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Old Oct 10, 2012, 08:56 AM
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Ljubljana Brnik, Slovenia
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Originally Posted by awmeade View Post
.. Superb master class as usual.
And that at warp 10 speed!!
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Old Oct 10, 2012, 10:30 AM
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Roodepoort, South Africa
Joined Aug 2007
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Canopy outline and mold

Hi all
So target for this weekend is to start the first side of the big mold, but for now its still finishing off the plug.
I am adding lots of detail so this build thread can show all the steps it takes to scratch build a high end composite sailplane.
just say if its boring and I will add less detail.

When making a mold , you have to constantly think in reverse/negative for example you knock a small hollow into the plug, this will be a bump in the mold easy to flat down and polish, but a high spot makes a hollow in the mold , very difficult to remedy, also canopy lips etc must have a slight angled or rounded shape so the mold will release.

Anyway moving along, the painted canopy was masked and taped and carefully cut just inside the black shape, this was later sanded exactly to the line, the canopy was removed with the hot wire, nice to see how well the centre line is still showing through.
After some modelling blade cutting, a step was created , this was rough sanded and then filled with a mix of resin/micro balloons and cabosil, to which I added a red pigment so its easy to see whats going on and keep any fresh epoxy of the pre polished white fuselage areas.

A few cycles of filling and shaping will now follow, before spraying this area.
cheers
Mike
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Old Oct 10, 2012, 01:22 PM
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DETAIL!
It's what seperates the men from the boy's.....Keep bringing it Mike, simply awsome!!! THANK YOU for taking the time!
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Old Oct 10, 2012, 04:18 PM
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Originally Posted by IHAVAWDY View Post
DETAIL!
It's what seperates the men from the boy's.....Keep bringing it Mike, simply awsome!!! THANK YOU for taking the time!
Agreed! We need the detail if we're going to emulate. You know way more than you realise.

One thing that would help me would be if you could explain (a) which resins/hardeners/additives and (b) what weight/weaves of cloths you typically use for different jobs. e.g. describe what you'd use to lay up a typical 1/4 scale fuselage right from gelcoat to finish. A good starting point would be to assume I am an idiot who knows nothing whatsoever.

Rog

Wait a minute.... I am an idiot who knows nothing whatsoever
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Old Oct 11, 2012, 03:46 AM
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Roodepoort, South Africa
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Hi Rog and other interested parties,
Once the molds are done and the first fuselage is being built I will show the materials involved, type of resin, cloth etc however people often have to use whats available, and often have favourites for resins etc, my composite shop sells 2 brands of resin one I just dont like yet they keep telling me lots of people do, so it might just be what works for you.
I know a lot of people use the West System but although its available here I have never used it, I like the pump dispenser idea though.
regards
Mike
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Old Oct 11, 2012, 04:05 AM
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Titus ZA's Avatar
South Africa, GP, Randburg
Joined Jul 2012
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Great work Mike. Agree with the others, the detail is awesome and is really appreciated.

I for one certainly find it very interesting and helps me understand the build process a lot better.

Cheers
T
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Old Oct 15, 2012, 03:54 AM
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Roodepoort, South Africa
Joined Aug 2007
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Some more steps

Hi All,

Time for a progress report, flying season is comming.
Last posts I had started several round of filling to get the canopy frame lip just right. Next was to spray a 2k primer and after it cured , wet sand it so I could prepare for a final coat. This all went reasonably well and to prevent any over spray on the now polished plug , I coated it with release wax except the areas to be sprayed, I also masked it carefully and using an airbrush gave it a coat of 2k white. Some small cleanups and it will be ready for molding, this was on the cards for sunday, but some intense preparation first.
Anyway some pics in sequence of the building.
cheers
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Old Oct 15, 2012, 04:35 AM
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Titus ZA's Avatar
South Africa, GP, Randburg
Joined Jul 2012
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Great stuff Mike. I really enjoy the master classes you provide with your builds. Fantastic

Cheers
T
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Old Oct 15, 2012, 06:39 AM
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Roodepoort, South Africa
Joined Aug 2007
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Ready for molding

Hi All

The last post basically finished of the construction and preparation of the Plug. For those that are following this thread is a comprehensive how to build a molded glider, this is what works for me , other methods work for other people. The beautifull shape you now see, is refered to as the "form" or shape, and once its been used it gets binned, sad really.

However some major work has been done on sunday and finished late, real late. so here are the steps, the mold was totally waxed, then a splitter board made of some melamine faced chipboard. this was maked and cut.
Next some sanding was required to get the plug to fit snugly in the splitter board. Lots of time was then spend getting it exactly midway, some of my little drilled marker holes, really helped with alignment. Spirit level confirmed accuracy and it was time to stick some glass beads on and fill the small gaps with modelling putty. I heat the Putty ,press it in place and later scrape it of flush with a mixing stick , so as not to mark the plug.
A good round of wax next followed by just the plug being polished off and buffed.
The now shiney plug half is wiped with a smooth layer of PVA red release agent.
Next post Gel coat time, anybody ever planning to do a build like this note this is decision time, once the gel coat goes on there is no stopping,
so you need
a. Plenty of time.
b. Plenty of resin
c. Plenty of Glass cloths
d. Plenty of gloves.
I started at 16-00 Hrs which was actually too late.
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Old Oct 15, 2012, 07:11 AM
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South Africa, GP, Randburg
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The amount of time and effort going into the build is staggering. But damn the results are going to epic!

Cheers
T
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Old Oct 15, 2012, 12:31 PM
yyz
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Looking good, Mike!
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Old Oct 15, 2012, 05:45 PM
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North Yorkshire UK, on a big hill facing the prevailing wind. Coincidence?
Joined Oct 2007
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This is such a useful insight Mike. I was peering at the photos on my little iPhone screen at lunchtime and couldn't wait to get back to my PC for a proper butchers!

It occurs to me that you'll probably have built this entire plane from scratch including plugs/mould-making etc quicker than it takes to order one and get it delivered from many of the European scale sailplane manufacturers. And cheaper too.
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Old Oct 16, 2012, 07:05 AM
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Invercargill, New Zealand
Joined Nov 2006
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Mike, can I ask a silly question?

Why do you make a dividing wall for each side instead of cutting the plug in half and just gluing each half to it's own base?

I have seen other threads do the same thing but can't remember if anyone explained why they used this technique. Can you give us your reasoning please, or have you always done it that way.

Thanks
Phillip C
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Old Oct 16, 2012, 09:01 AM
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fishs eddy n.y.
Joined Apr 2003
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Cuting the plug in half removes material and will not recreate the plugs profile cleanly no matter how carefull you are. You use the splitter to create the mold for one side, then remove the splitter and lay-up the opposite side. This will make for the smallest and smoothest mold line
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Old Oct 16, 2012, 09:15 AM
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Roodepoort, South Africa
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Quote:
Originally Posted by talonxracer View Post
Cuting the plug in half removes material and will not recreate the plugs profile cleanly no matter how carefull you are. You use the splitter to create the mold for one side, then remove the splitter and lay-up the opposite side. This will make for the smallest and smoothest mold line
Exactly great answer. That is also why the half round beads are added as locating keys so a perfect product every time.With perfect alignment.
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