Hotwire Cutter Power Source/Supply

Don’t believe anybody posting in this thread is saying a Variac power source isn’t the most desirable option.

But it’s not the only option.  Routers, planers, band saws, sanders … and so on, can injure the user.  Resin fumes, glass particles and organic solvents can do long term damage to the user.  I think most understand that proper safety equipment and precautions should be used when building.

But a battery charger is no less a power source than a Variac.  Set up correctly with care and precautions, a battery charger hotwire cutter can be used safely.

It is likely that there are plenty of members/lurkers here who can’t drop a lot of coin to make one or two blanks/boards.  I’m sure there are more than a few who still use hand sanders, planes, surforms, handsaws, card scrapers, a ruler, and a protractor to make their boards. And a large french curve would be a high-tech luxury.

I’m sure Mr. Surfding knows his stuff, but his approach could have been more helpful with a little tact.  I doubt Mr. mike or BgSurfer will be knocking out 30 boards a day for the Surfing Industrial Complex.

If they do, I’m sure they will both buy Variacs, or maybe they will just sub-contract.

battery chargers cost as much as variacs.

I believe he said he already has a barely used battery charger.  I’m guessing Mr. mike already had one too.

The Variac is an additional expense (+ shipping).

I’m not interested in hijacking this thread.

For what it’s worth, I use a 24V AC power supply ($17 Arlec brand) for my 24" hotwire, and I use a 12V AC light transformer (~$8) for my shorter (approx 10-12") railband hotwire (with 0.32mm nichrome). Couldn’t find an affordable variac here in Oz (I won’t do enough boards to justify the expense), but this basic setup works well enough for me.

What kind of amperage are you running in both? Same wire type and gauge for both (0.32mm nichrome)?



Very nice post surfding.  Thank you.

I’m playing with EPS for a foam core mountainboard decks idea right now.  I will be making 2 or 3 surfboards over the next year or two.  I bought a battery charger I barely used 3 or 4 years ago.

I don’t want to buy a Variac and have it sit on a shelf for another 3 or 4 years if my mountainboard idea doesn’t pan out.  I do all my surfboard work by hand, which I actually prefer.  I truly wish I had a fully outfitted shop.  Hold one hand out for wishes and another for manure… (another TX saying).

@ all posters in this thread.  I was doing a standard Google search with the search string below, just trying to convert 0.32 mm Nichrome wire to a gauge value:

“0.32 mm nichrome gauge” 

got these results:,27415,27585,27816&sugexp=ldymls&xhr=t&q=0.32+mm+nichrome+gauge&cp=22&pf=p&sclient=psy&aq=f&aqi=&aql=&oq=&gs_rfai=&pbx=1&fp=9b84a0f9b294c817

This was the first link that popped up (and probably the thread most useful to me about hotwire power so far):


Bottom line, searching and finding good information is purely random -- luck.  If I can't find a way to vary voltage/amperage, looks like 24" of 24 to 26 guage Nichrome wire should do the trick with 12 volts and 6 amps.  Shouldn't be too hard to dial that in.  Might try bailing wire too, just for grins.


Peace and giving thanks,


You want to DUMP big deal..... I'm good....I don't need you....really..... it's no big deal........I'm nobody.

You want to Blow Off one of the top shaper / board builders on this Forum........You lose....................


Hey Surfding.......Thank you for all your information over the years......I've learned quite a bit from you....

...Bailing wire.........nope.........not good....

Dumping… Blow off… lose?

Whoah.  Too much hostility brutha.

I just want to try using the battery charger I have in hand.



Dumping... Blow off... lose?

Whoah.  Too much hostility brutha.

I just want to try using the battery charger I have in hand.



From post #1

....."Anybody know of a way to vary the voltage or amperage output from a battery charger?"............

........we adressed that......It's a Veri......???????? ..........oh som ' thin'......Oh whatever........

No anger my friend.....we're here to help....I'm in San Marcos, Ca.

Post your location..... Hook up with other Swaylock's  members in your area....Don't be shy....You would be suprised who lives near you........

We went down that road.....we failed......we posted.....we've helped people out....No Bad vibes.. Wire matters....

Got it ..............................









I don’t think I am biting anybody’s hand.  Just wanted to use a battery charger that I already have.  In this earlier thread, other Swaylocks members seemed willing to discuss the use of a battery charger – a disscussion related to what I have asked:

I’m a member of many forums and know how it works.  I have been a part of that counter culture you mention for 58 years.

I respect your input.  I am not rejecting anybody.  I am collecting information and opinions.  Multiple perspectives often provide useful/practical solutions.

I had planned on using Nichrome all along.  I find mike’s bailing wire suggestion interesting.

I wanted to see if there was an everyday solution for varying the output of a fixed output electrical power source (battery charger).  While a Variac varies voltage output it is also a power source-- a Variac uses a much higher range of voltages. Stingray seems confused about my original question – his reaction seemed a bit emotional.  

I called Ken at Segway Composites several weeks ago about an EPS foam question.  We started talking.  Hotwire cutters came up.  He suggested using a Variac power source but thought I could probably use a battery charger.  He suggested Nichrome and Inconel wire for a cutter.  He felt that Nichrome wire would be plenty good enough and was cost effective.  Ken is an electrical engineer.

I thank you for your offer of wire and everybody for their inputs.  I might hit you up on that offer,  but I insist on paying postage.



Order a blank from Ken. Problem sloved.

I'm way past confused......

Have a happy day



Ken at Swegway is your answer. Problem solved!

Good luck in your project!

I called Ken for information about the minimum compressive strength for 3-lb EPS to compare with a new material I stumbled accross.  He did not know.  (It is roughly 60 psi.)

We had a very long and amiable conversation after.  He asked what kind of project I was working on.  I was pleasantly surprised that an electrical engineer had time to divert from his day job.

Ken does not make EPS blanks for mountainboard decks.  He suggested making a core from EPS.  He told me it should be easy to do using a hotwire to cut it from an EPS block.  He told me the plan for his hotwire harp was here on Swaylocks.  I told him that I lurk here occasionaly.  Our conversation got me thinking.

I had already planned to make a few surfboards in the next few years.  I decided making a hotwire cutter and playing with EPS for mountainboard decks might be good practice and an interesting porch project.

I welcome further input about varying the voltage/amperage output of a 6/12-volt 6-amp manual battery charger.  Now I am also interested in information about the type, length and guage of wire that would work with this battery charger to make a hotwire cutter.

Thanks to all.



Startin’ to look like … ‘Locals Only.’

Sorry Brah, wish I could help.

BTW Nice deletes Mr. SurfDing …

Guess you should have quoted him Mr. BgSurfer.

**“I’m sure Mr. Surfding knows his stuff, but his approach could have been
more helpful with a little tact.”


Stoneburner: My option as no value to Mr. BgSufer since I would never use a battery charger again after using a variac.  Therefore my comments are not valid in this discussion. I felt that I Hijacked his tread and I was very harsh and had no tact whatsoever. There was no good reason for me to even comment so I was just cleaning the garbage I posted, My philosophy is very different when it comes to building things and the tools that I use or the materials I choose to work with. My experience in this area seem to be nonsensical and unusable to the viewers of this TREAD. With Ken from Swegway helping there was no point in my posting. Mr. BgSurfer has his go to guy so problem solved.


I have a few boards to make today my way.

Here’s one of my Team Riders in INDO getting air on a board made in EPS/EPOXY.

I’m just a surfer/shaper.


Kind regards,


Ken isn’t my go to guy.  He inspired me to try using a hotwire and EPS foam as an alternative approach for my current project.

I called him once about an unrelated topic.  Ken mentioned hotwires.  We briefly discussed them as a conversational topic.  He spent more time on the phone with me than he should have.

Ken suggested I come here to Swaylocks to learn more.

I came here because I think I burned up too much of Ken’s time already while he was on the clock.  Ken did not instruct me about hotwires or the use of battery chargers.  He gave me some basic tips and directed me here for more information.

While I want to use a battery charger, I didn’t find your opinions valueless and non-sensical – sorry you feel that way.  They just won’t help with my small battery-charger powered hotwire/EPS project at the moment.

Based on past threads, I thought for sure somebody would have an answer.




... I would never use a battery charger again ...


So you "started out" with a battery charger.  You said so for sure in one of your deleted posts.

Mr. BgSurfer has spent a good amount of time responding to your posts.