DIY CNC Machines

[Altra]

Qiaozhi,
My cnc is a recycled automated IC wafer tester. It came from
Applied Materials in San Jose and was going to the crusher.
Lucky for me a friend saved it.

I added the z-axis, motor drivers and RS232 interface.
Very useful for cutting out panels, making widgets and engraving pcb's.

For lots of diy builds, check out CNCZONE.COM forums. Many machines on ebay also.

If anybody wants to start a thread under off topic or general, I would
be happy answer any questions.

Here's some stuff I have made

[Qiaozhi]

Qiaozhi,
My cnc is a recycled automated IC wafer tester. It came from
Applied Materials in San Jose and was going to the crusher.
Lucky for me a friend saved it.

I added the z-axis, motor drivers and RS232 interface.
Very useful for cutting out panels, making widgets and engraving pcb's.

For lots of diy builds, check out CNCZONE.COM forums. Many machines on ebay also.

If anybody wants to start a thread under off topic or general, I would
be happy answer any questions.

Here's some stuff I have made

Now I'm jealous ...

Recently I've been looking at various hobby CNC milling machines, either as complete units or as a kit. The complete units are so horrendously expensive that a kit, or a build from the ground up, seems the only way to go. There are several DIY units on youtube - some better than others - but it would be good to know what other members here have done. In particular, I'm interested in PCB milling / drilling and making "widgets".

[WM6]

Qiaozhi,
My cnc is a recycled automated IC wafer tester.

Here's some stuff I have made

Very impressive machine.

Two questions:

- how did you fixed "PCB" material used for sensor from 1st pic before grinding/cutting it around (through middle hole?)?,

- how many two sided PCB-s of say about 10x10cm (4x4")can last one drill before you need to change it?

[Altra]

Two questions:

- how did you fixed "PCB" material used for sensor from 1st pic before grinding/cutting it around (through middle hole?)?,

- how many two sided PCB-s of say about 10x10cm (4x4")can last one drill before you need to change it?

Question 1 - I use tape or a few clamps on top of a sheet of scrap wood/plastic material.
The holes are drilled first, then the outline is cut. On those parts I used a screw driver to hold each one in place for the final cut. In production you can draw thin tabs which hold the part in place.

Question 2 - I don't know. But I think quite a few. All the V cutters are solid carbide and stay sharp for many cuts. Carbide steel is very brittle and will break if dropped on the floor or you try to take too heavy a cut.

The trick to engraving circuit boards reliably is a "floating head" attachment. This maintains a constant cutting depth on uneven pcb material. I'll post some more info later.

[Altra]

Here are two videos. The first is with a home built machine and no floating head attachment. Everything has to be perfect or the cut will be too deep/shallow. The bits tend to break often.

http://www.youtube.com/watch?v=4xBU9NyhaNY

http://www.imsolidstate.com/archives/category/cnc

The second video is a low end commercial cnc router with a floating head. I copied it almost exactly on my machine and it has made pcbs easy. Never break bits anymore, constant depth of cuts.

Denford probably wishes they hadn't posted a video of their proto. On the net forever

http://video.google.co.uk/videoplay?...57761193093037#

Official video

http://www.youtube.com/watch?v=7pWzlk9_DYU

Here's my clone. A new micrometer adjustable one is in the works

[WM6]

Thank you Altra, very much.

Those floating head is really a good idea.

As I understand from Denford official video, they engrave PCB and bore holes in one step, without changing grinder/cutter and adapting his depth? Is it true? How?

What material is cutting drill suction and distancing ring of? Out of Teflon (PTFE)?

[Altra]

The official video skips that step, they have to change bits. Thats why the first video is great to study, it shows all.

The nose cone on mine is nylon. You could use teflon, polyprop, delrin etc.

Photo of the three main pcb bits I use. From right to left
Right- Drill bit for thru hole components
Center - carbide "v-bit" 60 degree, used to cut the copper isolation between traces
Left - Router Bit used for cutting the pcb outline

Second photo adjustable floating head, needs more work

[Altra]

The only other diy floating head project I have found.

http://www.robio.be/cnc/final/index.htm

[WM6]

The only other diy floating head project I have found.

http://www.robio.be/cnc/final/index.htm

Very clear pictures.

How positioning with floating head perform? Isn't someway difficult, cause spindle is not really well visible?

Sorry but I do not understand your micrometer fitting and functioning (look at pic):

[Qiaozhi]

The only other diy floating head project I have found.

http://www.robio.be/cnc/final/index.htm

OK - I understand what the floating head is supposed to achieve. i.e. to make sure you get a constant depth of cut across the whole surface. But I have to admit that I don't understand how this actually works. I couldn't find a satisfactory explanation by googling.

[WM6]

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

[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

[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?

[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.

[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.