On Wed, 26 Oct 2016 06:43:19 -0700 (PDT), rangerssuck
wrote:

On Tuesday, October 25, 2016 at 11:24:37 PM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...
On Tuesday, October 25, 2016 at 2:45:37 PM UTC-4, Jim Wilkins wrote:
"rangerssuck" wrote in message
...

So, the foot is spring loaded towards the board and the router to
foot distance is controlled by a solenoid? That seems pretty easy to
rig up. I'm not sure why you'd (at least I'd) need to vary the Z axis
at all. The range of widths in their bits seems to be only a couple of
mils. Seems like if you're (I'm) drawing outlines of copper, a cut's a
cut. If I need a wider cut, why not just take two or more passes? The
software for that would be pretty simple once the rest was done.

=======================

I don't exactly remember how the head operated. IIRC a stop screw set
how far the vee shaped cutter extended below the foot when the head
was down, maybe pulled by the solenoid? It could also drill the holes
with a longer stroke.

I planned jobs such that the board fab time didn't delay the project
and didn't use the T-Tech any more than I had to. Since it only made 2
layer boards without plated vias it wasn't that much better for
prototyping than perfboard, and tended to require a lot of inspection
and hand deburring. I usually needed 4 or 6 layers with internal power
planes, or RF microstrip on Duroid.

--jsw

Their hottest looking machine has a tool changer to do drilling & other width milling, and auto-zeros in the z-axis. The also have (not inexpensive) hole-plating & multilayer stuff. I could do without the tool changer, and the auto-zero would be pretty straightforward. Many of my boards are far less demanding than the 6x6mil I said before. even 12x12 would be good enough to get a lot of work done. I don't do microwaves, I do mostly industrial controls and that stuff tends to be bigger. many of the parts I use are available on breakout boards (generally for robotics hobbyists) and sometimes as arduino-type shields. Given that, and the fact that I'm rarely constrained by small enclosures, I usually don't need the high precision. I'm starting to think that I really could do this with an x/y positioned dremel and a two-position z axis.
The problem with the Dremel is the way excessive runout. But if you
can fiddle with it to get the runout down to just a couple tenths then
it would work. The runout has to be tiny at speed, not just when
turning by hand, and it needs to be pretty good over the length of the
cutter. With a limber spindle runout can cause the spindle to describe
a circle as it spins at speed so that your .002" dia. cutter mills a
..004" wide slot even though the tip is perfectly concentric to the
spindle axis. You can buy carbide engraving cutters that have very
small points so getting small spaces between the traces would be no
problem. If you can tame any runout.
Eric