Looking for a good PCB milling machine - Page 1
Forum section: electronics / projects

author: Hugoneus
author_rank: Frequent Contributor
timestamp: May 30, 2017, 08:34:03 pm
content: Hi members,Any suggestion for a reasonably good CNC machine below $2K?I want to make some microwave PCB modules, etc. for video tutorials.

author: danadak
author_rank: Super Contributor
timestamp: May 30, 2017, 10:24:59 pm
content: The 3020, 3040, 6040 basic mills, ebay for starters, will do PCBmilling as well as other GP milling.Software, MACH3, and there is also leveling software to adjust gcodeto handle thickness variation and warpage in the actual PCB boardbeing milled.Tons of youtube stuff on PCB milling, setup, design, manufacture.Regards, Dana.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: May 30, 2017, 10:33:04 pm
content: Quote from: danadak on May 30, 2017, 10:24:59 pmThanks, I would not mind getting something a little better. But I will take a look.Cheers,

author: loxodes
author_rank: Contributor
timestamp: May 30, 2017, 10:44:26 pm
content: It is a bit over your price range at $3200 USD, but I've had some success milling RT/duroid 5870 and 6002 on an Othermill Pro.Fixturing soft substrates without a vacuum table or proper backer board isn't an ideal experience, but double sided tape seems to work okay..

author: danadak
author_rank: Super Contributor
timestamp: May 30, 2017, 11:06:30 pm
content: Keep in mind if you buy a GP mill you can get Laser attachmentsfor cutting films, injection heads for doing 3D printing (albeitz axis height limited), machine aluminum, brass, plastic, PVC,........Just a thought.

author: Dubbie
author_rank: Unknown
timestamp: May 31, 2017, 09:44:03 am
content: Who was the guy who posted here about his mill that everyone shat on? (Including me) mainly because we deemed routing pcbs to be somewhat obsolete. Anyway, it was a very nicely built affordable mill with unusually good performance. It would be perfect for your situation Shariar, where routing is really the (almost) perfect solution.

author: nctnico
author_rank: Super Contributor
timestamp: May 31, 2017, 06:36:14 pm
content: Quote from: Hugoneus on May 30, 2017, 08:34:03 pmWhy not have the PCBs made? That way you could also sell the (bare) PCBs to people who want to experiment for themselves.

author: DaJMasta
author_rank: Super Contributor
timestamp: May 31, 2017, 07:08:09 pm
content: I think the idea is that you can do fast turnarounds for designs that are very physical-properties dependent. Especially if you're not designing on FR4, one-off prototypes until you find a layout that gives you the performance you want will not be particularly fast or cheap. I'd assume a general CNC mill could also give you some flexibility for milled shielding or tuned cavities or whatnot, all of which could be desirable for small-scale microwave prototyping and experiments.It also probably makes for good footage to show the physical design process - I know I'd watch!

author: cdev
author_rank: Super Contributor
timestamp: May 31, 2017, 07:43:03 pm
content: I'm sure you likely already know this but for others benefit, as somebody who likes to make RF PCBs at times, an RF PCB made by any home made method is going to look a lot different than a factory made PCB because invariably you'll find yourself not using extensive copper groundplanes on top as much because of the impracticality of putting a grid of vias every few mm to minimize resonances (thats the main problem it causes).So for an LNA, I have just the components and the traces on top, the entire bottom is GP, and the grounds on the top are clustered around components. If I dont have areas of "should be better grounded" copper on the top (except around components where its necessary) it just works out better, Ive found.Also, make things as small as you can.I don't mill my own PCBs, I etch them. I use a short piece of copper wire for each via thats soldered on both sides and then chopped off. Ive also seen copper grommets used for them. I put the vias literally right underneath components when they need grounding, as many as possible.Again, I am sure you already know all this but as I haven't read this anywhere I thought people could use the info.

author: Unknown
author_rank: Unknown
timestamp: May 31, 2017, 07:47:51 pm
content: Quote from: Dubbie on May 31, 2017, 09:44:03 amI think this is what you're referring tohttps://www.eevblog.com/forum/reviews/prometheus-for-rapid-prototyping-forget-everything-you-know-about-pcb-milling/msg1189948/#msg1189948

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 31, 2017, 08:45:42 pm
content: Quote from: Hugoneus on May 30, 2017, 10:33:04 pmthe problem with generic cnc machine is they dont have automated bed levelling mechanism, you have to take care those on yourself which can be tedious, esp if your pcb is not flat side to center, you'll get a hard time getting uniform milled traces. besides, those are heavy and big machines, its ok if you have space for that mechanical thing. and youtubers that demoed their machine usually mention that they need to mod and upgrade due to underspeced parts, add some partitioning, cooling and all. but the good thing is that you can extend the purpose to like milling aluminium enclosure for your rf design.why dont you just stick to toner transfer etch method? that can give you better resolution with some effort. and afaik, microwave design usually have large area of etched copper, that can be problematic in cnc milling, your FR4 surface will not be nice will be a lot of worm trails. otoh another option will be cnc machine thats specifically made for ee hobby, but they are of high side priced and not extendable to mechanical purpose. such as...prometheus:https://www.eevblog.com/forum/reviews/prometheus-for-rapid-prototyping-forget-everything-you-know-about-pcb-milling/https://cirqoid.com/but no auto bed levelling mentionedymmv...

author: Dubbie
author_rank: Unknown
timestamp: May 31, 2017, 09:15:33 pm
content: That was the one Steve.The PrometheusShould be MUCh better than the usual ebay kits.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 31, 2017, 10:51:20 pm
content: If what you primarily want is PCBs, especially ones without many holes, then chemical etching using pre-coated boards is way cheaper, and will generally produce better results than all but the best CNC type solution. Don't forget that milling will have some ongoing cost for cutters, probably at least as much as coated photoresist boards.I have a Chinese 3040, which is great for doing PCB outlines, drilling for test jigs etc. but doesn't have the accuracy to do any serious PCB milling.

author: G0HZU
author_rank: Super Contributor
timestamp: May 31, 2017, 11:48:04 pm
content: Best bang for buck will be a used T-Tech or LPKF machine if you can find a healthy used example.Something like the LPKF C30. I think this is the model we have had at work for about 15 years and it has been a great asset. It wasn't cheap when it was new but used examples will be quite cheap today if you can find one.http://www.lpkfusa.com/datasheets/prototyping/c30.pdfHere at home I have a used T-Tech 7000S which I've had since about 2001. It cost me £800 back then and I bought a second (tatty, abused) one a few years later for about £600 for major spares. These tools are fabulous for RF design and we have been using mills like this at work since the early 1990s.However, no matter what I say, some forum experts will come along with no RF background and tell me we should have been using UV and these machines are a waste of timeI can remember going through the UV phase at work before we bought the milling machines. Smelly chemicals in the labs weren't popular on hot days and two layer boards were always a pain to make (and drill). Complex PCB shapes were a pain to create. Usually you could tell when a PCB had just been etched and cut out because the engineer would be furiously filing it for many minutes to create any custom apertures for exotic RF components or if they were filing it to make it fit in a snug location.Note: Without the enclosure these machines are very noisy. My T-Tech 7000S is extremely noisy as it has a powerful Nilfisk/Hepa extraction/filter system. So best to put the machine in a separate room if you don't have an enclosure. Our C30 machine at work came with the sealed enclosure to minimise noise and keep the vacuum system sealed.

author: Fire Doger
author_rank: Regular Contributor
timestamp: June 01, 2017, 04:34:42 pm
content: This is an example with chemical etching, its a logo with thin balls (and a hair for size reference). And it wasn't as good as it could be. (weird shape was actually weird on EDA too)For smt packages its perfect, here precoated 160x100mm cost only ~3€The key for chemical etching is proper UV chamber, mirrored sheet to avoid light scattering and a basic knowledge on chemicals.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 01, 2017, 07:42:52 pm
content: Quote from: danadak on May 30, 2017, 10:24:59 pmchecking in ebay, at $550 the 3020 comes with no board, display and no control at all, only steppers and mechanical machine, this will be a lot of setting up before it can actually work. btw this thread has been a poisonous to me i'm start buying parts myself for my next cnc project, another unplanned project...

author: edavid
author_rank: Super Contributor
timestamp: June 01, 2017, 08:16:37 pm
content: Quote from: G0HZU on May 31, 2017, 11:48:04 pmUnfortunately we don't seem to get those deals in the US.Quote from: Mechatrommer on June 01, 2017, 07:42:52 pmYou are looking at the wrong listings, here is an example of a complete 3020T:http://www.ebay.com/itm/CNC-ROUTER-ENGRAVER-ENGRAVING-Drill-CNC-Milling-Machine-3020T-300W-DC-Motor-/141973487884If you are really in Malaysia, you should look on AliExpress instead of eBay.There's also a smaller type of engraver machine with very limited Z axis travel:http://www.ebay.com/itm/DIY-CNC-Router-Kit-USB-Mini-3-Axis-Wood-Carving-Engraving-Machine-PCB-Milling-/302292473345I don't think either one is what OP is looking for though.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 01, 2017, 11:48:26 pm
content: Quote from: edavid on June 01, 2017, 08:16:37 pmi think i'm not so far off... i thought the unit box is for powering the spindle only, maybe thats the control unit, but parallel port? duh i thought parallel port are extinct, it will be equally difficult for me to setup on my pc... the first link doesnt ship to malaysia, thats $373, the seller that can ship to malaysia will charge $150 more... all the pictures dont show whats on the back of the control box, the seller in ebay indicates stepper wires just danggling around not connected to anything, so its suspicious... why aliexpress? i checked it the price is about the same, some are even more expensive, aliexpress doesnt have the same level of my confidence because no seller rating. and most things that i want will available in ebay just as in aliexpress... the 2nd link you gave uses smaller brushed motor, i saw that too in ebay, cheaper than 3020 yes, but that motor is lower rating and will not last long, so its not a option..btw, i already ordered 500W spindle and z axis slider for it, plus with some other higher rating steppers and parts that i cant build myself. i'll build the rig/gantry myself, larger and stronger for my need, that i aim the end product will similar to larger cnc that is sold in ebay for many thousands of $.. i already have arduino and reprap shield and 2004 lcd with sd card reader ready for it

author: edavid
author_rank: Super Contributor
timestamp: June 02, 2017, 12:06:49 am
content: Quote from: Mechatrommer on June 01, 2017, 11:48:26 pmI don't know why people make a big deal over this. If your motherboard doesn't have a parallel port or header, you can buy a PCI or PCIE card for $5.

author: john_c
author_rank: Contributor
timestamp: June 02, 2017, 12:13:27 am
content: Quote from: Mechatrommer on June 01, 2017, 11:48:26 pmYou'll need a PCI-e parallel card. I've read that the one to get is WCH CH382L chipset. That works with LinuxCNC as well as Windows.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 02, 2017, 07:43:12 am
content: For controlling a small CNC I highly recommend the little Chinese standalone controllers rather than messing around with parallel ports and MACH3 etc.http://www.ebay.co.uk/itm/CNC-Controller-4-Axis-Offline-Stand-Alone-Engraving-Router-Machine-DIY-Kit-/232101123785?hash=item360a4e16c9:g:EE4AAOSwzLlXh1f4http://www.ebay.co.uk/itm/4-Axis-CNC-Controller-Offline-Stand-Alone-DDCSV1-1-500Khz-G-Code-Replace-MACH3-/122386044140?hash=item1c7ec6d4ec:g:Aj4AAOSw4A5YvhbTI've used both the above - both have their plus and minus points but either makes life a lot simpler.For a while these were the only ones around but there seem to be a few more now.

author: Fred27
author_rank: Unknown
timestamp: June 02, 2017, 07:54:45 am
content: I didn't realise a PCIe parallel card would be OK. If you do want a reasonably recent PC with onboard parallel port, look at a Dell. They might have dropped them now, but we're still included on some models only a couple of years ago.

author: fcb
author_rank: Super Contributor
timestamp: June 02, 2017, 01:33:43 pm
content: Definitely have a go with chemically etching your own first - probably faster to make & certainly nicer/more accurate finish.

author: langwadt
author_rank: Super Contributor
timestamp: June 02, 2017, 11:13:11 pm
content: Quote from: mikeselectricstuff on June 02, 2017, 07:43:12 amif you have a spare PC with a usb port another option is GRBL~$40 worth of ST boards gets you 3x 10A stepper drivers and a controller

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 03, 2017, 12:13:01 am
content: Quote from: langwadt on June 02, 2017, 11:13:11 pmAnd the space and monitor and cabling and boot-up time of a PC...Nice thing about the standalone ones is they take up minimal space and are ready to go in a couple of seconds.

author: rstofer
author_rank: Super Contributor
timestamp: June 03, 2017, 01:09:23 am
content: If you don't have a parallel port you might look into either the USB or Ethernet version of the SmoothStepper:https://warp9td.com/index.php/productsThe PC I use for my CNC mill has no possibility of adding a parallel port so I use the Ethernet version with Mach3. Works well!

author: edavid
author_rank: Super Contributor
timestamp: June 03, 2017, 01:35:46 am
content: Quote from: rstofer on June 03, 2017, 01:09:23 amBut that costs a rather ridiculous $155 (USB) or $180 (Ethernet). It would be much cheaper to just buy another PC ($40).

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 03, 2017, 02:47:34 am
content: where do we get a pc for $40?, even if we found it, it will be ancient pc whose spare parts for everything inside are not sold anymore. i agree add on parts for cnc machine are expensive, just like mike's link, the small controller monitor is GBP150++ its half the price already of the mechanical parts of the cnc machine, nuts. and its a surprise that, reprap compatible cnc machine and the pc control sw through usb port is not that popular yet (or maybe non existence), i need to meditate on this...

author: edavid
author_rank: Super Contributor
timestamp: June 03, 2017, 03:51:27 am
content: Quote from: Mechatrommer on June 03, 2017, 02:47:34 amDell Optiplex 745/755/380 etc. from eBay or craigslist. Spare parts readily available (much easier to get than CNC machine parts).

author: quint
author_rank: Contributor
timestamp: June 03, 2017, 03:58:22 am
content: Another thing to consider with RF circuits is what type of board material you want to mill. Some of the RF materials, like Rogers, seem to have a lot less adhesion between copper cladding and the board substrate and so are more difficult to mill. I believe LPKF even has some applications notes and special high speed spindles for doing things like some of the Rogers materials. I would be a bit skeptical about anything in the $2K range for such materials.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 03, 2017, 09:54:43 am
content: Quote from: edavid on June 03, 2017, 03:51:27 amthere is no $40 Optiplex i can found in ebay... the one near that price is the motherboard only or used unit currently in bidding... $100++ without a monitor, still...http://www.ebay.com.my/itm/Dell-Optiplex-380-DT-Desktop-PC-E8400-3-0GHz-4GB-500GB-Win-7-Pro-1-Yr-Wty-/201428977935?hash=item2ee61a490f:g:K-IAAOSwTM5YyaQt

author: H.O
author_rank: Frequent Contributor
timestamp: June 03, 2017, 06:00:50 pm
content: There are cheaper alternatives to the Smoothsteeper. The PoKeys57CNCd25 for example, it basically looks like a LPT port at the end of a USB cable. These devices are not simple USB-to-printer port adapters (which won't work for this).Pretty much any PC newer than 10 years will run Mach3 fairly well. If you're going to use the LPT port, be it onboard or on a PCI / PCIe card you MUST use a 32bit operating system. 64bit versions of Windows does NOT work with the LPT-port, if that's what you have you MUST use an external motion controller such as the Smoothstepper, PoKeysCNC or one of the more industrial oriented units.

author: IonizedGears
author_rank: Regular Contributor
timestamp: June 04, 2017, 07:45:18 pm
content: Why not use a raspberry pi in conjunction with a cheap grbl controller?Sent from my Pixel XL using Tapatalk

author: Devian
author_rank: Contributor
timestamp: August 01, 2017, 04:01:32 am
content: There is one mini PCB milling machine recomended: ChinaCNCzone CNC 3040, the price is low about 900-1000USD if i am not wrong, and i remembered this machine uses USB CNC software, can read gerber file directly,very ideal for PCB millingas below linkhttps://youtu.be/9aYMIZ1_MRgThe Gerber file is a collection of document formats for the PCB industry software that describes the image of the circuit board (line layer, solder mask layer, character layer, etc.) and drill and mill data. It is the standard format for image conversion in the PCB industry. Gerber documentation is usually generated by board designers using professional electronic design automation (EDA) or CAD software, so the USB CNC software is very handy for CNC drilling for PCBs, and the DXF file 2D conversion format can be Directly generated by the CAD, for 3-axis engraving will be very convenient, so USB CNC system for file format support is very advantageous

author: legacy
author_rank: Super Contributor
timestamp: August 01, 2017, 07:57:07 pm
content: the real problem is: conductive holes; my PCBs always happen to have many, and holes are made conductive by electroplating.Or lined with a tube orrivets. But we can forget all of these methods.

author: cdev
author_rank: Super Contributor
timestamp: August 02, 2017, 10:44:40 pm
content: You can buy HP thin clients that have real parallel ports for $30-40.

author: lbattraw
author_rank: Newbie
timestamp: August 03, 2017, 11:05:02 am
content: Quote from: danadak on May 30, 2017, 10:24:59 pmDefinitely a good idea, from personal experience (Last year) I went ahead and bought a 4-axis 3040 mill with ball screws (A real must to reduce backlash for PCB milling!) for about $750, delivered. It shipped from California (Apparently there's a ton of sellers there) to me in NC, which only took about 4-5 days. The first thing I did was chuck the stepper drivers that shipped with it since they had this weird behavior where they would randomly step an extra amount when changing direction... Super annoying! Fortunately everything is modular and each stepper driver was a complete stand-alone device that they mounted within the parallel port/stepper driver/power supply box. I spent about $60 (4 drivers at $15 each from Amazon) on some TB6600 32X microstepping drivers which were trivial to wire in and mount.Since the mill arrives without any actual intelligence, just power and stepper drivers, I used an Arduino Uno running GRBL, which works wonderfully and allows you to send G-code to the mill via the Arduino's USB serial interface. Using something like Mach3 or LinuxCNC are also options, though I wasn't too crazy about dedicating a PC to drive the mill. I use an application called bCNC (Running on my Ubuntu PC) to take care of talking to GRBL; it's very powerful and easy to use and includes a ton of functionality (And is free/open source). I completely avoided talking to the mill via the 25-pin parallel port since though it added opto-isolation all the stepper driver boards also have optical isolation, which didn't seem to be worth the hassle of trying to wire the Arduino to that connector, particularly since I need a USB port to talk to my PC. The Arduino runs off the same 24V power supply as the driver boards and is mounted inside the driver/PSU enclosure.The only drawback is that GRBL only supports 3 axis control, though there are several forks of the code that port it to ARM processors with the eventual goal of adding a fourth axis (GRBL uses every last bit of space and CPU resources the Arduino has so there's no way the author could add a fourth axis and keep it on the same platform). It's not really a big issue for me since I haven't gotten to the point where I would need the fourth axis, but it's definitely a bit of a disappointment.The last thing to mention is that PCB milling is quite challenging to get working and you'll spend a significant amount of time evaluating which milling bits work best (Destroying a few along the way!), how to get things level, and trying various spindle motors/mounts. The 3040 I bought came with this weird configuration-- instead of your standard spindle motor that mounts directly onto the mill it used a large universal (DC or AC), brushed motor (560W 25,000 RPM) at one end of a flexi-shaft cable which connected at the other end to an assembly on the spindle mounting plate with a small, adjustable drill chuck. Not really ideal since you have to find some way of keeping the motor cable from getting in the way when the mill moves, and I wasn't terribly impressed by the run-out of the chuck. For around $200 you can get a large (1.5KW or larger) brushless, water-cooled spindle motor that seems to be the way to go. Since I spent all my money on other stuff I ended up 3D printing a mount and used a lathe to modify a 100mm (10mm dia) shaft with a ER-8 collet holder (And 1/8" collet) to connect to a high-speed 44V BLDC motor (Running at up to 60,000 RPM) that I modded to incorporate water-cooling jacket since it would have overheated very rapidly otherwise. I used three bearings that the 10mm shaft passed through to reduce runout and vibration as much as possible.If all that didn't scare you off try and remember that you will be limited in your usable trace size and spacing due to the size of the milling bit you use, since obviously you will always cut at least the diameter of the bit (More like 50% larger in practice due to vibration and run-out). There are programs like FlatCAM that will simulate the results of cutting with a particular bit and run-out estimation to give you a better idea of what you'll get vs. wasting a ton of PC boards.One major benefit is that you will be able to drill your PCBs almost perfectly, regardless of what process you use to etch/mill your boards. Being able to cut your boards to a particular shape precisely (Such as boards that plug into edge connectors) is also a great bonus, and you can even add slots to snap apart multiple boards, particularly handy if your boards need to be both small, precise, and an odd shape to fit your enclosure/product... Think round boards for example, a real pain to do by hand.Anyway, that's some of my experiences CNC milling things. I've always dreamed of being able to CNC drill a board, saving a great deal of time (And my eye-sight!) in the process. I still think that milling PC boards is a useful and valid applications for a CNC mill, at least for the boards with larger, through-hole components. There are also a few ways to plate the holes/vias, though that is another topic completely, with a lot of time and moderate investment to do with some success. At least one person has had success activating the holes using graphite powder in ink to coat the hole walls before electroplating them.Cheers!Larry