Making a Fiberglass Mold and Duplicating
- Thread starter oldog
- Start date
oldog
Been Around the Block
chrisf said:
That does not sound like "way" to much I don't think. We used resin from a 20 litre pail so can't say exactly how much was used. You have the mold and the final part to make. Be generous with resin on the mold!
The gel coat sounds like you have about twice what you will use.
BTW...I have decided to sell the mold if any one is interested. It would be a good money maker but I just don't have the time. I'll take $250.00 CAD (plus ship or pick up) for it. It's made 6 seats so far and each part popped out flawless.
seven54 said:
Maybe I'm missing something but why is it cheaper to buy a pre-made seat? Fiberglass stuff couldn't be anymore than $50 and Bondo is $7/can. Again, maybe I'm way off but it doesn't make sense to me to say it's cheaper to buy a $130-$250 seat when the prices I've found on the items needed (or what I perceive to be the items needed) is only $60 at most
rockcitycafe
I make things.
I think you might actually find that starting from scratch, it would be at least very close to a ready made seat... if you get a sheet of urethane foam, (not the flower stuff, but something 2" and flat for laminating), super77 to adhere it, your sandpaper grades, a can of dyna, (good) resin, not the auto store stuff, and a couple yards of 10 oz, you're probably up over $100
foam 4x8 sheet, home despot - $40
super77, home despot - $12
sandpaper, 60,120,220,400 - $15
1qt dyna gold - $13
2yds 10 oz s glass - $10
1qt 435 laminating resin - $20
-$110
you'll have stuff left over, but the initial layout is considerable... usually what happens is we start a project, and buy stuff as we go, so we don't really keep track of the complete cost
foam 4x8 sheet, home despot - $40
super77, home despot - $12
sandpaper, 60,120,220,400 - $15
1qt dyna gold - $13
2yds 10 oz s glass - $10
1qt 435 laminating resin - $20
-$110
you'll have stuff left over, but the initial layout is considerable... usually what happens is we start a project, and buy stuff as we go, so we don't really keep track of the complete cost
I got about that into mine... this is the last seat i will ever make, from now on i will hit up Rock City... i just wanted a specific shape for this build, and wanted the seat to fan out after the bump... i have achieved that but after about 35hrs into it... the seat is not even done as of yet, i still have one more glide coat and sanding... then i can prime for paint... would have been nice to just scuff and paint! NEXT TIME!
I guess if you're going for quality, then I can understand how it might get pricey. I feel that in the true spirit of cafe, I'll make mine out of things I have lying around...which is less likely to render pro looking results but I'm ok with that given my financial situation. 
Can you give me a list of supplies that i need to start producing seats?
From start to finish... I plan on making at least 10 of the same seat, so it would be easiest to buy supplies in bulk. also if you could give me links to your supplier, i would be forever grateful.
From start to finish... I plan on making at least 10 of the same seat, so it would be easiest to buy supplies in bulk. also if you could give me links to your supplier, i would be forever grateful.
cb750 cafebhoy
My cb750 cafe project with vintage rickman fairing
Love your bike and the Quality work your doing,where did you get those alloy/spoked rims? i'd like to get those for my 76 cb750koldog said:A friend of mine that builds fiberglass chemical spray tanks for helicopters showed me a process for making a mold for my seat/cowl and then producing a part (or several) from the mold. I thought I would post the procedure if others want to try it. If you have worked with fiberglass before,its fairly easy but time consuming. If you have not worked with fiberglass before, I would not recommend that you jump into a project like this. You'll need an air compressor and spray gun as well. Materials needed can be obtained from a composites dealer like "Composites Canada". Just google out composites dealers and you'll find more answers there. I won't go into huge detail about mixing hardener with resin or the different weights of fiberglass materials cause it's too damned complicated for me too...read the can...
One more note here. I'm sure that someone reading this will think "well there's a better or different way to do that". There probably is and feel free to add your comments. The guy that showed this procedure is well seasoned in the field and I was very impressed with what he knows. THANKS BOB!
Shown below is the seat/cowl that I made by using the spray foam wood and fiberglass technique. It's somewhat heavy so I'm going to make a mold from it and then make a lightweight part from the mold.
Prepping the part.
This is the part that I'm going to duplicate. It is important for you to know that I went through all the trouble here because I wanted to incorporate the original 1971 tail light. This part I will call the "plug". It was mounted to a flat board for a reason and you'll see why later. Important things to remember here are...the primer used here is epoxy primer (this primer has hardener that needs to be mixed in and applied with a spray gun), not acrylic which is the more commonly used primer for bodywork. The primer you get in a rattle can is acrylic and is not recommended. After you get a few coats of primer on the plug, dry sand and finally wet sand to remove as many imperfections as you can. The smoother you get the surface at this point...the less rework you will have to do when you pull a part from the mold.
Aside from the resin, hardener and fiberglass that you'll need, these products are essential for mold/part fabricating. Mold release wax and coverall film. The wax goes on first and is applied like any other...wax on, wax off. The coverall film shown at right is a very important step in the process. This stuff is applied with your spray gun. No mixing, just dump it in the gun and apply it generously. When dry it will form a very thin film or barrier that resin will not penetrate. So to recap, epoxy primer...sand...apply wax...apply film. The plug is now ready to cover with material.
Next step is to cover the plug with a product called "tooling gel". This stuff is a thick resin goop. Hardener is added and then applied with a brush. Tooling gel is used in the first layer of the mold because it offers a thick shell/layer that will allow you to re-tool or sand out any imperfections that may have existed on the original part. This layer took a couple of days to fully cure.
After the tooling gel has hardened, your fabric layers are ready to apply. It's a very good idea to have all of your layers preselected and precut. If you have worked with resin/hardener before, you are aware that when resin starts to "kick" things start happening real fast. A good technique for laying in the resin/fabric is to use a cheap disposable paint brush and "dab" all around to remove air bubbles. For this mold, I have chosen the 5 layers as shown. The first 2 layers are called "veil". Veil is very thin and is good for conforming to tight corners and curves. This will minimize any air pockets. I applied both layers at the same time and left it overnight. The 3rd and 4th layers are similar to veil but much thicker and was referred to as "chop". The 5th layer is beefier yet and is a combination of chop and weave.
Here is the mold after the tooling gel and 5 fabric layers. Ready to separate from the plug.
Excess material around the outer edges was ground off and the mold is separated from the plug. The mold is a solid 3/16" to 1/4". I will now be able to mass produce the same part should the need arise.
Now on to the second stage of the process...Making the original part.
Clean the mold with soap and water. The same process that was used to coat the plug with (wax and coverall film) is used to coat the mold with. After that has dried the first layer to go on is the "gel coat" layer. This is the white layer (shown below) and was sprayed in with a gun. (Oops, forgot to mention that a special gun is required here. About $60.00 from the composites store). you could brush it in with good results but will require 2-3 coats.
Once again, predetermine how many layers you want and precut all of them before you start. For my part, I'm using 5 layers of common fiberglass weave or cloth followed by a final 6th layer of chop.
After 6 layers of fabric/chop was applied, The final part is ready to be released from the mold. Note. the black section inside the hump was a piece of carbon fiber that we had laying around. It was not necessary to use it.
Below is the final result just pulled out of the mold. You can see the white color which is the gel coat. The stuff that is being peeled off is the "coverall film" that I mentioned earlier. It is easily washed off with soap and water.
And finally, here is the part after trimming, cutting the "glove box" hole, epoxying a piece in the bottom of the cowl, mounting system etc. I had to fabricate the aluminum piece to mount the tail light and license plate to. I still have to add the decals and a few coats of clear coat to finish completely. Oh yea...and a trip to the seat upolsterer.
I have added this pic as a tail light comparison with a stock 71 CB750 . I wanted the original 1971 Honda tail light to fit well with the seat/cowl.
cheers jimmy O
Staffy
It's not yours 'til you cut it up.
Great writeup there olddog. I've seen a few bits out there on making molds and plugs and blah blah but yours is good, simple and to the point. Well done.
What i'd really like to know is, can anyone point me in the direction of an article, youtube video, forum thread or any other place of information that has a writeup on the building of a full fairing or dustbin fairing. I've already decided to make the mold as a two piece and have most of the end work planned out, i'm just not quite sure how to go about making the plug. I'm considering building it up around the bike but that does seem a bit awkward and messy. Once the plug is made it's all smooth sailing from there. Ideas?
What i'd really like to know is, can anyone point me in the direction of an article, youtube video, forum thread or any other place of information that has a writeup on the building of a full fairing or dustbin fairing. I've already decided to make the mold as a two piece and have most of the end work planned out, i'm just not quite sure how to go about making the plug. I'm considering building it up around the bike but that does seem a bit awkward and messy. Once the plug is made it's all smooth sailing from there. Ideas?
HerrDeacon
Over 1,000 Posts
Staffy said:
Here's a writeup for modifying an existing fairing. You could do something similar to create a complete one from scratch.
http://racingcomposites.net/unt?id=684#7254
sharperdill
Been Around the Block
Everyone wants something unique and custom. When the plug, mold, and part are all finished it will be over the cost of a pre-made part. In the long run it may be worth it though. If the bike is laid down or in an accident, one can easily get the mold off the shelf and make a new part. When the bike is sold the mold could be sold to the new owner, saved for a future build, someone may ask for a similar part that could be made for them, or sold to someone else. The plug could also be saved to improve functionality, or modified to change the shape slightly.
