Hot wire construction

[Neal Johnson]

Has anyone got any plans for a good hot wire design. I was thinking of building something spring tensioned which would absorb the slack that increases with heat and release tension as the wire cools. Just looking for something different.

 

NEAL JOHNSON

Lafayette, LA

Cozy IV #1034

[dust]

I'v done all of the cutting for two planes (except the verticle stabilizers) and the plans model works just fine - you learn how to use it making the straight cuts (where lag is a non issue) in that phase of the cutting you will learn the voltage settings and the pace that is appropiate. After each "Money cut", a curved cut of a flying surface, you just take a moment to retension and off you go to the races. If the blocks didn't need to be squared off in the beginning, an improvement might be necessary, but it just isn't.

 

And BTW hot wire cutting is EASY - it is not to be feared, thousands have done it with no experience and obtained excellant results.

 

The canard is first and it is not taperred like the wings and is easier than the wings. The wings are taperred and are a little harder, but not to worry, you will do it just fine. For the canard 2 people is fine for the wings, a third is advisable for temp setting and cutoff catching!!

 

The plans are laid out in a teaching/learning order, simple parts in the beginning, with more complex ones as you go. By the time you need more skills - whallah, you now have them. My advice is to start and not read ahead, reading ahead is scarry, just do each sentence at a time and just worry about the current sentence, once you complete a sentence go on to the next one.

 

I would occassionally read ahead and it would scare me, all for naught, you just worry about what you are working on and having three months of supplies on hand at any given time.

 

Some of the suppliers are small and do limited production runs, don't call for the landing strut and figure it will be shipped immediatly, buy three months ahead and guess big on progress so that you don't run out, this stuff has a great shelf life, an extra 2 or 6 months on the shelf won't hurt it, but waiting 6 weeks for a little or big part will frustrate you.

 

Mike

[Wayne Hicks]

I found the 4-dollar plans saw to be more than adequate. The one "improvement" I made was to drill a hole through the base end of one of the pipes for tensioning the wire. I stuck a phillips screw driver through the hole and turned the pipe to tension the wire. Sure beats using channel-lock pliers. I found that after a while the pliers would eventually crush the pipe just enough for the pipe to collapse and loosen the wire.

 

Wayne Hicks

Cozy IV Plans #678

[Chris Byrne]

Would agree entirely with Wayne.

Simple works real well, and the hole for the screwdriver is the way to go.

 

The most important thing you can do is have a a good power supply.

I started with the two battery chargers hooked together to give 24 volts and then a simple rehostat to reduce the voltage to 18 for the large saw and 9 for the small.

 

It didnt work for me. Battery charges kept o'heating and tripping off even after bypassing the safety switch.

Seems you need to be able to get to at least 6 to 8 amps at 18 Volts to heat the wire. If you have battery chargers with this capability then they would prob work well.

 

The battery chargers wouldnt work at 5 to 6 amps and the present set up is using less than 10 amps, so somewhere in between is required.

 

I now use a 240V to 32 Volt transformer to give me the 18 volts I require. Voltage is controled by a hosehold dimmer switch placed between the mains and the transformer. (ie:reduce the voltage before it gets to the transformer)

Dont ask me how this works but I think it has something to do with the dimmer not being able to handle the large amperage downstream of the transformer.

 

Just cut all the wing cores with this setup last week.