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View Full Version : Idea's on a cheap, nice CNC project



Stern
01-13-2014, 01:36 PM
OK, I know the title may sound contradictory, but more and more I am finding myself wanting a small CNC "router type" machine ...... basically for nothing more than PBC making. I have made PCB's for so many years i can do it in my sleep, but things have changed since my youth and its getting harder and harder to make your own now. Used to tape up films and have negatives made for photo resist work..... Now the spray resist is next to impossible to find, and tape is a thing of the part (all cad now). I find "Photo resist transfers" are great for bulky stuff, but for fine trace work they suck.

Anyway, what I want is a small CNC type machine that will process small board (max size would be 12" x 24"), even something using a dremel as its spindle assembly. I would have no problem making the assembly (thats half the fun) but after a few days searching there is so much stuff out there im now confused as hell.

Have seen MANY kits with look really good, but I sure cant drop a few grand on one, plus making your own stuff is half the fun. Problem is you also have to buy plans, and you could get 40 sets before finding one you liked. Also, the LAST thing I want to have to do is buy a $10K autocad package thats so hard to use its easier and quicker to pick the copper off the board by hand. I use FREE PCB software (had a great one that went belly up, now I use design spark) and want something that I can use ITS file format to run it (and while I spent many years writing machine code software, I DONT want to do that lol).

So, I guess Im asking if anyone has made one, or used a good one .... anything that can start me on the right track to making one.

dp
01-13-2014, 06:14 PM
You might drop a note in the CNC forum here: http://bbs.homeshopmachinist.net/forums/9-Digital-Machinist and take advantage of the CNC talent there.

outback
01-13-2014, 06:17 PM
From a builder of a number of CNC projects I can tell you that you don't need any kits. Just decide what you want for ways and spindle. From experience I can say dovetail ways can't be beat when it comes to rigid.

For electronics all you need is a computer and software like Mach3. You will need to make a DC power supply usinga tororidal transformer, a breakout board and a driver board for each axis. For driver boards you can use Gecko drivers or use Chinese drivers board available on Ebay. I use Geckos for my industrial duty machines and the Chinese drivers for my prototype projects.

Then you will need either stepper motors or servo motors to run your project.
Jim

doorknob
01-13-2014, 06:46 PM
How about a Shapeoko 2?

Plenty of people are using them to mill PC board traces.

I started building a Shapeoko version 1 for that purpose, and just bought a 400-watt spindle on eBay to use with it.

See https://www.inventables.com/technologies/desktop-cnc-mill-kit-shapeoko-2

jlevie
01-13-2014, 07:34 PM
It would take a very precise (expensive) machine to make fine traces. A CAD package and a flat bed ink-jet resist printer would be more affordable. Or just use the services of one of the on-line prototype board makers.

lwalker
01-14-2014, 08:07 AM
If you want to make a CNC machine for the fun of it, go ahead. But doing it for making PC boards is likely never going to be cost-effective. PCBs are simply too cheap. OSHPark etc., will make you 3 high quality boards for $5/sq. in total.

I guess if you absolutely, positively need boards in hours/minutes instead of overnight or in a few weeks, a CNC mill might be a good idea, but only if you don't put a dollar value on your time.

Stern
01-14-2014, 09:26 AM
I have done a lot of surfing (and still at it) and actually never realized we have a section here (search didnt work for me). I have no desire to make PBC for a living or anything, but I DO have a need to make them time to time with projects I work on (like gauge clusters for my bike etc). ( have looked at lits and while they are probably great, I dont have $2K to drop on something like this (plus all the other stuff needed to run it).
I am sure getting the resolution will be a challenge, but isnt that part of the fun of making something yourself (I could have bought a mill and press thats better than what I made myself, but really whats the point, its a hobby for me?)

As for OSHPark and other "use our free software and we make the board for you" places, most are NOT cheap, most are size limited and almost all are in the US (nice shipping and duty fee's). Back in the day I had a PCB place make 10 block prototype runs for me all the time, now its freaking expensive for anything other than a final run. Used to do prototypes myself, but the lack of good materials now make it almost impossible.

Anyway, figure this will be a good project for me to learn how to get my accuracy a lot tighter, even using the non professional equipment I have. My big headache is finding and putting the NON hardware into place (motors, drivers, software). I could make driver boards .... DONT want to. Would prefer pre made ones with software thats "plug and play" on windows and comparable with Design Spark (which I think generates G code, cant remember). Im sure an auto tool changer would be nice, but I would be happy with a dremmel used as the spindle.

Anyway, going to check out the link dp, thanks a lot, the site search never seems to work well for me

Stern
01-14-2014, 09:27 AM
duplicate

Jaakko Fagerlund
01-14-2014, 10:00 AM
For cheap PCB's, check out http://imall.iteadstudio.com/open-pcb/pcb-prototyping.html

An example, 50x50 mm, 2 layer board, 10 pieces, 9.90 USD.

Stern
01-14-2014, 10:08 AM
For cheap PCB's, check out http://imall.iteadstudio.com/open-pcb/pcb-prototyping.html

An example, 50x50 mm, 2 layer board, 10 pieces, 9.90 USD.

Well, not sure how you came up with that figure, but when I entered data for a cheap board 45 mm x 50 mm double sided 1 oz I get $495 + $5 shipping ????

This is ONE reason why I want to make my own, second is ONE mistake and the board is crap, and you just blew $500+ I can walk into a place here and get a prototype run of 10 for $400, which is STILL too much

MotorradMike
01-14-2014, 11:59 AM
If I want it shipped from Canada I go to Alberta printed circuits (http://www.apcircuits.com/).
They will make 2 double sided boards 5cm x 5cm for 51.50 in 3 days.

I prefer an outfit in California but find it difficult to get electronic stuff across the border.

Stern
01-14-2014, 12:20 PM
If I want it shipped from Canada I go to Alberta printed circuits (http://www.apcircuits.com/).
They will make 2 double sided boards 5cm x 5cm for 51.50 in 3 days.

I prefer an outfit in California but find it difficult to get electronic stuff across the border.

Again, 5cm x 5cm is smaller than anything I would uses (4" x 4" would be small, 16" x 6" would be common) and when its all said and done, I end up paying a fortune for a prototype board that has a 95% chance of changing at LEAST 5 times lol.

Anyway, this is really about the "project", not PC boards. For me to pay $2K-$5K for a CNC router is not going to happen.... EVER. For me to make one as a project .... far different story. I can take 300 years if I want to, spend money ONLY when I have it to spend, and more importantly .... have fun making it. After all, this is a HS forum, where people MAKE things for the joy of making them.


Anyway, thanks to dp I found the CNC section of this site (seems any search I do just sits there and never ever stops ?) and have been able to look through some posts and try to learn some more about CNC :)

Jaakko Fagerlund
01-14-2014, 01:37 PM
Well, not sure how you came up with that figure, but when I entered data for a cheap board 45 mm x 50 mm double sided 1 oz I get $495 + $5 shipping ????

This is ONE reason why I want to make my own, second is ONE mistake and the board is crap, and you just blew $500+ I can walk into a place here and get a prototype run of 10 for $400, which is STILL too much
The figure is right from that page. When you scroll down a little, you see multiple options that you can add to your cart. That 50 x 50 mm double sided is the second from the top, costs 9.90 USD. Click on "add to cart" and it then asks you for board thickness, coating, E-testing, (color), and what else was there and shows the amount of money that some options cost extra.

The last time i ordered I got 50 x 100 mm PCB's, 10 pieces, all E-tested and together with shipping I paid about 25 EUR. So at 2.5 EUR per ready made PCB with all the silk screens etc., just having to wait 1-3 weeks, it just isn't worth it doing at home anymore.

Added: I calculated that your 16 x 6 inches board would be 286.82 USD plus shipping, this includes 5 PCB's, all tested.

vincemulhollon
01-14-2014, 01:40 PM
Anyway, what I want is a small CNC type machine that will process small board (max size would be 12" x 24")

Dremel will be too wiggly. Guess it depends on your precision. I've been using my mill. Copper cutting results are usually awful, but sometimes usable.

As for all the "$50 is cheap" posts this is things like MMIC amplifiers using microstriplines, where the "pcb" is pretty much two very precise passes of the endmill to make perfect width traces, then chop gaps by hand for the MMICs themselves and DC blocking caps and everything else can be Manhattan style or dead bug style. I would hesitate to mill something complicated. So anyway WRT $50 is cheap, I'm doing things with $2 MMICs and fifty cents worth of chip caps, so no $50 is not cheap in comparison. Of course you can Manhattan microstripline easier than you can etch/mill it although soldering heat tends to screw up every glue I've tried. So I started sweating copper pads, and occasionally setting the boards on fire, its a craft or art more than a science.

I've found thin PCB material to be a challenge to work-hold because its thin and flexy and nothing grabs and tears quite like copper. Nothing more frustrating than setting up the perfect trace accurate to a thousandth and the mill grabs and tears the thing clean off the board.

The first time I tried this I was so unhappy with the result I swore it off, but ugly as it is, it actually works well enough. So I mill copper PCBs occasionally.

This is microwave RF stuff, haven't used thru-hole for that stuff since before the 80s, so I'm all/mostly SMD so I have no assistance to provide WRT drilling thru holes. I've been told PCB fiberglass is super abrasive to drill so you need amazing, expensive drills which wear out very fast, or so they say.

If I had the money, I imagine one of those 30K RPM air spindles would be really nice for PCB cutting.

Cutters are not free, so there is likely some tradeoff point where its financially cheaper to just order out PCBs.

I'd never one-off a PCB, I'd Manhattan or dead bug it, so there's a pretty narrow window where its too many to just grind it out by hand, but not enough for commercial production. My guess would be something like 5 to 20, where less than 5 just wire by hand, and more than 20 its hard to not come out ahead with commercial production.

If you cut into the surface of the fiberglass, I've seen it behave like cold rolled, so it'll pretzel a little due to relieved stresses. Not all the time and not all materials, but it happens.

The mill sometimes shoves little bits of swarf literally into the board, another annoyance.

Stern
01-14-2014, 02:02 PM
From what I have gathered so far, the "milling bits" are actually special for PCB work, and look like a spade bit. Have used all forms of "prototyping" and breadboard is still my favorite (lends well to changes). Basically, the only boards I WILL make ore one-of or prototypes, and with the stuff I do, nothing beats having a "real board". I DONT use SMD as the cost is too high and you need special equip to do it right, especially when you get tight. I stick with DIP and discrete parts, and they can get very tight.
Since working on a project that has tight dimensional restraints can mean making 8 boards for one project, making them myself is the only option.

Contemplating using a motor spindle in place of my dremmel, but at $200-$1K they are way too stupidly priced for my budget. Will still kick the idea around a bit, and maybe if all goes will using a dremmel I can swap it out for a real spindle down the road.

EVguru
01-14-2014, 02:33 PM
Take a look on http://www.milinst.co.uk/

Their three axis machine is just about as simple as you can get. I think you may be able to download the plans.

I used their code as a base, be re-wrote it entirely for the PCB drill at work (now mine!). We made our boards by photo etching, then drilled them. Double sided was usual and we made boards up to A4 in size.

Stern
01-14-2014, 02:46 PM
Thanks so much for the link EVguru, it will be extremely helpful. while I would prefer photo etching, its getting to hard to do myself (cant get spary new resist anymore, rub on stuff sucks for detail etc). So far, looks like once I have the mechanical stuff done, the rest will be pretty easy. MANY packages with the 3 axis controller/motors/PS all designed to run from MACH3.
Looks like the big question now is if the schem/PCB software Im using will generate the right G file for Mach3 (Design Spark generates "Gerber code", which hopefully is the same thing as G code used by Mach3. Getting tired of learning new stuff all the time LMAO)

doorknob
01-14-2014, 03:49 PM
Gerber code is not the same as the Gcode used by Mach3.

But you can convert from one to the other:

http://sourceforge.net/apps/mediawiki/pcb2gcode/index.php?title=Main_Page

Toolguy
01-14-2014, 04:06 PM
I have had good luck machining copper using TapMagic for Aluminum. I don't know how it would work on a PC board but might be worth a try. Just the thinnest film of it should be enough.

Stern
01-14-2014, 04:11 PM
Thanks very much for info Doorknob, that really helps a lot, as it seems I need a converter like this to allow Mach3 or similar to run anything DS would generate.

RichR
01-14-2014, 04:34 PM
Glass epoxy is very abrasive. I used to use one of the machines made by T-TECH to mill PCBs about 15 years ago. The drills and
cutters were carbide.

lwalker
01-15-2014, 11:34 AM
I've found thin PCB material to be a challenge to work-hold because its thin and flexy and nothing grabs and tears quite like copper.

I don't typically make my own PCB's because as I mentioned earlier, they are so cheap ($1.60/sq. in), it's not worth my time, but occasionally I do mill some very simple boards such as for mounting LEDs. I use a 3M thin double sided tape (from Digikey: I can look up the part number if you're interested) to hold the PC board down and it doesn't budge but yet it peels off easily. Only problem I have is the dust: keep a vacuum handy and try not to inhale it!

Lyndon

EVguru
01-15-2014, 11:39 AM
while I would prefer photo etching, its getting to hard to do myself (cant get spary new resist anymore, rub on stuff sucks for detail etc).

We always used pre-coated. We could get two tracks between 100 mil spaced IC pads if we needed to. Most of our work was one offs and when we were doing on a regular bases we could design and make a PCB quicker than we could build it on stripboard.

Stern
01-15-2014, 11:50 AM
Yep, used to do the same, only like spray on neg resist, which allowed me to cut the board size, make reg holes, spray it, quick UV exposure, develop and etch in under an hour. Since all artwork was photo reduction of taped double size layouts (didnt have CAD stuff back then lol) making them allowed trace flaws to be found and fixed before a 10+ prototype run.

Anyway, Im planing on making this unit sturdy enough to also do aluminum and possible some fine steel engraving work ... just in case lol. Always like to build things a little MORE than required.

So, guess I start with the frame and gantry and get that right before worrying about anything else :)

Glug
01-15-2014, 11:54 AM
A number of folks have given great advice on how excellent mail order PCB's can be, and also how affordable.

But even if you end up going that route, I still encourage you to get into CNC routing. You will learn so much with the project, and adapting to CNC machining of parts will be really healthy for your brain.

To get your feet wet, you might try using an arduino with steppers or servos to experiment.

doorknob
01-15-2014, 02:14 PM
I use a 3M thin double sided tape (from Digikey: I can look up the part number if you're interested) to hold the PC board down and it doesn't budge but yet it peels off easily.

If it's not too much trouble to look it up, I'd appreciate the part number for the double-sided tape that you use.

Thanks...

Stern
01-15-2014, 04:33 PM
A number of folks have given great advice on how excellent mail order PCB's can be, and also how affordable.

But even if you end up going that route, I still encourage you to get into CNC routing. You will learn so much with the project, and adapting to CNC machining of parts will be really healthy for your brain.

To get your feet wet, you might try using an arduino with steppers or servos to experiment.

Well I sure appreciate everyone's help, but no worries, I WILL continue with the CNC project. Havent played with the arduino stuff, but spent 20+ years making custom hardware/software [machine code ONLY] around specialized MPU like the 68705, 6900 series ... and recently, the single chip PIC units).

I guess maybe some dont look at things the same way as me when it comes to projects. I always wanted a hydraulic press but never got one because I could not "justify" having one .... I had no use for it. Once I made my mill and started making other things I had a need for broaching ....... and THAT gave justification to a press. Also, I was in bad need for a sheer and bender. The 3 in HF one I got was really a hunk of crap and simply wouldn't cut or bend the sheet steel I use (stainless and 16 gauge CR) ... SO .... NOW a hydraulic Press can be justified.

Same with this project, I have always wanted one but couldn't justify the cost of a project with no use (Im not a carved art type of person). However, since I started working on a gauge cluster for my bikes, PCB's were needed .... and BLAM! now I can justify it. This really has about 1% to do with PCB's and 99% to do with A PROJECT that can be JUSTIFIED :) Dont think many here get that, maybe its just my posting isnt clear lol.

Im full steam ahead on this and already looking for a place to find aluminum, especially formed type (shaped channel stuff etc). I will concentrate only on making a solid base and gantry with rock solid and accurate slides (x-y-z) and then once its good enough move onto the easy stuff (electrics)

lwalker
01-15-2014, 07:08 PM
Not a problem. I try to keep at least one label from everything I buy if it's not an item I track so I just have to look in the drawer.

The 3M part # is 1/2-5-9088, Digikey's P/N is 3M11464-ND. 1/2" double sided tape 5 yards, $3.90 each qty 1.



If it's not too much trouble to look it up, I'd appreciate the part number for the double-sided tape that you use.

Thanks...

tricklidz
01-15-2014, 07:27 PM
Well I sure appreciate everyone's help, but no worries, I WILL continue with the CNC project. Havent played with the arduino stuff, but spent 20+ years making custom hardware/software [machine code ONLY] around specialized MPU like the 68705, 6900 series ... and recently, the single chip PIC units).

I guess maybe some dont look at things the same way as me when it comes to projects. I always wanted a hydraulic press but never got one because I could not "justify" having one .... I had no use for it. Once I made my mill and started making other things I had a need for broaching ....... and THAT gave yjustification to a press. Also, I was in bad need for a sheer and bender. The 3 in HF one I got was really a hunk of crap and simply wouldn't cut or bend the sheet steel I use (stainless and 16 gauge CR) ... SO .... NOW a hydraulic Press can be justified.

Same with this project, I have always wanted one but couldn't justify the cost of a project with no use (Im not a carved art type of person). However, since I started working on a gauge cluster for my bikes, PCB's were needed .... and BLAM! now I can justify it. This really has about 1% to do with PCB's and 99% to do with A PROJECT that can be JUSTIFIED :) Dont think many here get that, maybe its just my posting isnt clear lol.

Im full steam ahead on this and already looking for a place to find aluminum, especially formed type (shaped channel stuff etc). I will concentrate only on making a solid base and gantry with rock solid and accurate slides (x-y-z) and then once its good enough move onto the easy stuff (electrics)

Sounds like me. I'm a bike guy too, mostly tricked out Ducatis. And I'm addicted to this new maching stuff. So far within the last few months I've bought a new mill, rebuilt a used lathe, spent a fortune on tooling, got a HF bandsaw coming tomorrow and can't help thinking I need to build a CNC machine, even though I know nothing about programming or what these things do!!
Here's who I've been following lately and just sent him an email about his "kit".
Www.neo7cnc.com
So much to learn, money to spend!!!
Steve

darryl
01-15-2014, 08:37 PM
I was just thinking about this again today- the making of pc boards. My latest 'thing' had been surface mount, but using standard components. That way no holes except for mountable devices and mounting holes. It wasn't a big deal for me to lay an ic into a channel, then bend the tips of the leads over to make little feet for surface mounting. So much depends on the size of the layout and the components that are going to be used.

At any rate I stayed with etchant, so the real bear of the whole thing was doing the artwork on the board itself. I never did like the iron-on method for the resist, and today I was thinking about how a cnc machine could be used to 'blast away' a pattern on a board that would be solidly coated with a resist of some type. Maybe a micro-bead blast method? I don't know what resolution would be possible- just an idea anyway. The blasting might etch into the copper as well, but that would just ease the job for the etchant later. The main idea behind all this as I was thinking about it today was to eliminate the need to machine the copper, with its attendant requirement for a sturdy machine and 'expensive' cutting bits, as well as the potential damage to the pc board itself.

When comparing results, which would give a better and/or finer result- physically machining the board using a cutting tool, or a blasting process?

I allowed myself to actually consider an old technology- use a pattern follower to guide the cutting or blasting head. Place your paper pattern in one side of the machine and start the automated process of scanning the pattern and raising/lowering the cutter in response. I realize that this is crude compared to cnc, but would not require control software- just motors to drive the axes and a simple indexing arrangement to create a mechanical raster on the board.

Stern
01-16-2014, 09:18 AM
I actually DID think about a CNC plotter that would draw ink on the board, but the big problem is the ink itself. has to be pretty thin for uniform thin traces, and has to air dry not to fast. I suppose an "ink jet" idea could be used to coat the board with the pattern, but my success with using a normal ink jet printer is bad (about 14 have taken the "flight of shame" out my office window (before I realized I could get rods, motors and other good stuff out of them) as they ALWAYS gum up unless you print something at LEAST every day. Now I stick with Laser.