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Author Topic: Zen CNC for PCB Milling Progress...  (Read 3335 times)

knkp

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Zen CNC for PCB Milling Progress...
« on: November 23, 2013, 10:51:41 PM »
OK, so some of you guys know I've been working on the zen - trying to get the machine user friendly enough for us all to be able to quickly and easily prototype our own pcb's. It's not finished yet, but we're getting closer, here's an update:


I originally posted the photo "First PCB Cut Attempt.JPG" on the google hangout when I originally made some worth-while progress on the device.


Unfortunately for the first case, the trace's looked nice from a distance, but a quick continuity test with a multimeter revealed the board was unusable and my method had to be revised. Fortunately, a slight configuration change in pcb-gcode and increasing the width of the trace's from 0.016 mills to 0.05 made a far better result that you see in "Second Attempt.JPG" There are several trace's that made it through the process, but I had to quit the cut early because some of them had been cut through. I think a combination of mechanical rather than software issues are in play right now. Mostly, that I cannot get the PCB to hold still while the cut is taking place. The vibrations are strong enough that even with tape and metallic grips on the side the board seems to move just enough to bring it out of alignment over time. There have been a few good suggestions on how to fix this. My favorite of which was to use a non-stick surface on top of the sacrificial wooden piece to keep the board steady as it is worked on. There is another issue though that I'm not as certain how to solve. It's difficult to see by eye; but it seems that the pcb's we have are not level, each one seems to be bend randomly throughout certain parts of the board. Despite how small of a difference these bends are, they seem to raise the board enough in certain area's and lower it enough in others to vary the cut by a little bit too much. I have found a possible fix online where the drill electrically probe's the board to edit the z-axis and edits the g-code respectively of the pcb-gcode file; however, implementing that looks very difficult and the results have been known to vary by a decent sized margin. Any suggestions on that one would be appreciated.


I also regret to report that in these most recent experiments I did manage to break one of our drill bits. It had a black plastic cover and had the numbers 59 on it. I left it in a blue folder that I found in the box with the other parts related to the zen. I thought I might get a better cut with a thinner bit. It did work a bit, but I let it travel around a corner too quickly.


Anyway, I've also uploaded a video of the machine in action - I've only got a camera that comes on my laptop to work with right now so I apologize for the quality.


If anyone else is interested in helping get this up and going. Please let me know I'd be happy to have a partner on this; it does tend to get tedious on your own.




knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #1 on: November 23, 2013, 10:52:21 PM »
couldn't load all at once: second attempt

knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #2 on: November 23, 2013, 10:54:16 PM »
sorry guys the forum won't let me load any video, apparently it's too big of a file.

johnbentcope

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Re: Zen CNC for PCB Milling Progress...
« Reply #3 on: November 24, 2013, 12:36:16 AM »
Talk to da3v about his tap-off method. It loads the curvature of the board into the computer before generating the cut's gcode and raises/lowers the head accordingly to keep the cut depth even.
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ki4swy

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Re: Zen CNC for PCB Milling Progress...
« Reply #4 on: November 24, 2013, 08:03:34 AM »
those bits can easily be had online, also, you may want to slow the cut down, looks like your going to fast for the material and its causing jaggy cuts ans bit breaking :)
"Good engineers keep thick authoritative books on their shelf. Not for their own reference, but to throw at people who ask stupid questions. Hoping a small fragment of knowledge will osmotically transfer with each cranial impact." - eeguru

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knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #5 on: November 24, 2013, 06:06:49 PM »
OK cool, thanks guys, I admit though I don't know how to determine the size of the bit, I imagine the big "59" had something to do with but but what does it mean? .59 inch or something? Also, da3v right? Cool, is he on the hang-out?

knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #6 on: November 24, 2013, 06:13:55 PM »
btw, I've joined a yahoo groups that deals with this sort of thing (pcb-gcode group if your interested) They had a suggestion for a good set of bits for the zen:


http://www.aliexpress.com/item/Free-Shipping-15pcs-0-8-3-175MM-Diameter-PCB-End-Millinging-Cutters-Drill-Bit-CNC-Router/1127846356.html


Looks like it's specific for PCB milling - though I'm not sure but some of the one's we have already look like these. Did someone already order this set?

P47

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Re: Zen CNC for PCB Milling Progress...
« Reply #7 on: November 24, 2013, 09:04:45 PM »
knkp,


I looked at you bit link, and I think those aren't what you want to use. I would probably use those for drill operations. I remember Dan trying to use those, and they were breaking real easily (especially when using the small ones). And, the small ones of that type aren't small enough to engrave boards with dip sockets or that size spacing. Maybe the fatter ones could be used for roughing in large areas. I gave Dan some D-Bits and V-Bits to try (that's what I use), and his results were much better. There should be some there, and they look like this.



2 V-Bits are on the left, and on the right is a .010" D-Bit.







These give you a lot more strength to engrave, the downside is as the depth of cut increase so does the width, so height is real important.


This Instructables link shows the Zen engraving a PCB and using a V-Bit.


http://www.instructables.com/id/Make-your-own-PCBs-on-an-inexpensive-desktop-CNC-m/


Hope that helps a bit (sorry the pun), and keep up the great work.


~P47
« Last Edit: November 24, 2013, 09:07:37 PM by P47 »

knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #8 on: November 25, 2013, 08:59:55 AM »
Wow! That has the whole process down to the letter!  :D


I was using the v-bits up to this point because they are definitely more stable, but i wasn't sure how we could drill holes into the boards without making the cuts too wide. However, I only saw the thicker one I haven't seen the thin one's yet. I can't come in until I get paid next because of gas but that's just around the corner and that's the first thing I'll do when I get back.


Thanks!

knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #9 on: December 05, 2013, 01:22:55 AM »
Welll looks like we're all gonna be rolling in PCB's pretty soon!


FINALLY Got Autoleveller


Got Autoleveller working!! Now the Zen will probe the pcb for all depths! :D


Although the final result was not perfect still it seems obvious that once I get a non-slip pad or remove the sacrificial piece and tape the board down it will work beautifully! At least this is my expectation - either way it won't be long now....

knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #10 on: December 05, 2013, 01:25:11 AM »
Oh and the shot that shows that:


The sacrificial piece moved a bit because I did not have one of the clamps tight enough which resulted in the damage you see - however had that not happened the cut looked like it would have been accurate enough to cut 3 mil traces.


Compared to configuring the probe and everything else I've had to do this will be a piece of cake.... (i hope)

knkp

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Re: Zen CNC for PCB Milling Progress...
« Reply #11 on: December 15, 2013, 02:26:15 AM »
SUCCESS!!!


The tutorial is now up in the drop box under labtools -> zen cnc


Fair warning, there will likely be a bit of a learning curve even with the tut if you've never worked
on this before. Either way, I hope it's helpful and good luck!

darkmoonsinger

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Re: Zen CNC for PCB Milling Progress...
« Reply #12 on: December 16, 2013, 11:08:45 AM »
Cheers, thanks!

Hybridsix

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Re: Zen CNC for PCB Milling Progress...
« Reply #13 on: December 16, 2013, 11:26:48 AM »
Nice work. :)

Simply7

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Re: Zen CNC for PCB Milling Progress...
« Reply #14 on: December 16, 2013, 02:37:21 PM »
Very cool. I am looking forward to using it.