Hi John,
Yeah, UMB is like nylon. It would be a good surface to work on. There
is also that dense foam I mentioned, another TLA (three letter acronym)
that I still can't recall. UWF??
Alan KM6VV
crankorgan wrote:
>
> 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
> > > > >
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> > > > > Homebrew_PCBs-unsubscribe@y...
> > > > >
> > > > >
> > > > >
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> > >
> > >
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> > >
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> > >
> > >
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