How to refurbish plotter pens?

[Mattis Lind]

It has been almost two years since I visited this topic. But just before
christmas i got around doing something about it.

I interfaced it to the PDP-11/05 using an XY11 board. It seems to be very
little information on the XY11 board saved. At least I didn't find
anything. But the board is a quite simple dual module so I made a schematic
of the circuit and then got the understanding how it should be connected to
the plotter and how it should be programmed. Created a quick program for
the PDP-11 and tested it. It worked just fine but then the problem was the
pens.

All my pens were obviously dry. Refurbish a pen seems to be impossible. The
type of ink used is quite thick and I couldn't figure out how to get it
into the ball point pens. Even though it was possible to clean them
reasonably well using an ultrasonic cleaner there was no way I could get
the ink in there.

The other option is to find compatible pens. I searched google for pen
refills with dimensions that would fit but couldn't find matching pens to
modify and use.

So I concluded that the best option is to make a new pen holder plunger
which could take standard ball point refill. The Pilot  BRFV-10M seemed to
be very common refill and would probably work well if I had another pen
holder. I asked around and found a guy with a lathe that made one for me.
Unfortunately it wasn't working immediately. I hadn't thought of certain
mechanical properties of the mechanism.

Essentially it is two parts. The pen holder plunger itself and a small
plastic part to insert into the cut off ball point refill. This latter part
will reduce the exterior diameter of the pen from 4 mm to 3.2 mm so it will
work with the spring in the lid. It also has a small 1 mm hole in it to let
air through.

Then I had a problem that the pen stayed in the up position. Most likely
held by some kind of remaining magnetism that could withstand the force of
the spring. A couple of M3 washers was used to reduce the contact area
between the pen holder plunger and the top lid which made it work.

http://i.imgur.com/PRGUa9U.jpg

And in action:

https://i.makeagif.com/save/QCDG_W

controlled by a quick and dirty PDP-11 program :
https://github.com/MattisLind/pdp11-plot

Next is to draw some nice things on the plotter.


Den mån 24 apr. 2017 kl 06:59 skrev Philipp Hachtmann via cctalk <
cctalk at classiccmp.org>:

>
>
> On 22.04.2017 15:21, David Gesswein via cctech wrote:
> > Felt tip was also available.
> > picture here http://ferretronix.com/1627/
>
> Wow, great page! I think I also have the felt tip metal thing somewhere.
> I have to find that plastic box with Calcomp stuff again....!
>
>