[JamesMegaWatt]

Hello everybody, my name is James and I am an electrical engineer (just graduated). In my free time I like to mess around with homebrew electronic projects and have come to the point where I need a method of making my own custom PCBs.

I have tried different methods before (etching using UV-radiation, toner heat transfer) but I would like to get into PCB milling. I have zero experience with milling so I am asking for some advice here. I'll try to summarize my requirements:

- 200mm x 200mm working size (smaller also OK if needed)
- single sided PCBs
- accurate enough for regular trough-hole parts and SMDs (if possible a pitch for TSOPs, but no need for QFNs)
- price tag < 500€/650$
- if possible I should be able to cut plastic for front panels

I would like to know if it is possible to find something based on these requirements and what you would recommend a beginner like me. If you think my price tag is too low, please tell me what ammount you had in mind. I would also like to say that the building of the CNC machine itself is also like a fun project to me and I am willing to invest a lot of time. Let's say that I would rather invest more time than more money. I know this is a question that probably has been asked a million times before but I would appreciate any advice you can give me because this is a major purchase for me.

Thank you in advance for any help!

[blinkenlight]

That won't be easy. The lowest price I've seen on a hobby CNC that actually looked legit was around $500, for the Chinese / Taiwanese Sable 2015 (and myriad of clones) on ebay - it still seems to have that price today. The one I have is from carving-cnc.com, a 3020Z model, which is a bit higher up with $699 - all I can say, my friends ordered several machines from these guys, they actually are legit (but still from China). And I mention that because that obviously implies import tax, and a non-negligible shipping fee - none of the hobby CNCs are very light, really, especially properly packaged - which practically raises the cost with a couple hundred dollars.

All I can say is that this type of mill can indeed do about a 1.27mm pitch for SMD - smaller than that is pretty much black magic. And if I were you, I'd stay away from potentially even cheaper but wood-framed machines - the 3020Z has a more rigid, aluminium frame, a proper (non-dremel-style) low-runout spindle, and ballscrews on all axes, and it still can barely do that 1.27; what do you think you'll get with a 0.2mm backlash nut, a 0.1-0.2 runout dremel-style tool, and a frame prone to flexing / bending based on air humidity...? Yes, exactly - a through hole-level CNC, maybe...

[JamesMegaWatt]

Hello blinkenlight, thank you for your reply! The Sable 2015 looks good, but I wonder, do I need to buy a spindle for it myself? And if I for example buy a Dremel can I just mount it to that or do I need to order/make special mounting brackets? The 3020Z model you have looks even better, especially since it has everything included and it does not seem that there is much setup needed. I wonder though, the only thing I find about accuracy is 'Repeat positioning Accuracy： 　0.04mm' while you say it can just barely do 1.27mm, that's strange right, or do these things have nothing to do with each other? Can you use any software on your 3020Z like LinuxCNC? Also, I found this online, what do you think about this one: https://www.inventables.com/technolo...-kits-shapeoko
Thanks anyway for replying!

[Jay C]

If you are going low cost, do not sacrifice the spindle. Kress or Bosch Colt (what I use) would be a good first choice. I have also used Proxxon IB/E but it doesn't like long sessions. I have to disagree about a wooden frame not holding, MDF has been shown to be quite stable and sturdy by other members. That said, my machine is all aluminum and cost me $1300 just for the machine. The weakest part of my machine is the Delrin ACME nuts and the custom sleeve bearings.

[blinkenlight]

Indeed, the Sable needs a spindle that you would need to buy. I'm not sure exactly what kind of mounting bracket they offer, but the point is you's need to buy a really precise spindle, not just any hand-held dremel - the runout is really critical here. Regarding the 3020Z accuracy: positioning accuracy and doable SMD pitch are two different things - for a 1.27mm pitch you presumably need TWO grooves milled for a pad with a 0.1...0.2mm wide V-tip engraver that hopefully won't carve a groove MUCH wider than that (you do have to factor in that the groove depth is non-zero, which means a groove that much wider with a V-tip, and that the PCB top surface will never, ever be PERFECTLY level - which will significantly impact your groove width, as you'll see) and after all that you still need to have a copper trace of reliable width left between those grooves. Also - to be honest, I haven't gotten around to break out a proper comparator dial and measure the actual physical repeatability of the mill, but I have a hunch that what they quote there is the ideal number derived from the ballscrew pitch and stepper resolution, as opposed to what the machine can actually do in the real world; even though ballscrews are much better than ACME thread, the backlash is never actually zero, and neither is the spindle runout - it's just much better than what the typical low-cost mills have. Specifically, there is a definite distinction between repeatability of a machine and the smallest pitch SMD part it can carve tracks for.

Regarding software used - virtually ALL hobby CNC machines come with some sort of parallel-port driven interface, which means that yes, LinuxCNC is definitely an option for controlling them. Other popular options are Mach3 (non-free) or the Arduino-based GRBL hardware controller (my choice). Rather amusingly, the latter seems to be exactly what ShapeOko seems to be using (note "grblshield"), but - other than the remarkably similar price tag ($599) - there's not much I can say about the ShapeOko; I have no experience with it. I have to say though, I much prefer my proper ER11 collet to the dremel-like tool they seem to use; but to find out what kind of PCBs the ShapeOko is able to do, you'll have to dig up referrals from people who actually tried to use it for PCB work...

[victorofga]

with that pricetag buy a Chinese..
if you can build a business then you buy later another with ballscrew and spindle..

regardless of size if machine has good rails, spindle, ballscrew then it will start about 2000 with shipping handling..

if you don't build a business, then you have only invested 600...

[JamesMegaWatt]

Thank you everybody for your replies they have been really helpfull and have helped me give a better idea of what I should be looking for. I guess the 3020 from carving-cnc would be my best bet. I fear that when I buy the shapeoko I will never be able to attach the dremel or any other spindle just right meaning I would have a large spindle runout. The cost of the 3020 + shipping to me is about 650 euro so that seems fair to me. I just would like some confirmation that anybody has infact been able to do smd work on this machine. I also wonder if there are ways to manually do two sided boards. Something I was also wondering, if I have a board with different hole sizes, will the software stop to let me change drill bits? Also, let's say I want a 1cm x 1cm area to be milled completely. The program has to take a different route if I put a 0.1mm drill bit or a 1mm drill bit, how does the software know what bit I am using, do I need to specifiy it at the start? Thanks for your help!

[blinkenlight]

I just would like some confirmation that anybody has infact been able to do smd work on this machine.

Well, the best video I could find was this one: http://www.youtube.com/v/Ng9LCBZK89g - you can spot a SMD footprint at the close-up at the very end of the video.

I also wonder if there are ways to manually do two sided boards.

Absolutely. Admittedly, it is harder, and you have to somehow maintain alignment - most commonly, this is done by drilling a few "indexing" holes (usually - but not necessarily - the mounting screw-holes of the PCB that would exist anyway), to a very specific diameter, into which pins can be inserted - after you flip the PCB, it gets aligned by the pins. My personal favorite is using the 3.175mm (1/8") shaft of common milling bits (the 3020 itself uses this diameter in its collet) as a "pin" - I just had to make sure to buy a 3.175mm drill too; afterwards, the holes work perfectly fine as M3 screw mounting holes...

Something I was also wondering, if I have a board with different hole sizes, will the software stop to let me change drill bits?

That's not really depending on the machine or its control software - they don't care or know what you are actually doing, they just execute the g-code you feed them. Now, g-code does have instructions for tool changes, but it's up to the CAM software you will use to make your g-code out of your PCB drawings (gerber files, usually) to use them or not - you might even decide to generate different g-code files for each drill diameter, which obviously would let you do whatever you want. If you go the one-file route, the machine will retract to a predefined position (defined by your CAM software and / or the machine control software) and stop, waiting for you to change the tool and confirm it to resume operation - depending on the specific control software however, it might not let you recalibrate the tool height, which must somehow be dealt with (eg. by inserting the new tool to the exact same depth, either by depth setting rings or by placing a block of fixed height under the tool before tightening the collet)

Also, let's say I want a 1cm x 1cm area to be milled completely. The program has to take a different route if I put a 0.1mm drill bit or a 1mm drill bit, how does the software know what bit I am using, do I need to specifiy it at the start?

Generally, the simplest way to mill a PCB is to simply "isolation route" it, meaning that just the contours of the various traces are getting milled out, everything else stays covered by copper (there is an even MORE simplistic approach - look up "Voronoi isolation", which strictly just isolates the general areas of copper that need to stay connected, without any regard for any trace shapes). Of course, if one wants, supplementary operations to remove the copper can be run ("rubout") - the planning of which is wholly the job of the specific CAM software you use to generate you g-code. If the software has no such feature, you're out of luck. But if it has that, you can be sure it will ask you what diameter tool you plan to use, and it will plan the path accordingly (this sort of job is not usually done with the 0.1mm tipped V-bit, for obvious reasons - if nothing else, tool wear...). Usually, decent PCB milling CAM software is able to generate g-code for indexing pin drilling, isolation milling, rubout, hole drilling, and even PCB contour cutout (if you have a suitable mill bit - I'd recommend "chipbreaker" 3mm bits: the way they chew up PCB is just scary); done right, at the end you pretty much lift a finished PCB off the MDF bed, with perfectly centered holes, and I find that pretty cool...

Oh, and a final bit of advice - think of mill bits (especially fine tipped engraving V-bits!) as consumables: never buy just one or two or three, at last until you learn how things work. You WILL be breaking them like crazy at the beginning, no matter how careful you are - thankfully, they're generally not terribly expensive. Good luck!

[JamesMegaWatt]

Thank you for all the information, as I said, I have no experience with CNC so this information is very valuable to me. I'll be ordering the 3020 model from cnc carving then. I'll let you know what my experience with it is! Two last things: what software would you recommend a beginner like me? And where can I find drill bits, can they be any drill bits I find in my hardware store? Or are they special drill bits? (I just feel the drill bits in my hardware store would instantly break off)

[aarggh]

Thank you for all the information, as I said, I have no experience with CNC so this information is very valuable to me. I'll be ordering the 3020 model from cnc carving then. I'll let you know what my experience with it is! Two last things: what software would you recommend a beginner like me? And where can I find drill bits, can they be any drill bits I find in my hardware store? Or are they special drill bits? (I just feel the drill bits in my hardware store would instantly break off)

James, if your budget is extremely tight as you've indicated, I'd strongly advise checking on the controller supplied with the 3020. Most of these Chinese machines are fantastic value and are built really well, but almost all of them use the same rubbish controller that just doesn't work. Carving on some of their line I believe doesn't use the universally hated "blue controller", but a newer one instead that is believed to work reasonably well. If the machine come with one of the blue controllers, steer clear of it.You'll spend months trying to make it work properly.

Also, try and avoid the cheap dc powered spindles if you can, or check on them thoroughly. Some of these models came with a spindle that most people found to be rubbish, and a lot of them just packed up after minimal use. If it comes with a proper spindle, such as the 0.8kw and VFD, that would be really great for you. If you had to pay a bit extra for it, it would be well worth it. You certainly wouldn't regret it.

I have a Sable-2015 that I bought mainly for PCB work myself, with a short and long neck IB/E, and love it. I'd highly recommend a Proxxon for PCB work if you need to buy a router. A standard woodworking router such as Makita's, Bosch's, etc, are completely unsuitable and will not last or provide good runout figures, and unfortunately a Dremel is useless for fine tracks or layouts. Far too much play to be of any use for any degree of precision work. Not too mention that they just pale into insignificance after using a Proxxon!

For drill bits, just buy the sets of 10 in various sizes from the myriad of Chinese Ebay sellers, I have bought many from a lot of sellers, and all have been great quality. Some of them have done literally thousands of holes without issue. They are dirt cheap but perfectly fine.

cheers, Ian

[JamesMegaWatt]

I don't know what kind of controller is included, but by looking at the pictures here CNC 3020Z+D52(new version) ROUTER ENGRAVER DRILLING AND MILLING MACHINE - carving-cnc.com it doesn't seem to be a blue controller.

I am also not sure what kind of spindle it comes with, the only information that is given is: Spindle motor： 　230W/11000r/min（(Very small noise)）; Precision ER11 collet. What if I wanted to buy another one, would it be easily attachable?

[blinkenlight]

Yes it is a DC spindle. Admittedly I'm not doing industrial amounts of work on it, but haven't had problems with it so far at all, and guess what - they even included a spare set of brushes. I don't expect to need them any time soon though. Some of the larger models do come with VFD spindles, but those are more than a bit more expensive than the base model, and frankly, I don't see the difference (other than the ungodly amount of EM noise the VFD puts out and the water cooling the spindle needs - a friend of mine has one of those models). Twice as fast? Yes, sure. Necessary? Hell no. Oh, and they both are rather quiet indeed.

Also, about the control boxes - yes mine came with a black box, and since then they even updated the site with the new pictures that feature it. However, I've read more than a fair amount of *****ing about all TB6560 based designs (especially the Chinese ones), and I have to say that while in a strict technical sense many of those are not wrong at all, many do blow the theoretical faults horrendously way out of proportions; while I'm definitely not defending the designs (yes I'm an EE), the faults being nitpicked on often seem to turn out not to cause any discernible problems. I still recall a thread around here somewhere where the actual Chinese OEM showed up not understanding why people were insisting that component A, B and C is just not right and MUST be changed asap, since in his experience the mill was working fine - actually, both camps were right. Anyway, I wouldn't worry too much about the box, and if it were to turn out you're not satisfied with it, it could relatively easily be tinkered with to your satisfaction (it's a fairly simple circuit), or can be replaced completely with a different box relatively cheaply (and yes, this is much like the sports car / tuning scene - you can ALWAYS buy an even more hideously expensive model that's supposed to be SO much better than the current one).

More to the point: choice of software is a rather personal thing, it's not like there is a clear "bad" choice. It depends on going with free software (eg. Visolate, Line Grinder or the Eagle export tools) or willing to pay a bit (eg. CamBam), using a PC to control the mill (LinuxCNC or Mach3 is pretty much the norm) or a dedicated piece of small hardware (eg. GRBL - not to be confused with the driver control box you are already buying anyway). You'll probably end up experimenting a lot and trying a dozen different programs before settling on the one that fits you.

Re: tools - the issue is not so much the quality of the drills you might pick up randomly but the fact that this mill has a proper fixed diameter collet, not a variable chuck as a typical drill might have; so the only shank you can grip with it is the 3.175mm (1/8") or a 3.0mm one - typical drill bits simply have the diameter of their tip all the way, so you can't grip them (you're free to buy a set of different diameter collets later if you feel like it - they are easily changeable, as long as they are meant for "ER11"). Luckily, drill bits with standard 1/8" shanks are easily available online, just as v-tip engraving bits too. Here, again, you'll have a choice of different materials the bit is made of (carbide, HSS, etc.) but when you start up, this is not really crucial - ultimately they all cut fine when new, and you'll have to judge yourself what the price / performance sweet spot is for you once the bits stop breaking too often...

[aarggh]

I don't know what kind of controller is included, but by looking at the pictures here CNC 3020Z+D52(new version) ROUTER ENGRAVER DRILLING AND MILLING MACHINE - carving-cnc.com it doesn't seem to be a blue controller.

I am also not sure what kind of spindle it comes with, the only information that is given is: Spindle motor： 　230W/11000r/min（(Very small noise)）; Precision ER11 collet. What if I wanted to buy another one, would it be easily attachable?

It looks like the spindle supplied certainly looks to be better than the ones supplied previously, the prior ones used to make a racket, as brushed motors simply aren't as quiet as induction ones, and were prone to wearing out the brushes pretty quick, and then dying. Hopefully this model spindle is better. The ER11 collets come in a range of sizes up to 7mm in metric sets, and 5/16th in imperial sets, so you can use cheap 1/4in router bits! That's a bonus! But, don't buy a collet set until you've received your machine, as there are two variants of the ER11 collets and nuts floating around for the Chinese machines, and you may have to buy a new nut depending on the collet design your sent. If you wanted to replace your spindle the weight should be fine for the gantry, but the 0.8kw spindle is 65mm diameter so you may need to machine a mount for it depending on the size of the current spindle. The spindle and VFD are far superior in every way to any hobbyist brushed motor, with far better runout values. Not too mention the vastly decreased noise, long life, and increased reliability.

A few others in the forums have commented on the new black controller and that it seems to be pretty reliable, carving state that they are the only proper YooCNC controller supplier, and that all the garbage blue controllers are using fake controllers, I don't know how true that is, but others here seem confident in the newer controller, and it might help explain why almost all of the crappy blue controllers have the same fatal design flaws.

Congrat's on the machine, you'll be very happy with it!

cheers, Ian

[JamesMegaWatt]

Thank you once again for all the info! Right now I'm trying to figure out if I will have to pay import taxes into Europe on this thing, because that would increase the cost with about 20% which is actaully too much...

[JamesMegaWatt]

What do you guys think of this one?
2013 CNC 3020 Upgraded Router ENGRAVER Drilling Milling Device New Spindle | eBay

It looks almost identical to the carving-cnc one
CNC 3020Z+D52(new version) ROUTER ENGRAVER DRILLING AND MILLING MACHINE - carving-cnc.com

but the one on ebay would be around 100euro cheaper for me (no shipping costs). Is it to be trusted?

[aarggh]

What do you guys think of this one?
2013 CNC 3020 Upgraded Router ENGRAVER Drilling Milling Device New Spindle | eBay

It looks almost identical to the carving-cnc one
CNC 3020Z+D52(new version) ROUTER ENGRAVER DRILLING AND MILLING MACHINE - carving-cnc.com

but the one on ebay would be around 100euro cheaper for me (no shipping costs). Is it to be trusted?

I would be highly doubtful, it looks like a clone and I wouldn't be surprised if it has the bog standard and utterly crap TB6560 based boards inside it! I would be wanting a picture of the inside of the case, and a firm guarantee that the controller shown (with supplied pics) is the actual one you will be supplied. Unfortunately, many sellers will substitute different parts as they get them or place the orders with the bulk supplier, so it's possible you may get a pic of genuinely good controllers inside it, but they ship you a different one.

As I mentioned previously, Carving appear to be the only company that claim to ship genuine YOOCNC controllers, and maintain that all the others, supplying the blue box controllers, are fake.

A 100 euro saved may be a few hundred wasted if it's no good.

cheers, Ian

[JamesMegaWatt]

Thank you for the warning! It looks to me that every picture I find of the TB6560 boards have multiple parallel input connectors, like this one here: http://www.georgegardner.info/wp-con...2/IMGP4564.jpg

On his ebay website, he sells the controller unit seperately here: CNC 3020 3040T DJ ENGRAVER Machine Router 220V Control Box | eBay

And it looks like on the back of the unit it has only 1 parallel connector. Do you think it is safe to say it is not a TB6560 board?

Thank you in advance!

EDIT: I have contacted the ebay seller and am waiting for his response

[blinkenlight]

Do you think it is safe to say it is not a TB6560 board?

I think it's safe to say it is a TB6560 board, since practically every single Chinese driver (and quite a few non-Chinese) I've seen is. There's a reason everybody knows them, and it's because they're everywhere. Note that while TB6560 isn't really a pinnacle of engineering, it's not like there's anything particularly wrong with it either - most objections to the Chinese drivers are related to how exactly they incorporate those ICs (with particular regard to step clock signal level / polarity / integrity and specific optocouplers used etc.) and those are the things that have somewhat been improved in the type of driver PCB usually seen in the "black box" controllers compared to the ones seen in the blue ones. However, it's practically impossible to establish with certainty what your exact PCB setup is, short of tracing the specific circuit and parts from the PCB in your hand once you get it. It's likely though that all black boxes come with the improved PCB - it's just impossible to know for sure. Oh, and I have no idea what the other port is for on the pic you linked, but it's not another LPT - those have 25 pins, this one has 15, so it looks more like a game port or some proprietary pinout. I wouldn't be too surprised if they tapped the game port only because it has a +5V pin, which they might need for the PC-side of their opto-isolation, depending on the exact circuit they went for...