cnc milling machine - Page 1
Forum section: electronics / general

author: snipersquad100
author_rank: Frequent Contributor
timestamp: March 08, 2013, 07:37:54 pm
content: I’m interested in getting a small cheap cnc milling machine for making pcb's, Does anyone know where I can get one?

author: smashedProton
author_rank: Frequent Contributor
timestamp: March 08, 2013, 08:05:40 pm
content: Santa

author: PeterG
author_rank: Frequent Contributor
timestamp: March 08, 2013, 08:09:41 pm
content: Look at ebay. Search for 'CNC 6040'.Regards

author: snipersquad100
author_rank: Frequent Contributor
timestamp: March 08, 2013, 08:11:21 pm
content: why santa?

author: snipersquad100
author_rank: Frequent Contributor
timestamp: March 08, 2013, 08:12:03 pm
content: Thanks peterg

author: Spawn
author_rank: Frequent Contributor
timestamp: March 08, 2013, 09:05:08 pm
content: Price at eBay is bit high because of the shipment I think, you should check GOCNC, they are German manufacturers and I think quality is little better.They have a lot small CNC’s and even one special for PCB’s:http://gocnc.de/product_info.php?cPath=22&products_id=122&osCsid=c02d88a96dee89876ce84d4503001a16http://youtu.be/vwuzAoernKU

author: snipersquad100
author_rank: Frequent Contributor
timestamp: March 08, 2013, 09:11:12 pm
content: Thank you Spawn, that is very usefull.

author: ecat
author_rank: Frequent Contributor
timestamp: March 08, 2013, 10:06:25 pm
content: I would advise you to do the maths, pro boards vs machine cost + running costs + tool costs + alignment issues + headaches etc.If you really must have a machine at a reasonable price there is a guy onwww.mycnc.co.ukwho does some home PCB work, I think he uses one of these:http://www.ebay.co.uk/itm/Sable-2015-CNC-ROUTER-ENGRAVER-mill-PCBs-engraving-/190804707486?pt=LH_DefaultDomain_0&hash=item2c6cd8c89esame machine as this iirchttp://www.cnc-sable.nl/sable-2015-p-21.html

author: Psi
author_rank: Super Contributor
timestamp: March 08, 2013, 10:57:15 pm
content: Making PCBs with a CNC isnt as easy as it sounds.The UV resist method will produce better results with less problems.

author: akcoder
author_rank: Contributor
timestamp: March 09, 2013, 04:40:22 am
content: Quote from: Psi on March 08, 2013, 10:57:15 pmI second what Psi has said. I've spent probably $1,700 on a CNC kit and another $300 on a spindle, plus another probably $100 in cutting bits and other pieces. And I still haven't been able to mill a board successfully.The thing with milling a board on a CNC is every .001" counts. Being ever so slightly out of alignment at one end and you can be very much out of alignment at the other end. And trying to do double sided boards is even more difficult with a CNC.If I had it to do over again, I don't think I would have spent the money. I could have bought a lot of boards from a fab house for the money I've spent.-dan

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 09, 2013, 09:51:04 am
content: If you need PCBs in a hurry, go the UV/chemical route, which is both quicker & much cheaper for comparable results.If you're not in a hurry, just leave it to people with the right gear.If you need a lot of drilling, a small CNC may be useful, and doesn't need to be as accurate/expensive as you need for reliable routing.

author: awallin
author_rank: Frequent Contributor
timestamp: March 09, 2013, 10:09:40 am
content: I've used a few different "protomat" models by LPKF, and they work well. Even with a pro machine you need to have a bit of practice with the work-flow and the cad-cam-cnc toolchain before everything goes smoothly.The most critical part is the correct Z-height of the V-cutter for cutting isolation grooves between traces. It needs to be checked/adjusted before every run. The LPKFs use a V-cutter that should produce a 0.2mm (8mils) wide groove.If you search ebay/google for used LPKF machines they will sell for 3-5k$/eur, but as mentioned by others in this thread that is not wildly different from what it costs to DIY a similar machine.

author: Gall
author_rank: Frequent Contributor
timestamp: March 09, 2013, 10:52:22 am
content: A cheap (or even DIY or even Lego!) machine may be used for chemical process. A paint marker may plot traces directly. A narrow focused blue laser pointer may be used with photoresist. Look at old XY plotters, too. A 1970's flatbed pen plotter may be used with an paint pen.A milling machine is much harder to run due to its limited precision. It is much easier to achieve high precision moving a pen with no force than moving a cutter with force.

author: nctnico
author_rank: Super Contributor
timestamp: March 09, 2013, 11:18:20 am
content: There is one area where a CNC milling machine doe excel for quick prototypes: RF boards with microstrip 'components' (components made out of PCB traces). On those the tolerances on the trace widths are tight and that is difficult to achieve by etching your own boards.

author: snipersquad100
author_rank: Frequent Contributor
timestamp: March 09, 2013, 03:09:29 pm
content: Thank you guys for the replys

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 09, 2013, 03:23:21 pm
content: Quote from: nctnico on March 09, 2013, 11:18:20 amYou'll need to spend a lot on CNC to get better accuracy than UV etching, provided your printer produces resonable accuracy.

author: Dongulus
author_rank: Regular Contributor
timestamp: March 12, 2013, 09:01:08 am
content: How disappointing. A PCB milling machine sounds like such a fun toy to play with, but it really doesn't seem worth it.

author: Mike Warren
author_rank: Unknown
timestamp: March 12, 2013, 09:22:20 am
content: I can't imagine getting anything like the same accuracy from a hobby level CNC machine for PCBs.The rings around the fiducials on this board are only 3 thou. I can reliably get 8 thou tracks and spacing. I finished the layout of this board in the morning and had code running on it by the afternoon.

author: M. András
author_rank: Super Contributor
timestamp: March 12, 2013, 05:46:24 pm
content: sorry for the off topic, but what is the reason for those ground, and mounting hole connections with 4 little copper strip attached to the plane instead a full contact?

author: Mike Warren
author_rank: Unknown
timestamp: March 12, 2013, 08:31:28 pm
content: Quote from: M. András on March 12, 2013, 05:46:24 pmNo reason except I forgot to switch off the thermals for those pads. It was only a quick prototype and was discarded a week later.

author: Psi
author_rank: Super Contributor
timestamp: March 12, 2013, 10:57:44 pm
content: Normally that's done so the soldering iron is able to heat up the pad without having to heat up the entire ground plane.But yeah, as said above, its not needed for mounting holes.

author: M. András
author_rank: Super Contributor
timestamp: March 13, 2013, 08:17:46 am
content: for simple gnd connection on a terminal block is this done the same while defating the current capability or its made solid where current capacity matters?

author: Mike Warren
author_rank: Unknown
timestamp: March 13, 2013, 09:23:27 am
content: Quote from: M. András on March 13, 2013, 08:17:46 amI use thicker spokes (and sometimes more spokes) in that case. The specifics depend on how much current. Remember that the spokes are only 10 to 15 thou long so they don't have a lot of resistance.

author: poorchava
author_rank: Super Contributor
timestamp: March 13, 2013, 02:06:12 pm
content: Milling machine is tremendously useful for electronic hobbyist, but not for milling traces on pcbs. They are perfect for making enclosures, drilling DIY pcbs and cutting the outlines. I don't think that any purchasable machine below like $5k mark has the accuracy and precision to mill pcb traces. You can build one like that yourself, but that would have to be very rigid, most likely made of metal (as opposed to plywood, MDF, and all plastic+metal rods arrangements). In theory you can build one like that using only calipers and clock indicator, but that will take a lot of effort.And of course sharp engraving bits which are used for pattern engraving are rather expensive, and you ARE going to break quite many.Buy/make any CNC, drill holes in raw laminate with it, cover it with uv-sensitive paint (like Positiv 20), dry, expose, develop, etch -> you get a nice pcb with 8/8 mils track and clearance.

author: snipersquad100
author_rank: Frequent Contributor
timestamp: March 13, 2013, 09:39:23 pm
content: Thanks guys, I dont think I will get one after reading your posts, thanks for the warning.They do look like fun toys to have thou, Maybe I look into a cnc drill instead.

author: elliot42
author_rank: Contributor
timestamp: March 13, 2013, 11:19:06 pm
content: I'll just pop my head in to agree with the general comments here. I bought a Chinese 6040 CNC router from eBay and it's pretty fun to play with, but setting anything up takes time and planning. I wanted to do PCB routing and aluminium panel cutting and engraving with it, but it takes so much effort to get something half decent it just hasn't gotten that much use. I haven't even tried PCBs with it and I don't think I will. I'm designing some PCBs at the moment that I'm just going to order from OSHPark. I have ideas/plans for routing some wood panels for an amp, DAC and some other things, I just have to set aside enough time to focus on it to get anything done.

author: JuKu
author_rank: Frequent Contributor
timestamp: March 14, 2013, 09:21:41 am
content: Quote from: poorchava on March 13, 2013, 02:06:12 pmDepends on the precision requirement of the PCB design, but you might be surprised. This is from a <$600 machine:http://www.shapeoko.com/forum/viewtopic.php?f=28&t=1039And you can get much better by spending some more money. Sub $2k machines can be so good that the problems of milled PCBs are elsewhere. Simple designs can be done on simple PCBs. When the design is complex, you need a double sided PCB, and soon you have to figure out how to align the layers and how to make vias. You can do a few vias by soldering a piece of thin wire on both sides, but at few ten vias or so, that becomes unpractical. And of course, milling is really sensible only on one-offs.Personally, I find commercial PCBs so cheap nowadays, that between ready-made boards and soldering one-offs on protoboards, there is no need for me to get the capability to do my own PCBs, etching or milling. I know it can be done, but it is not worth the effort for me. For example, I would have done the board pictured in the link on a protoboard.Now, when someone develops a commercial product to easily do my own double sided PCBs with plated through vias, I'll buy!

author: poorchava
author_rank: Super Contributor
timestamp: March 14, 2013, 09:41:08 am
content: If you want, you can build a cnc machine for like $300, maybe even less. Mine costed me like $600-800, but I have invested in nice spindle motor, supported guide rods and linear bearings. Using dremel clone and drawer slides you could achieve quite good accuracy too. Drilling pcb and milling pcb laminate + occasional ABS frontpanel doesn't involve huge forces, so rigidity is not the main problem here.Definitely a very useful tool if you have space for it.