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CNC PCB 'milling'


philetaylor
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Hi.

I have been doing a lot of research recently into getting a small tabletop 'hobby' CNC milling machine. The prices seem to be very variable (from about £1000 to 'id better sell the car and re-mortgage the house :) '). I guess that the quality is similarly variable??

One thing that peaked my interest though was the use of CNC milling machines for PCB protytyping. I like the thought of no more messy chemicals and light boxes. Obviously though, with something like this the accuracy of the unit becomes critical so I thought that I would ask if anyone has any experience of this if so what machine they used?

It does seem that every machine that I find on the Internet for around £1000 mark have some really terrible reviews mainly with accuracy and build quality so I would be really interested to hear anyones experiences. Many of the 'good' units seem to be in the £5000 bracket which I really can't afford but I would happilly purchase a kit (as long as it has all parts as I have no machine to do any fabrication!)

Cheers

Phil

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Obviously though, with something like this the accuracy of the unit becomes critical so I thought that I would ask if anyone has any experience of this if so what machine they used?

i built my own mini 3 axis cnc mill/engraver before i found midibox and i actually cut my own core board... that was about 2 years ago and i got to drilling the holes to mount parts and decided to just buy a ready made core board from the shop to complete my first project, so i can't tell you how it all worked out yet... it was a fun process though!

-- you can convert board files with eagle and pcbgcode to the cnc programs needed to run the machine and cut or drill boards for you

-- it's messy (way more messy than some etching chemicals)

-- building a machine capable of the precision needed for some of these small traces is a serious challenge!

here is a video of the core board being cut on my machine for an example:

http://www.youtube.com/watch?v=kl0guIkizVQ

if you need any help along the way of the cnc route i'll add my two cents!

-- chr0n1c

EDIT: if someone wants to fix this embeded video, go ahead, i tried to make it work, ha!

Edit: fixed!

Edit: no it's not... I can't find any such video... just find the vid, and when you're viewing it in your browser, copy the URL from your address bar, and paste it between the youtube tags.

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1/8" (.125") diameter 45 or 60 degree v cutters... it's just a hardened drill rod (or carbide bit)  with EXACTLY half the tip ground away after you have ground it to a point at the included 45 or 60 angle.  you only need to mill about .005" or .010 deep, make sure your PCB is REALLY FLAT or bits will start breaking.

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for drilling component holes use a .030" or if your part requires it .062" drill bits.... tiny stuff. run both the endmill and drill bit as fast as the machine spindle will go without exploding.

no joke... i've been running cnc machines professionally for about 12 years, the one in my basement (the one you see in the video above) is just a toy to hone my g-code skills when i am bored!

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I have an old Hewlett Packard X-Y pen plotter data recorder.  It takes analogue voltages for X and Y position and a switch signal for pen up/down.

It doesn't look robust enough to mount a milling head, but perhaps a lazerrrr?  And what would it take me to get g-code to analogue voltage conversion?

Note I'm not expecting to mill 0.000001" PCBs on this - it's just a what-if project.

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