Homebrew PCBs

hi Dave!

thick wall.. yes maybe, i will check.
i tried to flex a 4 meter piece, it is sturdy enough on 1 meter length for 
anything i can imagine.

NO i want not to use aluminium.
i don't have it and don't want it.
i think if i want to make a mill which can also mill aluminium it has to be 
steel.
that's my opinion, i know this is wrong in principle but i want it so.
( ;-) this is the advantage of building it from scratch)


i think about your method of straightening...
but i found a huge supply of this tubes and maybe i can select pieces which 
are already perfect (for me).
the surface is pretty fine and i think they are straight...

i have used this measuring tools before (i had a very classic electrical 
engineering education including machinist
work like milling, using a lathe, welding etc. as well as programming 
microcontrollers.....)
so i would be able to do this but i don't have this measuring tools at 
home, neither do i have a flat steel table.

thanks for the suggestions but i really have to inspect this stock closer 
before i can do anything...

you know a lot of other work now....


regards
stefan...

only another thougt:
if you use two of this "rails" in parallel and put a toolpost on it and 
construct a lathe head on the end........
hmmm..... maybe in ten years i have enough time for this ;-) i ever wanted 
to have a lathe..


On Sat, 02 Aug 2003 01:01:13 -0000, Dave Mucha <dave_mucha@...> 
wrote:

> Hi Stefan,
>
> from what you describe, you are talking about square steel tubing.  
> probably pretty thick wall.
>
> this is common for HEAVY duty router tables, depending of the size of 
> course.  I was looking at 2 inch x 2 inch square with a 0.187" wall for a 
> 4 foot x 8 foot  (1.2 meter x 2.4 meter (just guessing)) table.
>
> to check accuracy, this can be complicated.  and getting really high 
> accuracy will take lots and lots of time.
>
> If you are only looking for a PCB table, considder making a frame with 
> aluminum as extruded aluminum is usually pretty darn straight.
>
> or, attaching a rail to the top (or bottom) and one side.  all you need 
> to do is make the rail accurate and you can bolt that in the middle 
> pretty easily.  your bearings would ride on the rail.
>
> If you want to true up the steel box, get a machinests level, and a small 
> grinder.  level the table at best you can taking measurements so you know 
> all the lowest points are at the same level, check them a fet times to be 
> sure.
>
> then mark the height of the high spots with a feeler gauge and chaulk. 
> think topographical map here.
>
> then grind off the high spots.  one note is that grinder wheels are 
> cheaper in the 10 pack.
>
> additional notes,
> wear hearing protection
> wear eye protection
> wear breathing mask of some sort
> get wifie to rub your poor aching back.
>
> Once you get the thing close, start checking side to side.  then mark it 
> all over again.
>
> lotta work, but a really great result.
>
> Dave
>
> above is synopsys of a proceedure written by Les Watts
> http://home.alltel.net/leswatts/straightedge.html
>
>
>