Hot Wire Question and Fin Material (US)

I’ve seen a few diagrams for hot wire cutters and I’ve yet to see a close-up shot of the bow ends, where the wire meets, and I can’t quite get my head wrapped around what the assembly should be like there in terms of the connections and suspension, or the site, if other, where the wire should be jumped

Anyone have a good close up shot of your good-working hot wire cutter at this point(s)?

Also, just to save a thread: I was thinking a good thing to do would be procure some sheet G10, or some other fiberglass impregnated resin, to cut and shape fins out of, as I’ve seen so many G10 fins shaped by Griffin (over at Surfermag’s “design” forum)

I’m in Texas, so I was wondering if anyone here knew of a US source… or Texas…

Gracias fellows

Thumbs up

(oh on this template the “nose” is the tail and the “tail” is the nose-- drew the thing backward in APS to see if it would work, but in PDF those things are labelled)

McMaster-Carr or other plastic suppliers have stock G-10 in puke green, saving you the trouble of laying it up.

OTOH, G10 is simply glass and a high modulus epoxy (not the RR lam epoxy which is too soft to make G10 like sheet), and you can do your own layups in whichever color you like.

Thanks, that’s helpful–both ways

How hard is it to cut and shape? Pretty tough?

I’ll see if I can get a pic posted later but if I can describe it…

I ran a bolt through the ends of my wood bow on both sides. On the bolt head side I put crimp U connectors over the ends of my power wire ends. I got those ends by splitting one of those cheap extrension cords which I think are actually made to split the two wires. They have a little notch running down the cord. I also drilled a couple of holes through the wood bow to run the power wires through all the way to the center of the bow where it comes out and forms into 1 power cord. I pulled it tight here and tapped up the wire so it won’t slip through and keeps all the cord running through the bow nice and tight.

Anyways, so on the backside of the wood I have the insulated power wires bolted down to the wood with U connectors. On the front side I have a nut to keep the backside tight.

On one side (left/right) I put another nut loosely with room to put a looped hotwire in between the two nuts. You can tighten it down or not. Doesn’t usually make a difference since you should have a lot of tension on the wire.

So you’ve made a loop on one side of your wire just by twisting the end of the wire around itself with your fingers or some pliars. On the other side you make another loop on the end of the wire that is long enough (the wire, not the loop) to go past your other bolt on the other side and curve 90 degrees up the arm of your bow on that side. That loop connects to your spring which is mounted at the top of the bow and stringed down towards the end of the arm. You can put a nut on this bolt as well to keep the wire in place but the threads and the tension is usually enough to keep it from slipping off.

The actual length of your wire depends on how strong your spring is and how far you need to stretch it to get the tension you want.

I guess you really need pics…

LOL! You described the hell out of it though! I got that you used an extension cord for something and split it and it went somewhere! Big smiling at how many words pictures are worth!

3000 words worth of pictures

G-10 is stronger/stiffer than fiberglass sheet, but you use the same tools and will get used to it quickly.

Looks a bit more complicated than mine :slight_smile:

I just have a nail in the end of each arm.

Stripped ends of the outdoor grade 12 volt wire twist around that a few times.

The stainless steel leader wraps around that once and is tied off.

My spring, etc are on the tension arm.

Works fine… Maybe I’ll post some photos if I ever remember!

if you get a chance Doug…your method sounds good too…thanks guys, this is great

if there were a thread (with pics) like this for EPS epoxy glassing and one for shaping concaves, and one for setting fin boxes…

are there?

Ah, Greg Loehr:

Conversely it is quite easy to make a polystyrene blank. You can generally get blocks of foam locally from insulation foam suppliers. The rocker templates are made from 1/8 inch masonite. They are attached to the block with nails and you then slice the foam with a harp, strung with a piece of nicrome wire, that is powered by a variac. A variac is a voltage regulator. For the foam, look in the yellow pages under insulation and look for a supplier of foam. Almost every major city has at least one. For the variac, they are available from Wicks aircraft. They have a nice voltage regulator for hot wiring for about $100. I think they also have wire. They have an online catalogue at The harp is just a piece of plywood cut in a U with the wire strung across the open end. It has to be wide enough to fit across the foam your cutting and deep enough to cut the thickness of the blank. Give yourself lots of room on that one. You attach the voltage regulator to each side of your harp (we use alligator clips), turn the regulator up to about 25 volts and your ready to cut. Set the wire on the templates that are attached on either side of the foam block and push the wire slowly through the foam. When you finish the deck, hook the wire under the templates and pull it through the bottom. It helps to have a fan blowing down the block of foam to cool the exposed wire that’s outside the block otherwise that portion of wire super heats and you break a lot of wires. After you’ve cut your blank, set it on a shaping rack bottom up. Get a piece of hot wire long enough to reach the length of the blank and about 2 feet extra. Attach a piece of wood (these are handles) to each end of this wire. Now attach the voltage regulator to each end of the wire. Now you need to find the middle of the blank and mark it on each end. You need a friend to hold one end of the wire while you hold the other. Set the voltage at about 70. Stretch the wire from end to end on the marked center of the bottom of the blank and turn on the variac and slowly pull the wire from the bottom of the blank to the deck. You now have the blank cut for the stringer. You need five bar clamps to glue up with. For a stringer you can use 1/8 or 1/4 inch Luan plywood which is available at Home Depot. This stuff doesn’t shape great but its easy to find and works. You can also use 3 mil PVC which comes in 4x8 sheets and is available from sign supply companies. Comes in colors and looks great. For gluing Luan you can use good old Elmer’s glue. For PVC there is a glue called Roo Glue that works well. You can probably find that on the web. When you glue up, you wet both sides of the stringer and both sides of the blank line up the parts and then bar clamp it together. And that’s about it.

Crude - but flexible, effective and easy.

Actually I usually prefer the simplest method that achieves the desired result.

I have been meaning to change the wire and tune a couple of other things. I think I can get it to cut faster and cleaner that it is (do we all have this drive to fiddle with these things so much?). I’ll take some snappies and

post em.

As for the rest… Where’s the search function ;D


nice explanation and pics. One question… Are you using the wall outlet for your power source? that’s kind of what it looks like, and I was wondering about the safety of that method. I always thought using a car batery was the way to go from other posts. Never having made one myself, I’m just not clear. Thanks!


Hi Janklow,

Here’s my version, costs about 10 bucks from home depot (not including the wire).

you’ll notice that one side is fixed. Only one side can move like a lever, to increase tension

the wire is just connested to the wood with eyelet hooks, nothing fancy. the wires connect to the hotwire via alligator clips that attatch to the eyelet hooks. You’ll also notice the thimbles, good for going over the masonite template so as not to burn it.

Just a close up.




That would be great! I’m going on some trips this summer, but maybee in August will be planning on an eps longboard. My housemates have been bugging me about it for a couple months, but my HWS project has been bogging everything else down. At this point, I’ll be happy to finish the hws fish by september. I’ll shoot you a PM with my contact info.


Hi Pat,

I edited my post because I realised you weren’t the OP and I didn’t want to assume that you needed a hotwire. But yeah, you’re welcome to pick it up and use it. I just hotwired my first three 1lb’ders and that’s alot of blanks for me to go through so my hotwire’s getting dusty from not being used.



Here’s a nice diagram by that Airframe posted some time ago:

And a pic of it in use:

Again, all credit for these goes to Airframe. I really like the simple straight-forward setup.

My variac has a normal plug outlet on it.

I also have the other end of the extension cord that I cut up that I can plug into if I need to connect to a post type power supply or a car battery or I can just connect the car battery leads to the bolts themselves.

got it.

Thanks Kai.

Here’s another really crude one I did a couple of year’s back.


nice posts!

here is one more possibility for a hotwire cutter:

this one is made of pvc and also cheap on the wallet. (if you go with their desin, remember to cut the pvc pipes wider than they suggest.