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Old Jun 27, 2015, 05:37 PM
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Whoa……it flies
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Mini-HowTo
Hot Wire airfoils

I have just recently tackled this method for foam wing builds and it's working well.
Previous wings were tape-covered and folded depron which have been excellent.
Here's my beginners perspective on hot wire cutting.

Hot wire airfoils (6 min 8 sec)
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Old Jun 27, 2015, 07:01 PM
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Build straight - Fly twisty
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Good one Andrew.
You don't need to burn the nylon off the leader wire. If you run a blade along the wire it'll cut a long shaving and then you can easily peel the remaining coating.
Is that foam from Bunnings?
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Old Jun 27, 2015, 07:13 PM
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Thanks for that great tip Whiskers. Yes the foam is from Bunnings in Geelong. Might be a recent addition because I have never seen it there before.
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Old Jun 30, 2015, 10:38 AM
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Trabado por las importaciones
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Quote:
Originally Posted by anewton View Post
I have just recently tackled this method for foam wing builds and it's working well.
Previous wings were tape-covered and folded depron which have been excellent.
Here's my beginners perspective on hot wire cutting.

https://www.youtube.com/watch?v=JIRz...ature=youtu.be

good video.

what do you use to laminate the wings? can you paint over the laminate?
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Old Jun 30, 2015, 03:23 PM
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75 micron document laminate
EZload laminate - http://www.neopostonline.com.au/lami...load-roll-film

I have not tried painting it
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Old Yesterday, 03:18 AM
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Here's another video on spar channel forming

1. Hot wire slot for 6 x 1mm flat spar
2. Hot wire circular channel for arrow shaft spar
3. Drill jig for drilled circular channel

Spar hole drilling jig (3 min 15 sec)
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Old Yesterday, 08:27 AM
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Excellent work on the cutting and the videos.I have a few tips you may find helpful.
First the wire. The correct wire to use is very difficult to find locally even here in the states, but thankfully there is a fantastic on line distributor http://www.jacobs-online.biz/rene_wire.htm. You won't need to purchase large quantities of this wire as it lasts a really long time ( 30 sets of wing halves and numerous test cuts on the same wire and still going strong). You'll see that it heats up faster and retains it's temperature longer than the wire you're currently using, that equals faster cuts and less distortion.
Second, if you're serious about doing a lot of cutting, a transformer setup is the way to go. You'll get constant volts and amps, making smoother cuts, and be able to cut away to your hearts content with out having to stop to recharge. Less chance of damaging your batteries plus the added ability to control your voltage and amps and keep those settings constant. Jacobs is an excellent resource for everything you'll need to build your own ( just a transformer and dimmer switch in a box, instrutions available @ jacobs. )
Third, it looks like a lot of work and materials went into making that bow, but your not keeping enough tension on your cutting wire( hence the wire lag and the need to move very slowly (( wire lag is the reason for the weird trailing edge and difficulty going around the leading edge)) ). It's actually a combination of your power supply, the type of wire and the design of the bow that's giving you this. I've attached a couple of pics of an easy to assemble bow that when used with good single strand wire will keep good tension and lessen the amount of wire lag. Super simple design ( copied from http://www.acpsales.com/Hot-Wire-Bows.html) I used pine for the back bone with holes for the music wire drilled at 20 degrees outward, and 1/4" music wire. Funny thing about doing this, the electrical current only runs between the alligator clips, any wire ( or the steel legs) outside of the clips does not get hot or seem to carry any voltage, but as a precuation , I've taken to covering the steel legs of my bow in shrink tubing just to be safe.
I'm not overly technical when I cut( don't measure volts or amps, I know the speed I want to cut at and just turn the dimmer up or down until I get the speed I want to work at, put a piece of masking tape on the switch plate to make a mark so I can repeat the setting for that particular cut).
Hope my suggestions are helpful, fantastic work so far. That bow design I recommended is infinitely adjustable, I just made a smaller one with a handle off the back ( like a paint brush) for cutting fuselage " slices" similar to the designs by Tetris here on rcgroups.
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Old Yesterday, 11:10 AM
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Quote:
Originally Posted by rcguy1958 View Post
Second, if you're serious about doing a lot of cutting, a transformer setup is the way to go. You'll get constant volts and amps, making smoother cuts, and be able to cut away to your hearts content with out having to stop to recharge.
Before buying a step down transformer, have a look at your battery charger. Quite a few of them have a mode for hotwire cutting where they supply a constant voltage/current. My Reaktor 300W charger does this with control over both voltage and current supplied along with a timer function. All of the various i-charger clones and similar designs should have this as well.


Mark
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Old Yesterday, 03:07 PM
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I used my i-charger at first...but you'll notice that it is difficult to get the proper amps supplied at the desired voltage. Even after changing the settings, the charger will over ride the input and lower the voltage based on the amperage picked. My transformer set up cost me approx. $60.00 and makes much better cuts than when controlled with my charger. Also, the time to get the wire to temperature is much longer and makes gravity cutting less reliable.
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Old Yesterday, 05:04 PM
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Excellent links and suggestions, many thanks.
My simple battery operated setup works well enough for the moment. I have a brushed ESC and servo tester on the way to allow voltage control.
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