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Epoxy for vacuum-formed canopy?


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I've barely started building a 1/72 Helio U-10 Super Courier, and am hitting one snag after another.  This polyurethane resin kit (LHMO28) is by Lift Here Models, in Serbia.  The instructions are ... uh ... brief.  Positioning tabs and holes are non-existent.  I can cope with most of what is a very challenging build, but I'm unsure about what to do with the vacuum-formed canopy.  The kit includes two canopies (a spare).  I've cut out one, which doesn't fit very well, but I can make it fit well enough, I think.  The instructions say to use two-part epoxy for gluing the clear parts.  In the past, I've always used white glue of one kind or another, but never epoxy.  Epoxy is so unforgiving, I'd hate to mess up this model with it, unless I have to.  I've had to cut the other clear windows out of thin sheet plastic.  They fit into openings with nothing to stop them from being pushed in (or out), so maybe epoxy would  be better than white glue for holding them.  I don't know.  Anyone had any experience gluing thin clear plastic to resin with epoxy?

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Epoxy is a good choice for clear parts, it usually dries  clear. You can clean up excess before it cures with denatured alcohol.   I have not used it on the thin edge of an vacuform part. I would try it, you just need to be sure to use the smallest possible amount to minimize the amount that will ooze from the seam when you push the part in place. 

 

How much handling do you need to do after putting in the clear parts? if the part fits well, and it can go in last then white glue or similar is fine. if you need to sand and fit the clear part to the rest of the fuselage, or if it goes inside the fuselage before putting the halves together, then epoxy will probably hold just a little bit better if you need to handle it a lot.

Edited by Kurt H.
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1 hour ago, Kurt H. said:

Epoxy is a good choice for clear parts, it usually dries  clear. You can clean up excess before it cures with denatured alcohol.   I have not used it on the thin edge of an vacuform part. I would try it, you just need to be sure to use the smallest possible amount to minimize the amount that will ooze from the seam when you push the part in place. 

 

How much handling do you need to do after putting in the clear parts? if the part fits well, and it can go in last then white glue or similar is fine. if you need to sand and fit the clear part to the rest of the fuselage, or if it goes inside the fuselage before putting the halves together, then epoxy will probably hold just a little bit better if you need to handle it a lot.

 

Thanks for the suggestion.  I'm having trouble getting the vacuform canopy to fit at all.  I'll definitely have to figure out how to hold it in place while the glue dries.  Know where I can recruit a crew of trained ants?  The "glass" on the fuselage sides will have to be masked.  I've cut them to fit the openings.  I intend to apply masking tape to the windows before installing them, cut the masks to fit, then remove the tape before gluing in the windows.  That will cut down the chances of pushing in a window after the fuselage is built.  My plan is to paint the interior and window openings, glue in the windows, then mask the windows.   I'm leaning toward clear epoxy, as it should hold the windows better than anything else.  The two port-hole windows are small enough to make with Micro Kristal Klear.  Do you see any holes in this plan?  Worst case, I push in a window, it disappears inside, and I have to make another one.

 

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2 hours ago, dnl42 said:

For resin to resin, I only use epoxy.  But for the canopy, white glue, or better yet an acrylic, will do just fine.

Thanks.  I might try acrylic.  What acrylic glue would you recommend?

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2 minutes ago, Unglued said:

Thanks.  I might try acrylic.  What acrylic glue would you recommend?

I use both Gator's Grip and Formula 560 Canopy Glue. Both can be cleaned up with water. Glue the part on, tape the canopy to clamp, wait for it to set just a little, and then clean up with a wet cotton bud. Both are also great to gluing PE to plastic or resin for surface bonds. Don't use it for edge joints, though...

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29 minutes ago, dnl42 said:

I use both Gator's Grip and Formula 560 Canopy Glue. Both can be cleaned up with water. Glue the part on, tape the canopy to clamp, wait for it to set just a little, and then clean up with a wet cotton bud. Both are also great to gluing PE to plastic or resin for surface bonds. Don't use it for edge joints, though...

Trouble is, edge joints is what I have with this kit.  No way around it.  Like you, I usually use "560" for the clear stuff.  But this is going to call for something stronger.  I recently pushed a door window into the cockpit of a DHC-6 Twin Otter, and ended up cutting the door out to get it out and fix it.  I don't want to repeat that goat-rope on this one. 

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What I would suggest for the flat windows is to find the smallest plastic strip, Plastruct or the like, and glue the strip in around all four edges of each window, set back far enough from the outer surface of the kit, so that when you install the windows, they will have a tiny ledge all round to lay on. This will help keep them from "pushing in" as well as offer more gluing surface than an edge joint. This fiddly, but doable. The thinness of the strip will also permit this to be used with some curved windows, but will be much more difficult on a resin kit than with, for example, a vacuform kit. Plastic to resin, I would probably use CA.

 

Plus 1 on the 560 canopy cement, or you could try some watch cement. Epoxy would work, but would be a pita to mix small batches at a time, using 5-minute epoxy. Longer drying times would give more chance for the windows to fall out during handling, until they dry.

 

Ed

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27 minutes ago, TheRealMrEd said:

What I would suggest for the flat windows is to find the smallest plastic strip, Plastruct or the like, and glue the strip in around all four edges of each window, set back far enough from the outer surface of the kit, so that when you install the windows, they will have a tiny ledge all round to lay on. This will help keep them from "pushing in" as well as offer more gluing surface than an edge joint. This fiddly, but doable. The thinness of the strip will also permit this to be used with some curved windows, but will be much more difficult on a resin kit than with, for example, a vacuform kit. Plastic to resin, I would probably use CA.

 

Plus 1 on the 560 canopy cement, or you could try some watch cement. Epoxy would work, but would be a pita to mix small batches at a time, using 5-minute epoxy. Longer drying times would give more chance for the windows to fall out during handling, until they dry.

 

Ed

I hadn't thought of this idea, but it doesn't seem practical.  None of the windows have angled corners, which means a strip would look odd because it wouldn't go around the radiused corners.  I suppose I could paint to the edge of the strip, but masking would be tricky.  Hmm.  I'll think about it.  Thanks for the idea.  Have  you done this?  If so, do you have a photo?  I only have four windows to deal with, but that's 16 tiny strips to glue in.  I do like the idea of having something in back of the windows.  I plan to put them in and mask them before i glue the two halves of the fuselage together, so the only risk is in removing the masks and during handling.  This model shouldn't require much handling.  I'm thinking I can tape a protective piece of cardboard over the windows on both sides to protect them while I'm attaching the windscreen, gluing on the wing, putting on decals, etc..  

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I would second Ed's approach.  Some .010" square strip to build a thin ledge inside the opening will help immeasurably.

 

The alternative is to cut your windows slightly oversize, and use something like this to chisel a lip into the fuselage.  This gives the benefit of moving the glue join away from the clear areas, so you can fill/sand to blend them in.  May not be feasible depending on the wall thickness of the fuselage, though.

 

Either way - and especially if you DON'T add some sort of ridge behind the glass - you should use some thin strips of tape to hold the window in place while the glue dries.  Sort of like

 

IMG_2833.jpg

 

Lastly, when dealing with vac formed parts, always, always, always cut them oversize, then carefully file/sand to the exact shape.  It's a slow, tedious process, but the more carefully you shape the parts, the better they'll fit.

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I use 5-minute epoxy almost exclusively for vac canopies, either on resin or plastic.  Just make sure it's mixed properly and use the least amount required to do the job. 

 

I like it because it has gap-filling capability and can be smoothed with a q-tip dampened in lacquer thinner before it cures which greatly reduces the need for filling and sanding later.   This works on plastic kits, too, as long as the vac canopy is something like acetate or some other non-styrene plastic - the lacquer thinner is a solvent, and can craze clear styrene, but a quick swipe with it on a q-tip won't give it enough time to harm the reqular plastic unless you go back and try to make multiple passes.

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Here is what the strips look like on a practice kit piece:

 

_IGP9707-vi.jpg

 

White strips are .010" x .020". Size to suit your needs. What I use will bend around corners when softened with hot liquid glue, and then pressed into placed with a metal dowel, etc. I always put the windows in before painting, and then mask the window a little smaller to cover these strips when I paint the body color, so they really can't be seen after the fact. Window shown above is from a 1/72 scale F-117.

 

Ed

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16 hours ago, TheRealMrEd said:

Here is what the strips look like on a practice kit piece:

 

_IGP9707-vi.jpg

 

White strips are .010" x .020". Size to suit your needs. What I use will bend around corners when softened with hot liquid glue, and then pressed into placed with a metal dowel, etc. I always put the windows in before painting, and then mask the window a little smaller to cover these strips when I paint the body color, so they really can't be seen after the fact. Window shown above is from a 1/72 scale F-117.

 

Ed

This looks like a good solution, if you have enough patience and steady enough hands to do all that fiddly cutting and placing of strips.  It doesn't look easy, especially keeping the edges of the strips equi-distant from the outside of the fuselage while you're gluing.  Thanks.  I'll keep it in mind.  

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On 2/5/2017 at 0:09 AM, Unglued said:

I've barely started building a 1/72 Helio U-10 Super Courier, and am hitting one snag after another.  This polyurethane resin kit (LHMO28) is by Lift Here Models, in Serbia.  The instructions are ... uh ... brief.  Positioning tabs and holes are non-existent.  I can cope with most of what is a very challenging build, but I'm unsure about what to do with the vacuum-formed canopy.  The kit includes two canopies (a spare).  I've cut out one, which doesn't fit very well, but I can make it fit well enough, I think.  The instructions say to use two-part epoxy for gluing the clear parts.  In the past, I've always used white glue of one kind or another, but never epoxy.  Epoxy is so unforgiving, I'd hate to mess up this model with it, unless I have to.  I've had to cut the other clear windows out of thin sheet plastic.  They fit into openings with nothing to stop them from being pushed in (or out), so maybe epoxy would  be better than white glue for holding them.  I don't know.  Anyone had any experience gluing thin clear plastic to resin with epoxy?

 

Not an answer to your question, but a helpful tip: cover the vacform canopy with foil, so you can SEE what you're doing. I found that the transparancy is the main problem in cutting and fitting a vacform canopy. I have a tutorial on my website: Canopy masking with Cheap Chocolate Foil. As an alternative you could maybe use removable paint. Acrylic will dissolve in ammonia for example.

 

Rob

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43 minutes ago, Rob de Bie said:

 

Not an answer to your question, but a helpful tip: cover the vacform canopy with foil, so you can SEE what you're doing. I found that the transparancy is the main problem in cutting and fitting a vacform canopy. I have a tutorial on my website: Canopy masking with Cheap Chocolate Foil. As an alternative you could maybe use removable paint. Acrylic will dissolve in ammonia for example.

 

Rob

Thanks, Rob.  Another good tip.

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On 2/8/2017 at 2:36 PM, Unglued said:

It doesn't look easy, especially keeping the edges of the strips equi-distant from the outside of the fuselage while you're gluing. 

 

Tack windows in place.  A piece of tape on the outside of the fuselage will help set the level.  

Flip the model over and glue in the supports from the inside, allowing you to butt your strip up against the vac window.  

Be careful to glue the strip to the fuselage only, not the window.

Peel off the tape and pop out the windows.  Secure the strips with some more CA, clean up any excess glue, and paint them.

Glue your windows back into the hole, with your cement of choice.

 

* if your windows end up getting glued in place, just cut your mask a little smaller, so the white styrene strip gets covered with paint.

** if you're worried about the windows getting glued in place, cover the inside with BMF, wrapped up around the sides of the plastic, then tack it in place.  Any glue will stick to the thin foil, but you'll still be able to pop the vac window out.

 

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54 minutes ago, MoFo said:

[deletia]

if you're worried about the windows getting glued in place, cover the inside with BMF, wrapped up around the sides of the plastic, then tack it in place.  Any glue will stick to the thin foil, but you'll still be able to pop the vac window out.

THAT is clever!

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I'll stow away these tips for another model.  I decided to just seat the windows flush with the fuselage and glue them in with 5-minute epoxy, just to see how it went.  For this particular model, it went well enough.  One thing is certain: Those windows aren't going anywhere.  After letting the glue set up a little, I was able to clean up where the glue had spread out from the opening with lacquer thinner on a cotton bud, and a toothpick cut into a mini-chisel.  They actually look more real than the windows that usually come with kits.  The downside of these "do-it-yourself" windows is that they take a long time to make and install.  Building this short-run resin kit has been a good learning experience for me, and it's far from over. I glued the fuselage together this morning, and the fit is not good.

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