Engraving machine operators have this problem and if there is bow in a board
it shows up badly in line width when using a "V" D bit. I have always used
double sided tape, rather than clamps to secure the board to the table. This
makes sure the whole surface of the board is in contact with the table and
consequently 'flat'.
Another John.
----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <homebrew_pcbs@yahoogroups.com>
Sent: Wednesday, August 20, 2003 3:32 AM
Subject: Re: [Homebrew_PCBs] Re: Phenolic boards for PCB Milling
> sure, you have much more experience in that than i have..
> i already said i have no mill (until now).
>
> maybe it depends also very of the quality of pcb stock.
>
> i only wanted to add what i have read, if one starts pcb milling
> the best is to try it without a foot (because you already have all you
> need)
> and if it doesn't work make the foot later.
> but i have read several times from different persons that it didn't work
> for them without
> depth foot... and so maybe if one has to design a holder
> for a new spindle it is wise to add "sliding" for foot useage..
>
> maybe it is also the tip angle of the milling bit.
> i can imagine it this is very flat angle the difference in with would be
> much more
> than with a narrow tip angle..
>
> what is the problem with wider boards?
> isn't it flat enough in the middle where no clamping screws are?
> maybe stromger vacuum may help to keep it down...
>
>
> how do you set the height/depth of the milling bit (the z axis).
> have you set this to a constant value determined by experiments?
>
> so to conclude this i think the following is true:
> these problems depend very much of:
> used mill
> pcb quality
> mill bit tip angle
> pcb size
>
> and maybe a foot if needed if it doesn't work fine without.
> with using a foot also a vacuum cleaner is needed.
>
> ... so the best still is experimenting... like ever..
>
> st
>
>
>
> On Tue, 19 Aug 2003 22:27:09 -0000, crankorgan <john@...>
wrote:
>
> > Stefan,
> > I sell plans for a PCBMill called the Brute. (US and Canada only) It
does
> > not use a foot! Yes you will see some variation in the isolation
channel.
> > I milled and sold Piker boards for over a year. They were milled on my
> > older Brute design called the PCBMill. Like I said, if you stick with 4"
> > X 6" boards you will be fine.
> >
> > John
> >
> >
> >
> >
> >
> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> > <stefan_trethan@g...> wrote:
> >> I have no mill (until now)
> >> but on a german page i read he couldn't manage to get a board
> > milled
> >> without "depth foot".
> >> he wrote the board material was not flat enough and the triangular
> > shape of
> >> the bit
> >> caused the resulting milled grooves to be wider/narrower depending
> > on
> >> height of pcb.
> >> he also wrote this effect is very dependent of the mill bit tip
> > angle.
> >> and i assume it is also very dependent of the board quality.
> >>
> >> i don't remember the url but if you can read german i may search it.
> >> but i have seen several pages where a sensing head is described.
> >>
> >> the device the guy uses is made on a lathe (i think of aluminium.).
> >> it is VERY important to use a vacuum then for dust because
> > otherwise it
> >> will lift up the sensing foot.
> >>
> >> also i may suggest you think about this dremel tool again.
> >> i have seen a handful of webpages where the guys ended up building
> > their
> >> own spindle
> >> with loaded bearings because the dremel was too bad.
> >>
> >> maybe you can use a proxxon IB/E or another better motor....
> >>
> >> if you design a motor mount for your new spindle maybe you want to
> > add
> >> sliding
> >> capability if you ever need the sensing depth foot....
> >>
> >>
> >> st
> >>
> >> On Mon, 18 Aug 2003 23:27:43 -0000, crankorgan <john@k...> wrote:
> >>
> >> > Arnie,
> >> > I buy 4" X 6" single sided boards. I mount the board on a piece
> > of 1/4"
> >> > pvc plastic which is mounted to the bed of my machine. The blank
> > board is
> >> > held by the edges to the PVC using the heads of 4-40 bolts. The
> > board is
> >> > held on three sides with two bolts per side. one bolt is added to
> > the
> >> > forth side after the blank is slid in and the bolts tightened.
> > Because
> >> > the tip of the bit is triangular, variations in board thickness
> > and
> >> > flatness do not show up if you stick with boards 4" X 6" or
> > under. The
> >> > real machine has an adjustable foot and a vacuum system to remove
> > the
> >> > dust so it does not affect the foot.
> >> >
> >> >
> >> > John
> >> >
> >> >
> >> > --- In Homebrew_PCBs@yahoogroups.com, "acfrankenberger" >
> >> <acfrankenberger@y...> wrote:
> >> >> I wasn't planning on using a depth guide. If I keep the boards
> > flat will
> >> >> I be ok, or am I kidding myself?
> >> >>
> >> >> Thanks,
> >> >> Arnie
> >> >>
> >> >> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan >>
> >> <stefan_trethan@g...> wrote:
> >> >> > why don't you use a household hoover with a flexible
> >> >> > hose (for electrical installations there are thinner ones) to
> > get rid
> >> >> of > the dust?
> >> >> > > the glass is bad for the bits...
> >> >> > > > here nearly anyone offering fr4 has phenolic too...
> >> >> > > any supplier should have it..
> >> >> > > i can't tell you names because i am too far away...
> >> >> > > > you should have a sliding milling depth guide for
> > isolation
> >> >> milling. have > you?
> >> >> > > st
> >> >> > > On Mon, 18 Aug 2003 20:08:05 -0000, acfrankenberger > >>
> >> <acfrankenberger@y...> wrote:
> >> >> > > > I have a Taig mill I was hoping to use to mill out (trace >>
> >> isolation) and > > drill some circuit boards. Would phenolic
> > based
> >> >> boards make the milling > > process less demanding on the tool
> > bits?
> >> >> Could I avoid dust collection?
> >> >> > >
> >> >> > > Does anyone have a source for phenolic copper clad boards?
> >> >> > >
> >> >> > > Thank you,
> >> >> > > Arnie
> >
> >
> >
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