Saturday, December 3, 2011

2011, 1202 - YouTube Update

Hello Everyone,
Thank you for visiting our blog and here are some brief links for the most recent YouTube Update (2011, 1202)

Main Link to JacobsOnline -
Step Down Transformers -

I have selected the XFR-1006D as my primary power supply. As a sneak preview, here is the diagram I showed in the video but will be creating a custom power supply within the next month or so.

This electrical arrangement will allow for three power states from this supply - 6v8.3a, 6v16.7a, 12v8.3a - when the DPDT switch toggles the circuit to series (double voltage), parallel (double amperage), & off (single voltage, single amperage.

All that for a transformer under 30 bucks!! (yes yes... there are other costs in the switches, etc, but c'mon 30bucks!)

Stay tuned for more videos!

Monday, November 7, 2011

Large Scale Cutting

Hello everyone,

Just another question on cutting foam..! I've gotten this one a few times before, not necessarily for surf boards, but just larger hand held projects. The questions are in blue, take a look!

I am a surfboard builder and am interested in cutting blanks out of EPS foam -I know nothing about electrical systems but would like to build my own cutting tool- 
what do you recomend for this type  of project?

I'd certainly recommend a large scale hand held cutter

the bow needs to be aproximately 32" inches wide. 

You should easily be able to make this cutter at any length you desire. 

You could even use 3/4" PVC rather than 1/2". The 3/4" will be a bit heavier, but will be more rigid and strong for larger cuts. 

If you want me to make you the electrical end caps, just let me know and I can send them to you. But I will be uploading some new videos tonight, so you may be able to follow along in those and make them yourself. 

what should I use as my power source? ( I have been looking at variacs on ebay)

The variac series are nice. They are an AC power supply rather than the typical DC power, which works well at a wide range of voltages and amperes. has the greatest selection of variacs available online, and they are very reasonably priced. Check out what they have for AC transformers, and you can always get model numbers to see what you can find online.

Be VERY VERY careful when using AC transformers. Typically any voltage above 45 volts can penetrate human skin and cause electrocution. While you'll probably need less than 20 volts, ever, this wont be a problem. But just be careful!

Here are two power supplies I'd choose for your project

The first one SHOULD be enough power for you. It says it can only put out 3.3 amps at 150 volts, but its rated as a 500VA (or watt) transformer. So at lower voltages you should be able to safely obtain a higher amperage.  I'd guess the first one will be more than enough for your project, but the second one will DEFINATELY work!

I  can build the cutting bow but dont know what gauge on nichrome wire to use or if it would be best to use stainless steel.

I would recommend NiChrome, only because it is most reliable and there are known electrical values. (Meaning, we know how much amperes/voltage it requires to heat up.)

I'd recommend either 24 gauge or 22 gauge wire. 20-22 gauge are pretty stiff, so might not be ideal. I've personally used 26 gauge at lengths under two feet, but you should probably use 24 gauge.

the good news is, Nichrome is CHEAP. so you can always buy 24 and 22 and see which you like better.

On the other hand, with the variac transformer you will be able to test out 22 gauge, 24 gauge nichrome, as well as stainless steel if you wanted. The power supplies are hearty enough that they will heat up a lot of different wires. 

Check out this fishing line retailer, they have stainless steel fishing line, that I had a customer use for making RC plane wings. He said he liked it better than nichrome at longer lengths and is pretty cheap too.

here is the link to their stainless steel leader wire page

I don't remember the recommend lb test wire, but I THINK it was between 30-60lb test stainless steel wire that worked the best. But at a few dollars per pack, it's still pretty cheap to buy a variety of wires, and see what you like!


That's it guys! I hope it was some what informative. And remember, all those links are already on the website!


Monday, October 31, 2011

Calculator Question

Happy Halloween!

I just wanted to post a quick question I had from a user that used the Jacob's Online Calculator, found on the website. This is a copy/pasted message from the email I sent back. His questions are in blue, my responses in black.


Please help me to understand your calculator.

Here is a link to the main help page, which may answer some of your questions.

I need the tempereture to be 160 degree celsius.
The length should be around 60cm.
The gage should be 32 because i am using it as a heater.
The diameter is 0.203 mm the volts would be 12 volts .
if I punch this on your calculator 

the result show that I need a power that is =+/- 7 Watt with the current of +/- 0.5 amps . Is this correct ?

So if I go to a shop for my particular application I need to buy a power supply that has 7 watt ,12 volts,0.5 amp.
Is this correct?

You're pretty much correct, yes.

Check out the electrical theory page to reference what I am about to discuss.

Just remember that the VOLTAGE needs to be similar between what you calculated and what is on the power supply. From the power supply, the output voltage is always constant. But the amperage or current flow is a function of the resistance of your circuit. (See Ohms law).  The listed amperage on the power supply is the maximum safe output amperage for that power supply. 

Think of it this way. You need to find a power supply that is 12 volts, but has an amperage rating HIGHER than 0.5 amps. A 12v 2a power supply would work great, because you're always putting out 12 volts, but your circuit will only draw 0.5 amps and it's rated for a maximum of 2 amps.

If you reduce the length of your wire, or increase the gauge, you will reduce the resistance of your circuit. Lower resistance, when you apply the 12v from your power supply, will draw a greater current from the power supply. 

But a long-story-short, find a 12v power supply, and an amperage rating of anything higher than 0.5 amps, id probably say 1 amp or more. 

As for wattage, it is similar. The listed wattage is the maximum safe wattage output from the power supply. 

Watts = Volts * Current
Current = Watts / Volts

If you find a power supply that has just voltage and wattage, just divide the wattage by the voltage and you'll see the maximum safe output current. 


Okay everyone, as promised just a quick note. Take care and don't eat all your candy at once!


Thursday, October 6, 2011

New, new, and redone... Welcome YouTube!

Hello everyone! and happy fall!

For those of you who were directed here from my YouTube page, WELCOME!

I've found it much easier to compose messages within Blogger than I have the retched YouTube description window. Not to mention I absolutely despise the YouTube mail/message system, but hey... what do I know? CARRYING ON!

YouTube Video Description - Update 

_ Shouts & New Banners _
         - Tim with transitioning from
                  - beautiful miniatures conversion work, scratch build, and painting
         - Loden with
                  - awesome terrain, shop not yet open
         - Dave Graffam with
                  - a whole genera of terrain making... PAPER
         - Brandon with
                  - Author of CNC hot wire foam cutter listed on HWFCI
                  - Will build you any wing imaginable!
         - General Splatton & Splatton Studios, check the channels on youtube!
                  - http://youtube/generalsplatton   &    http://youtube/splattonstudios

_ Communication _

I've decided to broaden the use of Blogger to include the following :
         Address - (
         - YouTube Video Descriptions
         - Answers to FAQs
         - Obscure reference data & materials 
         - General website updates & new content

Twitter account - @LetsCutFoam
         - Quick, on the fly website updates

_ New Designs & Content _

- Renamed the cutters to Small, Medium & Large to ease understanding and explanation
- Created all new, printable / downloadable PDFs for all of the cutter designs
         - PDFs available on each design page for the cutter
- New information available through links on the Calculations Tab
         - Revamped the entire calculations section, more user friendly and better point clarification
         - Added information on circuit / electrical physics as well as improved the data in the resistors and rheostat sections

- New foam option?
- Use spray foam for foam cutting, cheap alternative?
- Maurizio from Ibiza, Spain suggested it's use.. maybe some testing in the near future
         - May be a viable option in areas of the world were extruded or expanded polystyrene are otherwise unavailable

_ Terrain Website _

I know I've been throwing out this teaser idea over the last year, but I am anticipating creating a hobby terrain website, much like I have for Just a main source of information, with informative links. The one difference is that this website would be founded upon user submitted content. 

I will have a website that contains the nuts'n'bolts to materials and categories (buildings, fences, rocks, trees, etc). But I will be inviting members of the community to submit videos through YouTube to be posted on the website.

Steve, the Kamloopian, attempted a website where a wikipedia of terrain making was going to be the cornerstone of the hobby community. But after being hacked, it broke him, and he's really left the community as a result. I intend on picking up where he left off...

I have started communications with the Kamloopian to acquire access to his site, and build the site from there. It will be a long process to see if we can work together towards a common goal, but he might give free range too. The big difference with the new style of site is while there is user submitted content, it will be managed and secure.

While the website will not have a STORE, per se, it will have links that may direct you to the submitting-user's own websites / online stores / ebay stores for you to purchase or contract their services. I have been trying to convince to create a new niche for this market, but I have not yet heard a reply, but that will come with time and persistence. 

Thank you everyone for bearing through with this published recap of my latest update video. Please feel free to comment and subscribe to my YouTube Channel and Blogger account. Stay tuned!


Sunday, August 21, 2011

Custom RC Wings (.com)

Hello again!

In my efforts to continuously bring all things NiChrome to the attention of my readers, I had come across a video by one of the subscribers on my youtube account (LetsCutFoam).

Brandon over at has used his genius as a mechanical engineer and aeronautics enthusiast to create a home built / DIY CNC hot wire foam cutter! The thing is absolutely amazing.

Check out the video here :

Now don't get me wrong, I bet there are probably 3 other people that would be able to build on of these set ups, so my hats off to Brandon for what he was able to put together. I have requested that he submit an article for me to add to my new page of "User Submitted Content." It is my first official submission, as everything else is just pictures on people own foam cutters.

I like Brandon's cutter because not only is it a great DIY CNC cutter, it has a lot of really great design features for those that wish to build a manual version of his cutter. Personally, I'm in the process of building a large table cutter for my work shop and have been collecting ideas from around the web. So pieces like this are great inspiration and it's always great to see what other people design. If you take the time to really sit and digest what he has created, you'll have a lot of great ideas you can apply to large and small cutters alike.

As previously stated, I really doubt that many of you will be able to build something like this, and I KNOW I can't. BUT the good news is that Brandon is selling foam cores from his website for RC airplanes! His prices are very reasonable and for what you're receiving is mountains better than what you'd find at many commercial sites. Plus, having the personal touch of a small scale production is worth it's weight in gold!

I'll be adding this website among the latest updates to my affiliates and making a mention on youtube, so stay tuned!


Thursday, August 4, 2011

General Update & New Designs

G'morning everyone!

I wanted to write a quick update for those that might be wondering what is going on with the website and such. Much of this I'll have on my next most recent video update.

I'm sure many of you remember that back at the turn of the year I moved to my new home with it's sweet workshop... While this has been great in feeling like I "get away from it all" when I get home, I literally have gotten away from it all... haha! Not having the availability of internet out at the farmstead has made things incredibly difficult for me to create updates for the website and post new videos. That certainly doesn't mean that I'm not working diligently behind the scenes, but keeping everyone update has become more difficult than I originally anticipated. I am still taking custom orders from customers, and helping users with questions as they come. Just because I'm not posting videos doesn't mean I'm not here to help all of you should it be necessary.

I've started to build a database of users for my upcoming terrain website. I must give many thanks to Kamloopian as he is the grand father of terrain. It's just a shame that when he tried to make a community driven terrain wikia, it was the final straw that broke the camels back when he got hacked. As exemplified through his behavior, he is no longer making new terrain videos.

I intend on picking up where he left off and creating a mass terrain website, but not reinventing the wheel. I intend for it to be a source of information as well as a how-to website. I'll likely utilize many websites (i.e. Beasts of War, Miniwargaming) for their forum aspect, and drive users to those sites for forum based conversations as well as user submitted content. While maintaining my bank of content creators to link videos in specific fields (tree making, grasses, hills, full tables, buildings, sci fi, etc). Should you be one of these people, wanting to submit videos or written documents, please feel free to contact me and I'll add your name to the list.

If you read back in April I have a new cutter that I'm developing specifically for all of you, the hobby foam cutting enthusiast. I am currently in communication with a very well known terrain supply company and am creating a prototype for them. My hopes are that I'll have the yeah or nay within the next two months on the project moving forward. It is all very exciting, and I know I've been incredibly vague with this whole thing, but it's killing me that I can't share more specific details for legality reasons, but it'll be worth it.

Aside from the new hobby cutter I CAN'T write about, be sure to expect new diagrams and projects you too can build for hobby foam use. While videos will be slowly coming out, the website updates are a bit easier and I should have those coming soon too.

I hope all is well, take care

Wednesday, August 3, 2011

Small scale cutters

Hello everyone!

This is a question I receive with some regularity, and figured it not only applied to small scale cutters but also to larger scale projects. The process is the same, but this is a bit more specific. The contents of this blog entry come directly from the email I replied to the user. But when I get an email from y'all regarding "How To" on these custom projects, this email exemplifies my exact thought process and how I'd tackle a project such as this. The blue text is the question from the user. I hope some of you find it useful and can use this blog entry as a stepping stone to your own cutting project! 

Remember these two things as we go through the email :
1.) Voltage from a power supply is constantly output, and the amperage pulled is dependent upon the resistance of your circuit. This is how you use ohms law (Amperage = Voltage / Resistance)
More about this on the electrical theory page

2.) The amperage rating on a power supply is the MAXIMUM safe output amperage.

I'm trying to make a small hot wire cutter that uses only 2.75" of 21awg ni-chrome wire.

21ga is 0.83 ohms per foot, making your cutter a theoretical resistance of 0.19ohms - we'll round to 0.2ohms
Keep in mind the other electrical hook ups in your cutting device will have some resistance, so purchasing or using a multimeter to test the actual resistance might help with choosing a power supply.

21g requires approximately 3-4 amps to heat to a cutting temperature (400-600°F) for most commercially available foams.

This will be important as these values help you choose a power supply

Check out the NiChrome Page for more data

I used 4-D batteries at first, thinking that this will at least get me going, and sure enough it cuts the foam. But I want a continuous power supply and stop using the batteries. Calculating this small a piece of wire has been difficult for me. I tried a DC power adapter that was putting out 6v (similar to the 4 batteries in series) and is rated with 3.3 amps. This would give me about 2 small cuts and then "cut out", no more heat..?

IF you desire battery power in the future, here is my section on battery usage

The reason I included the battery section is because the functionality of a solid state power supply (DC power adapter) are very similar to that of batteries.  Basically, the batteries have a fixed output voltage, and their output amperage is dependent upon the circuit resistance, but the true output current is limited by the battery's internal resistance (which limits the outflow of current). This is why many people can get a small cutter to work with batteries, but not with DC power supply of similar voltage.  

When you hook up a 6v power supply to your device, you need to remember that the amperage pulled from the power supply (and/or battery) is a function of resistance and voltage

Ohms Law
Amperage = Voltage / Resistance
Amperage = 6v / 0.2ohms
Amperage = 30 amps

Remembering that your power supply is only rated safely at 3.3 amps, you have effectively "short circuited" your power supply by attempting to draw 30 amps from that unit. It sounds like your power supply has a built in over current protection, or OCP. 


If your power supply did NOT have an OCP protection, it would have either burned out the internal circuitry OR if given enough time unprotected it would have probably set on fire or melted, lol

When you use batteries, they PHYSICALLY only allow so much output amperage from each battery, dependent upon a few internal factors. Granted, if you over load (short circuit) a battery it will heat up quicker and eventually die quicker as a result. But batteries basically are their OWN OCP just based on the nature of batteries, their chemical make up, and internal metals. Kinda cool.. check out that battery link for more (above).

Any suggestions on how I can make this small cutter work?

No problem at all. Basically you work ohms law backwards to determine your power supply needs OR use that calculator file on the power supply calculations page provided by Jacobs-online. But if you do the first few calculations by hand, it makes it easier to understand what you're actually calculating. 

Ohms Law
Amperage = Voltage / Resistance
using algebra
Voltage = Amperage * Resistance
Remember, your amperage is derived from your desired cutting temperature, check out the nichrome page for more data on each wire's specific requirements. 

For this set of calculations, you know you need 3-4 amps, lets just say 4 amps to make it easy

Voltage = 4a * 0.2ohms
Voltage = 0.8 volts


Voltage = 5a * 0.2ohms
Voltage = 1 volt

Generally speaking, finding a cheap 0.8v power supply is going to be tough. But I'd round to 1v just to make it easier on yourself.

Another thing to consider is that you can add a resistor to your circuit to increase the resistance and effectively allow you to use a greater range of power supplies.

The more resistance you add to your circuit, the greater the voltage requirement. That means if you add resistance, you will NOT change the amperage requirement to heat your wire, but simply a greater voltage from the power supply. Only changing your nichrome gauge or desiring a higher temperature will it affect the required amperage. So if you find a 10 volt, 5 amp power supply, you'll need to add a total of around 2 ohms but still use your cutter length of 2.75"

Lets say you WANT to use that 6v3.3a power supply you have...
Using 21ga, the 3a max might not physically heat the wire enough to cut, but bare with me for the sake of the argument. 

Ohms Law
Amperage = Voltage / Resistance
Using algebra
Resistance = Voltage / Amperage

Resistance = 6v / 3a
"They" say you should never fully use a power supply's full wattage (Volts * Amperage). That supply is about 20 watt max, and i usually drop it to about 90%, hence, 3a
Resistance = 2 ohms

So, in order to use that power supply safely and NOT activate the OCP, you need to have a 2ohm circuit. Being that you only have a 0.2ohm circuit, you need to add 1.8ohms. 

To find the resistor wattage, take joules law
Wattage = Resistance & Amperage
Wattage = 1.8o * 3a
Wattage = 5.4

You therefore require a resistor with a max of 1.8o and a minimum of 5.4 watts.

Because this is going to be tough to find, you can place a 1ohm and 0.75ohm resistor in series with each other, totaling close to 1.8, and then you add the wattage. If theyre 1ohm3w and 0.75ohm3w, they add to 6 watts which is more than enough heat dissipation. 

Check out Digikey's website, which allows you to search for resistors using a set criteria.
through-hole resistors
basically set your resistance, wattage, wire wound composition, and select "in stock" to search


You have a few options for power supplies should you want something a bit bigger and stationary

If you want a solid state (DC charger) power supply that you just plug in and go, you REALLY need a power supply that has some level of built OCP. This power supply is the ONLY one I've found on the internet yet that has it all... and believe me, it took probably 6 months of searching... and ive ONLY found it through this website

While it IS a 5v4a power supply, over-voltage AND over current protection on it. This little thing is the SHIT! I've used it on a few custom projects that I too am working on. Basically the OCP on this unit allows you to keep working with your cutter and it wont clip out or turn off because it's OCP reduces the output wattage to a safe level for the unit. From what I can figure out, it actually regulates the voltage down to create a maximum of 4amp output based on your circuit's resistance but retains the ability to reduce the current if you overload the entire power supply.

I still have to do some testing on the supply myself, but I've used it and it works for me. And for 7 bucks, it is at least worth trying out. If you happen to fry the supply, you're not out a crap ton of money. But I think you might be pleasantly surprised with this unit. IF you end up purchasing this unit, let me know how it works for you, I'd be very interested. 

If you want a variable power supply - one that allows you to vary the voltage and amperage manually, you're going to have to go with a bench top power supply. 
I have some listed on my website
I've been VERY happy with the selection at
They have the greatest selection & the lowest prices of any website ive been able to find yet. I'd probably go with a Linear Power Supply, they have a tendency to be cheaper than a Switching unit

One of the cheapest linear power supplies you'll be able to find is the 30v5a supply

Remember that with these power supplies, you can vary the voltage and maximum amperage with the dials. So I'd set the amperage to 5a, and then just gradually turn up the voltage until your wire is hot. (1-1.5v). Granted, you wont need all 30v, but it allows very low fine tuning. The other thing to consider, is should you ever want to build a larger cutter. This power supply will support very large lengths of wire (10-40 FEET depending on gauge)


Send me an email, let me know what you thought of this article? Did it help you understand how to do hand calculations? Did you learn how to retrofit a power supply? Let me know

The hot wire foam guy

Wednesday, April 27, 2011

New Products


Sorry it has been a while since my last post, but I've been busy at designing new cutters in addition to everything else going on in life..!

I am really proud of my most current design because I feel that it will be able to extend itself to the entire community. All the other designs on the website are easy to make, but realistically are just too difficult and expensive to ship to people across the country and globe... Taking that into account I've been trying to reduce the size of the hand held and table top cutter to become smaller and smaller and smaller so that they can not only ship in a box but also be functional to those that use them.

To give myself a big pat on the back, I've actually come up with a revolutionary design that I think will blow everyone away..! However, there is one catch...

I was about to post my design when I considered the profitability in this cutter. Not so much so that I intend on making millions!! off of my users and subscribers. But more-so that if one of the big box companies see or find my design, they might end up stealing it, patenting it, and selling it for their own profitability.

For this reason, I have delayed the release and production of my current invention and have sought the consultation of a patent agent. We have begun preliminary discussions regarding this invention and hope to have a decision in the near future regarding whether or not I'd want to proceed for a patent or release it to the general public.

I still have a lot more diagrams to make and descriptions to write in order to make it official, but I hope to have everything released to the public in the near future!

So SORRY! for the delay, but it will be worth it to all of us and the community in the end


Tuesday, February 8, 2011

Two birds..?

" If I was to power two long bows at once, would you recommend a dual output power supply or just one larger power supply? "

The only benefit of a dual output power supply is that you would be able to control the temperature of each wire individually, but really foam cutting rarely requires that level of precision. The other problem is that many dual output cutters are a lower overall amperage supplied to each heating unit.

Meaning.. For the money, you could get a single output 10 amp power supply, or a dual output that supplies 5 amps to each output. Granted, many dual outputs allow you to power a single output at full capacity, but what's the real added benefit of dual output? One may argue not having to change cables between cutters, which I suppose is personal preference. 

If you simply place your cutting devices in series, the power supply just sees it as being one long cutter. The amperage requirement does not change for heating the wire, but because it is a bit higher resistance you just have to increase the supplied voltage. So ensuring that your cutter has enough voltage to power both cutters is also important. But again, most cutters only require about 10v at the most.

if you place your cutters in parallel, it will throw off the dynamic of the resistance circuit and alter your power supply requirements. 

Additional information regarding multi-cutters can be found on the website ::
        Multiple Wires
                 ( )

Sunday, January 2, 2011

RC Wings

Hey Guys -

Time for my first blog..!

This will be a quick note just to give y'all some reference on where my next project/update is going for the website.

As many of you will notice, I have a variety of cutters and cutting designs that I had adapted from online sources and my imagination (naturally!) But one thing that I get constant questions on is how to cut foam cores for RC Plane wings.

Now, if you go to the website (, under the links section I do have some other reference websites for RC planes, and certainly send me an email if you have others that you know of. But that would be a great start for some of you.

But what I have found is that there are two ways that people are cutting wings. Some use a bow cutter, which I simply call the Large Hand Held Cutter under my design section. But another is a hand-block system which has fallen into my favor and a few other people that I have helped.

Basically with a hand block cutter, you have a block of wood on the far side of the table (or a bolt) with an eye hook that mounts your nichrome wire. Then the naked wire spans your entire wing to terminate on a wooden block that you hold in your hand. Hence, a "hand-block cutter".

It is a bit difficult to explain, but here are two videos that should help ::

Bow Cutter Method
    ( )

Hand Block Method
    ( )
     This user also has a website ::

Check out those two links. I know that the bow cutter video uses an alternative power source than your normal DC power, but it just goes to show if you know your wire properties and power supply limitations you can make most anything work!

So hopefully I'll have the Hand-Block section completed under the design section soon. Actually, someone who had contacted me through the site (John), who I subsequently made the hand-block system for, will be supplying me with pictures of his rig. He makes the delta series flyers and says they work quite well. That way y'all can get an idea of how they work and I'll try to get some videos going shortly.

__ Update :: 01.08.10 __

The long search is OVER!! 

John was able to find a website that supplies 3" extruded polystyrene, in addition to a variety of other materials, at 12"x24" sections

     ( )

This is great for anyone wishing to have a little more meat on their foam when cutting out a wing!

I have contacted the website moderators and should have a link to their site on hotwirefoamcutterinfo shortly..!

Take CARE!
-carlo, the hotwire guy