Hotwire Tools

Been some good posts lately, lets continue the stoke.

A good friend helped me out with some eps blanks, so I decided to make my own hotwire setup. First things first, I needed a power supply.  After a bit of looking online, I decided the most flexible setup for me was to use a computer power supply I had sitting around. The site below has a neat calculator that can help you estimate the approximate voltage and current for various gauge wire of different lengths.

http://www.jacobs-online.biz/nichrome/NichromeCalc.html

I decided I wanted approximately up to around 15 amps, at 3 volts and 12 volts DC.

Technically I would need variable voltage, but I designed an addon to my computer power supply that does PWM output to get varying current at the voltage output from the power supply. Specifically I used the 3.3 volt line, and the 12 volt line. I then fed them into a N-Mosfet, which is basically a switch. I then used a microcontroller to switch it on and off. Then the duty cycle determines the amount of current going through the wire. The duty cycle is controlled through a potentiometer, that is read from the microcontroller. I ran the positive lead through another chip that detects the amount of current going through the wire, and output that to the led display.

It works pretty well, here is the parts list for the main parts;

led pushbutton $1.5 16mm Illuminated Pushbutton - Red Latching On/Off Switch : ID 1442 : $1.50 : Adafruit Industries, Unique & fun DIY electronics and kits

led display $9.95 Adafruit 0.56 4-Digit 7-Segment Display w/ I2C Backpack - Green [STEMMA QT / qwiic] : ID 880 : $9.95 : Adafruit Industries, Unique & fun DIY electronics and kits

arduino microcontroller $7.95 Adafruit Trinket - Mini Microcontroller - 5V Logic : ID 1501 : $6.95 : Adafruit Industries, Unique & fun DIY electronics and kits

20 amp current sensor(ACS712) $5 http://www.allegromicro.com/en/Products/Current-Sensor-ICs/Zero-To-Fifty-Amp-Integrated-Conductor-Sensor-ICs/ACS712.aspx

10K audio taper potentiometer $2 radioshack

10K resistor, 0.1 microfarad capacitor, 1 nanofarad capacitor, banana plugs, banana plug outlet, circuit board, dpdt switch, spdt switch rated at 20amps, fuse holder 20amps, project box $20-30  radio shack

It wasn’t too hard to put together, and if you can build a surfboard, mix resin right, use a planer, this is doable. What I liked about this method is , if the smoke goes out of any part I can replace it. It also works with any pc power supply. I didn’t alter any of the internal parts of the power supply. Also Pc power supplies are pretty robust as they are designed to be run constant for several years, at more than the current needed for my hotwire setup. I will post a circuit diagram later. 

 



Another note, buying alot of one off parts from radio shack adds up quickly. Look online, or in a parts store, and you could probably spend alot less money.

Now I have a power supply, its time to make some tools.

I decided to make a railband cutter, and “band saw”. The band saw was inspired from seeing Barry’s multiple stringer glueups. They look awesome, I gotta try some boards like that…

I made both tools adjustable by using T-track from woodcraft.

One note of caution. It is metal, and conducts electricity, so you have to have the different ends of the wire on different pieces of track. Otherwise it is real easy to work with, and I got a pack of the nurled knobs with the bolts to attach the wire with, real easy to use. 

For the wire I went online to acp composites, and got tekoa sizzle wire and some inconel wire. Other guys have had success with stainless steel leader, etc…, but after reading a bunch of rc airplane forums, they recommended getting a good quality wire. It wasn’t that expensive. I also ordered some composite carbon fiber strips 6 feet long for a couple dollars, for a project.

http://www.acpsales.com/Sizzle-Wire.html

For the spring, I went to city mill and picked up a screen door spring, about 1 1/4" long, maybe 1/4" in diameter. Make sure the wire gauge of the spring is thick enough. I bought some other springs too that ended up not being heavy duty enough.


So I made a bunch of tools does it work?

Yep, it does. The wire cut pretty fast at round 1.8-2 amps. The only reason I have some wandering, is because I have to make a better guide for putting the foam through. Otherwise, can’t wait to get back to making surfboards.

 

Cool stuff!

Very nice Melikefish! Would this design be adaptable to running off a car battery or a different type of 12v supply? -J

If it works for you and you are happy that’s all that matters.

I got a variac for free…looks like this http://www.ebay.com/itm/Powerstat-3PN116B-Variac-Variable-Autotransformer-120V-10-Amp-/191206599872?pt=LH_DefaultDomain_0&hash=item2c84cd2cc0

I just plug it in and spin the big black dial. I’m sure there’s Labs all across the county with unused Variacs taking up space. They are heavy so beware of shipping…

So… do what makes you happy… And please wear safety glasses or a face shield. When a red hot wire snaps it will fly towards your face. I had a close call…go slow , start with low voltage and work up from there…Use the search box at the upper right hand side of the page. Surfding has posted lots of great information…so has Airframe…

Thanks everysurfer, pretty stoked when it actually worked.

Jrandy: This will work with any dc voltage, the specific parts I have, I think will work up to 30v DC. A 12V battery would work great. If you don’t need the current display, you can just use a 12v DC led dimmer switch rated for the right amperage. It basically turns the voltage on and off to vary the current.

Stingray: Appreciate the safety tip, don’t want to pick out melted wire from my face.

Glued up the pieces today with gorilla glue, and colored the glue blue. Came out nice, with the exception that my hands are going to be blue foe a bit.

Welp, going to turn this into a build thread. more stoke less chatty cathy, i believe is the terminology. Caughts some waves in the dark tonight, kinda the same feeling shaping, not entirely sure whats going on but you paddle, make it, and there you are. there may be better ways to do it, but this is how I am going to do it.

used the perfect amount of blue gorilla glue in the center  decided to go to town on the outer strips, and went overboard.

when i glued the outer strips on, i put them around an 1/8" lower then the center as a channel from nose to tail.

came out ok, next time will tape it off like I have seen in other posts.

This is my first time working with eps, but so far i like it. mixed the templates of two of my favorite boards,

got the round tail from one of my hpsb, and the front half from my tomo-esque board.




gorilla glue is brittle

ask charlie

there’s other options like roo or even some super flexible RR epoxy

Cool, thanks Oneula.

I went to a bunch of places this weekend looking for roo glue, and couldn’t find it. Does anyone on island sell it?

Thanks,

Jason

Been a while since I have posted; kids, grad school, and a trip to kauai cutting into my surfboard building. Here goes my progress. I got some 2" thick blue dow foam from Lowes and cut it in half with my hot wire, so it was 1" thick to put on the bottom. Glued it on with more gorilla glue. I used about every thing in the carport to weight it down onto the foam.

Then used my hotwire to remove some foam to get to the exact thickness of the board I wanted. Used the rail cutter to get my rails. I learned on this design that if you want to build the rail cuttter you need the wire in the middle, which I was shown in other threads. Otherwise when you go down one side it will cut the rail a little different. 

 



While I was hotwiring the deck out a little bit, I had some screaming kids, and rushed things. Put a big gouge by the tail. Sanded it out and epoxied in a piece of cork. I am curious how it will work out, the cork will be internal, but should add some toughness to the back foot when stomping down. 

Now the rails are shaped, a simple single concave in the center, and the board feels light and good in my hands. The way I have glued all the foam together has given it a nice flex like a fast action fly rod.

Now it is balsa time. Gotta say, gettin on swaylocks and meeting some really good people has made it possible for me to attempt to make my own board. 

 I received some tutelage, i.e.

Vacuum Bagging 101

Vacuum Bagging 202

Vacuum Bagging Balsa 303

etc…

 from a good friend. 

We put 1/8" thick on the bottom, did rails with 1/16" and then did the top. I had sawed off the nose prior, and am going to try and do the wooden nose block again. Hopefully this time will look a little better.

This board is a mix of the backend of a 5’11" hpsb with round tail I love, and the front of a second board I made. 




is charlie helping you out?

looks like his new no nose builds

i have tom sullivan’s video on vacuum bagging eps cores

its old school and for sailboards, but it the only video I ever found on vacuum bagging composite cores

if you’re interested PM me with an address

Keith said he saw you in town when he was here

still out of action but let me or my brother know if you need stuff

charlie taught us well

its all out sharing

 

I have a vacuum setup that you can use if you want. If you remember what Charlie did you should be able to do it, or I can help you. My brother made the pump, but I did some of the plumbing and it needs to be redone (leaks). I think I have everything needed to bag a board.

PM me or email me and we can talk about it. I live in St Louis Hts, so I’m close to you.

Actually looks like you already did the wood.

Did you get some of the swell this week, I surfed Diamond Head Monday, it was going off but it was a bit bumpy. I surfed Courts yesterday and it was going off there too. Courts is such a perfect wave, but the crowd is a hassle.

that looks really cool. can’t wait to see more progress.

Hi Oneula,Sharkcountry, 

Charlie has been helping me out alot. Definitely a good man, which I do not say lightly. 

I brought the board over to his house and the nose was almost like a gemini, but just didn’t look right. It was not pretty. It got cut off:)

I have to thank you guys too, because he gave me some of the wood from your yard that you guys had cured. It is light, and has a pretty cool look to it. I am going to make the nose block using that, and put two strips of koa right on the tip. 

It was pretty cool surfing with Keith. It was small at lighthouse, but fun to talk story.

I did get out in the water a little. I was teaching some friends how to surf on Sunday, and Monday, and didn’t get a full surf session until Tuesday. I will tell you though, towing people from your leash for a couple hours two days in a row, is a pretty good workout.

Diamondhead on tuesday was real windy, and the swell had a weird direction. Surfed passed lighthouse towards waikiki and was just nasty. Today I went to tongs/ricebowls, and caught a couple nice ones. It was much better. I have to start trying ala moana side. I need a break from the tradewinds. Glad to have some swell again.

Sharkcountry, 

I live in St. Louis Heights also. Not far at all:)  Let me know if you ever need an extra set of hands when you are working on your boards.

 

Jason

I have quite a bit of that wood at my house, so if you want a bigger piece let me know. I still have several uncut branches about 3’ long maybe a bit longer and up to 4" or 5" in diameter.

What street are you on? I’m near the top of Noah Street, about 3/4 of the way up the hill.

that’s probably a piece of the wiliwili tree (hawaiian balsa) we salvaged from iolani palace years ago. The story is here on swaylocks somewhere. The backstory ended up even uglier but you live and learn,

should have plenty of mana (spirit) in that wood since it came from a tree several hundreds years old that sat right in the front of Iolani Palace until the wasps(that’s why its wormy like agave) got t it and it had to be cut down. So sad that we could only save maybe a dozen large branches, but at least we saved that much.

One thing about wiliwili though, it was know to be honey for tigersharks (mano). Hawaiians used it for the ama’s on their koa outrigger canoes because of their floatation capabilities.

seems like my brother is making a new board under his house in the dirt every two-three weeks so you both should be at home togethor up on the hill.

And you are right, Charlie is an inspiration. Good man, good family, great heart and spirit.

pm sent.

Oneula,

That is really neat story associated with the wood.  It is definitely going in the board. Hopefully the men in grey suits will give me a pass.

I haven’t lived in Hawaii too long, but really like to learn the history and the culture. I looked it up on the Bishop Museum, and found this for anyone else that is interested.

Mele: Hula Mano (performed as ko‘i-honua, no instrumentation, hula noho). Auwe! Pau au i ka mano nui, e! (Alas! I am seized by the shark, great shark!) Lala-kea niho pa-kolu. (Lala-kea with triple-banked teeth.) Pau ka papa-ku o Lono. (The stratum of Lono is gone,) O ka ai ia e ka mano nui, (Torn up by the monster shark,) O Niuhi maka ahi, (Niuhi with fiery eyes,) ‘Ōlapa i ke kai lipo. (That flamed in the deep blue sea.) Ahu e! au-we! (Alas! and alas!) A pua ka wili-wili, (When the flowers of the wili-wili tree,) A nanahu ka mano (That is the time when the shark-god bites). Auwe! pau ai i ka mano nui! (Alas! I am seized by the huge shark!) Kai uli, kai ele, O blue sea, (O dark sea,) Kai popolohua o Kane. (Foam-mottled sea of Kane!) A lealea au i ka‘u hula, (What pleasure I took in my dancing!) Pau au i ka mano nui! (Alas! now consumed by the monster shark!) (Emerson 1909:221)

 

On another note, there have been several times on the weekends in the past, when I was pretty sure I heard the sound of planer in the distance from my lanai. I thought my ears were still ringing from using mine. It would be funny if that was Sharkcountry.

 

Might have been me. Someone below me was using a planer a while ago too. I don’t use the planer that much. When I do I also use loud shop vac.