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Old Apr 23, 2007, 03:54 AM
Builder Pilot
Joined Mar 2007
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Constructing a wing mold for vac bagging

Im looking to move into vac bagging of wings, Ive had enough of foam and balsa.

I can carve a mold in Jellutong or in Ureal, but Im thinking that these materials wont last that long. On the other hand Ive recently used tooling gell to construct a fuselage mold and it has worked exceptionally well.

What Im planning to do is carve a mold in timber, sand and polish it, make a male mold from the female original, then do a reverse and make a female mold from tooling gell. This sounds like double handling to me!

So my question is, what are people using for vac bagging molds for wings. Theres aluminium but I dont have the facility to carve that, whereas I can mill pattern timber and ureal all day long...

Any thoughts?

Flynn
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Old Apr 23, 2007, 07:01 AM
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Christchurch, New Zealand
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You don't vac bag with a female mold. Foam core, spars and all, with glass over the top then into the bag.
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Old Apr 23, 2007, 05:29 PM
Builder Pilot
Joined Mar 2007
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Quote:
Originally Posted by tomahawkflier
You don't vac bag with a female mold. Foam core, spars and all, with glass over the top then into the bag.
Have you seen the rather good F5B wing construction video that is about? It shows a very nice way of Vac bagging into two female halves then joining the two together. Quite simple and straight forward. Question still is, what are people using for such molds. It is definitiely done.
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Old Apr 24, 2007, 01:58 AM
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No I haven't seen that video, Do you have a link at all?

As for timber I would use anything that has a high glue content as this is likely to be more stable than normal planks.
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Old Apr 24, 2007, 03:31 AM
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http://www.hotgliders.com/video/rw1f5b.mpeg 240Mo
or less quality
http://video.google.com/videoplay?do...wing+f5b&hl=en
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Old Apr 24, 2007, 06:53 AM
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Christchurch, New Zealand
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I love my broadband. Download video, Go for a smoke and make a cuppa, Watch video.

Cool vid, Have to try it out over the weekend. I usually do foam cores in Mylar then bag that but have also done female molds, Lay the glass and carbon in then just clamp them together.
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Old Apr 24, 2007, 09:42 AM
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Ward Hagaman's Avatar
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Quote:
I can mill pattern timber and ureal all day long...
If you have the facilities to CNC mill a wing, then you can mill a male wing half in MDF and then seal it and pull a fiberglass mold off it. If you have a good existing wing then you can make a parting tray and pull the mold straight from the wing.
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Old May 02, 2007, 06:37 AM
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Regensburg, Germany
Joined Apr 2003
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Hi Flynn!
I think you saw my threads about building full-molded F5B ships like Eisvogel, Raketenwurm, Twister, Flamingo or Flamingo II!
We always do cnc-cut positive plugs for our models!
For the real production molds we make the molds with special Aluminium- or Korund- filled epoxy resins over the plugs! Then several layers glass fabric and at the end poraver, which are glass bubbles with about 1-2 mm!
After curing some layers of glass are added on the backside of the mold and additionally a steel-frame could be added!
Here are two pictures of a mold for a new High-Speed electric model! I only say 14S Lipos and a special 10 KW motor !

Ciao, Marcus
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Old May 02, 2007, 10:17 AM
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The Germans RULE!
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Old May 04, 2007, 07:21 PM
Builder Pilot
Joined Mar 2007
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Quote:
Originally Posted by M. Koch
Hi Flynn!
I think you saw my threads about building full-molded F5B ships like Eisvogel, Raketenwurm, Twister, Flamingo or Flamingo II!
We always do cnc-cut positive plugs for our models!
For the real production molds we make the molds with special Aluminium- or Korund- filled epoxy resins over the plugs! Then several layers glass fabric and at the end poraver, which are glass bubbles with about 1-2 mm!
After curing some layers of glass are added on the backside of the mold and additionally a steel-frame could be added!
Here are two pictures of a mold for a new High-Speed electric model! I only say 14S Lipos and a special 10 KW motor !

Ciao, Marcus
Thankyou Marcus, yes It was your video of the Raketenwurm I was referring to. We were watching it and trying to deduce how the mould was assembled, given the ease with which you were able to lift it, and its thickness, it seemed unlikely to be aluminium, but I wouldnt have thought you would get an accurate part from a wooden mould. My guess was a composite. When you say special aluminium I assume you are referring to cast tool plate?

When you say you cut positive models, what do you use for your initial plug? do you use Ureal or some other tooling board? And do you cut top and bottom halves or a complete wing part as a positive plug?

We are at present moving towards vaccuum bagging and have used your example of carbon tow as spas already to great advantage.
I will post a thread of what we have done after the maiden test flight tomorrow.

Cheers
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Old May 04, 2007, 07:55 PM
Builder Pilot
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Marcus, on the subject of your video,

Some questions relating to the control surfaces.

We noticed that you glued the electric system into the wing. and then closed the halves together. I assume from that that if a servo dies, the wing is no good or you have to cut into it to get to the servo?

When you glue the servos in, you dont have the horns on them or were they turned down or enclosed in some way?

Also, you must cut the control surfaces into the trailing edge of the wing? Is the push rod mechanism assembled inside the wing or does it protrude through the surface?

In your video, you seem to be laying a thin strip of fabric at what appears to be the hinge point of the control surfaces. Is that kevlar for an embedded hinge?


Questions questions questions...

Thanks in advance
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Old May 08, 2007, 02:53 AM
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Regensburg, Germany
Joined Apr 2003
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Hi Flynn!
The video of the Raketenwurm is not mine! A plane build in such a way would last only one minute in flight with my flying style till it explodes ! The spar is too weak! My spar looks like the one like in my threads of the Raketenwurm and the Eisvogel! A lot of different layers of carbon and balsa not only foam with an glass or carbon sock!
The molds are really thick but really light weight due to the poraver which weighs only about 20 kg/100l!
The molds are made of spezial resins! The black one on the parting board is an extreme hard one, which you only can treat with diamond tools! Its good for using a sharp blade to remove the excessive glass at the leading edge! The grey one in the middle is a weaker one you can sand and polish to high gloss!
For our plugs we use tooling boards from Cibatool or so!
The green one is very expensive but you can polish it directly after milling! For the high speed-plane we used the brown one, which is a lot cheaper, but you have to paint it after milling before polishing to close the surface! We always cut the complete top and bottom plug with the parting board! See the thread of my colleague at :

http://www.rc-network.de/forum/showthread.php?t=64628

For the servos:
Normally the plane dies before the servo ! But if a servo dies you can easily cut the bottom surface and remove the servo, put a new in and close it again with the cutout or use servo covers as on our website:

http://www.MSC-Naabtal.de/ > MK-Modelle

I build in about 100 servos till now and had no problems! The servorhorns are still on and turned forward or back to glue the servos in!
The pushrod mechanism protudes through the surface! I use a small carbon cover to hide it!

The thin strip i use for the ingrated rudder hinge is peel of tissue (Nylon)! But you also can use kevlar for this purpose!

Ciao, Marcus
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Old Oct 24, 2007, 02:45 PM
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Joined Oct 2007
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hi Marcus

Nice models

could you tell me how you are painting the molds and which release agent you are using I have been try to spray my molds with acrylic 2 pack but can't get the part to release

Rick
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Last edited by 1highfly; Dec 17, 2007 at 12:43 PM.
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Old Oct 24, 2007, 04:52 PM
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Regensburg, Germany
Joined Apr 2003
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Hi Rick!
I use 2 component acrylic car paint for painting in the molds!
As release agent i use the wax from Sei▀ler which works really good but is a little bit hard to polish! For new molds i use ten layers with 6 hours drying between them! Then after the first releases only one or two layers!
A lot of here in Germany use the wax W 70 from R&G or Lange & Ritter! Easier to polish but not so resistent against scratching!

I hope this helps you a little!
Ciao, Marcus
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