To prepare this model for the molding process, the first thing I need to do is mount it onto a parting plane. My inclination is to use some nasty looking piece of scrap 1/8 inch piece of press board that I have laying around. However, since I am going to take a bunch of pictures of this process and turn it into yet another fiberglass instruction manual for my current series, I decided to use a nice looking piece of wood from the local Home Depot … Read the rest of this entry »
When I first started working with fiberglass, I found it a fascinating yet frustrating material. While I enjoyed the fact that it was water proof and could be formed into any shape, I was often frustrated by my attempts to finish it in a way that would make my final product look presentable. Over the years I have come to the realization that Read the rest of this entry »
I have written blog entries in the past in which I have shared my experiences with new techniques and new products that are available for construction with composites. This is another one of those.
Whenever I am building the surface of a part that is being made of chopped mat, I end up with a fairly course surface that will need a final finishing.
I have employed various means to smooth out a fiberglass surface. Some of these finishing methods include the following: Read the rest of this entry »
At this stage of the build, the project gets a little tedious. Sand, prime and fill – sand, prime and fill. This process is repeated over and over until the surface is smooth and the two halves join in the center with a nice smooth border.
Spending time at this stage pays off in the end. Like I always say, every flaw that you are too lazy to work out of the plug at this point will Read the rest of this entry »
Its funny how we do things that we think are not only the right way but the only way only to find out later that there are better ways. Years ago, when I first discovered the use of dry foam, ( No I had no experience with surf boards), as a medium for plug construction, I thought that I had found the perfect plug building material. Read the rest of this entry »
I don’t know about you guys, but sometimes my work gets in the way of my projects – I hate it when that happens! Anyway, I had not taken photos of my sketches for this project at the time of my last post. I will post more pictures with more text this weekend.
In order to mount this plug to a parting plane, I am going to need a flexible piece of material, something that will easily follow the curve of my fender plug without causing distortion. What I ended up with is a six-inch wide piece of mahogany door skin that will act as the parting plane that will be mounted to a one inch thick, six inch wide by 36 inch long piece of MDF.
To mount the fender plug to the door skin, I used some bondo to stick wooden blocks to the inside of the fender plug and then I screwed the mahogany to the blocks. I then used my hot glue gun to attach the ends of my newly mounted plug and parting plane to the MDF. Just for visual reference, what I ended up with was similar looking to the Dunlop walk-over bridges that you see crossing over the track at automotive races.
With the plug mounted, I am ready to start the molding process. As with all plug molds, I begin by filling any and all gaps that exist between the plug and the parting plane with clay. In this case, I had no gaps so I went straight for the mold release wax. Since my parting plane is a very porous mahogany, I used 5 full coats of wax to ensure that the chances of my plug sticking to the final mold would be minimal. I allow the wax to completely dry and then apply two coats of PVA mold release and allow it to dry.
This plug is now ready for molding. Anyone who has read any of my prior blog projects knows the process that I am about to explain. I begin by mixing enough black tooling gelcoat to brush a nice thick coat over the surface of my plug and parting plane. Once this cures to a tack, I apply three layers of 1 ½ ounce fiberglass matt and fiberglass resin.
When applying the fiberglass mat and resin, I am always careful to make sure that the material has no air bubbles trapped inside. This is especially important with the corners. In this case the critical area is where the plug meets the parting plane. Remember, hurrying through this portion of the mold build will result in defects in your final product. The more defects that you have – the more repairs you will have to make to your parts.
Happy Glassing
Steve
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Since my last post I have been chomping at the bit to get this hull to the point of starting the fiberglass mold. I have not been very successful. This hull has two sets of strakes on it that I have just had a tough time getting right. The first ones that I attached were too wide and too deep. The set that is attached now is much closer to scale.
When I do build the fiberglass mold for this hull … Read the rest of this entry »
One way to make light, strong and clean parts is through a technique called vacuum bagging. In general, parts made with vacuum bagging techniques show better strength and stiffness than simple molding lay-ups and they are smoother to the touch. The strength and stiffness of vacuum bagged parts obviously comes from Read the rest of this entry »
I have received many questions from those who purchased my manual set regarding mold releases. Especially when preparing the plug. The bulk of the questions seem to come from the use of PVA as a mold release.
Let me start by saying that I like and prefer to use PVA (polyvinyl alcohol) mold release at all stages of my projects – both to release the plug and my parts. I like the security it provides. I have never had a part or a plug get stuck in mold when I have used PVA.
The problem that some people have with PVA is the orange peel appearance that is left on the inner surface of the mold after you have separated the plug from the mold. More often than not this orange peel is visible but can’t be detected by touch. Unfortunately, sometimes the orange peel appearance can transfer to the parts that you will make with your mold.
For me, this orange peel appearance has never been a problem because of the type of projects that I like to build. If you are planning on painting your finished pieces, as I do, the orange peel look of the gelcoat is of no concern. You will be at the least priming and painting the parts so you will never see the gelcoat. Even with R/C boat hulls that I have made I always plan on painting them for the final finish.
If you want to produce finished parts that have that glowing perfect gelcoat surface you will need to take a different approach with the plug. You will have to rely on mold release wax alone to allow for the separation of the plug from the mold. With this approach, you will want to follow the waxing procedures outlined in my manual. Use great care with applying and polishing the plug.
Another consideration with an approach that doesn’t involve the use of PVA is that more than likely you will damage (if not destroy) your plug when you de-mold. This is another reason why I like using PVA – I work hard on the plugs that I build and I like to save them.
I hope that this helps with your PVA questions
1/10 Scale Radio Controlled Fiberglass Mach 5
Happy Glassing
Steve
5 Fiberglass "How To" Manuals
