Hi Hans,
I find Delrin is worth the extra cost. UMB has
me stumped. I have trouble getting clean edges. PVC make
the best bed for holding circuit boards. It cuts with
normal homeowner tools. The batch of PVC scrap I bought
off EBAY is very straight. It is almost black rather
than grey. It might not be true PVC but it taps well.
Nylon and UMB tap but the hole swells tight after
tapping. The scrap UMB I got does not have a level
surface like my PVC scrap. I have no way to machine
it flat.
John
--- In Homebrew_PCBs@y..., HW <hans@c...> wrote:
> I just checked out a whole bunch of this kind of material and using
> this size for comparison 12"x12"X0.25"
> prices range from $6.00 to $600.00
>
> http://www.interstateplastics.com/fmabout.htm
>
> Examples:
> Pomalux $14.39
> Delrin $15.75
> Lenite $6.04 It's Polyethylene but easy to machine and may be
stable
> enough to hold PCB's for milling.
>
> Hans W
>
> Alan Marconett KM6VV wrote:
>
> > 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
> > > > > > >
> > > > > > > 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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> [Non-text portions of this message have been removed]Message
Re: LPKF and Z axis
2002-05-25 by crankorgan