Aug 30
Why Vacuum Bag Fiberglass Parts
posted by: Steve Jones in Fiberglass Tips & Trix on 08 30th, 2017 | | No Comments »

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 »

Aug 29
Tooling Gelcoat for a High Gloss Finish
posted by: Steve Jones in Fiberglass Tips & Trix on 08 29th, 2017 | | No Comments »

I’ve received some more questions about Fiberglass Mold Making Gelcoat and how to end up with a high gloss shiny finish.

Sonic 1 High Gloss

When constructing a mold for duplication of parts, there are several considerations that must be addressed.  The main reasons for using tooling gelcoat versus finishing gelcoat have to do with the hardness of the finish and the shine of the finish.

The finished surface of your mold should be abrasion resistant.  Polyester gelcoat is used for making tooling masters and molds where good gloss retention of the surface is of paramount importance.   A high gloss finish of the molds surface allows for easier release of your parts and thus extends the life of the mold. Read the rest of this entry »

Aug 26

Continuing with the helicopter build …

 

At this point, I can begin to produce profile drawings of the copter.  I definitely need to start with a view from the top and a view from the side.

Some of this is accomplished through artistic ability and some of it is what I consider cheating.  The model that I bought had these views in the painting instructions.  Based on the diameter of the fan blades, I figured that the fuselage should be about 40 inches from nose to tail.  I simply used my copier to blow these views up to the size that I need.  Then I drew in some details that were lost in the enlarging process.                            

 

The next step for me was to trace these profiles onto a base that I can use to build a plug.  I like to use 1/8 inch mahogany door skin for this.  I like mahogany because I can buy it at home depot for cheap and one sheet is more than enough material for a project like this. 

 

Next, I want to decide along which line to epoxy the primary horizontal shape to the vertical shape.  Having access to my plastic model makes this decision easy.  Angle aluminum stock helps me align the mahogany pieces with each other.  I use the angle aluminum to clamp the pieces to each other which assures reasonably accurate alignment of the parts.

                                                                      

In addition to angle aluminum making alignment of not so straight pieces easier, it also gives a pretty good 90 degree alignment of one piece to the other. 

 

At this point I need to make a statement concerning scale.  I am no artist, I know from the outset of a project like this that when I am done, anyone who knows anything about helicopters is going to look at this and say “Hey, that’s a Huey UH-1”.  That is good enough for me.  You can put as much talent and time as you wish into a project.  This is your prerogative.  I like to get a project’s detail to the point where I am satisfied.  I think that I am usually satisfied with my projects bearing a close resemblance to the vision that I started with.  That being said, nothing that I ever build will ever be completely scale (unless I happen to trip over a bucket of talent and patience).  That is all I have to say about that.

 

More Soon

 

Steve

 

Aug 14

I have a bit of experience working with silicon molds so as expected, the mold cures perfectly and peals easily from the parting plane and the plate.  Oddly enough, the mold removed some rusted paint flecks from the plate – oh well!

 

With a perfect mold I go ahead and load it up with a layer of gel coat and a few layers of resin and mat.  Since this process is covered completely in the fiberglass mold manuals I won’t do too much detail on this except for re-hashing the differences between a fiberglass mold and a silicon mold.

 

When using a silicon mold you have to make sure that the mold is sitting on a flat surface – if the surface is curved your mold will be curved as will your final parts.  The other major difference here is that the silicon needs no prior preparation before making parts.  Simply apply gel coat, fiberglass mat and resin into the mold – no need for mold release wax or PVA.

 

Mold ready for Gel Coat

 

With a layer of Gel Coat applied I can now lay a resin and mat.

 

Plate is removed from the mold about 24 hrs later and is ready for paint.

 

This was a very simple process and in the case of duplicating a flat object like this license plate was much easier than using a traditional fiberglass mold.  Please email me at srjones199@yahoo.com should you have any questions regarding plate duplication.

Aug 13

 

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

 

 

 

 

 
 

 

 

Aug 10

Ask any group of composites fabricators, and it is quickly apparent that everyone has encountered a problem with sticking a part in a new mold. It is just a fact of life in the open molding business, that on occasion a new mold will stick the initial part, regardless of the  Read the rest of this entry »

Aug 3
Joining Fiberglass Mold Part Halves
posted by: Steve Jones in Fiberglass Tips & Trix on 08 3rd, 2017 | | No Comments »

There are several ways to join fiberglass halves.  Fuselages, boat hulls and car bodies usually require joining of at least two pieces in order for the project to reach a point of completion.

With some applications, a sleeve can be built into the plug with will allow the second part to slip into which will result in a nice joint that can be epoxied together.  An application that comes to mind in this circumstance would be the deck of a model boat to the hull.  This technique needs to be planned well in advance since it requires Read the rest of this entry »