Printed circuit board, pcb, milling

[ttrikalin]

I know that this is not really relevant to the forum, but it involves a CNC Sherline mill, and it is a stepper motor controller for converting a Sherline lathe to CNC (using small steppers), so why not...

The Eagle schematic is based on the Arduino platform. (Eagle is a wonderful CAD for PCB layout) Conversion of the double sided pcb traces to isolation routing paths in G code was done with the pcb-gcode macro of Eagle. I wrote custom python code to manipulate the G code files (rotation, offsets), but this could had been done from within Eagle.

Here's a short video...

[ame]http://www.youtube.com/watch?v=-fEI4whz16E[/ame]

take care,

tom in MA.

 

[steamer]

Nice Vid Tom!

Gotta get me a small CNC mill!...........hmmmm

Dave

 

[waynes world]

the mill is flying through that circuit board , i have also purchased the pro version of eagle but have not used the program yet nor the machine , good but pricey stuff.
also for the intrest of other programs for the cnc router/mill i will be using vectric aspire cad/cam also seems to be the most appropriate package going for ease of use. btw loved the video footage nice.

Wayne

 

[lazylathe]

Cool Video!!!

I think it has been sped up considerably though!
Look at how quick the air squirt flies in and out...
I am thinking that doing circuit boards takes a lot longer than 3 minutes...

Andrew

 

[Lakc]

That looks like fun! I also use Eagle but I make my boards by the toner transfer method.

 

[agmachado]

Hi Tom,

Very cool this!

I have an arduino duemilanove, other arduino mega 1280... and also two xbee shields for wireless comunication between these two boards... the idea is make a remote control with many channels available!

Cheers,

Alexandre

 

[ttrikalin]

I think it has been sped up considerably though!

Andrew is very right. I have a short subtitle in the video stating that it is sped up by 800%.

This is actually not a very practical method to do a board, at least with my setup. My CNC is kept to slow speeds -- as I encounter missing step problems in faster speeds. For machining it's not a problem -- i typically feed slower than my current maximum. ;D

It is OK for fun, and when the toner is out of ink... :big:

It took 2 hours to do this double sided board... I will post some photos and perhaps a video of it controlling a stepper. Not counting a ruined board where I cut too deep and another one where the X axis had 6 thou of backlash (after a recent cleaning I ... forgot to adjust the backlash nuts on the X axis : ). So a whole weekend ruined. With toner transfer - I can do this in half a day (double sided board with fine traces, tricky to line up both sides.)

Alexandre, yes, Arduino is so much more versatile than BASIC STAMP.

Dave, I do much more manual machining than CNC - but having it helps.


take care,

tom in MA

 

[GailInNM]

Tom,
Very relevant topic for this forum. A lot of us do electronics stuff also in support our shop "toy" modifications. Thanks for posting.

I use Eagle with isolation path output to an old 30 watt laser engraver. Spray paint the board blank with lacquer or enamel and then blow the isolation path away with the laser. Follow with an etch and manual drilling. Have only done single sided boards, but could do double sided if I made a pin locating jig out of acrylic so I could register properly.

Gail in NM

 

[ttrikalin]

very interesting... a laser engraver... I'm already googling.

 

[ttrikalin]

they are quite pricey...

 

[GailInNM]

Tom,
The key word on mine is OLD. Mechanics were worn and the laser tube running about 85% of rated power. New ones normally run about 110% of rated power. It was being retired and I bought it for very little money. One that is about 15 years newer would be nice, but this does what I need to do, although it is a quite slow cutting acrylic over 3/16 thick.
Gail in NM

 

[Tin Falcon]

Tom thanks for sharing. there is so much to learn with this hobby. I went the easy route with the cnc G540. but I am interested in it all. I am an electronics tech by trade. usually remove and replace PCB. occasionally do a little reprogramming (change software settings) . Maybe someday I will make my own pcb somewhere along the list with blacksmiths foundry work , anodizing etc.
the arduino looks interesting.
tin

 

[Jeremy_BP]

I do a lot of PCB milling with a small gantry router. I find that it often only takes about 5 minutes to make a whole board. The long part is the drilling. With a carbite engraver, I can really fly when cutting the traces.

I've been experimenting with lasering the mask for etching with the laser at my local hackerspace. So far Krylon paints seem to be best, but I haven't done too much work with that.

 

[ttrikalin]

Jeremy,
does the router have servos or steppers?

 

[doubletop]

I like it, but I think I'll stick to my own laser based solution.

• Laser print the two masks on laser film,
• staple the two sheets back to back, in register to make an envelope,
• slot in the photo resist board and a few more, staples to hold the board in place,
• 4 mins each side in the UV box,
• Wash down with developer,
• 20 mins in the etch tank,
• rinse,
• drill (now this is where CNC would be useful)

I would worry about all that fibre glass dust in my mill

Pete

 

[picclock]

For resolution, speed and repeatability I use laser printed overhead projector film and photosensitive board with a UV lamp. Two films printed one after the other on a laser printer and stacked together give very high contrast with no pin holes. The UV lamp is an Edison Screw Mercury one down the end of a 3 foot 8" dia plastic tube (soil pipe ?) with a piece of special glass on top which does not attenuate UV. Normal glass is loaded with iron oxide has a greenish tint when viewed from end on, filters UV. Typical exposure 6 mins. Very high resolution results with track sizes to 8 thou easily achievable on 1 oz copper. From the printed mask to develop/etch under an hour, Ferric chloride etchant warmed in microwave to about 30C.

Used to teach at a technology college which had bubble tanks and all the gear, but my home made boards were visibly superior, especially under a microscope.

So fast, and exceptional quality - can't think of a reason I'd do it any other way.

Best Regards

picclock

 

[Troutsqueezer]

I am the Responsible Engineer for a number of projects in a well-known company. For our "PCB's" we are currently down to trace widths of 9um (0.000354330 inches, 0.354330708 mils). Via drill size is down to 67um (0.002637795 inches).

Repeatability is good at around 300 million units @ >99% yield. ;D

 

[Lakc]

Not exactly carrying any current at those trace widths huh?

 

[MachineTom]

On PCB and other stuff Smaller is cheaper, but it seems modern tv, stero's do not live near as long as 20 years ago. The other day I read of a comparaison between a Baker electric car 1907, and a modern electric car. In another 100 years that Baker will likely still be around, but that Chevy will be a chinese coffee can in 30 years as all the electronics in the car will be dead and irrepairable.

 

[doubletop]

Not exactly carrying any current at those trace widths huh?

I'd guess relatively high instantaneous currents but extremely narrow pulse widths so very low mean power

Pete