DIY Hotwire.... minimal cost ( pretty much £0 )

Im a self confessed foam junkie , i love its properties (especially the bounce when it noses in ) and find it very easy to build with but one of the things that used to annoy me a little was cutting ,you always needed a sharp blade to get a good cut or the foam might snag or drag and when making my own parts i used to hate using a knife because if you werent careful you ended up with chunks missing or you would hit a hard bit in the foam blah blah etc etc......

So i decided to read up on making a hotwire cutter , well truthfully i was reading up on cutting wing profiles out at the same time and the 2 methods coincided with each other. I could have invested a few quid in a transformer etc etc but as i try to do everything on a shoestring budget i started to experiment. Through reading the various threads i decided i needed a power source that could output approx 12v at around 4 amps ( i might be wrong it was nearly 2 years ago ) looking through the online shops and ebay i found what i was looking for but it was too expensive for my budget , then it hit me , my batteries are quite capable of doing that.........

So with all the knowledge of a genius i set about slapping together something that would work ( not something that would look good )

A bow in the shape of an H was made using some old scrap wood (really scrap wood lol ) , the bottom of the bow needed a way of attaching a cutting wire to it so i used 2 curtain type brass hooks and screwed them into the bottom legs, also needed to be able to keep the wire under tension so i used 2 more in the top legs, elastic bands tied together would do that well enough. Next i needed some sort of cutting wire , now, in the loft was an aold bar heater which i know from the web used a decent enough wire for cutting as did my guitar and i had a spare set of strings . I used a guitar string the same legnth as the --- in the H bow andlinked it to the 2 bottom hooks and linked enough elastic bands together with just enough tension to keep the wire taught. I congratulated myself on a fantastic job of making an H bow out of nothing but stuff i had lying around the house lol

Next i needed a power system and something to regulate the flow , WAIT !! we use this method all the time ! using some old flex cord i attached a piece to each end of the guitar string in the H bow. Rooting around in my "box of cr@p" i found a couple of Esky BRUSHED escs , perfect. I linked one of the power cords to the + of the MOTOR lead on the esc and the other to the -. Next i plugged the esc into a receiver powered up the transmitter and attached a battery ( 3 cell 1500 mah 25c ).

Now for the test , i put the H bow into a table top workmate to keep it from moving and very slowly raised the throttle on the transmitter gently pressing a piece of foam against the guitar wire until it started to cut through the foam ,,, bingo !! It works

https://i.servimg.com/u/f23/16/23/29/97/dscf5011.jpg

Not the best pic in the world , ill upload more if anyone is interested , excuse the messy bed . You can see the process from foam block to first cut , straight to sanding and the piece it will eventually replace.

Ive been using it to rough cut then sand replacement parts but it very easily be moved to cut straight lines for plane parts , curves , 45 degree cuts for taped control surfaces and eventually when i get a little better comabt wings of pretty much any size within reason.


**i will eventually remove the transmitter and receiver and replace those with a servo tester , it should do the job perfectly , i just dont have one yet **

I've finally got around to making a bow for mine scouse its 40 inches long as i needed to cut a few bigger than average cores, Its pretty much good to go after a few test cuts tonight i should be ready to start cutting a few cores out later this week as I'm hoping to get a few flights in tomorrow if the weather is kind to us.
The bow's not pretty to look at but it works and does what i want it to do untill I come across a few better materials to work with.

Good post bud..

Keith

As long as they work m8 doesnt matter what they look like. Which profile are you using to cut ? i read the other thread , clark Y is a good starting point, I was going to buy one of Lees 60inch titans but the postage ( and his bit on top ) was a little excessive for me, the mcclain cores are also nice as is the BIG Maxi swift.... Ill get one done eventually lol the £4 a block orange xps/eps foam from b&q will do for me m far too much fun those wings

Lets just say dont go for lee's 60 inch wing as I should have a few around that size very soon bud, I'll sort ya one out no probs. I have a few profiles cut out Scouse its a matter of what your looking for the wings to do as this would determine the type of core needed.

Weird you posted about the orange blocks, guess what I was playing around with earlier.

Lol i have one here that im playing with just getting to grips with making spare bits for my stryker so i can make spares for a project that will be here hopefully this week.

I have the sipskill and some other one that were recommended to me on rcg , i got them cnc cut by a friend so theyre spot on , both roots are 25cm which is about right i think for a 36-48 inch wing theyll get a try one day, i like my wings floaty i want to take it up to about 500 feet and go and get a cup of tea come back and its still there lol