Vintage HP 7475A Felt Tip Pen Plotter Part 2

Taking a vintage HP 7475A pen plotter from the 1980's and adapting it so it can accept Sharpie pens of all colours.

[@constantinosschinas4503]

looks so much better with the markers protruding, just like a pen case! lovely prpject.

[@devlinmacpherson1069]

Did you provide AJC3D with the files yourself? Or were they selling them on their own? If you have the file, I'd love to buy it off you!

[@szabolcsmolnar2218]

Hi there! Very nice machine! I got one for myself as well. It's a bit modified, it came with an arduino mini inside already (FT232RL). I was able to set up, instal and find the port, but when I try to print anything from Inkscape (just a line at first) I always got the blinking yellow error and nothing else. Until then I do not push the execute. it's not blinking, it does the test page properly though. Do you have any suggestion what it might be? Thanks in advance! Cheers!

[@tapvolt4128]

I would skip Inkscape for now and try a handwritten bunch of commands to select a pen and draw a square. en.wikipedia.org/wiki/HP-GL#Examples. I have not been able to print from Inkscape directly, any outputed file needs a bit of manual intervention. In summary Inkscape is not good without a little nudging.

[@olepigeon]

Hah. I did the _exact_ same thing with my 7475A. I don't have it anymore, but I did make a video: kzbin.info/www/bejne/Y2myhHidr9toZpo I found that with the smaller sharpies, you have to set it to a slower speed when you print. It'll print too fast, leaving gaps in the lines. The bigger sharpies worked better, as they dispensed more ink faster (as seen in my video.) The paint pens also worked. So do gel pens, but they need to go fairly slow. I couldn't get the mini Sharpies or gel pens to work on my Roland DXY-1150, the solenoid wasn't strong enough. I don't have my STL files anymore, but I got around the offsets by using a digital micrometer and measuring the _pen lid_ . I then duplicated the inside of the pen lid, then added the ring on the outside for the carriage arm. This allowed me to snap on the rings like they were just pen lids, and it resulted in reliable prints.

[@StefanWolfrum]

Very nice! Were you able to fix the offsets of the different colors? And if: how so? And have you experimented with the Sharpie minis as well?

[@tapvolt4128]

The offsets were because of the 3D printed pen holders all being a little imperfect. I think with a little practice and sanding they could be made more regular. May switch to metal created on a lathe. Not tried Sharpie minis no. Will take a look.

[@StefanWolfrum]

@@tapvolt4128 Thanks for answering! 🙂 I got a 7475A myself and was able to locate an online shop here in Germany who still sells the „original“ (well, not from HP, of course, but 100% compatible) pens. So I ordered a few and didn‘t notice any offsets in the plots when the pen changed. I found online shops in the US, too, but shipping costs were hilarious.

[@tapvolt4128]

Let me the shop please as I would be interested too.

[@StefanWolfrum]

@@tapvolt4128 www.draftingsteals.com/catalog-plotters---plotter-supplies-plotter-pens-fiber-tip-plotter-pens.html or www.artstuff.net/Koh-I-Noor-Rapidoplot-Archival-DPP-Disposable-Plotter-Pens.html in the US, plotterstifte-faserschreibfedern.de/Plotterstifte/Hewlett-Packard-Stift-Kontur in Germany

[@tapvolt4128]

Thank you!!!!

[@gabmar58]

Hi everyone! Between the 80s and 90s I had the opportunity to work with these wonderful plotters, now I have one and I ask you experts, who have worked and programmed these precious objects, if there is the possibility of interfacing them with a modern PC with Windows10 and you still see them working and possibly with what software. The 7475A plotter in question has an RS-232 - C/CCITT V.24 type serial port, are there any adapters from this type to the USB type serial port? Thanks in advance to anyone who can answer!

[@tapvolt4128]

Yes you can buy USB to RS232 adapters for pennies on eBay.

[@gabmar58]

@@tapvolt4128 thanks! Please can you even tell me what kind of software can I use for Windows10?

[@tapvolt4128]

Should work out of the box with the usb adapter.

[@paulklasmann1218]

Are there no short pens available so that you don't have to modify the case? I saw there is a way to "refill" the ink in dry pens.

[@tapvolt4128]

It is possible to open the old but it is a messy job. New pens can be purchased but are expensive.

[@aurobindorout8275]

Is there any way to buy this for like 100-200$

[@tapvolt4128]

Yes I bought the plotter seen here for £70 / $90 from eBay. HP have a family of devices so keep a saved search for all of them, you want the models with an RS232 serial connection on the year for an easier / cheaper life. I just have bought a HP 7476A A0 plotter for £5! It is as large as a piano!

[@tapvolt4128]

Roland DXY are another range to watch for.

[@MichaelKingsfordGray]

That was dreadful! Accuracy variation of over 2mm?

[@tapvolt4128]

The 3d printed holders needed a little work to make them more consistent.