Introduction: Make a CNC Hot Wire Foam Cutter From Parts Available at Your Local Hardware Store

Picture of Make a CNC Hot Wire Foam Cutter From Parts Available at Your Local Hardware Store

Make a CNC Hot Wire Foam Cutter from parts available at your local hardware store like HomeDepot . This machine can be used to cut wings for RC planes, surfboards, crown molding, packaging foam and lots more

The original design was built in order to cut RC wings (even tapered wings - where one side is different then the other side)

Polystyrene (EPS and XPS) will cut using a hot wire - other foams - like polyurethane should only be cut with a blade or saw.

When cutting, be careful !!! - wire will get hot, and some people may be allergic to the EPS fumes - always work in a well ventilated area.

Step 1: Over View

Picture of Over View

Most parts can be found in your local hardware store, like Home Depot..
The first prototype was made out of wood, but didn't look "professional" enough, so I decided to go with a more robust design made of steel.

The design can be modified to almost any size. Keep in mind that for longer travel you will need a longer lead screw.
The problem with a long lead screw is that because it its own mass, it will "wobble" in higher speeds.
One way to overcome this problem is to move to a larger diameter lead screw.
Another way is to move to a chain or belt driven design. Belt driven machines are usually 8' and longer but require the use of micro-stepping. An example of a machine larger then 8 foot would be a surfboard foam cutter.
Some surfboards are up to 12 feet in length, the only way to cut these boards would be a belt driven or chain driven mechanism
I will try to cover this topic in the future with a sample machine and pictures...

We started out building a machine to cut wing cores, but soon after we discovered a huge interest in the machine for other industries - like moldings, architectures, surfboards, Logos, props, packaging Willow Sills, Casings, Wainscoat , Fascia, Crown, Parapets, Wallcaps, Pediments, Quatrefoils, Columns

Step 2: The Y Axis - Vertical Axis (step #1)

Picture of The Y Axis - Vertical Axis (step #1)

If you are building the CNC foam cutter for RC wings, then you would
probably need 10" max travel on the Y towers.

If building a hot wire CNC foam cutter for props, crowns, moldings
You would probably want to go with a 4' x 4' (X x Y)
EPS Foam billets are usually 3' x 4' x 8' or 4' x 4' x 8'

XPS foam comes in sheets of about 4' x 8' x (1" or 2" or 3" thick)

If building a CNC foam cutter to cut Polyurethane foam - FORGET IT
Polyurethane foam should not be cut with hot wire, but a blade or a saw
There are CNC foam cutters for Polyurethane that work similar to a band saw
But use a abrasive wire instead of a saw - click here for more information

In this section we will build the two Y posts or towers (Y axis).
The posts can be found at the fence section at Home Depot
You can replace these posts by any other post as long as you
are able to keep them from vibrating during the cut.
Any vibration of the posts will result in vibrations on the wire
resulting in "waves" or not smooth cut of the foam.

The following can be found in the drawer section, you will need two 16" drawer slides
The Home Depot Catalog number for 24" slides made by Liberty 7-81266-18070-4

Step 3: The Y Axis - Vertical Axis (step #2)

Picture of The Y Axis - Vertical Axis (step #2)

The above picture is of the 2"x4FT Post with foot - that's the Home Depot name
Cat num: 204-008 Home Depot num: 6-39426-48607-7

measure 6" from the base, and screw in (or use a rivet gun) the slide to the post

Make two of these units - one for the left side of the machine and one for the right side of the machine.

Step 4: The X Axis - Horizontal Axis (step #1)

Picture of The X Axis - Horizontal Axis (step #1)

This U shaped part (the X axis carriage) will hold the Y axis stud.
Here is the Home Depot Catalog number for the part below:
"Half Base" made by Company named Simpson
Catalog number : C751-973
Home Depot num: 044315-10350
these parts were punched and then bent, when we decided to make our own parts we had
them laser cut and bent - then powder coated

Step 5: The X Axis - Horizontal Axis (step #2)

Picture of The X Axis - Horizontal Axis (step #2)

Drill the 3 holes on the slides (24" slides), and mount the U shaped carriage onto the two slides using rivets or screws.
You will need two of these units, one for the right side of the machine and one for the left side of the machine.

Step 6: The X Axis - Horizontal Axis (step #3)

Picture of The X Axis - Horizontal Axis (step #3)

At this point we have an Y axis carriage which is mounted on the X axis carriage.
We used large 5/8" screws to hold the post in place on top of the U shaped X carriage.

Now make the 2nd one - again you will have a total of two units.

Step 7: The Lead Screw (step#1)

Picture of The Lead Screw (step#1)

Using parts from Home Depot, I could only find threaded rods, I later found
online, stainless steel threaded rods.
For this section, I used a lathe and a set of tap and die.
There may be ways around, but I chose to go the safe route.
We later had ACME nuts made just for us - if you are interested in purchasing
ACME nuts Please visit our online store at
There are a few differences between threaded rods and ACMEs. Usually ACME
have a lower inch per turn.

A later design, we used ACME screws that can be found on ENCO - search for ACME threaded - here is the exact link
Threaded rods

Step 8: The Lead Screw (step#2)

Picture of The Lead Screw (step#2)

If you use a 1/2-10 ACME screw and ACME Nut that means that the ACME screw
will turn 10 times and during this time it will advance 1 inch. If you use 3/4-6 ACME
rods and ACME nut - this means the ACME screw
will turn 6 times and during this time it will advance 1 inch.
When calculating the steps-per inch on a machine you need to know the ACME
value and the stepper motor steps.
For example: using 1/2-10 ACME with a stepper motor driver at 1/2 step - to
calculate the steps per inch follow these steps 10 turns per inch times 200
(which is the usually stepper motor steps per turn) times 2 (this is the half step
of the stepper motor driver) the total comes to 4000. This means that the
resolution of your machine will be 4000 steps per inch

If you decided to go with the ENCO threaded rods, you can buy from them the ACME nut as well. Here is the link ACME Nuts

Step 9: ACME Screw (step #3)

Picture of ACME Screw (step #3)

A simple way to connect between the motor shaft and the threaded rod, is a plastic tube.
A better way is to make this "Coupler" out of rubber - this will help in case the motor shaft and the threaded rod are not aligned.
We later moved to ACME screws that can be found on These ACME screws come is 3' and 6' lengths. Since their diameter is 1/2" and the motor shaft is 1/4" you will have to machine these ACME rods to 1/4" diameter. Use your lathe of stop by at a machine shop and they can do it for you.

Step 10: ACME Screw (step #4)

Picture of ACME Screw (step #4)

Now, make another one just like it, but mirrored.
The last picture on this page shows that the two "T" brackets are facing each other,
This is where the hot wire will connect. For those who wish to mass produce wings,
simply add one or even two more "T" brackets and you can cut 3 cores at a time.

Step 11: The Software

Picture of The Software

There are a few software out there that will run the machine - some need special hardware - we spent months testing and evaluating many of these software and hardware.

1. FoamWorks software will work with the electronics in the package below - has CAD
capabilities as well
2. GMFC - needs a timer module - without the timer the package below will not work
3. Mach3 is a generic CNC router software will work with the package below, but you need to
be able to generate 4 axis g code.
4. KCAM - same as above - generic CNC router software - will do nice PCB boards as well
5. DeskCNC - is an additional hardware board that connects to the PC via the serial port and
its output is the electronics
package below, not very easy to put together but doable.

Online store

All of the software above other then DeskCNC require you to have a printer port on the PC

If you are going to cut wings or simple shapes we would recommend the use of Foamworks
If you want to cut complicated shapes and multiple shapes we would recommend DeskCNC or Mach3. We currently use AutoCAD to draw the shapes, then convert them into G code using DeskCNC, and the last step is to run the machine using Mach3.

Here are some tutorials for all 3 software packages - we have spent many hours creating them, and they are free of charge to use or distribute !!

Step 12: The Electronics

Picture of The Electronics

The electronics is the only part that is "kinda" hard to find.
You can search ebay and look for "4 axis stepper motor driver".
Then you will have to find 4 stepper that will match the drivers - pay attention to the type of driver you are getting. Some will work with Biploar motors and some will work with Unipolar motors.
The last step is to find a power supply. The power supply should be around 24V 5A, but its best to get all of the electronics from one source.
If you can't find anything on ebay try this

The Electronic box works together with the software you choose.
Make sure that the electronics you select can be programmed to accept pulse and direction for each of the 4 axis.
Mach3, KCAM and Foamworks will all work fine
Mach3 will only drive the electronics. Foamworks will also generate a file called "DAT" file, and with this file it will also control the electronics.

Sounds complicated, but take a look at all these web sites and after a while things will start making sense.
Mach3 -
Foamworks -

Step 13: The Stepper Motors

Picture of The Stepper Motors

Bipolar motors
There are only two coils, and current must be sent through a coil first in one direction and then in the other direction; thus the name bipolar.
Bipolar motors need more than 4 transistors to operate them, but they are also more powerful than a unipolar motor of the same weight.
To be able to send current in both directions, engineers can use an H-bridge to control each coil or a step motor driver chip.

Unipolar motors
In a unipolar stepper motor, there are four separate electromagnets. To turn the motor, first coil "1" is given current, then it's turned
off and coil 2 is given current, then coil 3, then 4, and then 1 again in a repeating pattern. Current is only sent through the coils in
one direction; thus the name unipolar.
A unipolar stepper motor will have 5 or 6 wires coming out of it. Four of those wires are each connected to one end of one coil.
The extra wire (or 2) is called "common." To operate the motor, the "common" wire(s) is(are) connected to the supply voltage,
and the other four wires are connected to ground through transistors, so the transistors control whether current flows or not.
A microcontroller or stepper motor controller is used to activate the transistors in the right order. This ease of operation makes
unipolar motors popular with hobbyists; they are probably the cheapest way to get precise angular movements.

(For the experimenter, one way to distinguish common wire from a coil-end wire is by measuring the resistance.
Resistance between common wire and coil-end wire is always half of what it is between coil-end and coil-end wires.
This is due to the fact that there is actually twice the length of coil between the ends and only half from center (common wire) to the end.)

Step 14: Finalizing the Machine (step #1)

Picture of Finalizing the Machine (step #1)

Clamp down both axis, one shown in the picture on the 1st slide.
I use strong spring to keep the cutting wire tight. The spring also keeps the wire tight when cutting a tapered wing.
You can get the spring in your local Home Depot. On some designs I have seen people using a bow instead of the spring design. I got better results with the spring, but feel free to experiment

Here is a setup which I also use on my foam cutting bow. The router speed control can handle up to 15A And the power supply can supply up to 3.5A which is more then enough current for a 30" wire. (about 1.5A) The low voltage power supply is used to isolate the main voltage (110V) from the cutting wire.

Another way to go would be to use an isolation variac - here is a good choice for one
make sure to get the isolation version !!!

Step 15: Finalizing the Machine (step #2)

Picture of Finalizing the Machine (step #2)

The router speed control can be purchased at for about $20
The router speed controller connects to the mains voltage and its output goes to a transformer (should be isolated)
These transformers can be found in surplus stores like

Another way to go is to use an insolated variac - this is better since it provides isolation from the main power.
You can find this variac at
Almost all variacs are NOT isolated, and by being not isolated, the user may get "zapped" if not careful. Use caution when powering the hot wire, try to stay at low voltage (below 50V), in some cased you may need to go beyond 50V - in case you have a long wire. make sure never to touch the wire or the springs.

A hot wire CNC foam cutters as its name - cuts the foam by melting it before having contact with the foam EPS foam - expanded polystyrene at 1LB density can be cut at speeds from 10 to 20 inch per min XPS foam - XPS foam has an innate combination of properties that make it one of the most efficient insulating materials available. The closed-cell structure, responsible for the foam’s excellent moisture resistance, also contributes to its high compressive strength and superior thermal performance extruded polystyrene foams may need to cut at a slower speeds, from my experience, when cutting XPS foam, I use a thinner wire - about 0.4mm. XPS cut are generally smoother then EPS foams.
Another kind of foam is EPP foam (the kind they make the Zagi wing flyer) - EPP (Expanded Polypropylene) EPP foam doesn't dent or break. It has a "spongy" quality to it, so on impact it compresses and pops back to shape

Hot wire:
We started out using stainless steel wire as our hot wire, this will work well, but the wire will not last long and can break under to much tension. If cutting a 2LB foam for a large project, wire breaking during the cut can cause a lot of $$ At a later stage we moved to Nichrome wire. Nichrome wire will last longer and will not break even when red hot. Keep in mind that the wire will tend to stretch when heated, so a spring is needed to keep it from sagging

The software I use is foamworks (
This software is the most popular foam cutting controller software, and also not to expensive (about $50) It will control up to 4 motors and let you cut tapered wings and other shapes, take a close look at the site There is a lot of useful information there, and even a link where people

Step 16: Videos

Picture of Videos
Cutting multiple shapes out of one 4' x 4' x 8' block of EPS foam

Step 17: Whats Next ?

Picture of Whats Next ?

We plan on Building a CNC plasma cutter and explaining how to - step by step


shiblee (author)2016-12-05

If, going for a 4X4 (XxY ) foam cutter, what would be the specification of the

stepper motors?

tbarnea (author)shiblee2017-11-01

Same - NEMA23 motors probably double stack 2V 4A or so

CaptCheryl (author)2017-02-09

Excuse my ignorance, but could this be used on wood as well? Is it 110 or 220?

tbarnea (author)CaptCheryl2017-11-01

a hot wire will only cut foam and some plastics,it would not work on wood :-(

madmark7 (author)2013-06-04

I could not find the exact part by the numbers and there is some 4x6 and some 4x4 half bases at home depot can you specify which is the one ?

Greatvlad (author)madmark72017-11-01

step 4.... second picture..... 6"

CaptCheryl (author)2017-02-09

Amazing, way to go tbarnea. Genius, I would say !!

trebuchet03 (author)2008-07-14

Is there such a beast as a 3 axis hot wire CNC? Can I index the bed and spin 90 degrees? For perspective... I want to make something akin to the photo below - well, a mold for it anyway... I would think, depending on design, I wouldn't be able to cut everything, but it would cut down on hand sanding time :) And I imagine I'd need a belt drive due to the long length... Or maybe I need to make a hot stick CNC and remove material that way....

professioncnc made it! (author)trebuchet032016-04-16

CNC Router is better suitable

tbarnea (author)trebuchet032008-07-15

This would look like a 3D CNC router job

professioncnc made it! (author)tbarnea2016-04-16

4 or 5 Axis 3D CNC router

Pkranger88 (author)Llewner2008-07-18

I run the 3D Prototyping Lab at NIAR. We have a Z406 printer. I highly discourage this technology for anything that needs tolerances or is used for fit of function.

likes56 (author)Pkranger882010-01-09

hi! I was just thingking is there a 3d printer that could produce an aluminum output or any type of metal? things would much esier and more faster in the field of manufacturing and engineering...just thingking how will this things be made, since designs are abundant...and just can't wait when will this things be made or even see how will this machine works.^_^. 

Pkranger88 (author)likes562010-01-09

Direct Metal Laser Sintering is a process that uses a powdered form of a metal, i.e. titanium, chromium cobalt, aluminum, stainless steel, and builds the part layer by layer by sintering the powder together with a laser.  I've priced out an EOS Direct Metal Laser Sintering (DMLS) last year.  It costs around $540,000 and an extra $20K for the titanium setup. 
Other companies make them, but they are still tremendously expensive.  My wife and I were considering purchasing some RP equipment in support of my product development company.

KungFuChicken (author)Pkranger882011-01-09

3d printer that uses tin/antimony solder instead of plastic might be a interesting idea.

likes56 (author)Pkranger882010-01-09

Thanks!..i just saw the video from youtube it was really quick it is from design to its actual prototype....just cant keep on wondering how much faster will it be in the coming future...

KungFuChicken (author)likes562011-01-09

Instead of direct metal sintering, maybe a 3d printer that uses a soldering iron as heat source and tin/antimony solder instead of plastic?

Llewner (author)Pkranger882008-07-18

I don't even see the Z406 on their site anymore. We have been working with Zcorp on a new product manufacturing application and have had no problems with their newer machines. Perhaps your issue has been resolved in newer models.

Pkranger88 (author)Llewner2008-07-18

Rapid proto can be done any # of ways. ZCorp printers are great for color prints, desktop models, form concepts, surface verification (we've done some models from video games, etc. ZCorp Printers are bad for Fit and Function prints due to their anisotropic scaling that results from the powder prints. From my industry contacts, the newer machines have improved the "processing" of the parts, but the accuracy of the tolerances and the quality of finer detail is still an issue. I print a lot of aerospace prototypes with very fine edges, etc. The 310 has a smaller print capacity than ours though it is more automated. If I had it my way, I would have both a ZCorp and a FDM or a SLA machine. What organization do you work for?

trebuchet03 (author)Llewner2008-07-18

I guess it's hard to see the scale from that picture - that thing is about 8+ feet long (that one is not the one I was involved in, but is a great example of the compound curves involved) :p I've used a zcorp machine for printing parts - but, here's an FDM I made a few months ago for this past year's project (second picture is of the model in a water tunnel). Oh, this is a fairing for a human powered vehicle ;) The last picture shows the stacked cross section method...

Llewner (author)trebuchet032008-07-21

Nifty! Actually, my comment was a bit of a joke. I used to build kayak's and know that foam stacking process all too well. ;) But just imagine if there WAS such a thing as a 12' zcorp! ;) Minimal sanding and insta-mold!

Edgar (author)trebuchet032008-07-17

How about the model boat makers techinque, draw a set of slices, sandwich them, then sandpaper them into a curve.

Edgar (author)Edgar2008-07-17

Wait, complex curves can be made, to a point... Just make the 2 points were the wire sticks from, move in angle to each other, i.e. one higher, one lower, then leveled, the to the other side. How? Hummm... Get some 3D wizz to do a program!

Edgar (author)Edgar2008-07-18

...Or see this:
Foam cutter

trebuchet03 (author)Edgar2008-07-17

Check this out

So that's the current method I'm using - but I'd like to save time and potentially some money by making it from a single block of foam - with a decent degree of accuracy :)

Ceriand (author)trebuchet032008-07-17

You could probably make it work with this setup if you added a 3rd axis to rotate the block of foam. Of course, you could only reliably make convex or axially-symmetric shapes.

professioncnc made it! (author)2016-04-16

4 or 5 axis 3d foam cutting cnc router machine

macrumpton (author)2016-04-07

I have to wonder why the author bothered to create this "ble", there is absolutely no information other than somebody made a cnc hotwire cutter, and it can be used to make surfboards wings and moldings, but there is not a hint how.

tbarnea (author)macrumpton2016-04-07

the subject was how to make a machine and not how to make a surfboard

try searching for foam surfboard and foam wings - i am sure you will find the answer

good luck

Deathstick (author)2015-12-30

I'd be interested to see someone build this with these sparse instructions. This is more of a concept than an Instructable. The title is massively misleading, none of the main electrical components can be acquired from a "local hardware store".

Marvinfoamdecor (author)2015-10-02

Hallo everyone; we are eps decor company ; we found from internet 1 manufacturer company about hotwire cnc foam cutter , can you share about this machines comments ?

vicsrc (author)2009-08-26

has anyone built this cutter? how did you connect the horizontal axis to drive the vertical tower?

drderwood.jah (author)vicsrc2014-12-11

Oh great, someone else has asked this too! I'm curious myself heh

vicsrc (author)drderwood.jah2014-12-11

I built one and it was too flimsy to be reliable so I bought a professional one

If you are cutting minor hobby items its ok but if you cut airplane wings pay the price and get a good one

drderwood.jah (author)vicsrc2014-12-11

Can you send me a few images of the way the Y carriage connects to the lead threaded rod if possible. I'm really curious. To the point where I have redesigned the carriage with a welded but in position on a plate connected to the center open section in the U section..

vicsrc (author)drderwood.jah2014-12-11

drderwood.jah (author)2014-12-11

I'm curious to know how you have linked the lead screw to the Y axis, I ran through the tutorial but could not find how it is linked? Am I missing something?

alphasierra (author)2014-11-28

The wobble is a serious problem with this design. The x axis lead screws are at the bottom, which gives the y axis a lot of flexibility to rock back and forth. It would be better if the x axis screws were mid way along the y axis, and support both y axis at the top and bottom with additional sliders.

Andy S. (author)2010-02-10

Is there any one willing to build this CNC Cutter for me I am in northern California willing to travel any were in California looking to cut 4X8 blocks of foam to make crown molding, Thanks

Rototiller (author)Andy S.2013-12-12

I would love to build this project for you while building one for myself. I live in Los Angeles. 818 two o9 four 967

pcjerry (author)Rototiller2014-04-29

Can you Build CNC Hot wire foam cutter machine? I am looking to cut 4'x8' blocks of EPS foam. 571 seven 2 two 4839

tbarnea (author)Andy S.2010-02-10
Hi there
We are in northen CA -

bhaskaradari8 (author)2014-03-14

is there anyone to help by details of dimensions that i sholud use for the above model or else the ratios .?

madmark7 (author)2013-06-04

Taking into account that the instructable says parts available at the local store . Did you use regular threded rod and nuts from home depot as the leaded screw ?
Thank you

tbarnea (author)madmark72013-06-04

Yes - thats correct
you can always go the a larger diameter threaded rod and nut to get higher speeds

burnerjack01 (author)2013-03-11

interesting design. Very clean. one question though: What gauge/size wire did you finalize the design with? My instinct is to go with heavy gauge to minimize/eliminate breakage but will I lose resolution?

Kinnishian (author)2013-01-17

In the instructables, you mentioned "click here for more information" about the abrasive wire type of cutters. There is no hyper link, though. Do you have any suggestions for more info about abrasive wire cutters?

AJMansfield (author)2012-09-23

ACME threads are much better then UTS threads when the threads will be used for moving parts, not just permanent or semi-permanent assembly. ACME threads are more wear-resistant and contamination-tolerant than their UTS counterparts. The reason UTS is good is that they don't migrate out of their holes as much; ACME threaded screws need to be re-tightened far more frequently.

etopsirhc (author)AJMansfield2012-10-20

idk about ACME , if they make the screws the same quality as their rockets i'll pass

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