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POLYESTER RESIN ???

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Posted (edited)

I worked for years with REN epoxy and fiberglass, and made consoles for my boat using West System.  I need a small amount to modify my Horizontal Stabilizers and was considering getting Bondo Polyester Resin and cloth locally at Home Depot, Walmart, or Auto Parts Store.  Is this material / resin any different than working with the other Epoxy systems?  Will fabric stick to it with or without sanding?   Will this work with blue foam as a base, or eat it up?  Guess this stuff don't work to repair epoxy & fg?   EDMO

Edited by EDMO

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Polyester resin is NOT compatible with epoxy. I used to build racing jet boats under the instruction of Jim Youngblood. You can put epoxy on over polyester, but not the other way around.

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I used polyester building reproduction trees, rocks , Etc. for museums and after using epoxy on my Kitfox, I found epoxy is much stronger per pound than polyester and it will eat blue foam.  

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Posted (edited)

I used polyester building reproduction trees, rocks , Etc. for museums and after using epoxy on my Kitfox, I found epoxy is much stronger per pound than polyester and it will eat blue foam.  

So,  what kind of 1/2" thick foam can I use with polyester resin?  I just don't want to spend $100 + for a $10 job.   I could use plywood and 9460 instead of fg but almost out of 9460 and wood is heavier than foam and fg.   EDMO

Edited by EDMO

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Posted

I've used the blue foam with fiberglass resin, and kept it from eating the foam up by covering the foam with clear packing tape.  Works good!  JImChuk

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I will post some photos when I get the problem solved - My welder, for some unknown reason, left about a 4" gap between the root tube of my Horizontal Stabilizer halves and the fuselage.   I don't want to haul the plane 200 mile roundtrip to get him to weld on it, so trying to figure out how to fill the gap and support the fabric covering.    EDMO

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Maybe if you post the pictures now, someone will have a good idea for you.  JImChuk

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Posted

Epoxy resins don't eat blue foam - all the Rutan aircraft are blue foam with epoxy except the fuel tanks.  For that they use polyurethane foam.  More expensive and brittle, but not subject to dissolving in as many chemicals.  Doesn't sound like you'd need more than a quart of resin for that job, but yeah, a quart of west 105 epoxy and a pint of 206 hardener is about $50, + shipping.  But the PolyUrethane foam (Last-A-Foam at Aircraft Spruce) would be about $50 + shipping also.  

Oh, and don't use a hot wire to cut polyurethane foam - it makes cyanide gas when you do :bugeyes:

Rock, meet hard place!

Mark

 

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Posted (edited)

Thanks guys.  I will try to get a photo today and post it to get some ideas from you.  The other thing about welding on these, besides the 200 mile trip, is that unless they are welded while assembled to the fuselage, then they will probably draw/warp enough to not fit into the mounting tubes which are like Piper design.  My HS is in two pieces and not like Avid - Foxes.  This design got changed and I guess the welder forgot to move the root chord tube farther in.  I think I could use a sheet of plywood to fill this in?  It should be under the fabric when covered. 

Here are photos - The orange level shows where the fuselage fabric will be - about 4" from there to root tube. 

I am getting ready to make the wood ribs for HS & Elv.  My photos are blurred - Don't go for an eye test!  ;<)  EDMO

IMG_1686.JPG

IMG_1684.JPG

Edited by EDMO

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OK - I added photos to above post.  EDMO

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So,  what kind of 1/2" thick foam can I use with polyester resin?  I just don't want to spend $100 + for a $10 job.   I could use plywood and 9460 instead of fg but almost out of 9460 and wood is heavier than foam and fg.   EDMO

Divinycell, klegecell, and ... dammit... I can't remember the other. They are used as structural foam. Once you build a fiberglass box around it, it is bullet proof and very light. Cheap, not so much. You could encapsulate wood. It should be fine. 

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Posted

What about an aluminum tube epoxied into place parallel to the steel cross tube that should have been further out .  Could even use some fiberglass cloth at the joint.   Maybe a couple of tubes back to the steel cross tube so it doesn't bend in when you shrink the fabric.  JImChuk

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So,  what kind of 1/2" thick foam can I use with polyester resin?  I just don't want to spend $100 + for a $10 job.   I could use plywood and 9460 instead of fg but almost out of 9460 and wood is heavier than foam and fg.   EDMO

Divinycell, klegecell, and ... dammit... I can't remember the other. They are used as structural foam. Once you build a fiberglass box around it, it is bullet proof and very light. Cheap, not so much. You could encapsulate wood. It should be fine. 

Divinycell was the original polyurethane foam that Rutan used I believe, and they are no longer in bidness, too many lawsuits from the surfers that made surfboards from it and then hurt themselves.  I hate lawyers.  But I hate stupid juries even worse.

Last-A-Foam is what Rutan builders use now.

Mark

 

 

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Posted (edited)

What about an aluminum tube epoxied into place parallel to the steel cross tube that should have been further out .  Could even use some fiberglass cloth at the joint.   Maybe a couple of tubes back to the steel cross tube so it doesn't bend in when you shrink the fabric.  JImChuk

Thanks Jim.  You made me remember that I have some spare short pieces of aluminum trailing edge - guess one of those epoxied and braced  with some 1/4" thick plywood strips would get the job done.  I also have aluminum tubes.  May as well order some more 9460 - guess I will run out anyway before I get done.  Will try that RS Hughes company - I haven't tried them before, but Kitfox has raised their price on it.   Jolly Good Show!   EDMO

Edited by EDMO

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Posted

What about just shorting the HS by a few inches on each side? Do you think you would notice it?

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Posted (edited)

What about just shorting the HS by a few inches on each side? Do you think you would notice it?

TJay,  interesting thought - I wouldn't notice it until it was assembled and rigged - Fortunately, my welder noticed it, although he didn't notice to move the root tube.  It might have been my F-up, and I will go back and look at the plans I drew to see about that.  If it was shortened then the elevators would have to be mounted farther out, or shortened, or there would not be space for the rudder to swing either way!  "No change is simple - One thing leads to another."  Ha!  Good try tho!   You wouldn't believe how many planes I measured just to come up with the dimensions for the HS and Elevators!  ;<)  EDMO

Edited by EDMO

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Posted (edited)

Jim,  I am going to see if I can find some PVC pipe about the right size for the root tube and braces - It don't rot, don't need painting - 9460 ordered - $108 + $10 Missouri tax from R.S. Hughes Co. with free shipping.   EDMO

Edited by EDMO

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Jim,  I am going to see if I can find some PVC pipe about the right size for the root tube and braces - It don't rot, don't need painting - 9460 ordered - $108 + $10 Missouri tax from R.S. Hughes Co. with free shipping.   EDMO

Do you think this will work?  More "Experimental" ideas?  EDMO

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I suppose it would.  Unless the plastic is affected by the chemicals in the covering chemicals.  Aluminum might be stiffer, and not quite as heavy though.  JImChuk

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Posted (edited)

I suppose it would.  Unless the plastic is affected by the chemicals in the covering chemicals.  Aluminum might be stiffer, and not quite as heavy though.  JImChuk

I'm not worried about weight on the tail of this bird - Guess a good test would be to see how MEK affects PVC pipe - just for curiosity?   Donno what the Kitfox leading edge is made of, but guess it is not affected by Poly products.   EDMO

Edited by EDMO

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Divinycell was the original polyurethane foam that Rutan used I believe, and they are no longer in bidness, too many lawsuits from the surfers that made surfboards from it and then hurt themselves.  I hate lawyers.  But I hate stupid juries even worse.

Last-A-Foam is what Rutan builders use now.

Mark

 

 

I had to go look, seems there are still there. http://www.diabgroup.com/en-GB/Products-and-services/Core-Material/Divinycell-H

Aircraft Spruce has it too: http://www.aircraftspruce.com/catalog/cmpages/divinycellfoam.php

 

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Divinycell was the original polyurethane foam that Rutan used I believe, and they are no longer in bidness, too many lawsuits from the surfers that made surfboards from it and then hurt themselves.  I hate lawyers.  But I hate stupid juries even worse.

Last-A-Foam is what Rutan builders use now.

Mark

 

 

I had to go look, seems there are still there. http://www.diabgroup.com/en-GB/Products-and-services/Core-Material/Divinycell-H

Aircraft Spruce has it too: http://www.aircraftspruce.com/catalog/cmpages/divinycellfoam.php

 

Good info on the Divinycell, but I already spent $118 on more 9460, so this project wont be FG.  EDMO

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Posted (edited)

I cant show the finished HS because this 100 degree heat is just too hot for me to get any work done.  So not to keep this thread in suspense, I made a photo of the drawings for the wood ribs that I will make and install on my HS, bracing the root rib with a 1/4" flat piece of plywood (and some lightening holes) and some small blocks, all glued in with 9460.  Someday I will post photos of the HS in "Kitfox IV, FOXY FLAPPER FOTOS".   Thanks for all the suggestions.  EDMO

HS RIBS.JPG

Edited by EDMO

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I suppose it would.  Unless the plastic is affected by the chemicals in the covering chemicals.  Aluminum might be stiffer, and not quite as heavy though.  JImChuk

I'm not worried about weight on the tail of this bird - Guess a good test would be to see how MEK affects PVC pipe - just for curiosity?   Donno what the Kitfox leading edge is made of, but guess it is not affected by Poly products.   EDMO

Hi Ed,

Regarding the MEK with PVC: MEK is (or at least used to be) what the primer/cleaner for gluing PVC was made of. Softens it up for a bit.

MarkJ

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I suppose it would.  Unless the plastic is affected by the chemicals in the covering chemicals.  Aluminum might be stiffer, and not quite as heavy though.  JImChuk

I'm not worried about weight on the tail of this bird - Guess a good test would be to see how MEK affects PVC pipe - just for curiosity?   Donno what the Kitfox leading edge is made of, but guess it is not affected by Poly products.   EDMO

Hi Ed,

Regarding the MEK with PVC: MEK is (or at least used to be) what the primer/cleaner for gluing PVC was made of. Softens it up for a bit.

MarkJ

Thanks Mark,  I never thought about what was in the PVC glue - Just thought it was sort of like Acrylic Glue - the original material mixed with some sort of solvent.  I will try to remember this for future "ideas".   ;<)   EDMO

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