Homebrew PCBs

mostly @markus:

I just saw drawer slides used for cnc machine, but it was a cnc foam wing 
hot wire cutter...

http://www.8linx.com/cnc/


very low forces here....
seems to be REALLY simple to build a cutter for foam..
not much more complicated than the automatic unit i built for use with 
templates...
(the template making takes a hell lot of time...)

but enough "damn model plane stuff" - off topic i know.



i currently emailed to a german guy who uses the "rod with three bearings" 
type of sliding mechanism...
he is very satisfied with it.. uses metric allthreads with two nuts spring 
loaded to... M8 works...


with similar designs even 8mm Aluminium can be worked (with aluminum rails 
.....).

i still do not want to use the drawer slides, i want to make a cnc not only 
for drilling but also for other things
(front plates, perhaps pcb milling, various stuff) and i still think these 
slides are not as good as the 3 bearings method.

but i saw slides constructed the same way (like drawer slides) as 
"linearf\ufffdhrung" or so at rs-components for big $$...

i hope to have found a supplier for precision steel rods/pipes in vienna, 
waiting for reply mail..


i would really like to make the machine as sturdy as possible. using 
"heavy" material (mostly steel) not aluminium.
maybe then i need really strong steppers... damn..  hoped to use the 10 
motors i have lying around.. too weak i think...

i want to weld the framework together where i can (no play, more solid than 
screws), maybe use sqare steel tubing which i have in huge
quantities...

maybe i can use a angeled steel profile in a uside-down V arrangement over 
the round rail.
then maybe drill holes in it for the lower bearings (these will sit on two 
screws m8).

the one guy i emailed who uses "three bearings" doesn't spring load one.
he uses 3mm (4mm) alu sheeting bent to hold the bearings.. sheeting is 
flexible enough to ensure no play he says...
i still think about loading the top bearing with 20kg spring force or so...


but i am sure the cnc is in the "think about it before you start" phase for 
2 month or so from now...
too much other things... but i had a look at some web pages and feel 
confident now that it is possible
to make a good unit without a metal mill or lathe... (using angle grinders, 
drill stand, arc welding, hand tools)



okay, i hope i will soon read about some progress from you guys here...

i know there are better places to discuss homebrew cnc but not much else is 
happening here so please don't
ban it steve....

have a good night.... (oh yes in a couple of hours at your site but here 
it's dark outside now.....)

stefan