PC board milling?

William Danielson anviljenkins at gmail.com
Thu Dec 31 10:37:40 CST 2015 

My background is as a machinist....dipping my toes into the electronics.

Non ball type screws have backlash but IMHO for milling PCB you could 
just work them against a Nitrogen gas spring like holds the hood and 
rear door open on a lot of vehicles...keep the screws lubed up and you 
should be good to go.

The cutting forces on a PCB are not anything like milling a part from 
plastic or steel or aluminum where the cutting force tries to bend the 
cutter and pull the work into the tool, etc.

I have not tried the toner transfer process yet but it will be my first 
try, played a little with a Eagle to try to design a PCB and I'm not far 
enough on the learning curve to actually design anything yet :-).

The LowFER breadboard link somebody posted in another post might be a 
cool Arduino Shield project :-).


http://lowfer.us/k0lr/proto/LFproto.htm#Solderless%20LowFER%20Transmitter

Bill



On 12/31/2015 09:10 AM, Rob Seastrom wrote:
> Yeah, what Martin said...
>
> I can *maybe* see doing this if I had "free" access to someone else's
> expensive machine that had the accuracy *and* repeatability to exceed
> my requirements (which are actually pretty tight if you don't want to
> be frustrated with your QFP variants not lining up quite right), but
> trying to get something for home use?
>
> My big concern with a used training Sherline (which might or might not
> have originally had the specs you need) is worn lead screws and/or
> ways.  The lead screws at least can be easily replaced.  The ways, not
> so much.
>
> Given the race to the bottom on both pricing and time multi-layer
> circuit board turn-around from China, I don't see a compelling case
> for the milling machine.  Likewise, I've given up on the ferric
> chloride and am never looking back - that stuff was yucky.
>
> -r
>
> Martin <dcmk1mr2 at gmail.com> writes:
>
>> I had access to a Taig mini mill fully tricked out with nice steppers,
>> electronics, software, etc.  I forget which software had it but some include
>> the notion of registration holes that get milled first and are used to
>> accurately align the PCB so that both sides match up.  I did get usable SMD
>> and through hole PCBs.  I tried a lot of engraving mills and end mills but
>> eventually gave up.  There was a lot if set up time and poor yields.  Maybe
>> If I did more it would have gotten faster and more reliable.
>>
>>
>>
>> If I had the dollars to burn I'd look into one of
>> these:Â [[https://othermachine.co/othermill/tech-specs/]] Â I believe there
>> some write up about their design and how they hold their accuracy.
>>
>>
>>
>> Until then OSH Park [[https://oshpark.com/]] has 12 day turnaround, $15/square
>> inch for 3 each two layer boards.
>>
>>
>>
>> 73 Martin W6MRR
>>
>>
>>
>> On Wed, Dec 30, 2015 at 10:23 PM, Terry Fox <[[tfox at knology.net]]> wrote:
>>
>>            Thanks sandy and Alex.  I think technology has moved forward
>>       since then.  I heard the same comments about 3D printers, but my
>>       experience is that the comments that I heard here about them were
>>       based on older units.  I like my 3D printer, except that the vendor
>>       is constantly moving forward with newer designs.  However, I can
>>       get most parts from Amazon or eBay, so no worries.
>>       
>>       There are a lot of cnc mill designs out there, but many don't have
>>       the accuracy for pc milling.  I'm pretty comfortable with steppers
>>       and electronics for them now.  I'm not as comfortable with "MDF"
>>       wood for some of the frames.
>>       
>>       Alex, is there a place of look on the Internet for used machines?Â
>>       A proper mechanical cnc that I could upgrade would save time.  I
>>       already have a few nema23 steppers, controllers, and 24V supply from
>>       other projects around here - mostly a magnetic loop antenna
>>       controller project.  I'm not in any rush, as my interest is moving
>>       faster than my budget allows!!
>>       
>>       But, the primary usage will be pc board work, so I need pretty tight
>>       tolerances.  I'm familiar with rods and linear bearings, and acme
>>       rods to some degree now!
>>       Thanks & 73, Terry, N4TLF
>>       
>>       
>>       Sent from tfox iPad
>>       
>>       
>>       
>>       Sent from tfox iPad
>>       
>>
>>                 > On Dec 31, 2015, at 12:43 AM, Nan and Sandy Sanders
>>       <[[radiodog77 at pobox.com]]> wrote:
>>       >
>>       > Terry, I think we had an AMRAD meeting with a talk on PCB milling
>>       with the conclusion being it works but not well. When we looked at
>>       getting one for work it seemed like the biggest use was for RF
>>       prototyping.
>>       >Â  Â Sandy
>>       >Â  WB5MMB
>>       >
>>       >
>>       > At 10:53 PM 12/30/2015, Terry Fox wrote:
>>       >> Hey guys, I am considering building or maybe buying an
>>       inexpensive CNC milling machine that can make circuit boards, as a
>>       2016 project.  I often design stuff, and then hand build a
>>       prototype using point-to-point soldering.  It's getting old, and
>>       doing grounds is not simple - even though I have a few techniques
>>       for that. I've seen the prices of PC milling machines coming down,
>>       but I thought that I would try my hand at building one instead.Â
>>       With my exposure to 3D printers, and reading up on a few homebrew
>>       CNC machines and plans, I believe that I can build one that can do
>>       through-hole and simple SMT devices, down to about 10 mil or so
>>       traces/isolation runs.  For smaller parts, I would put the parts on
>>       small commercial chip carriers, and add those to the layout.  I
>>       don't need a huge 4x8ft mill, a smaller desktop unit would be
>>       fine. Has anyone built a CNC milling machine that can SUCCESSFULLY
>>       do PC boards? If so, what and how much?  Can it do double-sided
>>       (lining up both sides)?  I plan to add many through-holes for vias
>>       between layers. 73, & Happy New Year!! Terry, N4TLF
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