DIY CNC Machines

[Qiaozhi]

I'm surprised no-one has mentioned the Lego CNC machine on youtube ->

http://www.youtube.com/watch?v=Cf6mWQ8QreA

Not powerful enough for milling PCBs, but amazing none the less.
There's also another one made with Technik (search for it).

Now ... look at this beauty ->

http://www.youtube.com/watch?v=CQzoGTbPrSM&feature=related

It's being used to cut some gantry supports. So it's upgrading itself!
I've never seen such a clean and spotless workshop.

[Qiaozhi]

Hi Altra, how can you positioning drill to start drill trough hole PCB (after changing grinder to drill) if you use floating head. Do you remove floating head for drilling hole, cause drill is pretty invisible under plastic ring? Or this is all software solved if PCB remain on constant position?

From what I've seen in some of the videos, you drill all the holes first, then mill out the isolation tracks. The PCB is left in place during the changeover.

[WM6]

Hi Altra, how can you positioning drill to start drill trough hole PCB (after changing grinder to drill) if you use floating head. Do you remove floating head for drilling hole, cause drill is pretty invisible under plastic ring? Or this is all software solved if PCB remain on constant position?

[Qiaozhi]

Thanks for the link. That looks pretty cool, not sure how good it would work on pcbs? If it was cheaper I might order one.

Those motors will do pcbs and widgets without problems. The motor drivers are more critical.

Add:
This is a good starter kit, although the motors are a bit smaller. He also has ones with larger motors.
http://www.ebay.co.uk/itm/Value-CNC-...item231ee73085

Part of the challenge has got to be designing and building our own custom stepper motor driver board ... and then using the prototype circuit to mill out its own PCBs.

[Altra]

Thanks for the link. That looks pretty cool, not sure how good it would work on pcbs? If it was cheaper I might order one.

Those motors will do pcbs and widgets without problems. The motor drivers are more critical.

Add:
This is a good starter kit, although the motors are a bit smaller. He also has ones with larger motors.

http://www.ebay.co.uk/itm/Value-CNC-Kit-3Axis-Stepper-Driver-Board-Nema23-1-86Nm-Motor-24V15A-PSU-CD-/150842323077?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item231ee73085

[Qiaozhi]

Qiaozhi, Do you have a link for the spring loaded attachment?

Here's a video ->

http://www.youtube.com/watch?v=RYLtL1R440E

Do you have an idea of how much torque is required for the stepper motors?
You can purchase lots of 3 stepper motors at a time on the UK eBay site for £75 plus shipping. These motors have a torque rating of 3Nm (425 Oz-in).

http://www.ebay.co.uk/itm/3-X-Stepper-Motor-3-Nm-CNC-Mill-DIY-/250808317000?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item3a65573448

[WM6]

Qiaozhi, Do you have a link for the spring loaded attachment?

Probably link you posted in post #8 lead to such things.

Citation:

"I attached a second slider on the Z-axis. This slider is forced down with 2 springs and is upwards floatable. This flotation allows constant depth engraving across the material surface even when the material is not perfectly flat. The engraving depth is adjustable with a precision screw ring."

[Qiaozhi]

If somebody in the uk want's to build one would be happy to go 50/50 you do electrics and electronics and i can build head and do machining. Have workshop with lathe and milling mc's. Made a start with cnc a few years ago with a compumill and compucut but never finished it off.

That sounds a great idea. Let's do it!

It doesn't need to be a large machine for PCB milling and drilling. Let's say maximum working area of 8" x 6", unless of course you want to make PCB coils.

[Altra]

During my searches I also came across references to a spring-loaded milling attachment. Can this be used to achieve the same result?

Qiaozhi, Do you have a link for the spring loaded attachment?

[Altra]

If the drill head is actually resting on the PCB surface, how does this arrangement stop the copper from being scratched?

It does leave scuff marks, but without damage. A little polishing with steel wool or a brillo pad and its clean. Thats with a plastic nose cone.

The Elektor floating head looks like it uses a metal nose. The high priced routers from Accurate CNC use a polished stainless steel nose, shaped like a horse shoe.

[woodbob123]

If somebody in the uk want's to build one would be happy to go 50/50 you do electrics and electronics and i can build head and do machining. Have workshop with lathe and milling mc's. Made a start with cnc a few years ago with a compumill and compucut but never finished it off.

[Qiaozhi]

Here's the Elektor PCB Profiler kit ->

http://www.colinbus.com/en/toebeh_profiler_en.htm

The relevant Elektor articles can now be downloaded for free. The Profiler Pro article describes the addition of a floating head.

[Qiaozhi]

Now I understand. This also explains why some milling machine seems to have the drill head really close to surface of the PCB, with the result that you cannot see the milling taking place. The machines that clearly show the drill in operation are therefore presumably not of the floating head variety.

If the drill head is actually resting on the PCB surface, how does this arrangement stop the copper from being scratched?

During my searches I also came across references to a spring-loaded milling attachment. Can this be used to achieve the same result?

[Altra]

Its a mind twister at first, but actually simple. WM6 I think you are close. No spring, gravity does all the work. See below photo of Denford. I am tired, more on this later

[WM6]

Simplified draw on how floating spindle work (is this OK Altra?):