i just got finished hotwire cutting out some blanks and i can’t believe how long it took… like 45mins a side… i am using the hobby train trans method with nicr wire, not sure on the voltage etc. or wire size… any how how long is it taking you?
also if you have a photo of an off cut please post it too… i want to see how flat others are getting their cuts. mine are wavey and a pain to sand out… i figure there has to be a better way then what i am doing or people wouldn’t do it…
thanks
45 min!? Too slow. My wire moves about 1/8 - 1/4 inch per second. They key to clean cuts is temp and velocity control…cool, slow and steady is better…but 45 minutes is too slow.
And make sure your wire has some tension, keep it reasonably tight.
15-20 minutes, not including breaking wire and restringing, to cut the deck and hull rocker profile for a 19’6" paddle board.
Turn up the heat! If you break too many wires try to get a thicker gauge NiCro wire. I am running about 5 minutes a side for a longboard.
Slicing should be nice and smooth. If you accidentally lift up the cutter and and get a lateral ridge go back over and re-slice the ridge.
Gary
Jip,
I would think you need to be able to control your power supply better. Sounds like your not getting the wire hot enough for starters. Can you post a picture of your bow? How tight are you getting the wire?
Check this webpage for ideas and formulas on how to determine how much voltage or amps you should be using: http://www.morelectric.com/nichrome.htm
What I’d like to know is what is the temp that the wire should be for cutting 1# EPS. Anyone know? I emailed Insulfoam but never got a reply back. I’m sure they know though.
jip,
Come by and borrow my industrial wire cutter. Should take 45 second per side and if the bottom will match your rocker templet guide for the wire cutter. Should be a perfect as the guide you make.
warmest aloha,
cp
I use 5mins a side tops. I still think that’s a little slow. Have some way of tensioning the wire on the fly as it steches as it gets hot. Make sure the wire is in contect with the guide you are using for the rocker. Get a friend to help you.
regards,
Håvard
thanks all for the advice… i thought something must be wrong. my slices look like hell and i caculated that the one blank i made would cost well over $200 for the cutting and smoothing alone…
i have a new hope…
jjp
some handy advice…always test a new technique…in the long run it saves time and money…
…Check this webpage for ideas and formulas on how to determine how much voltage or amps you should be using: http://www.morelectric.com/nichrome.htm
Thanks for the reference to some useful tables. However, I also noticed that they claim that nichrome wire is often used “…for cutting foam (Styrofoam, polyurethane, etc.)…”. This is the first time I have seen a hot wire recommended for cutting urethane foam. My impression has been that one should not use a hot wire on urethane foam as it generates a toxic gas (as I recall, this statement was made in the instructions for building one of Burt Rutan’s Vari-Eze homebuilt aircraft). Do you know if this is correct?
Also as I believe that it’s a thermosetting plastic rather than a thermoplastic foam, I would suspect that “cutting” urethane foam would actually be a “burning” a cut, rather than “melting” a cut as with polystyrene or polyethylene foam.
mtb
1st-don’t worry about nichrome wire. Stainless steel works fine and comes in a lot of different guages.
Raise your power (volts or amps - my power source is a car battery charger that has 3 settings: 6v/2a, 12v/2a. 12v/6a ) until it cuts fast, then if you break wires, get the next size up wire. I never break wires anymore.
I saw this tip somewhere, maybe here on Swaylocks, and it makes a huge difference in cutting good, flat lines: Put a little mirror on the far side of your bow so you can see both rocker guides at once. I have almost no recutting of high spots now that I use a mirror.
I cut out a 6’ fish, top & bottom a week ago or so. Took about 10-12 minutes per side. 10’ longboards take about 20 minutes. If I push faster than that, the wires are at risk and any time I gain in cutting fast, I lose in restringing.
It takes about ten minutes to cut both sides with 2# foam (shortboard). About 5 minutes with 1#. Use 20 to 25 volts and use 22 to 25 gauge nicrome. Heavier wire is tougher but burns out a lot more material. Use nicrome 80 if you can get it. 60 is OK if you can’t. Run a fan over the block to reduce the heat of the exposed wire coming out of the sides of the block. Waxing your templetes will allow the wire to glide better and provide a cleaner cut. Will also save your templates. Push the harp on the deck and pull through the bottom. This will keep the wire tight against the template on each side.
DO NOT hot wire urethane. It releases TDI and other lovely toxins.
We do sell variacs for anyone interested… Same ones we use.
I know there is a bit in the archives regarding template material, but since I have your attention… what would be a good template material when cutting at faster rates with hotter temperatures? Hardboard/masonite/etc.? Looking for home depot-available materials.
1/8th inch masonite
Thanks Greg.
That is what I thought, but I figured that asking a dumb question would be better than lightin’ stuff on fire in my in-law’s garage 
If you are having a hard time getting proper sized nichrome wire, try stainless. If you still can’t find any of that to use, go to a luthier, or any music shop and get a few guitar strings. sometimes you can get free 2’ pieces from the luthiers, as it is too short to use on a guitar.
Hi, i haven’t checked the clock, but i do estimate 3 to 5 minutes per side…and i think i’m really slow!
I use a very very cheap wire, it’s a fishing wire, you can find at local fishing shop in different diameters, attached directly to a 24V 1Amp transformer .
Flavio