Author Topic: Hot Wire Foam Repairs  (Read 2550 times)

stephen.shannon

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Hot Wire Foam Repairs
« on: September 07, 2014, 20:38:00 PM »
I acquired an EDF jet from a chap a while back and finally got to have a look at repairing it in recent weeks. The Fantom was going in the bin and I thought it might be fixable.



the main issue was the broken nose and pitted wing surfaces. So to start I cleaned the damaged area with a sharp blade. It was important to bring the damaged section back to a clean surface.

I glued (gorrila) a new section of basic styro foam back on to the nose area, this was basically a large square block of that could be shaped later.

While that was drying I built a small hand sized hot wire cutter. A 30v 2 amp power supply thanks to a mate of mine from the old elctronic days was ideal for the supply



The wire used for the cutting was from my old fishing kit, 30lbs pike trace wire. Its a little heavy for the job but works nicely due with sufficient current running. An 'e' string from a guitar works really really well, so if you have something of this guage give it a go.



These wire cutters are relatively easy to make and use so don't be afriad of putting one together they work a treat to make foamie parts that are completely beyond repair. (I've a considerable degree of experience damaging foam parts beyond fixing so if you need any pointer in this area just shout

 :lol:  :lol:


So with the styrofoam firmly glued in place on the nose of the Fantom, it was time to mark up the nose shape roughly using a marker. So with this done the hotwire cutter was fired up and left to warm up. A couple of test pieces laid on the wire were used to test the temperature. So with the Fantom firmly held on the workbench, the hot wire was drawn from back to front to shape the nose. The nice thing about a small handheld deivce is that its easy to manouvre shape the part as you go. Just make sure to keep a constant pressure and movment through the foam to avoid burning or 'jagging' on the surface of the foam.

So the final shape after a little sanding was as follows




Sanding styrofoam is not a great way to finish this surface as it doesn't sand as well as EPP but a little 'snow' filler will sort that...
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