RE: Fiberglass How to: Plug to Mold to Parts  
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RE: Fiberglass How to: Plug to Mold to Parts - 11/26/2007 5:29:35 PM   
dreadnaut



Posts: 625
Joined: 3/13/2004
From: Vista, CA, USA
Status: online 		After several months of drawing (fifteen minutes at a time on the lap top while riding the commuter train to work), I have finaly ''gotten phyical'', and started on my plug.

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< Message edited by dreadnaut -- 11/26/2007 5:56:37 PM >

(in reply to DocJones199)
       Post #: 26

RE: Fiberglass How to: Plug to Mold to Parts - 11/26/2007 5:33:43 PM   
dreadnaut



Posts: 625
Joined: 3/13/2004
From: Vista, CA, USA
Status: online 		More pictures.

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(in reply to dreadnaut)
       Post #: 27

RE: Fiberglass How to: Plug to Mold to Parts - 11/26/2007 5:37:42 PM   
dreadnaut



Posts: 625
Joined: 3/13/2004
From: Vista, CA, USA
Status: online 		One half of the plug is almost done. Planking is a pain, but the results are pretty good. Still a lot of sanding and filling to do.

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(in reply to dreadnaut)
       Post #: 28

RE: Fiberglass How to: Plug to Mold to Parts - 11/27/2007 6:44:22 AM   
DocJones199


 

Posts: 106
Joined: 8/28/2006
From: San Diego, CA, USA
Status: offline 		Looks Nice! Should make a great plug. Keep the pictures coming. I am going to post more on the copter project tomorrow.

(in reply to dreadnaut)
       Post #: 29

RE: Fiberglass How to: Plug to Mold to Parts - 11/28/2007 5:22:19 PM   
DocJones199


 

Posts: 106
Joined: 8/28/2006
From: San Diego, CA, USA
Status: offline 		After the resin cures, the surface can be rough sanded to knock down any loose fibers.

Here is another installment in this project.

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.


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(in reply to AvoidingExpert)
       Post #: 30

RE: Fiberglass How to: Plug to Mold to Parts - 11/28/2007 7:06:00 PM   
dreadnaut



Posts: 625
Joined: 3/13/2004
From: Vista, CA, USA
Status: online 		I agree about the complexity of indenting the windows. Been there, done that, pulled out a lot of hair over it.

I plan to do panel lines on mine. I had tried this before by scratching them into the surface. Never Again! I have heard of doing it by masking, then painting it so that the masking lines do the job. This might work for your windows too.

Rivets anyone?

(in reply to DocJones199)
       Post #: 31

RE: Fiberglass How to: Plug to Mold to Parts - 12/2/2007 3:36:40 AM   
senna12625



Posts: 2
Joined: 9/24/2002
From: Crooked River Ranch, OR, USA
Status: offline
quote:

Rivets anyone?


dreadnaut... rivets are a simple matter... albeit tedious and requiring a bit of practice. Most scale builders use Titebond III and a syringe. Mark the rivet schedule on the plug and daub a metered amount of glue (practice on scrap just before you do the plug will let you get the hang of the metering) at those schedule locations. Keeping the tip of the syringe as vertical as possible helps to make the glue meniscus more circular. Allow the glue to dry completely before primer and final paint. Voila...! Rivets!!!

senna12625

(in reply to dreadnaut)
       Post #: 32

RE: Fiberglass How to: Plug to Mold to Parts - 12/5/2007 3:40:49 PM   
funkworks



Posts: 417
Joined: 3/24/2003
From: Houston, TX, USA
Status: offline 		Oh no... i have a composite bug bite and the infection has almost reached my hands! haha!

great job on the plugs guys... one question though... Ive been kicking an idea around in my head. I want to build a 1/12 scale U-2. I plan on using an electric ducted fan set up and decided to make a composite fuse. This will be my first atempt at making a large fiberglass part so Ive been reading all I can get my hands on regarding fabrication. As far as making a plug, i noticed you guys are making your plug in 2 halves... Im assuming you will be making your moulds and parts separately then. In other places Ive read about making a single mold and then using a parting board to pull moulds from each side... have any of you guys tried this??

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(in reply to senna12625)
       Post #: 33

RE: Fiberglass How to: Plug to Mold to Parts - 12/5/2007 4:39:07 PM   
dreadnaut



Posts: 625
Joined: 3/13/2004
From: Vista, CA, USA
Status: online
quote:

ORIGINAL: funkworks

Oh no... i have a composite bug bite and the infection has almost reached my hands! haha!

I noticed you guys are making your plug in 2 halves... Im assuming you will be making your moulds and parts separately then. In other places Ive read about making a single mold and then using a parting board to pull moulds from each side... have any of you guys tried this??


That was my original plan. A one piece plug w/parting board is the usual way it is done. It is very difficult to get the pieces to match up properly if the plug is made out of separate pieces. I had an idea of how to do it, and get it to work, but as work is progressing on the plug I am running into snags in that plan and will probably join the halves together and use a parting board.

I will add pictures this weekend, but I have allignment pins in the halves of the plug. I was going to join them, and shape them. Then I was going to set the half with the alignment holes on a flat board, and layup half of the mold. Then I was going to place the half with the alignment pins on this, and lay up the other half of the mold.

The problem is that as I was planking the plug, the mating faces moved a little and do not lay perfectly flat against each other. I will probably glue them and clamp them while the glue dries. Next time I try this, I will try to make the profiles out of balsa so that they can be ''lap sanded'' flat after planking. I will also consider using flower shop foam instead of planking to reduce stress.

Notice also that I am not making separate plugs for the canopy and cowl. It is my intention to put the one piece plug in a parting board, then erect ''fences'' around the canopy and cowl. Lay up one side of the mold, remove it and ''fence'' the other side, lining up the fences with the ones on the first side. Lay up the second side, remove the fences, then lay up the canopy and cowl molds. This should ensure perfect fit of the parts.

(in reply to funkworks)
       Post #: 34

RE: Fiberglass How to: Plug to Mold to Parts - 12/5/2007 8:03:28 PM   
funkworks



Posts: 417
Joined: 3/24/2003
From: Houston, TX, USA
Status: offline 		thanks for the reply. Sorry about the problems youre having but it sounds like you got a handle on them now...

Im working on drawings for a U-2 with about an 8-9 foot span. I think I can use an electric set up with a 5" fan since I probably wont need that much power to get her in the air. Im starting to see EDF set ups with 10+lbs of thrust now. I plan on making molds for the whole plane including wings and fins. I want to mold the fuse sides and vert fin together if possible and was worried the long fuse would give me alignment problems if I tried to make the molds from separate plug halves... Im still gathering reference material so I can start on the drawings...

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...will I see all my wrecked planes when I get to Heaven? www.thefunkworks.com
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(in reply to dreadnaut)
       Post #: 35

RE: Fiberglass How to: Plug to Mold to Parts - 12/5/2007 8:33:38 PM   
ByLoudDesign



Posts: 257
Joined: 9/19/2005
From: Mesa, AZ, USA
Status: online 		Has any one ever used tooling wax sheets to get panel lines. It comes in various thicknesses and shapes with just a little practice to about any shape you wish. I have used them for depressed lettering, and to get a 12" clean edge on a deck mold for a 65" power boat to end the non-skid pattern. It is a one shot thing on the mold as the wax sometimes stays in the mold. but you could even press in rivet lines. I am thinking of doing this on my Goshawk. Make the plug 1/8" shy and overlasy the tooling wax sheet, put in rivet lines panel breaks and the like and then, carefully make a left and right mold of the paneled areas of the fuselage, turtle back and bottom panels. CST sells .007, .015, .02 and .062 thicknes.
http://www.cstsales.com/mold_making_supplies.html

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Projects on the board: Stinson SR-9, Orion P-3, Dornier DO-24,Canadair DC-4M2. Pilatus PC-9 Future Projects: Curtiss F11-C2, Osprey C-22, Canadair CL-415, Connie CL-121, Stinson Model A Gruman TBM,
bylouddesign.com "Scale without compromise"

(in reply to funkworks)
       Post #: 36

RE: Fiberglass How to: Plug to Mold to Parts - 12/12/2007 2:17:34 AM   
DocJones199


 

Posts: 106
Joined: 8/28/2006
From: San Diego, CA, USA
Status: offline 		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.

Spending time at this stage pays off in the end. Remember that every flaw that you are too lazy to work out of the plug at this point will have to be worked out on every piece you ever make with the final mold. In other words, you can fix a flaw once here, or you can fix it on every piece you ever make, maybe 100 times. Do yourself a favor – Fix It Now!

It is at this time of a plug build that I like to apply a nice thick coat of heavy fill automotive primer from my air gun. This primer will fill all of the remaining imperfections and it can be fine sanded, polished and prepared for the actual molding of the plug.

At this point, I believe that I am done with the helicopter plug. Now is the last time to stare at it and make sure it is right before molding. As you can see in the picture, the two halves of the plug are clamped together so that I can check the alignment. I have already painstakingly aligned the two halves but now I am reaching the point of no return. I spend a good bit of time looking at the alignment of the two halves and at the plug itself.


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(in reply to ByLoudDesign)
       Post #: 37

RE: Fiberglass How to: Plug to Mold to Parts - 12/12/2007 4:55:32 AM