CNC Milling Double Sided PCBs Using Eagle, FlatCam and GRBL/Candle, Step by Step Detailed Guide 

Thanks, much appreciated. I'm happy people are finding my little guide useful. Cheers, Jake

Thanks, always happy to hear it was useful.

Thanks! happy you enjoyed the video.

Thanks, it's a good suggestion. It's also quite popular to use a guillotine cutter, but using the CNC for cutout is very convenient even with the mess from adding water, it always gives very precise dimensions in any shape. Cheers, Jake

Thanks, yeah I'm pretty happy with the GRBL controller and Candle, although I'm not sure if the Candle software is still being updated. Cheers, Jake

Thank you kindly!

Hi Richard, to use the auto level feature you need a GRBL board that supports this feature. Most new (GRBL 1.1) boards have this feature and as you suspected it just works like another limit switch letting the software know once the circuit is completed to measure the height. I can do a more detailed video on it as a few people have been asking about this feature. It's essential to use this feature for good circuit board engraving results. Cheers, Jake

Thanks!

Thanks, have fun making circuit boards on your new CNC.

Thanks, yeah Flatcam is a very nice piece of software, but it's a bit quirky and not super intuitive.

Glad to hear it was helpful. Cheers, Jake

Glad you enjoyed it!

Thanks, I've only looked at bCNC, I haven't actually tried using it. I kind of went directly from EMC2/LinuxCNC to Candle/GRBL when it became too much trouble to keep my old PC with a parallel port alive. Usually I only do the height map for the engraving step as I use drill bits with a collar and their depth variation is usually within 0.5mm, which is fine for drilling, but the Candle software will remember the height map, however you might run into a problem if you need tool changes for the drill bits, I don't think it will allow you to zero the Z axis on tool change.

Thanks Manny, 1. Yes, Candle will pause and you have to click continue when you are ready. The tool change position can be configured in FlatCam. I use x,y at 0,0 and then raise Z to 30 mm for tool change plus I have my spindle controlled by the GRBL board so it will auto start/stop for tool change. 2. No need, I always use drill bits with a fixed collar, those are in my experience accurate to within half a mm. Just make sure the bits are seated all the way in and your travel is high enough off the board (I use 1mm, but you could use 2mm) to make sure the drill bits don't crash if the board is uneven. Plus I always drill ~1 mm deeper than the board thickness, to make sure the drill tip makes it all the way through even if there are slight variations in the drill collar position and board height. Cheers, Jake

Thanks, in FlatCam there's an option to define that all holes above a specific diameter should be made using a milling bit. I don't have a video showing the details of this specific feature, but it's easy to use, it will just generate a tool path for these holes and then you can go in a define the milling details and generate g-code. I use the feature to make the larger holes in this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zUJt9sJ2mxU.html Cheers, Jake

@@TheStuffMade thanks

Hi, Thanks, if you use FlatCAM then there is an option on the tab where you configure hole drilling, here you can select what holes you want to mill and what holes you want to drill. I use the mill functionality in this project: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zUJt9sJ2mxU.html Cheers, Jake

Thanks, I'm happy you found the video useful. For the Z axis zero I always make sure the CNC controller is zeroed with the engraving bit at position 0 (touching the board) I always do the zero operation, then reset the CNC controller because the software sometimes have problems if you don't do this. Hope it makes sense. Cheers, Jake

Sorry, I can't tell without more info on the control board you're using. Have you tried asking the seller where you bought your CNC? Cheers, Jake

Thanks, I always keep my track and isolation above 10 mil, then I will usually not have any issues, however no need to keep tracks smaller than what you have space for, so often I will use 24 mil+ for signal tracks and larger for power. For the v-bits I use cheap carbide ones, they are like a rod that is sharpened then ground down on one side, very simple bits. Often sold as PCB engraving bits 30 degrees, 0.1 mm, cost around $10 for a pack of 10. I usually inspect the tips under magnification before use just to make sure the tip is intact, they do last for around 10+ boards before getting dull (you can tell it's dull when the burrs are getting large). Hope this is helpful. Cheers, Jake

Hi, the v-bits can be the reason, I just use the cheap 0.1 mm 30 degree engraving v-bits you can find online for around $5-10 for a pack of 10, they are basically just a rod that is sharpened and ground flat on one side. I have tried 0.2 mm as well, but never got good results with those. I usually inspect the tips under magnification before machining as I have experienced bits where the tip had broken off and it's very difficult to see without magnification. Another possible source of rough edges is the spindle itself, in my experience if you have excessive runout or vibrations then you will never get good results. Hope this is helpful, Cheers, Jake

TheStuffMade Thank you very much for your precision. I was using 10 degrees 0.1 mm v-bit. I have ordered some 30 degrees carbide. Looking forward to more great video of yours. Regards, RJM

Thanks, for PCB engraving I usually use a feed of 80-120mm/min, at 0.05mm depth with an RPM around 10,000. Cheers, Jake

Hi, yes I do recall having the Candle software acting strange a couple of times in the past, now I follow a strict order of doing things and if I deviate for any reason, then I will reload the cnc file, that seems to reset everything. So for engraving, load the file, create the heightmap, do the z probing, apply hightmap and then engrave. I don't really have any recommendations on a good spindle, I don't think the one I'm using is being sold anymore, besides it's a bit weak with only a 50W motor, but it's got an ER collet chuck and very little runout. Most of the cheaper spindles I see for sale are very high RPM and that limits their usefulness a bit. Cheers, Jake

@@TheStuffMade If you get a chance, when you do your next PCB job, could list the exact sequence as that would be really helpful. Thanks. I can then follow your recipe. BTW, I really appreciate videos like yours. Thanks again.

Thanks, yes, it runs close to 10,000 rpm. I checked it recently. I used to run a 30,000 rpm spindle but it had too much runout and the results were not as good.

I use some hardened 1.5 mm pins made from some 100mm rods I bought online, they were quite cheap, just grind a mark in them and then you can break them off in small pieces. I always use Scotch pads to clean my boards, it's rough enough to remove small burs but wont damage the boards.

Hi, I just solder in some cut off pins from through hole resistors etc. Of course this means you have to pay attention when you design the board to make sure you don't have vias under ICs and that the pad on top of the hole can be soldered where needed. Cheers, Jake

Thanks, I bought a pack of small hardened 1.5mm steel rods, I think they were like $2 on aliexpress. They work very well to align the board for double sided and will keep it in place during cutout milling. Cheers, Jake

I used to drill from the top, but there is a small risk when doing the height mapping on the bottom the bit will hit one of the holes, so really the best way is to complete engraving both sides before drilling, so I do flip both the solder side and the drill file as one of the first steps. I remember manually drilling etched boards back in the through hole days, it was quite a task, especially if you didn't have a good mini drill press, CNC makes it so much easier and you can make all the holes the right size.

Thanks, I use some small steel rods like these: www.aliexpress.com/item/4001198086769.html Cheers, Jake

Thanks, the waste board is piece of scrap rubberwood , guess it looks a bit like styrofoam because I've drilled so many holes in it over time :) .. I do take a few mm of the surface every 6 months or so. I also started out with LinuxCNC, but when my old PC with a parallel port died, it was time to look for alternatives and the GRBL solutions looked like the way to go. These days you can get a decent quality GRBL board with USB interface and stepper drivers for as little as $30.

Thanks, I'm sorry, but I cannot give a good recommendation of a CNC machine, I only have my small desktop one I use in this video and a larger DIY CNC I use for wood projects. I don't think the CNC I use in the video is available any longer, but I believe it was sold for around $500 under the name Sable CNC. I got mine second hand because the original owner couldn't get it to work right, I thought maybe just a faulty stepper motor, but it turned out the linear rails were not parallel, so it would bind up and the motors would lose steps resulting in failed jobs. Anyway I can share some general advice on what to look for in a good machine: 1. It should be sturdy, metal construction, no plastic. 2. It should use ball or acme screws, avoid belts. 3. It should not use the stepper motor bearings to hold any of the axis in place. 4. The spindle should have an ER collar. 5. The spindle motor should have minimal runout, also it should not rely on the bearings in a normal DC motor. Anyway, I hope this is helpful.

@@TheStuffMade Thanks for your quick response

@@TheStuffMade I typically

Thanks, the crocodile clips are to detect when the bit makes contact with the copper surface, then I can zero the z-axis very accurately. Cheers, Jake

​@@TheStuffMade I see, thanks for the info.

I've only done it for large round holes, for those you can just define them as a drill hole in the PCB software and then in flatcam you can select that holes above a specified diameter should be made using routing instead of drilling. You can see an example of it in my Tube Prototype Socket video. Hope that is helpful. Cheers, Jake

Thanks, you can use other types of boards, but I'd recommend sticking with FR4 boards as the copper is bonded really well to the fiberboard. If you use something like phenolic board you'll find that the copper layer separates much easier from the board material, especially when you have fine traces and small pads. Cheers, Jake

I mirror the solder side (back) and the drills, the component (top) side should not be mirrored because it's the side that it milled before the board is flipped over. You can see it at around 04:15 where I mirror both the solder side and the drill file as both of those will be machined after I flip the board.

Before switching to FlatCAM I used a plugin for Eagle PCB called PCB-GCODE, I think it's still available. There was also a piece of software called CopperCAM I believe, but I'm not sure if that is still around. However none of these are as powerful as FlatCAM so you might want to have another go at making it work, maybe try on another machine. Cheers, Jake

Hi Pablo, do you know what version of GRBL your control board is running? Cheers, Jake

You have to manually zero X, Y and Z before starting the milling, I do it at 14:35 in the video. Cheers, Jake

@@TheStuffMade Hi Jake, my question is not clear at all - sorry about it! for my machine, after it milled top, bottom, or drilled holes, the drill bit did not go back automatically origin like your machine, i have to manual move it back (0,0,0). what setup or buttons do i have to do? could you give me a hint? thanks again!

@@garynguyen6981 Are you using FlatCam to generate the G-Code?

@@TheStuffMade Jake, I 'm using Flatcam 8.993 Beta to generate the g-code.

@@garynguyen6981 I don't remember 100%, but I believe there are options under Preferences to make it return to 0,0 perhaps tool change X,Y, Z or end move X,Y,Z.

Hi, I'm using 30 degree 0.1 mm engraving bits, basically like a rod ground to 30 degrees tip and flattened on one side. If you use the same and experience issues with rough traces you most likely have an issue with vibrations or your spindle having too much runout. Hope it helps. Cheers, Jake

Hi, my control board is running GRBL v1.1

Hi John, I had a look in their bitbucket, there is a text file describing how to download v8.994 (latest beta). bitbucket.org/jpcgt/flatcam/downloads/FlatCAM_beta_8.994_installers.txt Cheers, Jake

@@TheStuffMade Thanks for that, but still can't get alignment hols added, the newest beta wants a Reference in the PCB alignment sub-section of the 2-sided tool. It has this field pre-populated with "Box Centroid", but this doesn't work and after I enter the two drill coordinates and click Create Excellon Object it says "There is no Box reference loaded, Load one and retry". No idea how to do this, not mentioned in any documentation. No help function no how-to's, generally this is more alpha than beta software at this point.

This is all shown at accelerated speeds, it would be very boring to watch in real time.

The desktop CNC machine I have is no longer on the market, I bought it 2nd hand many years ago, but you can see it in detail at around 13:17 Cheers, Jake

Hi, it's part of setting up the job in Candle, it's in the video around 15:52 Cheers, Jake

Sorry I'm not sure I understand the question. Cheers, Jake

It's a low power (~50W) engraving spindle with very little runout, however it's quite old, I don't think they are sold anymore.

@@TheStuffMade Does a 300W spindle is enough to make a good PCB engraving in your opinion?

10k

Nah, it's just minor inaccuracies from flipping the board over.