HOT tip, iron your edges

by tyoho | October 3, 2013 | (57) Posted in Tips

While building my Flite Test Spitfire speedbuild kit I came up with a way to round off those undercut lasered edges.

I actually stumbled upon this method by accident. while gluing the top of the Spitfire's fuselage, my "B" style fold slipped and became an "A" style. I guess I could have used a Swedish helper.

In an attempt to soften the hot glue and fix the problem, I tried using an iron to heat the area and re-melt the glue. All I managed to do was melt the foam, but I discovered that I could shape it with the iron and that the paper stuck to the melted foam.

Keen observers will notice that I installed my horizontal stabilizer upside down.  Again, a handy Swede may have prevented that.

Here's the tail after painting.

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COMMENTS

andre on October 7, 2013
That is a great tip!

Thank you so much.
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tramsgar on October 7, 2013
Thanks for the tip! What temp did you find worked best?
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tyoho on October 7, 2013
With the sealing iron I needed to run it wide open.
I had the clothes iron maxed as well and think it was a tad too hot.
Of course it will depend on your iron.
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RigoArevalo on October 7, 2013
What a great tip! Um, are you Seth Rogan?
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alibopo on October 7, 2013
Excellent! I was doing something similar with various glues - but never as neat as this. Do you notice how much stronger the panel becomes - closing the edges really stiffens them up. Fingers crossed this will work with my UK foamboard :)
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Bedrock on October 7, 2013
I'm in UK and went with 5mm foamboard from London Graphic centre, not a bad price. But the Flite test power pods and gear packages do seem to be a lot lighter board. I'm wondering of 3mm UK material would be strong enough for indoor flying (and keep weight down)?
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alibopo on October 8, 2013
Hi - I got mine through EBAY - buying it in Art shops at £5 & £6 a sheet etc was a non starter. I got it down to about £2.70 a sheet by buying packs of ten sheets. There does seem to be slightly thicker paper on my foamboard than the US variety but everything I build still seems to fly. Funny thing, the last pack I bought came with two padding sheets top and bottom of the 3mm foam they use to laminate-up the 6mm paper covered sheets I was buying. I'm thinking of building some indoor flyers from it. Have a look at my 'Lazy Gnat' - there's no end of useable foam out there being used for packing, plates, etc. etc.
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rick_harriss on October 11, 2013
hobbycraft have 3 A1 boards for £8 = £2.66 a sheet. Bigger than the 20 x 30 flitetest use.
If there is no shop close this is the web site

http://www.hobbycraft.co.uk/advancedsearchresults.aspx?query=foam-board

The finished weight seems close to the suggested weight.
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Bedrock on October 12, 2013
Thanks guys. I just weighed the power pod section ONLY of the swappable kits I had ordered from Flite test. Flite test foamboard 11g - UK foamboard 18g. Over 60% heavier! Is the recommended motor still up to it or do we need to power up?
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Bedrock on October 12, 2013
And I found ironing edges of the Ok stuff made the paper peel off very easily. :-(

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LordVader on October 7, 2013
WOW! That looks great. I'm going to try that on my scratch-builds. Looks like it really makes a nice finishing touch. Thanks!
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RobMackenzie on October 7, 2013
You just turned a minor irritant (that under-cutting caused by the laser cutting) in to a major plus! Great idea and I'll bet one that really catches on. Thanks you for sharing this with us all.
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Gryf on October 7, 2013
What a neat solution! Square leading and trailing edges never appealed much, and I'd considered using balsa to shape LEs and TEs when I build a swappable, both for aerodynamic benefits (if any) as well as to strengthen the edge. I see Josh B. recommends hot-gluing a BBQ skewer along leading edges, and that would work fine... but closing off and rounding edges with an iron is pretty darn slick. Thanks!

Gryf
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Jghanson25 on October 7, 2013
Awesome! I've been wondering how to overcome the peeling paper! Thanks!
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csarazin on October 7, 2013
Very nice... Thanks for sharing.
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28th St. Air on October 7, 2013
ive used an iron to adhere and shrink ultracote to the paper but have never tested what happens to the bond between the paper and foam if i heat the paper directly. i wonder if anyone reading this article has tested if ironing the paper at high heat reinforces the bond to the foam. i realize this can be risky to bubbling/corrupting the foam if done wrong.
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tyoho on October 7, 2013
I tried to re-stick the paper on some sections of a plane that had gotten wet and the paper lifted. At first it seemed to work, and I even shot another video segment to show it, but after the paper and foam fully cooled it lifted again. I think that to get it hot enough for the paper to stick to a flat section you would be distorting the foam.
When you do the edges like I've shown, you do melt the foam and it does seem to stick to the paper much better than the original bond, but you are changing the shape on purpose.
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Fly'n-V on October 7, 2013
Great post!!! Thanks for sharing!
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No love on October 7, 2013
I just tried your tip and what a difference! not also it looks neat but it reenforces the edges of the frame, now the rudder and the elevator on my scratch build are rock solid !
From now I will start using this technique
Thanks again for sharing !

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sailorJohn on October 8, 2013
Terrific ! you can under cut the edge of the foamboard with the tip of your hotglue gun laying down a slight bit of glue the round the off the edge for extra strength . I've been using the iron to clean up glue in chadd's hinges when I get them too globby.
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sailorJohn on October 8, 2013
Sharing tips like this will continue to improve the looks of our builds till they will rival the stick model builds
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sailorJohn on October 9, 2013
I do recommend that the edges are rounded off prior to assembly because it is possible to apply too much heat and ruin the piece , practice with scrap to develop your technic and the adjustment of your iron. remember as Josh says to make a pattern.
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sailorJohn on October 9, 2013
For scratch builders, using the hot tip of the glue gun to under cut the foam works better than starting right in with the iron. Thank you I've been trying to figure this out for two years.
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steadfast4life on October 9, 2013
Great tip!
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sailorJohn on October 14, 2013
Advantage to dollar tree (Adams Ready Board) fb is the paper is removed on inside of area you wish to bend into an air foil to allow a relatively smooth bend, other brands, the paper is difficult to remove. This allows the foam to compress on the inside radius . See Experimental Airlines Armin wing on YT
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animan on October 15, 2013
you are correct sir. good point. After building my 3rd F22, the Elmer's proved to be too heavy, I had a hard time throwing and crashed several times.
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pintokitkat on October 16, 2013
This would also be a great way of making the bevels in the control surfaces. Josh is a genius at cutting them cleanly and straight - mine are more of a bodge, but this idea looks like it could make very strong hinge edges. It might lend itself to using Mylar hinges too so there's no tape on the surface to spoil the paint jobs.
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Hell2Go on October 20, 2013
When I cut my hinge tapers,I Iay the piece with the edge exposed on the edge of the table which I have an aluminum 1 1/2in angle iron clamped. keep the hingeline flush with the ledge, using a new standard razorblade, hold like josh does, squeeze hard to lock your hand and wrist position in place and start really slow and adjust angle by moving at your elbow keeping hand and wrist locked. restart if you must or come back to clean the first part after. BUT start a little shallow to get the proper angle. i usually have it straight in the first 1/2 in or so then draw your whole body back to make the cut. after a little practice you should be able to do it as well as josh.
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sailorJohn on December 4, 2013
see foam tools by sailorjohn, then keep on the lookout for a wood block with 45 degree angle ---underneath old chair or table--makes cutting hinges a snap and better than josh's
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DKchris on June 20, 2014
That might actually be a very good idea, since it would create a paper "faced" control surface. Quite a few people building hi-$ composite competition level gliders swear by facing their control surfaces, as this stiffens the considerably and makes them last longer. Combined with the well described method of reinforcing the hinge with hot glue this might make an even stronger hinge section and control surface.
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Hell2Go on October 20, 2013
I tried ironing the edges with my old monokote iron and I like it alot. TIP.... iron the edges of each piece as you are building the plane cause its easier to do on a flat surface and if you go too far you won't have to cut a part off your plane to go back and repair it! if you have edges on the plane that come together that need to be ironed, iron in pre-assembly to about 1/2 to 1/4 in from where the edges will come together then after assembly go back and touch them up together so you get a smoother transition. On my first plane, I put a flat chamfer on the edges about 3/16 inch wide carefully bringing the edge of the paper to the center of the foam evenly on both sides till I get a sharp edge and the paper "just" comes together then I sand the sharpness off (don't want to get cut.) this technique would be good on a speed plane as the sharp edges will cut the air with less resistance. practice on scrap first!!!
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oldguy on November 4, 2013
Thanks tyoho ...... this makes a much more finished look to the wing ..... polyurathane and it is seal.
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Jaxx on November 13, 2013
Thanks for sharing!
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kanky on February 7, 2014
Brother that is a hell of a discovery man, Round the edges, add stiffness. Great all around.

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sameerkm on March 17, 2014
Thanks tyoho for sharing this tip.

What paint did you use for painting the airplane?
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Yogenh on April 27, 2014
I tried it and it works great. I did it on one that I cut out myself and it worked real good on that too.
You did great job with it. Keep up with the good works.
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DKchris on June 20, 2014
Great idea - I also like the idea of being able to put a bit of taper into TE's and other edges, for instance like the step on the underside of many of the FT plane wings. I don't have access to DT foam, but I'll sure try i out on Depron - think it'll be best to do it before adding tape to the surfaces in that case, as the typical unreinforced polyester packing or office tape will shrink much like covering film and may warp the surfaces.
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Dave.P.68 on October 28, 2014
Great tip, one of the best on the site! I can think of a bunch of mods you can do with this trick. It does go against the grain of the Flite Test build it fast and expect a crash mentality. I treasure every model I build, this is much more to my mentality. Bravo tyoho!
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capt_ks on November 12, 2014
I just tried this after acquiring an cover iron and it works great!!! The plane looks so much better and reduced the cheap look of rough-cut foam board edges on a plane. Thank you!!!
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chrisgalindo on January 15, 2015
I tried this last night on my foamie batwing that I just cut out of Dollar Tree foam, and this works AWESOME! I found my best results were with the hobby iron set to about 350 degrees Fahrenheit. Thanks for the great tip. Now I'm pondering sealing it with Minwax polyurethane.
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RC Plane Addict on March 7, 2015
Hey great tip!, looks tedious, but its might just pay off
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JonnyHilly on February 6, 2020
Just tried this on the Versa wing-tips... I didn't roll the edges, just ironed them flat to a sharp edge... worked great! feels much stronger/stiffer afterwards. going to do same on elevons' trailing edges. could probably do it along the hinge also, instead of cutting a bevel. Looks so much better, should be less drag and better aerodynamics also. Thanks !
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tyoho

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HOT tip, iron your edges