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Old Sep 13, 2013, 11:56 PM
making my own planes...
decones's Avatar
Curitiba - Brazil
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Blank 40

I've been building mouldies hotliners for some time, actually copying a raketenwurm for the last few years, now I decide to put myself into a new project, my first one from scratch, drawing, milling, sanding, building and all the other stuff related. I chose a plank cause it's cool for dsing, it's small (easy to work, develop and handle, my shed it's so small ), I can use for slope flying and the most important fact, it flys in poor winds that we have here in Brazil, so I won't need a big day to have fun with that toy.
It calls Blank 40, the first Brazillian molded plank
Basically I use the poky 40 dimentions as reference, chose a standart DS foil PW51 and use Tim's technique milling MDF and hand working the parts. For now I only had the wing moulds done, next step will be fuse and canopy. Nothing new but this is prestine method and more patience work than you could imagine

btw - include this one on the crunchie planks as well

André
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Last edited by decones; Sep 14, 2013 at 12:09 AM.
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Old Sep 14, 2013, 02:09 AM
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That's unreal Andre! I wish I had the know how to do all that cad/cam stuff!
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Old Sep 14, 2013, 05:36 AM
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What release agent did you use on the plugs?
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Old Sep 14, 2013, 08:56 AM
making my own planes...
decones's Avatar
Curitiba - Brazil
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Wax, wax and..... Humm, wax!!! :-)
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Old Sep 14, 2013, 09:00 AM
making my own planes...
decones's Avatar
Curitiba - Brazil
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Quote:
Originally Posted by josh18 View Post
That's unreal Andre! I wish I had the know how to do all that cad/cam stuff!
I thought you had, who draw your scorcher???
In fact I use solidworks, belive or not I learned all googling on the web
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Old Sep 14, 2013, 07:03 PM
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Haha, scorcher is all by hand baby!
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Old Sep 16, 2013, 08:19 PM
making my own planes...
decones's Avatar
Curitiba - Brazil
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Quote:
Originally Posted by josh18 View Post
Haha, scorcher is all by hand baby!

unbelievable, my hero!!!

I have here a 2m plane designed for me, draw almost finished, similar lines to scorcher but with special airfoil by DS developers (secret), x tail, full house wing.... well I just need a 30hrs day to let my planes come to life
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Old Sep 18, 2013, 06:36 AM
AvB
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Hey Andre, that is brilliant! I am acutely interested! I am gradually learning Rhino 3D and hope to be able to draw parts up one day.

What's the story with the trough all around the LE and tips? Do you do that to make it easier to sand, and then fill it level with the flange when you've done the polishing? I couldn't tell from the photos whether it was filled level. Since I'm getting a CNC machine sometime soon I am very interested in your method.

Scratcho moulds were from a vac bagged hand shaped plug, like Josh's Scorcher. Josh really got stuck in up to the armpits with epoxy to make the Scorcher in record time, and the finish on the wings looks absolutely gorgeous.
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Old Sep 18, 2013, 06:41 AM
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[QUOTE
I have here a 2m plane designed for me, draw almost finished, similar lines to scorcher but with special airfoil by DS developers (secret), x tail, full house wing.... well I just need a 30hrs day to let my planes come to life [/QUOTE]

That sounds like a rocket Andre- Cant wait to see it!
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Old Sep 18, 2013, 03:17 PM
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The Trough allows accurate machining of the LE and TE. The cutter runs into it. Allows a larger cutting bit to be used too, hence a better finish and faster machining time
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Old Sep 18, 2013, 10:26 PM
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I think the trailing edge trough is more so you know exactly where the trailing edge should be. Apparently it's really difficult without it because of the way the foil blends to the flat mdf.
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Old Sep 18, 2013, 10:38 PM
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Yep, that's why you raise that part in when making a mold from the MDF plug to form the TE trough in the mold
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Old Sep 19, 2013, 04:24 AM
AvB
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Yes I understand the TE trough and used it in the Scratcho wing moulds, and have to say it would be very hard to make a wing without it. When I was making a big stab mould (Stratos) I took a shortcut and didn't do the TE trough and later regretted it, and retro-cut a bodgy one with a dremel!

But in the pics above the trough is around the positive plug shape - I understand that it would help with machining, but how do you get it filled really level so that part of the flange is a perfect match with the one for the other side plug??

Interestingly when Shane CNC cut negative moulds in Corian, they made a small lip sticking up all around the tips and LE. Then once it's cut, they carefully block sanded the lip off level with the rest of the flange, which gives a really square sharp edge to the lip, better than you can achieve with the machining.
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Old Sep 19, 2013, 06:41 AM
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Sean (I think) explained it to me really well in the new deepend thread. The trough in the mdf plug is not for the trailing edge trough so much, but more to see where the trailing edge is exactly. If you have a curved trailing edge it would be almost impossible to see where to put the trailing edge trough to make the mould. When sanding with out the trough on the TE you would lose that location of the TE even more. I think the trough is filled with clay or splooge etc. If you fill it slightly lower than the rest of the mdf surface the finished mould will have that lip on it so you can sand it off later, and the perfection of the clay filler will not be as important as well I would think.
Heres a bit out of the deepend thread:

The TE trench will have a 15mm semi-flexible tube pushed into it prior to moulding to make the TE trench on the mould. I didn't put a TE trench on the stabiliser model (see earlier in this thread) and found it very hard to see where the TE was supposed to be when it came time to make the mould - the airfoil blends into the parting plane and you just can't see where it should be, especially with the curved TEs on this design.

Cheers
Josh
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Old Sep 19, 2013, 07:32 AM
AvB
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Ah, yes, thanks Josh. (and Sean).
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