[moreil]

I've just started building my CNC foam cutter.

Step-by-step progress is being recorded at http://www.homecnc.org/index.php/Cheap_Foam_Cutter

My objective here is to build a fairly cheap machine that's buildable with the tools I have (meaning, no drill press, no lathe )

Hopefully, the page above will be useable as a step-by-step guide for easily building a cutter.

My background is in software, so this real world stuff is a bit of novelty at the moment

I have all the electronics, and have cut the wood so the next step is to start assembly....

My cost to date is around $USD330, most of which is the stepper controller board.

Many pictures at the wiki page above.

[moreil]

Fully finished building one frame (didn't have enough Al tubing to do the other one end).

Now just need to add the motors and it will be working! yay!

[moreil]

dup

[moreil]

My M8 threaded rod is galvanised (or corroded). Which makes it too thick for my M8 nuts.

I started re-threaded it with a hand die, but it's hard going (it's removing quite a bit of metal) and the thought of re-threading 2000mm of rod isn't much fun.

Anyone know of a good supplier of metalwork materials in Sydney, Australia? That's open on a saturday morning...?

[fkaCarel]

Try stainless rod (304). Cost a little more, but there is no galvanising, nor will there be corrosion.

Carel

[moreil]

Sounds like a good idea. I've found a metal supplier that's open on a saturday, so here's hoping they've got M8 threaded rod.

I'm currently using 12mm Al tubing for the rails. I think I might replace that with 12mm stainless steel if I can. (Assuming that the metal suppler will cut it for me. No way am I going to try cutting stainless steel by hand

[fkaCarel]

The problems in handling stainless are a little overrated. You get used to it. The keywords are tools and patience (as in work progress is not linear with adrenaline level)

Carel

[moreil]

What would you normally use to cut it? I'm assuming a hacksaw isn't going to do the trick. Would a cutoff wheel from a dremal make any impact? I suspect an angle grinder would do something but that's probably overkill.

[fkaCarel]

A hacksaw for metal does the trick. Use a quality sawblade from your local industrial supplier. A consumer hardware store only sells tools that have the appearance of tools. Think off the bits they sell for electric screwdriving. If you look very carefully you see them disintegrate if they come within a distance of 5cm of the screw they have to drive

Carel

[moreil]

We went out this morning, in principle to meet a friend for breakfast. We 'accidently' detoured along the way to go to Edcon Steel in brookvale.

Very nice shop! I bought 4 meters of 12mm stainless steel rod. They nicely used their electric hacksaw to cut it into 500mm lengths. They directed me next door to another place to buy the 1000mm stainless steel threaded 8mm rod. Total cost was about $AUD65 which I thought reasonable.

The 12mm stainless steel is unsuprisingly much heavier than the Al tubing, but it's incredibly stiff. I can visibly bend the Al tubing in my hands, but I can't make a dent on the steel rod. It's also got a better surface than the Aluminium tubing (smoother and harder).

I spent a couple of hours putting the other frame together, and then added threaded rod and motors to be first one.

Just connected it up to the computer and yay! it moves!

Moves very nicely actually. No missed steps on the motor, silent and smooth. There's no detectable lash that I can see, but I'll need to measure that properly later on.

Am feeling very chuffed with myself at the moment.

[moreil]

I've extensively updated the step-by-step guide at http://www.homecnc.org/index.php/Cheap_Foam_Cutter with more photos. I've also move the bulk of the photos off into sub-pages so it isn't quite so bad to load (previously, it was loading more than 4 megabytes of pictures

[fkaCarel]

Congratulations! I know the feeling when an effort turns into a result. Bath in it and have a beer. Were you able to totally avoid sawing?

Carel

[moreil]

Were you able to totally avoid sawing?

Carel

Yup! I used the circular saw to cut the pieces initially, and then only did some minor sanding with the dremal later on. No hand sawing anywhere!

I used the dremal with a cutoff wheel to cut the stainless steel threaded rod (only 8mm diameter). The steel shop cut the 12mm for me to my specs.

[diarmaid]

That looks very nice. But Im not sure where the foam goes!!
1) Are you using a heated wire to cut, if so where does the other end of the wire attach to and what holds the foam in place and where?
2)What will you be using to heat the wire and what type of wire?
3)If not wire, what are you cutting with and where does it mount and how?

Maybe its just me...

Edit: Ok, it must be just me, I looked again and thought the diagram might show something but no cigar. How does this work?

[moreil]

Sorry, the photos just show the one frame. There's an identical one that's also built. They're clamped to either end of a table and the heated wire strung between them (attached to the 8A and 8B pieces). The foam is placed inbetween them to be cut.

I'll post a photo of it cutting when I get the hot wire sorted out.

[diarmaid]

Ahhh...the penny drops!...thanks. I look forward to the photos. Nice job.

[moreil]

As previously mentioned, here's a shot of the two frames fully assembled with motors fitted.



I still need to run the permanent cabling for the motors and fit the ballbearings for the hot wire to run over. (Slowed down a bit today: other commitments).

[diarmaid]

Is that HDF (Hardboard for u yanks ) that you built from, or is it hardwood and I just cant see the grain in the photo?

[moreil]

I know it as 16mm MDF or Medium Density Fibreboard. (About 5/8ths of an inch thick I think in stone age measures )

It's plenty strong enough. I was expecting to have to butress the joined between the 6A and 5A pieces, but not required.

[moreil]

I did all the wiring this morning. A very tedious job! It's all fully wired up now and I've been playing with using Foamworks to cut imaginary cores!



Next step is to hook up the hot wire and get it hot. I've currently got some 12 ohms per meter nichrome wire that I was going to use. Any advise from anyone here? Can I just hook this up to a 12V power supply? Will 1 amp heat it up enough?

(web page updated with more photos as normal).