Have you trialed anything yet? While I can't give you any specific wire/wire length advice for use with a battery charger (and it appears those who could are taking the weekend off), I can tell you how to test some things. Get some appropriate lengths of various wires you might have and run your available current through them. If the wire heats to failure (breaks), you have too much current for that wire. If it doesn't get hot enough to melt EPS, you have too little. Hopefully you can find a wire/charger setting that produces the correct wire temp. Turn the lights off and look for a pleasant glow from the wire. Test on scrap EPS before cutting a blank. Go slow to avoid breaking wire mid-cut.
surfding meant well, he believes in using the best tools available.
If you used a different wire your charger might power a 24'' length. That's sort of the point here, finding a wire/wire length combo that will work with the OP's existing power supply.
After the Clark Shut down December 5, 2005 I went to the Cerritos College one Seminar on EPS/Epoxy. I was a PU/POLY only builder. My friends Casey McCyrstal and Clyde Beatty were already making EPS boards for years before the Clark shut down. I was a late comer.
Ken from Swegway, Greg Lohr from RR and were very generous in there sharing. I became a EPS convert because of both of them.
I have a lot of respect for Ken so since you had confidence in the direction he was giving you there was no need to try to convience you to take my approch.
It's hard to believe Ken would ever cut out a blank with anything less than a Variac. He probaly has a hot wire CNC as well?
Greg was using a variac in the demostration and made it look real easy. When I went the cheap low income Jerry Springer route I bought a battery charger from Harbor Freight. I had to make two guns for Todos Santos for a big swell on it's way. It took me half a day two make 2 blanks. For me time is critical. If time is not important to you my bad. I tried the Battery route and wasted time and money. I was just expressing my distaste for taking my intial approch.
I love tools and gadets. Doing things the best way is the fun part. I'd rather frame a house with a Hitachi Nail Gun than a Hammer.
Kind regards,
surfding
no waves in HB today so time to make a few boards. Even make an XPS blank with my Variac (15 minutes including glue up)
my battery charger 12v/6v (8 amp I think) does not have enough juice for my 24" hotwire bow.
[/quote]
What gauge wire are you using?
[quote="$1"]
If you used a different wire your charger might power a 24'' length. That's sort of the point here, finding a wire/wire length combo that will work with the OP's existing power supply.
[/quote]
Exactly. Without the ability to vary power output, it's all about wire length and diameter.
[quote="$1"]
Have you trialed anything yet? While I can't give you any specific wire/wire length advice for use with a battery charger (and it appears those who could are taking the weekend off), I can tell you how to test some things. Get some appropriate lengths of various wires you might have and run your available current through them. If the wire heats to failure (breaks), you have too much current for that wire. If it doesn't get hot enough to melt EPS, you have too little. Hopefully you can find a wire/charger setting that produces the correct wire temp. Turn the lights off and look for a pleasant glow from the wire. Test on scrap EPS before cutting a blank. Go slow to avoid breaking wire mid-cut.
[/quote]
Good advice. Thanks. I have all of my hotwire bow materials except the wire. I wanted to see what information I could pick up here first. I especially like the "pleasant glow" tip (serious).
I think I'll get a piece of 2x4 and some brass screws and drill some holes to place the screws at several distances for wire testing -- start long and go short. I haven't made the plywood bow yet so I can adapt construction. For now, I only need a 20" bow gap and can get by with 12" of cutting wire surface if needed.
____
I stepped back from the keyboard this afternoon and got in a sweet session. Being stuck inland sucks. But my line is always clean and consistent, day-in/day-out. I took this up to stay honed for surfing and for:
Just string your different wire types/diameters up and use alligator clips, or even just bare wire ends, to attach leads directly to wire. That way you can adjust length. Only the wire between leads will get the current. If you only need 12''-20'' heated, I'm sure you can find a wire that will work.
Your input is welcome. The mountainboard pictured is a commercial (MBS) wood veneer laminate of some sort (with a “very little” glass in the mix, not much). The deck is 0.5" thick, 8-8.25" wide and 37" long. The deck weighs 5.0 lb.
I have custom rigged it for street riding as a surf-style carver. My physics is very rusty, but at one point I came up with a figure of 1.25-1.3 Gs exerted on the deck in a tight 180 cutback/re-entry (my weight = 190 lb). It probably experiences stress forces, especially torsional, that match or exceed skateboard decks.
While it is the closest thing on land that I have found to surfing, the deck shape is not an optimum design/shape for surf-style carving. It can be improved. I plan to test custom shapes with baltic birch plywood composites first. But I believe I can get the weight down using a composite/foam core lay-up. Ground Industries makes a foam core glass or carbon deck that holds up well to off-road use, but it is not right for surf-style carve either.
I want to experiment to see what I can come up with. I believe I can get the weight down to 2.5 lb, possibly 2.0 lb.
Be sure to check amperage ratings of alligator clips to test wires. The largest alligator clips I could find at Radio Shack only had a 500 milliamp rating. This is not good with a 6 amp battery charger.
Found some larger test clips with a 10 amp rating, but they will definitely bite down on the cutting wire and crimp it – I think I may have a solution though.
I stopped by Northern tool and eqiupment to see what it was that I was using. I bought a few packs because it was soooo cheap…$1.49. It comes with 2 guages 100ft of .20ga and 50ft of .18ga Solid Galvaized Steel Wire. I sure some one will say something about not welding galvanized, but this doesn’t get that hot. Also breathing the wisps of smoke coming off the melting foam isn’y too good for ya. I used the heavier guage, but they both work and they work great with a battery charger. My Bow is aboy 27" wide.
[img_assist|nid=1055576|title=Galvanized hot wire|desc=|link=none|align=left|width=735|height=555]
Thanks for the info. Saw several 100-foot rolls of the stuff at my local farm supply hardware today, 18-24 gauge @ about $3.00 per roll. Now that I have a way to test it, might just experiment with it just to see how it does.
But for my first test, I’m going to try a piece of Nichrome wire somebody gave me a few weeks ago.
I have used a tattoo power supply and works great (make sure you get the 2 amp with up to 15 volts, the 1 amp does not work). These are cheap and will last for ever. Also has a voltage regulator, so you can adjust to the thickness of the wire you are using to avoid burning it and can also control temperature. Also these supplies come with a pedal which is handy to stop and go if you need.
Re-invented? Just using a battery charger to power a hotwire, if possible. If the battery charger “I have” doesn’t work, I will probably just swap it out with a Variac.
MikeDaniel provided some useful insight/suggestions.
I responded to the latest posts as discussion. I appreciate their inputs.
BTW the search feature was dead over the Thanksgiving weekend. I have read many past Swaylocks threads and many from other forums about hotwires.
Re-read my original question. I decided to go with MikeDaniel’s input instead. Please forgive me.
You might want to consider zfennells advice, and stay away from a 1/2" thick , 3# density EPS cored mountain board… Unless you want to fall flat on your face,literally…You should be looking at high density PVC or core-cell foam, with solid wood or glass fiber inserts for mounting the truck bolts through, not eps…imho…
As for hot wire set up’s … Battery chargers work fine, although some of the newer models have an automatic short circuit shut off that might make it useless…
Surfding has offered to mail top quality wire to people. The right wire. The wire that a top pro uses to cut EPS foam. You guys went to the farm supply store and bought wire....???? I have plenty of nichrome wire down here in san Diego if anyone wants a blank cut. You guys can talk all you want about amps and ohms and wire length and whatever....
You bought clips at radio sack? Go to the auto parts store.
Remember I'm mentally unstable.....a Variac....adjust volts....in the US about 110v out of the wall.
20-24 gauge wire (good wire)....24 inch hot wire bow....start at 15 volts go up from there.....my mentally unstable comfort zone is at 17....my friends go with more volts and work much faster. Wear safety glasses please....
I like fire and smoke and red hot wire but it hurts when the wire snaps in your face....no pain no gain.
