Jun 24
Fiberglass Fender Build Part 4
posted by: Steve Jones in Uncategorized on 06 24th, 2017 | | No Comments »

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

www.fiberglassmoldmanual.com



Jun 18
Fiberglass Fenders
posted by: Steve Jones in Uncategorized on 06 18th, 2017 | | No Comments »

My most recent fiberglass project is a set of fenders for my beach cruiser. I know that there are already fenders available on the market, but I really didn’t care for them. In addition, I do enjoy building my own things when I can and it just so happened that this would be one of those projects.

To start with a project like this, I first needed to decide how I would get the shape and size of a fender that I was looking for. I want to have a fender with a round contour that would provide better coverage of the tire than what store bought fenders provide.

Initially I considered obtaining the right shape for the fenders by covering an inflated tire on the rim with foam weather stripping and then using that as the foundation on which to build a fender. The more I thought about this the more problems I was imagining.

Then one day I was walking by the 99 cent store and I saw those round foam pool toys that the kids use, I think they are called noodles. I knew right away that I was 99 cents away from the perfect base on which to build a plug for my fenders.

Once I got that foam roll home I pulled a wheel off my bike, removed the tire and proceeded to tape that foam roll to my rim. It fit the channel perfectly, and was the right height and width. I wanted my fender to cover about one half of the diameter of my tires so I used enough of the foam to accomplish this.

With the foam roll secured to the rim, I decided to cover the foam with a layer of masking tape. I did this to protect the rim and because I wasn’t entirely sure what the fiberglass resin would do to the foam, or if it would release cleanly from the foam.

At this point it is time to think about applying the fiberglass resin and mat. I began by building a simple cardboard stand to hold the rim steady while the materials are applied. Once I was happy with the stand I covered the entire rim and tape covered foam with PVA release agent.

Now I am ready to build a fender plug.

Happy Glassing


Steve

www.fiberglassmoldmanual.com



Jun 12
Fiberglass Molds – Multipiece Benefits
posted by: Steve Jones in Uncategorized on 06 12th, 2017 | | No Comments »

I just finished building a new mold for a 1/10 scale radio controlled car. One of the great things about making radio controlled car bodies out of fiberglass is the detail and the undercuts that can be formed using multi-piece molds. The realism is much greater than that which can be found in a vacuum formed body.

Multi-piece molds are always necessary for building three dimensional objects – whether those objects are hobby related or not. With the exception of very simple molds, multi-piece molds are almost always required or at least preferable. The obvious reasons for the use of a multi-piece mold are driven by the ease of extracting your parts from that mold. Molds that are very deep are difficult to lay-up parts in and can be very difficult to pull your parts out of.

The draft angle of your plug is a major determining factor that will determine the need for a multi-piece mold. Smaller parts may require no draft angle while larger parts that are deeper than 12 inches will require a draft angle of up to 5 degrees.

Automotive parts other than hood scoops, fender flairs, spoilers, etc are often done with one piece molds. Larger parts, such as doors, hoods, entire bodies and the like are almost always done as two piece molds.

I was looking at my first and main Fiberglass Mold Manual in which I outline the procedures for building a simple one piece mold. The funny thing about this manual is that the project that I follow in this manual ultimately required 3 separate one piece molds. A project requiring 3 separate one piece molds can also be labeled as a multi-piece mold.

Multi-piece molds do give many benefits to the builder, but there are a few drawbacks. Multi-piece molds do produce a flash line that must be dealt with. Flash lines require filling, sanding and refinishing. Flash lines are created by imperfections in the edge of the mold and in the general alignment of the pieces of the mold. In my opinion flash lines are a minor trade off for the many benefits of a multi-piece mold.

Happy Glassing


Steve

www.fiberglassmoldmanual.com

Jun 9
Fiberglass Mold Release Agents
posted by: Steve Jones in Uncategorized on 06 9th, 2017 | | 1 Comment »

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

Happy Glassing


Steve

www.fiberglassmoldmanual.com

Jun 7
Fiberglass Mold Construction Part 9
posted by: Steve Jones in Uncategorized on 06 7th, 2017 | | No Comments »

I let this mold cure on the plug for almost a week before demolding. This mold popped off its parting board with little effort. Likewise, the mold separated from the plugs with ease. The process for removing the mold from the plug is simple. I use a half dozed small plastic putty knives that I insert between the mold and the parting plane.

Once I have one putty knife between the mold and the parting plane, I simply insert another putty knife at the edge of the separation that occurred as a result of the first knife. This is repeated time and time again as I work my way around the perimeter of the mold. Once you get started, this is an easy process.

At this point the mold is inspected for any flaws, repaired and then prepped for its first part pulls.

Making parts with this mold is very similar to making the mold itself. I begin by applying five coats of mold release wax to the inside of the mold. Once the mold is waxed, I can apply a coat of PVA to the inside of the mold with my spray gun. After the PVA dries, I can do my first parts lay-up. This is part that I really enjoy – I am very close to seeing the results of my efforts and planning.

Happy Glassing


Steve

www.fiberglassmoldmanual.com

May 28
Fiberglass Finishing
posted by: Steve Jones in Uncategorized on 05 28th, 2017 | | No Comments »

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 a nice fiberglass finish requires a little preparation and a little improvising.

Obtaining a nice smooth finish can be obtained on a consistent basis when using a mold to produce your parts. Even so, thought and preparation are still necessary. A nice thick gelcoat layer that is covered with a layer of veil that is then covered with a layer of chopped mat will create an end product with a nice finish and no pattern transfer to the final product. The gelcoat layer should be thick enough to allow light sanding without getting into the mat.

When repairing a broken piece of fiberglass, getting a smooth finish takes a little more work. On painted surfaces, I like to remove the paint around the damaged area with sandpaper. Depending on the size of the damaged area, I like to remove enough paint around the damaged area to give me a couple inches of working room. I will then tape over the finished side of the damaged area and apply my repair to the backside of the repair.

Once the resin has cured, I remove the tape and access the exterior of my repair. If the repair is flush or depressed, I will smooth over the surface with either bondo, finishing putty or a thick mixture of resin and cabosil. Once this has cured, I will sand it smooth, primer it, inspect it and go from there. If there are defects in the surface, I will refill them with the medium that I find appropriate and repeat the sanding, inspecting and primering that I had done before. This process continues until the finish is right.

You should not be afraid to sand fiberglass. If you happen to sand it to the point that you expose glass fibers, clip the long ones off and brush more catalyzed resin on. Let the resin cure and re-sand. You may have to repeat this process several times to get your repair right. If your sanding continues to expose fibers, you may want to cut the surface down an 1/8 of an inch or so and fill over the surface with either gelcoat, resin mixed with cabosil or even bondo. Once this has cured you will have plenty of room to shape and sand without exposing fibers.

The bottom line is that many people feel as though the final outer surface of a fiberglass repair must be fiberglass. This is nice if possible, but there is nothing wrong with smoothing over the outer skin of a fiberglass repair with gelcoat, bondo, resin mixed with cabosil or body putty.

Fiberglass Shooting Star Body (Speed Racer) For RC Car

Happy Glassing


Steve

www.fiberglassmoldmanual.com

May 25

 

To begin laying up a fender, I mix about a half a cup of gelcoat with the recommended amount of hardener.  Once this is thoroughly mixed, I use a disposable chip brush to paint the gelcoat into the mold.  I try to get a heavy layer of consistent thickness.  This gelcoat needs to cure to a tackiness before I apply the fiberglass mat and resin.  Usually this takes about 45 minutes. 

 

While I am waiting for the gelcoat to cure a bit, I begin to prepare for the next steps of this process by tearing 1 ½ ounce mat into small pieces that will be easy to lay into my mold.  Since this is a fender, it has compound curves – one that goes side to side and one that goes front to back.  In my experience, smaller pieces of mat are easier to work with in a mold like this.  Just FYI, my pieces of mat are approximately 4” X 4”.

 

Now that the gelcoat has cured to a tack, I mix an 8 ounce cup of resin and catalyst (as directed by the manufacturer) and begin to work my way around the inside of the mold with resin and mat.  I soak a chip brush with resin and use it to blot the resin onto the mat over my freshly applied gelcoat.  Since the gelcoat is still tacky to the touch, it holds the mat in place while I soak it with resin.  I work my way from one end of the fender to the other and then back again (two layers of mat and resin) being careful to make sure that the mat has no air trapped underneath and that the mat overhangs the mold by an inch or so.

 

Once this mat and resin cure to a gel-like state (this takes about ½ hour of 45 minutes) you can safely trim the overhanging extra mat with a razor knife.  If the resin pulls or is too sticky to cut, check back in another 15 minutes and try it again.  This is the best way to clean up your parts of excess fiberglass.

 

After trimming, I allow the part to sit in the mold for a day or so to let it fully cure.  Once fully cured, I pop the part from the mold using a couple of plastic putty spreaders.  I simply use my fingers to pick at the part until I get slight separation from the mold then I push the plastic spreader between the part and the mold and work my way around until the part pops out.  Since I used adequate release wax and two coats of PVA, this part easily separated from the mold.  One fender down, one to go!  

My New Beach Cruiser With Fiberglass Fenders Installed

My New Beach Cruiser With Fiberglass Fenders Installed

 

 

 

 

 
 

 

 

May 14
Fiberglass Copter Build Part 8
posted by: Steve Jones in Uncategorized on 05 14th, 2017 | | No Comments »

I begin by applying black tooling gelcoat with a dump gun at about 80 psi. I make sure to keep the gun close to my work because gelcoat makes a huge mess if it gets on something other than your project. I lay down a nice thick layer of gelcoat making sure to get good coverage around the base where the plug meets the board.

Once the plug is covered with gelcoat, I let it cure to a tack. I did this project on a nice hot San Diego day so it cured to a tack in about 45 minutes.

At this step I used a different approach than I am used to. I came into possession of a large roll of veil that I decided to use in the corners and angles of the mold. In the past I have always used a combination of cabosil and resin. I found the veil easy to work with, especially when pushing it into corners with a chip brush. With the veil in place, I proceed to build the mold with three layers of 1 ½ ounce chopped mat.

I begin applying the chopped mat by brushing a nice thick layer of catalyzed resin over the area of the plug that I am working on. Then I place a piece of mat that has been pulled off of my roll and lay it on the plug. I like to keep the pieces fairly small on a project like this, no larger than 6 inches square. Pulling the mat apart will leave many loose fibers that will help the strength of my final product once it has cured. When applying the mat, I like to overlap my pieces by about 20% and build a nice flange around the base of the plug.

Happy Glassing


Steve

www.fiberglassmoldmanual.com

May 4
Building Fiberglass Models Part 5
posted by: Steve Jones in Uncategorized on 05 4th, 2017 | | No Comments »

At this point, I will start to fiberglass over the foam. I have decided to hold off on forming in the turbine housing and the top of the tail section. My thoughts are that I would like to have something to place clamps on so I can check the alignment of the body halves during this next phase of the plug build.

I begin the fiberglassing process by using a brush (a cheap disposable brush is best) to cover the foam with catalyzed resin. I have decided that initially I will only do the main part of the fuselage and I will do the tail later. Once the foam has been soaked with a coat of resin, I can start applying chopped mat over the foam.

Work the mat onto the surface of the fuselage. It must lay as flat as you can get it. I have spent a bit of time forming this fuselage. I don’t want to get sloppy at this point. Laying fiberglass mat over the foam will provide a nice hard surface for the next step of this build which will be the bondo application. Once the fiberglass has been laid, the only thing to do is let it cure. It is time to put the chemicals away and clean up.

After the resin cures, the surface can be rough sanded to knock down any loose fibers.

Once the surface of the plug has been cleaned up with coarse sandpaper, I can examine the pieces and decide where to go with this plug from this point. I began this plug imagining depressions with well defined edges where the windows should be. At this point, it seems that following this course will make this plug much more difficult to complete. This being the case, I have decided that the next phase of this plug build will see the side windows smoothed flush. Flush windows will make building the mold and pulling parts from the mold much easier.

After the rough sanding is complete, I can apply bondo to smooth out the surface of the helicopter. I only mix enough bondo that I can use in a few minutes. By mixing a little less bondo than I can comfortably work with, I am able to be much more efficient from a number of perspectives. First of all, I have time to work the bondo on the surface since I am not rushed by the thought of unused bondo curing on my mixing surface. Secondly, when I mix too much bondo, I end up just piling it on only to have to remove most of it later on because of sloppy application.

Happy Glassing


Steve

www.fiberglassmoldmanual.com

Apr 28
Fiberglass Model Build – The Final Product!!!
posted by: Steve Jones in Uncategorized on 04 28th, 2017 | | No Comments »

After the PVA dries, I brush in a nice healthy layer of gelcoat. Once the gelcoat cures to a tack, I begin to lay resin and mat. Since this is a fairly large item, I do two layers of 1 ½ ounce mat to provide a little strength without the part getting too heavy.

Once this fiberglass gels, I trim the excess with a sharp utility knife and let the mold cure to its full hardness. Since I will be joining the two halves of the helicopter, I don’t pull the pieces from the mold until I am ready to join them. This is because any shrinkage / warping will wreak havoc with my attempts to line up the two halves of this copter during the joining process.

Removing the parts from this mold is done just as described previously. I slip a putty knife between the mold and the part. Using several putty knives, I work the perimeter of the mold to loosen the piece. I progressively dig the putty knives deeper and deeper until my parts pop out of the mold.

Once the parts have been removed, I can clean / flatten the edges with a sanding block, align the two halves and use masking tape to hold them together and seal the seam. To finish this project I catalyze about 4 oz of resin and pour it along the inside of the seam that divides the two halves of this copter. The resin is poured into the fuselage through the opening where the exhaust port would be. I then tilt the copter forward and backward to cover the seam with resin. Once this cures, I can remove the tape and deal with filling any defects in the seam.

With this post, the helicopter project is done.

Happy Glassing


Steve

Fiberglass Huey Model

Fiberglass Huey Model

www.fiberglassmoldmanual.com

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