Hi Alan,
One of my customers was making things out of a
cutting board. Seems some of them are white UMB plastic.
UMB acts like nylon. I think it's UMB? So many letters
to remember. RCA-JVC-PVC-TRW-ETC.
John
--- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
> Hi John,
>
> Thanks for the comments. I hadn't looked for PVC on ebay. Should
be a
> lot cheaper to ship then BRASS! I have some Plexiglas, but I doubt
if
> that is suitable. I've heard of some dense foam (PDF or
something??)
> that is used on routers, but I have no source for it.
>
> I'm aware that PCB stock is available in 1 and 2 oz foil weights,
but I
> hadn't heard of the copper being any more or less soft. Copper WILL
> work harden, but that shouldn't apply here.
>
> Yes, milling a board first is a FAST way to get a prototype, and if
a
> Gerber file is generated, then the files can be sent off for
commercial
> boards.
>
> I'm a little dismayed at the short life of the bits. Especially if
they
> don't make it through a complete board! What speed spindle do you
> have? I have a Dremel tool that will have to do for a while.
>
> Yes, you are certainly doing OK for a $125 machine! After that,
it's
> the "law of diminishing returns", I'm afraid.
>
> Alan KM6VV
>
> crankorgan wrote:
> >
> > Hi Alan,
> > I only buy scrap PVC 1/4" thick grey. There is a guy on
> > Ebay who sells several 18" X 18" pieces for around $10 plus
> > shipping. I have picked up some for even less. You can drill it,
> > tap it, sand it, and glue it. Hobby stores sell it in thinner
> > sizes. Robotic people use it. I just mount the PVC to my Bed
> > which is also PVC. I used to mill my fixtures flat. Now my
> > designs are more accurate.
> > Some PCB have foil that is thinner and some have foil
> > that is softer. The surplus I buy is tough as nails. Not one
> > trace has ever lifted or torn.
> > The 60 degree bit will allow you to have an uneven Bed
> > or board. Some areas will be milled wider, but they will still
> > be milled! Since my boards come from the same place they are
> > the same thickness and size. This allows me to come off the
> > home positions to mill the board.
> > I consider milling circuit boards a great way to check
> > a design before you send the boards out to be made. I use the
> > method to make the boards I sell. I am able to sell a board for
> > the same price the customer could make it for. I also make a small
> > profit. The biggest cost is the bit! $7 each and in my case that
> > is only one board.
> > I see you asked about wear on the other group. I use a
> > LFKF-T-Tech type bit. Micro-grain carbide. You get about 600 good
> > inches and an other 200 inches of so so milling. I have my bit
> > make starter holes at the end of the run in each pad. That takes
the
> > bit its last mile. The expensive machines spin the bit much
faster.
> > This helps the bit last longer. Several people who use the real
> > machine told me I am doing ok! Not bad for a $125 machine.
> >
> > John
> >
> >
> >
> > --- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...>
wrote:
> > > Hi John,
> > >
> > > Where do you get the PVC, other then a "plastics" store?
Anything I
> > > missed? I think there is a TAP plastics in San Jose, CA.
> > >
> > > The 'L' picks up two edges of the PCB? Do you flycut the PVC
flat
> > > first? should true it up.
> > >
> > > I have a 60 degree engraving bit that was recommended to me.
> > >
> > > Yeah, getting two traces between pads is a little hard to
achieve!
> > I'll
> > > settle for a single trace. I've seen their sample boards,
really
> > nice.
> > >
> > > Are you saying that they use thinner copper or a special board
for
> > > mechanical etching? I hadn't heard that.
> > >
> > > Alan KM6VV
> > >
> > > crankorgan wrote:
> > > >
> > > > Hi Alan,
> > > > I mount a 8" X 8" piece of 1/4" PVC to my bed
> > > > using four flat head 10-32 bolts. I run the machine with
> > > > an old Mechanical Etching bit in it. I cut a fine "L" in
> > > > the plastic. In the "L" I drill and tap 2-56 bolt holes.
> > > > I then place a PCB under the bolt heads. This helps me
> > > > locate where the other screws go.
> > > > The board is held down on all sides with just the
> > > > bolt heads. If you use a 60 degree Mechanical Etching bit
> > > > variations in copper and board will not be a problem. This
> > > > is if the board is cuped up! The single sided ones I buy
> > > > are.
> > > > My machine will do a trace between a pad. Two traces
> > > > between a pad!!! No way! I have seen the sample boards on
> > > > those site. Show me the boards made by regular people using
> > > > their machine. No burrs either, just perfect traces.
> > > > The boards I use have very thick copper. If I get
> > > > the money, I will try some PCB made for Mechanical Etching.
> > > >
> > > > John
> > > >
> > > > --- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...>
> > wrote:
> > > > > Hi John,
> > > > >
> > > > > Good tips! When you bolt your boards down, how much
deviation
> > is
> > > > left?
> > > > > I just looked at LPKF (again, for the 1000th time), and
they are
> > > > VERY
> > > > > precise! TWO traces between pads. And I'm thinking that
if the
> > > > depth
> > > > > is controlled more closely, bit life will be improved.
> > > > >
> > > > > Alan KM6VV
> > > > >
> > > > >
> > > > > crankorgan wrote:
> > > > > >
> > > > > > Hi Alan,
> > > > > > I see that! I use the heads of 2-56 bolts to hold
> > > > > > my boards down. The ones I buy are cuped foil side up.
They
> > > > > > are 4" X 6". The bolts go into a piece of 1/4" PVC. I find
> > > > > > holding the board by the edge-the best method so far.
Since
> > > > > > all my boards are 4" X 6" I only have to take two bolts
out
> > > > > > and the board slides out the end. The bolts pull the board
> > > > > > down flat. When I do smaller boards, I have other rows of
> > > > > > taped holes in the PVC. The Tit4Tat board was 1/2 of the
> > > > > > 4" X 6" board. I would make two at once. I used to make 4
> > > > > > 1 axis boards out of one 4" X 6". Tape is fine for doing
> > > > > > a flat pcb, but most surplus boards come warped.
> > > > > > How would I fix a warped board when making a
double
> > > > > > sided board? Simple, use one or two bolts in the middle
of the
> > > > blank.
> > > > > > They then become mounting holes.
> > > > > >
> > > > > > John
> > > > > >
> > > > > > --- In Homebrew_PCBs@y..., Alan Marconett KM6VV
<KM6VV@a...>
> > > > wrote:
> > > > > > > Hi Listies,
> > > > > > >
> > > > > > > Some activity on the CCED list about LPKF and holding
PCB's
> > > > down to
> > > > > > mill
> > > > > > > them. Anyone here have the LPKF system?
> > > > > > >
> > > > > > >
> > > > http://www.lpkfusa.com/products/product/rapidpcbpro/index.htm
> > > > > > >
> > > > > > > I'd like to get a closer view of the Z height "tracking
> > donut"
> > > > on
> > > > > > this
> > > > > > > machine. And, I'm in the process of downloading a demo
of
> > their
> > > > > > > program.
> > > > > > >
> > > > > > > Alan KM6VV
> > > > > > > P.S. I'm also looking at a low-cost Gerber to Gcode
> > translation
> > > > > > program
> > > > > > > that should be available soon! More details when past
beta.
> > > > > >
> > > >
> > > >
> > > > Be sure to visit the group home and check for new Bookmarks
and
> > files:
> > > > http://groups.yahoo.com/group/Homebrew_PCBs
> > > >
> > > > To unsubscribe from this group, send an email to:
> > > > Homebrew_PCBs-unsubscribe@y...
> > > >
> > > >
> > > >
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> >
> >
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> >
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> >
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