CNC drill/mill for cutting PCB - Page 1
Forum section: electronics / projects

author: iceisfun
author_rank: Regular Contributor
timestamp: October 12, 2013, 07:05:47 am
content: I've built a XYZ table and have it working quite well, but I'm not sure what people are using for a drillThe plan is to do some PCB drilling and cuttingAnyone have suggestions?I would like something with good mounting holes

author: toli
author_rank: Frequent Contributor
timestamp: October 12, 2013, 07:22:14 am
content: My machine uses a dremel, and I've used it on some PCB's as well. I have some 0.8mm end-mils for the holes and a 0.2mm 30degree V-cutter for the isolation (sometime I use a 1.0mm cutter when I need thick isolation). To cut the boards out of the copper clad I'm using a 1/8" bit that I've purchased to use on aluminum panels and it cuts through the copper-clad with no problems at all. I usually do this in a 2 run process of 0.8mm depth each - just so it won't make as much noise.Mine is a relatively simple machine I've built about a year ago:https://www.youtube.com/user/16anatoli/videosIt had some modifications made after I took these videos, but I didn't update the youtube channel.

author: GeoffS
author_rank: Unknown
timestamp: October 12, 2013, 07:26:54 am
content: As you'll be using small drill bits, you'll need a fast drill, at least 20000 rpm.I have a Proxxon drill/grinder (similar to Dremel) and it's very good.Check out small die grinders as well.

author: WarSim
author_rank: Frequent Contributor
timestamp: October 12, 2013, 07:48:46 am
content: Nothing stopping you from buying a spindle built for this very job. If you do buy a purpose built spindle, insure there is minimal slop in your frame. Rapid movement due to slop decreases it's life.

author: awallin
author_rank: Frequent Contributor
timestamp: October 12, 2013, 07:52:56 am
content: Some pictures showing a proxxon mounted in place of the original spindle on an LPKF machine:http://www.anderswallin.net/2012/12/lpkf-protomat-s91-pcb-mill/You will want very repeatable Z-height when changing tools. Even with a good collet/chuck where you always push the cutter as far up as it goes and then tighten the V-groove cutter for cutting isolation tracks usually requires some test-runs after each toolchange to get the Z-height right. The one I uses is designed to cut 8mil (200um) grooves nominally. If you design for a deeper groove and don't need narrow traces/tracks then you can relax the tool-height tolerance a bit maybe.

author: johansen
author_rank: Super Contributor
timestamp: October 12, 2013, 08:39:24 am
content: I've had no problems drilling pcbs at 6700 rpm and 1 inch per minute for .040-60 drill bits. my spindle will run at 10,000 rpm but its rather loud.

author: WarSim
author_rank: Frequent Contributor
timestamp: October 12, 2013, 01:09:08 pm
content: Quote from: johansen on October 12, 2013, 08:39:24 amI would not consider 40mil to be small. 10,000RPM would be able to move the cutting edge fast enough to cut properly. When the bits are small 4-10mil the spindle needs to be much faster just to allow the cutting edge get to it's required speed. For example I use 10mil bits at 35,000 RPM. Other than cutting edge speed requirements path imperfections shouldn't exceed more than 1/10th of the process speed which should be no more than 2%. These generalized speeds can be exceeded but in general will cause shorter tool life.There are many factors, to consider when figuring out how small of tool can be used. Slop, runout, tool edges, tool type, accuracy, repeat ability, etc.the final determination of the right process speed is find the speed between tearing and burning of the coper layer. A microscope is the best way to dial in the right speed.

author: iceisfun
author_rank: Regular Contributor
timestamp: October 12, 2013, 07:00:18 pm
content: Ok this gives me something to work with.I thought maybe there was some magical source for awesome CNC heads with nice bolt holes that would magically line up with what I needStarting out I'll do something simpler while I find the correct head.I really need to get a cutting rig to cut some PCB pieces to finish the machine, I'm using PCB to make brackets for some encoders. Its kind of lame having to build a half built machine to cut pieces to finish the machine, I feel like I'm bootstrap compiling Mono...

author: jamiechi
author_rank: Contributor
timestamp: November 12, 2013, 07:22:39 am
content: Check out the Sherline Mill/Lathe website. They have some high speed spindle options. You can purchase the Z axis seperately with motor and controller ready to go. They have several different mounting options for their spindles.

author: poorchava
author_rank: Super Contributor
timestamp: November 15, 2013, 09:44:21 am
content: I've built a cnc mill myself and I also had some problems with picking right spindle motor. Here's what I've tried:-Black and Decker power drill: no speed control, quite a lot of play in the bearings. On the bright side it was compatible with a standard 43mm mounting brackets-Dremel knock-off bought in Castorama. Battery operated and thus only for emergency use. Non-standard mounting (some fancy thread, which I've moulded with epoxy and made a 'bracket' that way. Tools only up to 1/8" shank. Rather loud, heats up after about 30minutes of work.-Proxxon rotary tool. I think it was FBS-12, but I'm not sure, it was borrowed. Very quiet operation, but somewhat low power at low RPM (easy to stall the motor). Seems kind of fragile, so high feed 'hogging out' the material is probably not a good idead (haven't attempted that, the tool wasn't mine)-Kress 800FME. Very good tool. 800watts of power, very high build quality. Has an electronic regulator which maintains RPM no matter the load. I have never managed to stall it. The downsides include non-standard collets (standard 1/8" for small tools has to be bought separately) and EXTREME levels of noise at high rpm. At low RPM it's fine, but as you approach the max setting, you can hear it through 3 brick walls as if a jet plane was starting next to your head. My crappy clock indicator showed about 0.02 of runout. Costs around 150€, but it's worth the money. Fits a standard 43mm bracket. I have successfully milled various plastics, acryllic, pcb and all sorts of wood and its derivatives. I've also attempted aluminum, but this wasn;t going so well due to flimsy construction of my machine. I know that people have milled aluminum alloys with this spindle motor.My machine doing front panel in ABS plasticSome other machines milling Al alloys:You can also try chinese brushless water-cooled spindles. They are very quiet, but cost isaround 300-400€+shipping+inverter.For PCB it's also important what kind of toolbit you use. For drilling you want carbide bits only. They are quite expensive in comparison to HSS ones (like 1.5€/pc vs 1€/10pcs) and smaller diameters are brittle, so no free-hand usage. HSS gets dull extremely quickly (i mean like after 2 dozen of holes you can see the difference with naked eye) when cutting fiberglass laminate. Anything 0.7mm and smaller should be run at max RPM (at least that's what gave me good results)For milling I'd recommend multi-flute serrated edge endmills, like this one:http://www.frezycnc.eu/pcb-online-catalog/drilling-milling-and-routing/contour-router-bits-for-pcb/diamond-cut-endmills-for-pcb/. You'll also want to have a good chip&dust evacuation system in place before machining fiberglass laminate. Fiberglass dust is really nasty for your respiratory system. It also destroys soft and shiny surfaces (like plastic laptop enclosure for example) and greatly increases wear on mechanical parts of the machine (bearings, drive nuts etc) is they are not covered.

author: smashedProton
author_rank: Frequent Contributor
timestamp: November 15, 2013, 09:38:46 pm
content: Just to bring it to your attention, and to be a smart-ass. The part you identify as the drill/mill is actually the spindle. The drill bit is now the drill. You can really only call it a drill if the only purpose of it is drilling.

author: Dane Bear
author_rank: Contributor
timestamp: November 16, 2013, 02:33:23 am
content: Why not waterjet?

author: poorchava
author_rank: Super Contributor
timestamp: November 18, 2013, 12:01:20 pm
content: Lol. Because you can built a cnc mill at home and cheapest waterjet system is like 50k€ and definitely not something you can keep at home (unless you live in a factory hall that is).Besides, waterjet cutting is rather expensive (per given length of cut) compared to milling or CO2 laser due to the cost of consumables (nozzles, garnet, short-lived pumps systems). Waterjet us commonly used for cutting stuff which is very hard to machine with other methods, where material is very thick, or where heating is a big problem. Common uses include glass, stone, hard metals (refractory metals, superalloys like Inconel etc).To be honest I've never heard of anyone waterjetting pcb laminate

author: metalphreak
author_rank: Frequent Contributor
timestamp: November 18, 2013, 02:16:37 pm
content: If you've got serious money to burn, and want something proper, check out the VFD spindles from various china sources. 800W watercooled spindle on my machine does 24,000 rpm, and is *much* quieter than a router based spindle. Try and avoid the air-cooled ones, as they have a rather loud fan built into the spindle.

author: iceisfun
author_rank: Regular Contributor
timestamp: November 18, 2013, 11:29:08 pm
content: Quote from: metalphreak on November 18, 2013, 02:16:37 pmThats what I have on it now