Build Your Own PCB Milling Machine

mwandel writes "It used to be that one off amateur printed circuit boards were all etched in acid. A lot of companies nowadays use a special form of milling machine to mill them out of solid copper clad circuit boards. This guy Jonathan Westhues built his own PCB milling machine out of various parts, with a laminate trimmer as the milling head. Lots of other neat hacks on his Webpage as well."

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There are easier ways

[John Jorsett]

Seems like a lot of trouble to go to when it's pretty cheap to get small-quantity custom boards done.

Re:There are easier ways

[lirkbald]

A couple others to try:

ExpressPCB- Has an offer that will let you make 3 3.8"X2.5" 2-sided boards for about $60, as well as a more general off that's not too much more pricey. They have their own board design software you have to use, which is a bit primitive but adequate for hobbyist use, though it's a problem if you were to ever want someone else to make your boards.

Advanced Circuits- Has a deal to make 2-sided boards for $33/ea, min qty 3. These boards have a solder mask, which is required for dealing with fine-pitch SMT parts, and makes your board all pretty and professional-looking ;-)

Sierra Proto Express- Has a similar deal to Advanced Circuits, but also has a good price to make four-layer boards.

Some general notes- I've used the first two, and it worked alright, but I haven't tried the third one. The latter two require Gerber and Excellon data- this is the standard format for PCB plotting and drilling information information. Essentially any board layout software should be able to generate them. However, it is not trivial to figure out what precisely to send the board manufacturer- you can't just blindly trust your layout software to do the Right Thing. I keep meaning to write a little tutorial on my hard-won knowledge about this, but I've never gotten around to it :-/

Re:There are easier ways

[anubi]

I do all my proto work through Advanced Circuits.

I use PADS PCB ver 7.0 for DOS to generate the Gerber photoplot, aperture, and excellon drill files. Once I have the fileset intact, I zip them and email my rep ( in my case, Anthony Estes ) over at Advanced Circuits with my zipfile package as an attachment, and about a week later I get a large padded envelope in my mailbox with my boards in it. Every one has been exactly what was ordered. Excellent workmanship. And on time.

Getting started is the hardest part. They know that too, and thats why they have the reps. There is a little hand-holding to be done to make sure you are sending the right stuff, as you do not want a botched job, and they do not want unhappy customers either. When I started off, I first talked via email to my rep, sent him my filesets, and had him review them to make sure they made sense to him too, and were complete and manufacturable. I was impressed with my rep, as he knew just by looking at my files in his viewer if I had screwed up the aperture files or had a bad excellon file. ( The gerber photoplot files shows how the lines are routed, the aperture files show how wide the traces or pads are, and the excellon files show where and what size drill for the holes. You get one photoplot file and one aperture file per layer, and one excellon file per board. ) Once I had confirmed I had a producible fileset, I called him on the phone to set up an account and get the boards made. Since then, every time I need a board, I email him my fileset, and he sends my boards back.

They have quite a sophisticated system to track the progress of manufacturing the boards. You note that little window on their opening page. When you place your order, they will give you a key number to find your order in their database. They know minute to minute where your order is in the manufacturing process - and you can verify at any time where it is. It looks as if they have some very sophisticated PCB manufacturing automation going on over there. My guess is that its like a giant one-hour photo machine. Files go in, boards come out.

No, I do not work there. I am just a pleased customer. I feel I have spewed enough venom at those who did not come through that I feel I must give equal time commending those who did.

Re:Amateur

[bjcubsfan]

They're still called PCBs even if they are milled. It's a naming convention that has stuck. It is in no way incorrect.

Also, It is not difficult to make a double sided PCB with a milling machine. There are many times in circuit board design that you don't need more than one or two layers. This is a solution that solves a lot of smaller problems every day.

Do It Right - John Has Great Plans

[MBCook]

note: the site is down, so I'm going off a mirror of the front page of the site, sorry if I get things wrong

If you want to build a machine to mill circuit boards, do it right. Build a machine designed by John C Kleinbauer. The Brute is designed to make PCBs cheaply. I recently bought some of John's plans (well worth it) and they are quite nice. They are very well done, easy to understand, don't need things that are exotic and hard to get (if your in the US). He includes a booklet on how to mill PCBs with The Brute, or you can order it seperatly. He even maintains and activly participates on his forum, Hardware Store CNC.

I've started to build a brute, and things are going pretty well considering I'm doing this in my spare time with only some time to work on it. If you guys are like me (I really like to build things with my hands) this is a ton of fun. I can't wait to get it running so that I can make PCBs, robot parts, a wooden clock and more.

Re:Do It Right - John Has Great Plans

[Compuser]

Kleinbauer claims 3 mil accuracy whereas pcb lines
can be 5 mil wide or even smaller. I am saying this
because I had a design which needed to have ultra
thin traces and have them straight (low capacitance
and inductance were key). This method just isn't
accurate enough for the most demanding PCBs.

Re:milling machines are cool

[robwills]

CNC == Computer Numeric(al) Control

It's a shameless plug, but....

[Arethan]

My dad wrote some CNC control software that would work quite well for this application. It's designed to run anything from table top machines (such as this) all the way up to large scale CNC retrofits, where the iron is good but the control is shot. Very competitively priced as well. Even has a free demo version with no time limit for those that want to check it out. Requires a dos based machine to run it on though. FreeDOS works fine, of course so does MS-DOS.

I'm sure this will kill his pipe, but here is a link: www.cnczeus.com

It's listed in google as well, so you may want to check that out if/when the pipe goes dead from the load. :)

Milling machine

[oneiros27]

Milling is the process of cutting by movign a quickly rotating cuting head in relation to the item being cut down. Most machine shop milling machines have a stationary head, and move the item around, while some cnc machines have a head that moves.

Of course, questions like this are where search engines come in handy -- http://www-me.mit.edu/Lectures/MachineTools/mill/i ntro.html

Useless

[tftp]

I can't get to the site (slashdotted). But I used one of such machines. Nowadays they are absolutely, unconditionally useless. They can't make the fine traces that are required for modern chips. Instead, it is cheaper now to order your PCBs from a board house (such as Advanced Circuits). $30 per board is not that expensive.

Re:Electronics Enthusiasts...

[Smidge204]

How about sources for new/surplus components?

http://www.goldmine-elec.com/
http://www.alltro nics.com/
http://www.allcorp.com/
http://www.new ark.com/
http://www.jameco.com/

Try to never buy from Radioscrap. Overpriced and crap quality...

I've ordered from Alltronics before. They have a $15 minimum order, and sometimes an order may be delayed if something you requested is out of stock. They answer your e-mails rather quickly, though.

Jameco also sells the seemingly elusive PCI prototyping cards, though they're pricey ($70). Anyone know another supplier of these? (They're also good if you're looking to pick up a 266MHz PII motherboard for $20)

=Smidge=

Isn't it a salt?

[shoppa]

were all etched in acid

Isn't Ferric Chloride (the stuff you buy in bottles at Radio Shack, or at least I did when I was a kid) actually a salt? FeCl... looks like a salt to me!

Re:Isn't it a salt?

[Paul Neubauer]

Yes, it is a salt. Copper is more reactive than iron, so the etch works by the chlorine trading iron for copper. The "filings" left after etching are the iron that was freed in the reaction.

Some folks see it anything that 'eats' away at something as being caused by an acid, even if no acid is really involved. Wouldn't it be nice if chemistry was taught? And taught in a way that was effective?

Re:Electronics Enthusiasts...

[Kevin Burtch]

Well, there used to be Electronics Now and Popular Electronics (which merged, and became Poptronix), but the printed publications are gone (to my knowledge). You may be able to find all the old issues at your local library... although ones over 1 year old may be only on microfische.

As much as I'm annoyed with Radio Shack for turning into a toy and appliance store (they used to be an electronics hobbyist store), they do still have a handfull of items for the electronics tinkerer.
I'd recommend picking up all of their Engineer's Mini-Notebooks to start with.
I'd also recommend checking out some of their X-in-one kits... I think they have a 300-in-one now (I hope they haven't stopped making these).
They have all kinds of example circuits that you can make by hand wiring (read: no soldering) the circuits together - and some of the examples are kind of cool for a beginner. I started with a 150-in-one kit (it was the biggest at the time) way back when I was a teen.

After this... if you want to get into digital electronics, pick up the TTL Cookbook and CMOS Cookbook by Sam's.
If you want to get into audio electronics, pick up the Audio IC OP-Amp Applications (also by Sam's).
If you're a musician, there's a VERY cool one called Electronic Projects for Musicians by Craig Anderton. Use this one with the above audio book to come up with some really cool guitar effect "pedals".

I hope this helps!

Re:milling machines are cool

[madfgurtbn]

What would be perfect is if there were places where you could rent time on a CNC mill, sort of like kinko's for engineers.

Try your local high school or middle school industrial technology teacher. I betcha you could work a deal where you could use their equipment if you can provide something of value to them in return, other than money (although a few bucks for the budget never hurts). Most valuable is your time and expertise. Least valuable, most likely to get you a no answer is anything that is going to take up any of his/her most valuable asset--time.

It is a big hassle to have to help a newbie set up a mill and even if the user has experience, it is generally a hassle to help them find the tools, widgets, and toolbits needed for your particular project. So make it clear from the get-go that you are going to make it worth their time, or you will probably not get near the equipment.

Re:milling machines are cool

[madfgurtbn]

See www.desktopcnc.com for a comparison of various tabletop cnc machines. Depends on your personal definition of "affordable", but there are some small machines $3k

I don't think you could reach .0001 tolerance on those low-end machines, but most of them would get close to .001, which is plenty for most hobbyist projects.

Re:milling machines are cool

[zymano]

small engine cnc links

dremel cnc

big links

mini zoltar cnc(using dremel)

pretty unfortunate

[RestiffBard]

This is one of the cooler "News for Nerds" articles I've seen in a while and its completely unreachable at 4 in the morning because of the slashdotting.

this is no longer humorous. As much as I often enjoy the +4 comments on certain articles reading slashdot is pretty much no longer worth the frustration of not being able to RTFA.

Can't wait till this article moves down the frontpage.

Re:milling machines are cool

[anubi]

I read the links over at crankorgan and note he's come up with a nice homebrew CNC machine. Note.. if you are gonna brew your own, you might wanna check out any tossed copy machine, printer, or old 5 inch floppy drives. You would be surprised at the wealth of motors, gears, shafts, whatever, you will find in one of those big clunkers! ( Especially those with those big collator bins. ). You not only get the motors, but with a lot of old machines, they were made before everything went ASIC and you can probably retrieve the power supply and basic motor drive circuits intact.

Find the biggest ugliest old battleship printer at the swap meet. Its apt to be brimming over with usable mechanical parts. You may have to haul the thing away in a truck, but you can probably pick one up cheaper than the gas it takes you to get it home. I've seen sellers get so frustrated trying to rid themselves of an old line printer that they gave it away rather than try to pack it up for the next meet. And the older, bigger, heavier, and uglier it is, the more apt it is to have salvageable parts and powerful motors - because they were made from standard parts before everything was mass-produced for a specific use. As well as being over-designed.

A lot of those old 5 inch floppy drives had a quite decent stepper motor for head positioning that had a standard 1/4" dia shaft. And most had a standard driver chip for the motor too.. those quad-darlington on a chip things. A little inspection on the circuit board usually confirmed how to hook it up.

A side note - if you luck out and get one of those "pancake" spindle motors, some have one helluva disklike planar magnet in them - already mounted in a steel cup. It has a really unique magnetization pattern to it - where it has alternating patterns of North-South on the face that faces the windings. Once removed, it has an extremely powerful attraction. Do not remove it from its cup. Do not even try. You will ruin it if you do. The cup not only mechanically supports the magnet, it also assists in focusing its field. It makes one helluva "refrigerator magnet"! I would advise gluing a piece of felt to it. This magnet will stay where you put it.

Arethan has a post on this forum about some software his dad coded. . I looked at it and it really looks promising. Note it used the standard CNC G-code language and had a really nice port setup so you could drive the interfaces from a pair of standard run-of-the-mill parallel ports. I cite his post because if you are considering rolling your own, you will probably need something like this. This looks like good practical software.