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Flatcam settings for isolation routing

calvine
Sun, 13 May 2018 03:42:59 GMT

Hello Everyone! I have a zen toolworks 12x7 CNC machine. I am using a 0.1 mm tip 30 degree v-bit for milling isolation traces into a single sided PCB. I am using a calculator that says with my cutting depth at -0.125 my effective tool diameter is 0.1670 mm Everything appears fine in FlatCAM's viewer, but my traces are obliterated in the finished product. I am using 0.1670 mm as my tool diameter, so that correct, or because its a v-bit should it be diferent? Thanks for you help!

Marius Stanciu
Sun, 13 May 2018 07:38:53 GMT

Hi, Have you checked your leveling? You may enter into the material more than you think. Try to make the Z_cut value (-0.125) lower and see the results.

calvine
Sun, 13 May 2018 14:48:45 GMT

Thanks for the reply! I am using the z leveing function in bCNC I've tried lower, and it does not seem to cut all the way through the top copper layer. I'll try later today and attach a photo.

Marius Stanciu
Sun, 13 May 2018 15:24:29 GMT

Maybe your online calculator think that you have a tip that is sharp with a tip with 0 dimension like an complete angle. But actually your v-shape bit has a tip of 0.1mm which means that the tip of the so called "cone" is missing. Now, if you use leveling it will think that when it touch the copper is your hypothetical tip and it will plunge 0.125mm when it should plunge only 0.125mm minus the missing piece of the tip. What calculator are you using?

calvine
Sun, 13 May 2018 16:46:08 GMT

http://woodworkerb.com/home/pcb-isolation-routing/tool-width-calculator/

calvine
Tue, 15 May 2018 01:17:57 GMT

Sorry for the Delay! So I tried again with the settings in the screen shots and the board was about the same. I am not sure what I am doing wrong here. [Screen Shot 2018-05-14 at 9](//muut.com/u/flatcam/s1/:flatcam:T6mt:screenshot20180514at9.02.17pm.png.jpg) [Screen Shot 2018-05-14 at 8](//muut.com/u/flatcam/s3/:flatcam:eN8J:screenshot20180514at8.27.06pm.png.jpg) [Screen Shot 2018-05-14 at 8](//muut.com/u/flatcam/s3/:flatcam:JXxD:screenshot20180514at8.28.30pm.png.jpg)

calvine
Tue, 15 May 2018 01:38:42 GMT

Also here is a few photos of the board. [20180514_211530](//muut.com/u/flatcam/s3/:flatcam:jkIc:20180514_211530.jpg.jpg) [20180514_211528](//muut.com/u/flatcam/s3/:flatcam:ukHQ:20180514_211528.jpg.jpg) [20180514_211520](//muut.com/u/flatcam/s3/:flatcam:xAnV:20180514_211520.jpg.jpg) [20180514_211523](//muut.com/u/flatcam/s3/:flatcam:ifpE:20180514_211523.jpg.jpg)

Marius Stanciu
Tue, 15 May 2018 02:05:03 GMT

Could be a few things. Your feedrate may be too high, your spindle speed may be too low, your spindle may have unacceptable runout (or high usage on ball bearings). It's also possible that the board is not well fixed on the table. I don't think it's a software issue.

calvine
Tue, 15 May 2018 02:06:28 GMT

What spindle speed should I go for for this type of use?

Marius Stanciu
Tue, 15 May 2018 08:29:38 GMT

The faster the better ... experiment and find your own sweet spot. Unfortunately, in CNC work there are no universal answers, almost all the time you need to find your own settings, on your own CNC.

davidkitson
Sat, 26 May 2018 03:19:03 GMT

That looks like some of my early boards - From the pictures, it looks like you are not using an autoleveller and so the cutting depth is too much... Some traces look fine, others look obliterated. Also, even at 12000 RPM, I find a 0.1mm 10 degree bit leaves traces that look failed, but when I lightly sand the board with some 1200 grit wet-and-dry, they come up looking perfect and it would even be possible for me to run 3 traces between two 0.1 spacing pads using flatcam, though I mostly set my tool width to 0.0149" and leave it there for both 0.1 and 0.2 cutting bits. Aside from that, I've found that the default cutting depth in the software is pretty much perfect and I've failed to get better results from changing it. Working with it turned out to be the key I needed to get past where you are stuck. So, in case I have guessed right, set up a probe on your CNC software and use Autoleveller 0.77.exe ( https://www.autoleveller.co.uk/download/ ) - This is the old "free" version of the software - It makes a big difference. Second - if using a 0.1mm bit, clean the board wit h a little wet-and-dry of 1200 grit - Don't do it wet but if you need a little moisture, use some isopropyl alcohol. This also works wonders if you clean the board after polishing with a soldering flux pen...

davidkitson
Sat, 26 May 2018 03:20:00 GMT

Board examples in 0.1mm and 0.2mm tip tool, post AUTOLEVELLER077 [Point1mm board](//muut.com/u/flatcam/s1/:flatcam:fDSr:point1mmboard.jpg.jpg) [Point2mm board](//muut.com/u/flatcam/s1/:flatcam:ACYu:point2mmboard.jpg.jpg)

davidkitson
Sat, 26 May 2018 03:21:46 GMT

I'll add that the 0.1mm board looked a LOT like your photographs before I cleaned it up with polishing with 1200 paper, while the 0.2mm board has not been cleaned or polished.

calvine
Sat, 26 May 2018 18:16:18 GMT

Very interesting @davidkitson! I will try the sand paper! I gave up on that machine... I am pretty sure I messed something up while building it and also had a few pretty bad head crashes that I think may have messed up the frame. I bought a 3018 CNC machine from amazon for around $300 and its way better, and the frame is all aluminum! The boards work fine with FlatCAM now. FlatCAM is great!