DIY Hot Wire Foam Cutter - Lead Screw & Nuts

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.

There are a few differences between threaded rods and ACMEs. Usually ACME

have a lower inch per turn.

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

The above is a picture of an ACME nut made of brass - we also use ACME nuts made of ACETAL

With ACETAL ACME nuts we get less noise and vibration.

Since ACETAL is also non conductive its a good method of insulating the

hot wire power from the machine

Going back to the ACME screws and nuts - and where to get them:

Due to the huge demand we now offer 36" ACME screws - 3/8-12

The screws are machined on one side down to 1/4" to fit the common couplers.

With ACETAL ACME nuts we get less noise and vibration.

Since ACETAL is also non conductive its a good method of insulating the

hot wire power from the machine

Going back to the ACME screws and nuts - and where to get them:

Due to the huge demand we now offer 36" ACME screws - 3/8-12

The screws are machined on one side down to 1/4" to fit the common couplers.

Search for 1/2"-10 ACME screws or search Google for ACME screws

Time now to machine the threaded nut (not ACME). I will machine its outer side and then thread it. Threading the outer side of the threaded nut will enable me to mount this threaded nut onto the X axis carriage, as well as the Y axis carriage - make 4 of these

Lead Screw : Stainless Steel preferred

Threaded rod  USS/Course Stainless steel 1/4" x 20 x 36"  Home Depot catalog number : 0 30699 48000 5 Lead nut: 1/4" x 7/8"   Home Depot Catalog number:  0 30699 19116 1

Here is what I used for a motor mount

Showing the Barcode

Made out of plastic - easy to saw, drill and strong enough for any NEMA 23 motor

Why use plastic ? Plastic is forgiving, if for any reason the motor shaft and the lead screw are

not perfectly aligned, the plastic mount will bend a bit and the wobble will not be

noticeable on the cut.

A simple way to connect between the motor shaft and the threaded rod.

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 www.use-enco.com. These ACME screws come as 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.

Use rivets to hold the lead nut in place

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.

Now let's put it all together