Modifying 7475a plotter for long pens

I just bought a 7475a, and it's working fine on OSX Leopard, using a Prolific USB -> Serial adapter.

I'm wanting to plot with liquid ink, preferably refillable, and was wondering whether anyone has modified the plastic cover of this plotter so that long body pens can be stored in the carousel. It looks like it would be easy to make a cutout that would let the pens pass.

Also, if anyone can recommend a good supplier of pens, that would be good.

Also, looking for cut sheet plotter paper for liquid ink (preferably opaque, not vellum).

Neil

I cut the top plastic housing to allow for longer pens on several plotters we had at a prior job. At the time we had a large sheet drafting plotter in the main CAD area and the engineers had the 7475a plotters on their desks. The drafting pins fit the changer except for the length. It was a no brainer to modify so we could use the much nicer drafting pens.

I still have the plotter but no idea where to buy new pens.

Robert

Yes, I ended up cutting the plastic. The pens I bought (Koh-I-Noor) have different nob geometry than the standard pens, and do not fit correctly in the carousel. This makes the pen grabbing mechanism unreliable. The plotter seems to lose track of whether it is holding a pen or not.

However, If I manually load the pen into the pen holder (not the carousel) it plots fine. Turns out, I never change colors anyway, so modifying the plotter is not strictly necessary. It's just safer in case some code tells it to put the pen away, or to select a different pen.

Also, I experimented with refilling the disposable (DPP) style pens. This seems to work fine. No idea how many times they can be refilled, but at around $10 each, it's worth a try. I used pliers to remove the nib from the empty cartridge, and then refilled it with ink. I tried to have the nib out of the cartridge for the minimum possible time, and I didn't bother washing out the old ink. It plots fine with the new ink.

I recently ran across an reference to certain Staedtler pens that readily clip into slightly modified plastic pen cases. Though I don't seem to find the on line reference at the moment, It had to do with producing PCBs, and using the ink as etch resist.

Myself, I refill the fiber tips for general output, a search for HP Plotter pens will find many vendors.
At the moment, I am working on the Kohinoor nib holders that use the smallish (about 2inch long) ink cartridges. These are ideal for fine work with the "rapid -O-graph" look.
I have a 7550a with the same pens

Hypo needles work well for refilling plastic cartridges without disassembly

Quote:

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Originally Posted by CalG

I recently ran across an reference to certain Staedtler pens that readily clip into slightly modified plastic pen cases. Though I don't seem to find the on line reference at the moment, It had to do with producing PCBs, and using the ink as etch resist.

Myself, I refill the fiber tips for general output, a search for HP Plotter pens will find many vendors.
At the moment, I am working on the Kohinoor nib holders that use the smallish (about 2inch long) ink cartridges. These are ideal for fine work with the "rapid -O-graph" look.
I have a 7550a with the same pens

Hypo needles work well for refilling plastic cartridges without disassembly

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Yes, I have some of those smaller Kohinoor pens. They seem to work very well on the 7575a. When using a Hypodermic, how do you do the refill? Do you make a hole with the needle? Also, how do you refill the fiber pens?

I also tried some rollerball pens, but found them very unreliable for some reason.

The fiber pens have a "pop top" Just pry it off. I use a dropper to transfer India ink into the pen blotter. 7-10 drops generally fills the blotter to saturation. (there are likely better inks, but I live in a small town ;-)
The cap snaps back on. I have several pens that have been used for some time, the fiber tip draws a rather broad line. I store the pens in a glass jar with a tight fitting lid. In the bottom of the jar is a water moistened sponge to provide 100% humidity. Don't allow the pen nibs to contact the sponge for obvious reasons of capillary transfer.

Using the Hypo on technical pen plastic cartridges, I just poke a hole into the top, and depress the plunger. If an air vent hole is required, a second insertion leaves the first hole to provide that function. A bit of cellophane tape placed over the holes completes the process.

I have tried the gel pens as well, not very effective, perhaps I did not optimize pen down force and drawing speed.

I have two Flat bed plotters and the 7550, Useful for plotting graphics and cutting paper shapes etc.
Mamiki cutting knife holders fit the HP pen configuration.

Regards

CalG