First experiments in CNC

matt3o · 25 Jul 2014, 17:46

I finally got my CNC rounter and I'm slowly becoming familiar with it.

It's a pretty complex piece of hardware, there are so many variables to get a piece right. Material, spindle speed, motor speed, drill bits, not to mention that you need to be proficient with at least 3 kind of software (CAD, CAM and the actual CNC control software).

It is also a very expensive "hobby", the cnc machine is probably the least of your worries. Good drill bits are expensive and they don't last forever, sometimes you can sharp them and reuse but it depends on type and size. I bought a 2mm drill bit that was alone $30. Then you have cutting oil, grease, clamps, and of course the raw material and since it's hard to make it right at first try, you are going to have a lot a wasted material. Not to mention the cost of the software that goes from free to $5k and more.

That being said... when after 1 hour of setup you finally see this...

... all your efforts are repaid: 24mm sharp! This piece is actually a commission work for a guy here on the forum.

The other side is off by 0.0-something

But for being my very first experiment with acrylic I'm extremely satisfied. I know it may look something really simple... but I have to start from somewhere

and I hope you can see the potentiality

This weekend I hope to be able to work on a poker wooden case, then I'll start working with aluminum. A new world of custom keyboards is opening up

If you have any question or have any suggestion, please hit the reply button

Muirium · 25 Jul 2014, 18:06

(He's also experimenting with PCBs, folks. The first of which will be a wireless compact keyboard…)

How many dimensions can you work in? Is it all 2D, like laser cutting, or can you chamfer cases and such? And can you work on folded acrylic?

Questions questions! There's a lot for all of us to learn here.

matt3o · 25 Jul 2014, 18:20

I'm still fighting with gerber files, but yes this weekend I hope to make my first PCB too.

The cut can be actually 3D. It's very easy to do what is called 2.5D (basically carving or bas-relief), but I can also do 3D preparing a good setup. So the case would be a single, solid piece of wood.

Not sure what you mean by folded acrylic

Muirium · 25 Jul 2014, 18:27

A single solid piece case, you say? Oh yeah, that's real CNC!

You're right about acrylic. I was confused, and didn't remember that it can be heated and curved into new shapes after being cut by CNC. I'm thinking about how to make little inserts for holding controllers and such, especially inside classic keyboards.

matt3o · 25 Jul 2014, 18:29

show what you need to do, I'm sure we can find a solution

pyrelink · 25 Jul 2014, 18:31

I assume when you say 3D and a "solid piece of wood", that you can start with a block, and the CNC will basically carve out the entire damn thing?! That's very cool. Will definitely be quite an advancement in everything from prototyping and even production of small projects. Can't wait to see all that you come up with.

matt3o · 25 Jul 2014, 18:40

pyrelink wrote: I assume when you say 3D and a "solid piece of wood", that you can start with a block, and the CNC will basically carve out the entire damn thing?!

yes, exactly! I totally have to carve a Han in carbonite

pyrelink · 25 Jul 2014, 18:45

matt3o wrote:
pyrelink wrote: I assume when you say 3D and a "solid piece of wood", that you can start with a block, and the CNC will basically carve out the entire damn thing?!
yes, exactly! I totally have to carve a Han in carbonite

That would be awesome!

Muirium · 25 Jul 2014, 18:46

This thread plus this thread = you can guess my ideas!

matt3o · 25 Jul 2014, 18:54

ah alps... of course

mashby · 25 Jul 2014, 19:52

Very, very cool matt3o! You never cease to amaze me and I can't wait to see what you create next.

Zekromtor · 25 Jul 2014, 20:42

Looks like a nice edge finish, I'm assuming you didn't have to polish/flame the edge after. Are you using a single flute routing bit designed for plastic? What RPM?

lowpoly · 25 Jul 2014, 23:03

Awesome. Which machine did you get?

Grond · 25 Jul 2014, 23:12

Very interesting, I'd be curious to see some pics of the machine in action!

beltet · 26 Jul 2014, 13:07

Looking forward to more testing from your part. Very interesting!

matt3o · 28 Jul 2014, 19:36

made my first wood-case experiment today. this thing is fantastic

unfortunately I made some errors in the setup and I don't have much to show apart from the 3D model... but given time and dedication you can do really impressive things.

The piece of wood (that in CNC is called "stock") was too tall for my drill bit, very rookie mistake and I had to stop the milling process. I will be using the wasted material for keycaps and try again with the wood case when I get more wood blocks.

And this is where I had to stop it

@lowpoly: the CNC is an "upgraded" Chinese 40x30 router (PM if you want more info)

Muirium · 29 Jul 2014, 12:27

How long do you think a case would take the CNC to make, once you hit start?

And I am intrigued by these potential wooden caps!

matt3o · 29 Jul 2014, 12:33

Muirium wrote: How long do you think a case would take the CNC to make, once you hit start?

And I am intrigued by these potential wooden caps!

Approx 30-35 minutes for the roughing phase and another 40-50 for the finishing. You probably can make the finishing path (this is how it is called) way faster since wood can be easily sanded. I need to buy a bigger bit, though. The bigger the bit the faster the roughing phase.

Muirium · 29 Jul 2014, 12:35

Not bad. And what about caps: how many do you guess you could CNC in an hour?

matt3o · 29 Jul 2014, 12:46

Muirium wrote: Not bad. And what about caps: how many do you guess you could CNC in an hour?

caps are pretty quick to do. depends if you want them engraved with some fancy design or just the raw keycap. If the piece of wood is already of the right thickness you can probably have around 25-30 caps per hour. Wood has to be treated afterward anyway (sanding, sealing, varnishing).

CNC is not properly for mass production but more for prototyping and small/high-quality run. That being said, I want to try to make a 60% keyboard with two tones wood keycaps, probably cherry for modifiers and poplar for alpha.

Muirium · 29 Jul 2014, 12:59

A true cherry keyboard.

Zekromtor · 29 Jul 2014, 15:36

Zekromtor wrote: Looks like a nice edge finish, I'm assuming you didn't have to polish/flame the edge after. Are you using a single flute routing bit designed for plastic? What RPM?

^ don't leave me hanging man. Give us more specifics!

matt3o · 29 Jul 2014, 16:23

Zekromtor wrote:
Zekromtor wrote: Looks like a nice edge finish, I'm assuming you didn't have to polish/flame the edge after. Are you using a single flute routing bit designed for plastic? What RPM?
^ don't leave me hanging man. Give us more specifics!

whoops I'm terribly sorry. totally overlooked your message.

I cut it with a very sharp bit (2mm), actually designed for metal. The trick is to find the right speed of motors and spindle. Fast enough not to melt the plastic, slow enough no to break the acrylic.

In my case was 1000mmpm and 10000rpm. 1000 is probably too fast for small details, though. Probably 800 would be better but still fast enough.

PS: the cut was completed in two 1.5mm paths.

Zekromtor · 29 Jul 2014, 18:22

2 flute or 1 flute?

I've been doing my acrylic cuts on the high end of the recommended SFM, 600 f/min. Getting very smooth cuts at 18.5k RPM w/ a 2 flute uncoated end mill .125" dia at 90 IPM. By two 1.5mm paths do you mean the depth of cut? That'd be a .06" DOC, and I've been limiting myself to .02", maybe I can push that more.

I like to get my starting numbers from FSwizard and tweak from there. Polycarbonate is the material selected, it machines very similarly, if not a little worse than acrylic.
http://zero-divide.net/index.php?page=fswizard

matt3o · 29 Jul 2014, 18:51

the bit is 2 flute.

as you probably know each machine requires different values.

1000mmpm is approx 40 IPM. I believe 90 IPM is too fast if you need to do small details, but good enough for large areas. My spindle is 800w/24k and I tend to always keep it under 18k.

1.5mm is probably too much as depth of cut but the bit was brand new and sharp as it could be. 0.5mm (0.02") is really too small imho, I cut aluminum at 0.5mm, but you run your mill way faster so it makes sense.

Zekromtor · 29 Jul 2014, 20:48

Agreed. I was having fun pushing the machine to the limit and seeing how fast I could still get quality finishes. I use compressed air with a mineral oil mist for cooling, lubing, and chip clearing, which helps in that regard. For best results I'd slow it down slightly.

matt3o · 30 Jul 2014, 00:19

out of curiosity, have you tried any machinable wax?

Zekromtor · 30 Jul 2014, 01:44

Nope. Is that firm enough for actually protoyping or is it just to test your toolpaths?

matt3o · 30 Jul 2014, 08:36

Zekromtor wrote: Nope. Is that firm enough for actually protoyping or is it just to test your toolpaths?

yes it is pretty stiff, it is normally used to make molds, but I can't find a company in Europe to get some at a reasonable price.

cookie · 30 Jul 2014, 10:10

wooden Topre Spacebar, I am in!