Homebrew PCBs

Stefan,
        The Gas Pipe is used on my routers. They are used for cutting 
RC balsa parts and toys. The Brute model does PC stuff. It uses the 
aluminum window channel for ways. The auminum channel is within .001" 
over a 12" length. You will have to use drill rod.
                                                    John





--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> John,
> 
> thanks, but this is way of what i asked.
> 
> i know there are other options, i know there is drill rod.
> 
> but i hoped you may tell me which surface your gas pipes have.
> 
> the tpi of metric allthreads is about in the range of 20tpi (~1,2mm 
rough 
> guess)
> and i hope i find a software which compensates for wacky fractions.
> i really think they will work for now.
> even if i don't manage to have the software recalculate it i can 
still 
> change my drawings.
> and at least i can test the machine, only to see it working it 
doesn't 
> matter if the output
> is out of scale. i can still buy better threads later.
> 
> stefan
> 
> 
> 
> i'm sure going metric (and some day we will convince you guys to do 
so too 
> ;-) )
> 
> On Sun, 05 Oct 2003 19:44:41 -0000, crankorgan <john@k...> wrote:
> 
> > Stefan,
> > Drill Rod is cheap and very accurate. You will then need a 
bushing to 
> > ride on it. The bushing can be a block of nylon with a hole in 
it. The 
> > problem is you might not be able to find a drill bit that will 
produce 
> > the correct hole. But that would be a first test. You could also 
hack old 
> > printers. You have to test the waters.
> > The biggest hurdle is software. Are you going to work in Metric 
or 
> > Inches? Then on to the threaded rod. It needs to be fine not 
coarse. I 
> > use 20 tpi rod. With a 200 step motor that devides and inch by 
4000 
> > steps. 20 tpi with a 200 step motor gives a nice .00025 inches 
per step. 
> > This makes all IC pin centers and connectors dead on. A Metric 
rod with a 
> > 200 step motor will produce wacky fractions.
> >
> > John
> >
> >
> >
> >
> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
> > <stefan_trethan@g...> wrote:
> >> well, john, you said you are willing to discuss pcb mill here.
> >> so what i ask you to discuss maybe it the quality of rail 
surface.
> >>
> >> i saw some of your designs (and the designs of others) use some 
sort
> >> of common pipes or steel profiles.
> >>
> >> especially i saw gass pipes at your page... i wonder which 
surface
> > quality
> >> they have.
> >> I have lots of pipes and sqare stock here, but i have no idea how
> > smooth
> >> and plain the surface needs to be.
> >>
> >> obviously professional machines only use precision ground 
surfaces.
> > but how
> >> much is needed for accurate milling?
> >>
> >> it is hard to describe a surface quality, maybe you can find a 
way.
> >> how looks it when you put a straight edge against these pipes? is
> > there
> >> light shining through?
> >> are these welded pipes?
> >>
> >> the european pipes may differ from your pipes, and there are lots
> > of
> >> different surfaces available.
> >>
> >>
> >> have you ever had problems with these rails? i mean precision
> > problems.
> >>
> >> thanks
> >>
> >> st
> >>
> >> (by the way - don't you use a car for some reason? i mean you 
write
> > a lot
> >> about walking here and there and so on..?)
> >
> >