Homebrew PCBs

In Homebrew_PCBs, Stefan Trethan <stefan_trethan@g...> wrote:
>>Another note is that the G81 will repeat ever time an new X/Y line 
>>is read.  so there is no need to jump to another for more drill
>>instructions.
> 
>I do not understand that part at all.
>There is always a hole drilled when you read a x/y command?
>You needn't call the cycle? seems strange...

Stefan,

The canned drill cycle is what's called "modal". That means that once 
it's called it "stays" in effect until something else replaces it. 
Like a subroutine. In fact, here's a bit of background on why they're 
called canned cycles:

Originally NC (no computer yet, so not C-NC) machines were programmed 
by paper tape with holes. Drilling a hole was a pretty standard thing 
to do, so after awhile folks started making tapes with nothing but 
the drill motions onit, repeated as many times as the tape length 
would allow. These were then kept in a CAN (to keep them away from 
the shop environment;paper, remember?) and spliced into the program 
whereever needed. When the computer came into the mix, and NC became 
CNC, this functionality was programmed, only now the splicing was 
done in computer memory (you know; HUGE 2K arrays of wires and 
ferrite beads<G>)

So anyway, after you've told the machine to make a certain series of 
motions to drill; it will repeat those motions at each new XY 
location you give it.

we're gonna use the down up motion of a drill cycle to depress a 
plunger and retract it a bit so it doesn't "drip". And I'm gonna put 
that drill cycle inside a macro so that the z axis goes down and up 
too...

>I think a few different cycles would be required for paste 
>dispensing too. 

Yes.

>Might be good to have maybe 3 different "dot sizes". Might even get 
>impractical to do much more because it will not work good below and 
>above certain borders.

Correct. But more than three may be needed, and certainly as many as 
are needed can be "made". 

Remember also that repeating a given size WITHOUT moving will make a 
bigger dot. So you could have a 1-dot,2-dot,4-dot, and get 8 sizes by 
combining them in binary fashion...

>Do you think it makes any sense at all to try to place "beads" or is 
>it better to just make round "dots"? (and multiple if you need a 
>line)

Dots are easier, and will probably do all that's needed. Beads are 
faster, but harder to do cheaply, IMO.

Hope this helps,

Ballendo