. This will help keep the resin from sticking.

 

I plan on making one positive mold as well out of foam to see which way comes out better.

 

Here are the steps I took......

 

 

 

This copper should make the fiberglass super smooth..

 

Here is the fiberglass mold I made before I lined it with silicone sealant and copper. I coated the entire inner surface with silicone before placing the copper inside.

 

 

I used the fiberglass bumper Paul gave me as a template and pressed the mold with it.

 

 

 

 

 

[72240z]

From past exp I don't think the copper is going to work. The mold should be the texture you want to replicate, in this case glass, that looks pretty ruff. Unless you don't mind the extensive sanding after the fact anyway. Even if just for you if one day someone cracks your bumper I bet you don't want to spend hours sanding another.

 

When I did it I used a resin and polished it up really good, with wax nothing ever stuck.

 

Just trying to help.

[72240z]

You know Justin (280zforce) has a lot of recent experience on this too. Think he just picked up a whole bunch of z molds.

Edited July 20, 2009 by 72240z

[Dime Dave]

I'll try to help out here.

 

First a couple things.

 

Because of the shape of the bumper, the mold will need to be in at least 2 maybe three pieces. The FutoFab 510 bumper molds are 3 pieces, the main bumper and the 2 ends. The reason is the returns on the ends of the bumper when formed into a one piece the mold will "trap" the cured part inside the mold. Think of the mold needing to be shaped like a beer cup and the fabricated part a second beer cup. One fits nicely inside the other to stack them. The mold always has to have an opening larger than the part to allow the part to be removed from it.

 

Next, the surface of the mold has to be exactly like what you want the finish of the part to be. If it has bumps, even minute ones they transfer to the completed part. If you want a straight and satin smooth finished product the mold surface needs to be smoother and cleaner than what you want the finished part to be.

 

If you are reproducing a part there is no need for foam to create a replica (or buck). Just use the original piece and prep it to the point it can be painted with one finish coat of gloss black paint and look perfect. Sanding scratches will show in your finish product. Prepping the surface of a buck to make a mold needs to be done like you are building a show car. It must be perfect or every part removed from the mold will have every defect that the original buck has.

 

If you are trying to do this for the first time I suggest getting a copy of Fibreglast's 5 DVD library on fiberglass work, only $99.95. Fibreglast is also a reasonable source for hobby level quantities of materials. And remember resin has a shelf life; buying 5 gallons because it is cheaper may not be the cheapest when you only need 2 for your project and the other 3 gallons go out of date before getting used.

 

Link: http://www.fibreglast.com/showproducts-category-DVDs+and+Videos-118.html

 

Fibreglast also has online technical tips section that can help out a hobbyist fabricator.

 

Hope this helps.

[Phlebmaster]

WoW! Thanks Dave, that does help allot!

 

So basically I was essentially done at this point?

 

 

 

Cool! I will look into that video and at least get a FG book. :D

[72wagun]

I'm by no means an expert, but I've made some fairly large molds. Dime Dave's advise is good. There is a lot to explain on this subject. A video would be good.

 

A lot of the videos on youtube are not very good.

 

I watched this video a long time ago, and it's a good basic primer on how molded parts are made (sorry if you've already seen all this):

 

I just saw this one on there, and it looks pretty decent also:

 

If you are going to make multiple parts, you will need a good mold. Get some orange tooling gelcoat (I would to this either way). I also got a gelcoat gun. They are pretty inexpensive, and work well. The guy in the second video just uses a brush though. Also, get all the little accessories. You can do it without them, but it's a huge pain. Here are some things I would suggest:

 

-Gallon can of tooling gelcoat

-smaller paint brushes with the bristles cut to about 1" (use for "stippling")

-rubber gloves

-mixing cups

-stir sticks (I use "jumbo" craft sticks from JoAnn Fabrics)

-Catalyst despensing bottle with funnel top (I consider this a must have after getting one).

-Small plastic roller for stippling(optional but nice. Paint brushes work).

-Gel coat gun and disposable cups (optional but nice)

-MEKP catalyst (get more than you think you'll need

-plastic wedges for releasing molds

-Fiberglass (Mat would be fine for body parts. The other option is cloth)

 

I probably forgot something obvious. This is off the top of my head.

 

Resin:

You can use the cheap stuff they have a Home Depot, but it's a polyester resin. I prefer Epoxy resins, and the most popular brand, and easiest for the beginnner is West System. Polyester parts are probably the most common type, and they are okay, I just like Epoxy. The advantage is that epoxy is much more stable over time. Polyseter parts begin to shrink as soon as they catalize. The part is shrinking for the rest of it's life. You may have seen old fiberglass parts that are showing the weave of the fiberglass cloth. Most likely they are Polyester parts where the resin has shrunken, and weave begins to show.

 

I get most of my supplies from this place:

http://www.fibreglast.com/

 

This place has good prices on West System:

http://www.jamestowndistributors.com

 

This is very basic information. I'm sure the pros can chime in as well. There is a lot of information out there. Some good, some bad. I guess you just have to consider the source.

[Dime Dave]

When I purchased the QuikSkins molds several years back, my intent was to self educate myself and make parts during evenings. I found a local composites shop owner who was willing to work with me to build a few initial parts, kind of an apprenticeship type arrangement where I paid him his hourly rate and he allowed me to be part of the process as we built the parts together.

 

In doing that I realized that unless I had hours and hours of time to perfect my skills I was not going to progress to the level needed to actually make and sell decent quality parts. It is a hands-on process that takes a noobie tons of time to do it right and has several learning pitfalls like how much resin to catalyze, how much you can use before it becomes unworkable, precutting fabric for lay-up, setting up a work area large enough to layout and wet up the fabric, etc. I didn't have the time needed or the work space to do it in. Ultimately I found a full time shop that specializes in racecar composite fabrication and they make the all the parts FutoFab sells.

 

72wagun makes a good note with his list of tools; they are basically the minimum required to get the job done. Also location where you are doing the work needs to be very well ventilated. Polyester resin often gets used because the fumes released during curing are less objectionable. Epoxy fumes are even less tolerable. Don't do the work in your house! Or even in an attached garage. Do it in a building that can be left unoccupied, like a shed or dethatched (dethatched?, maybe in Europe, but detached is what I meant) garage or even outside. Everyone in your household will thank you for it.

 

I have the Fibreglast tutorials and IMO they are better than any book in understanding the physical part of making composite parts. You should also have a good book for reference. The tutorials are good at showing fabrication techniques and how tools are used. They are not good at referencing how different types of materials or tools work and when they should be used, this is where a good book is handy.

 

And YES there is a huge amount to explain, get those DVD's and you'll appreciate the frustration that can be avoided by watching them.

Edited July 23, 2009 by Dime Dave
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