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Old Oct 22, 2015, 09:30 PM
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Wing plugs from Hardboard & Elmers?

After several attempts, I had no luck with 1/4" or 1/2" MDF, the only spray adhesives that work cost $15.00/can & I'm trying to glue 6 layers together, contrator's wood glues flat just don't work, & are way to sensitive to temp./humidty... The only glue that simply has worked is Elmer's Glue-all & 1/8" hardiboard. The Elmer's sets up fast & is stuck on the hardiboard like herpes! It took about 6 hours to cut, glue, trim, & rough contour sanding. Tomorrow I'll start finish sanding & blending using some airfoil templates for every station along the wing (about every 2").

One question, I'm concerned, once I start gel coating it may cause the elmer's to turn loose. I thought about soaking the seams with CA but afraid the gel coat would fisheye on the CA... Maybe I'm worrying abour nothing, dunno.? Can someone chime in with some free advice? Thanks

Wormwood
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Old Oct 23, 2015, 12:53 AM
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This is the thread for my glider build using MDF plugs for the flying surfaces:

http://www.rcgroups.com/forums/showp...&postcount=161

I avoided joins in the tapered faces of the plugs at all cost, as it interferes with the hand shaping and sanding. You will see in the thread, that I joined slabs of MDF at the parting line only. I also used some 200 gsm carbon fabric in this parting line join, mainly to support the thin sharp trailing edge.
The method works well, but is is a lot of work.
There is another thread started by Kevin Bennett. It is he that put me onto the system.
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Old Oct 23, 2015, 07:44 AM
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Thats a method dating back to when they made canoes out of a single wooden log, they do it differently now..
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Old Oct 23, 2015, 12:11 PM
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Quote:
Originally Posted by Jim.Thompson View Post
This is the thread for my glider build using MDF plugs for the flying surfaces:

http://www.rcgroups.com/forums/showp...&postcount=161

I avoided joins in the tapered faces of the plugs at all cost, as it interferes with the hand shaping and sanding. You will see in the thread, that I joined slabs of MDF at the parting line only. I also used some 200 gsm carbon fabric in this parting line join, mainly to support the thin sharp trailing edge.
The method works well, but is is a lot of work.
There is another thread started by Kevin Bennett. It is he that put me onto the system.

Thank you for the link!
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Old Oct 23, 2015, 04:50 PM
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Very nicely done though.
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Old Oct 23, 2015, 04:53 PM
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Very nicely done though.
Thanks for that concession Hallo.
Almost as good as modern "canoe" don't you think?

Jim,
who has no access to, or room/budget for, a CNC.
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Old Oct 23, 2015, 05:16 PM
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One question, I'm concerned, once I start gel coating it may cause the elmer's to turn loose. I thought about soaking the seams with CA but afraid the gel coat would fisheye on the CA... Maybe I'm worrying abour nothing, dunno.? Can someone chime in with some free advice? Thanks

Wormwood
How are you going to surface finish your plugs?? Hope you aren't going to try and coat the hardiboard with polyester gel coat?? Most polyesters have much larger shrinkage and might bow your pretty new wing unless you do both sides at once. I recommend using a thin laminating epoxy( I would still do both sides at the same time for the first coat. ) Why the resistance to using epoxy for laminating the boards together????
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Old Oct 23, 2015, 06:50 PM
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How are you going to surface finish your plugs?? Hope you aren't going to try and coat the hardiboard with polyester gel coat?? Most polyesters have much larger shrinkage and might bow your pretty new wing unless you do both sides at once. I recommend using a thin laminating epoxy( I would still do both sides at the same time for the first coat. ) Why the resistance to using epoxy for laminating the boards together????
Absolutely!
See my post regarding the epoxy treatment of the plugs for my Entropy in the thread. Shortly after the post linked to above.
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Old Oct 23, 2015, 09:23 PM
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Jim,
who has no access to, or room/budget for, a CNC.
Alright Jim,

How many copyes of this project are you going to make? It's kinda funny beause when ever it's new year -I always wants to make something new.. not what I did last year.
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Old Oct 24, 2015, 02:16 AM
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Alright Jim,

How many copyes of this project are you going to make? It's kinda funny beause when ever it's new year -I always wants to make something new.. not what I did last year.
I have a bit of the same syndrome.
However, I have a few flying buddies interested in my Entropy. Two firm at this stage. And I will have two of them myself; one light and one heavy.
And I may even make a cranked joiner for a slight dihedral to make a (third) thermal version.
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Old Oct 24, 2015, 07:32 AM
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Well, thats what you are saying if you want to make a wing mold Jim;

-I'm not going to progress to anything else, I will just continue making this particular model over and over again for years and years, and it will be fun because my plane is going to be perfect, it will be perfect because I have such great experience in designing model gliders, -there will simply never be any need to make another plane after this, this will be an everlasting success.

Thats brave Jim..
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Old Oct 24, 2015, 08:02 AM
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One thing I have learned from participating in different competitions is that it's wise to choose the class you're going to enter -that is if you want to keep your panties dry.

If you want to make a hollow molded glider - this is what I will compare your work to; http://www.baudismodel.com/
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Old Oct 24, 2015, 09:20 AM
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Originally Posted by Rudy F View Post
How are you going to surface finish your plugs?? Hope you aren't going to try and coat the hardiboard with polyester gel coat?? Most polyesters have much larger shrinkage and might bow your pretty new wing unless you do both sides at once. I recommend using a thin laminating epoxy( I would still do both sides at the same time for the first coat. ) Why the resistance to using epoxy for laminating the boards together????
Honestly, yes, I was gonna try braving it with some Evercoat in a spray rig... My concern with the epoxy is with all the feathered laminates exposed, it's gonna swell along the feathered edges. I had also consider a tooling epoxy would do the same thing.

This hardiboard is behaving differently than MDF & for the better I'll say. I bought a bundle of them since they were cheap & have been impressed ever since. I got two test wings that I sanded, I'll try one with straight EZ-LAM, a thin sealing coat & the other with the gel coat. I'll apply it in the garage, then bring into the house for cure, due to the humidity. So we'll see what happens.

Thanks for all the input guys! These forums really make the whole effort, worth it.

Nietzsche
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Old Oct 24, 2015, 09:26 AM
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I think its realistic to asume that if you wanted to make a glider like that - with the same expertice.. you would end up with a price tag at about 4 times the price of a ready made model shipped to you.

Most brave attempts I have seen at trying to do this takes perhaps 2-3 years when they do it properly - unless its a team, and by the time you have just started.. mr. baudis have made perhaps a couple of steps further in to the evolution, - and you are left behind with yesterdays news at 4 times the cost plus labour.. and still a long way to go.
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Old Oct 24, 2015, 02:59 PM
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This hardiboard is behaving differently than MDF & for the better I'll say. I bought a bundle of them since they were cheap & have been impressed ever since. I got two test wings that I sanded, I'll try one with straight EZ-LAM, a thin sealing coat & the other with the gel coat. I'll apply it in the garage, then bring into the house for cure, due to the humidity. So we'll see what happens.
Nietzsche
Please try the EZ-LAM first, you will be pleased. Do a first coat, let cure, lightly sand to remove any fuzz, bumps or high spots. Flow on a second coat, trying for smoothness one side at a time. You may get some seams showing through, because the board will absorb the epoxy and the seams won't. It is not swelling the board like a latex paint would do. I can't see the gel coat or polyester doing a better job than the epoxy. I do like polyester resins for plugs sometimes because they cure so fast and sometimes I can get 3 or 4 cycles per day to get a plug done quickly, but I don't think you will like it, plus it stinks a bunch more, so bringing it into the house is out. The epoxy smells too, but not as obnoxious.

You are building a glider, 99% of the glider guys use epoxies , might as well get used to using them. If you haven't bought your Ez-lam, you might investigate what epoxies are popular with the US guys building gliders like yours.
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