Refilling or Replacing Vintage HP Plotter Pens

If you own a vintage HP plotter, you have certainly been faced with the vexing problem of finding new pens without paying a ransom to some ebay seller of dried out pens. Here is how I revive mine, by refilling or making adapter holders for entirely new pens.

[@CraigPetersen12f36b]

I have a HP 7470A plotter that came with only one pen. The tip of the pen (Staedlter P3) was mostly still white so it didn't appear to get a lot of use but had dried up. I was able to revive the pen by forcing 130 degree water back up through the pen tip with a 10 ml syringe (no needle), I was able to pump about 3 to 4 ml of water back into the pen till ink started to come back out of the tip. I let it sit for about an hour or two, put it back in the plotter and it worked, not perfect, but good enough till I receive my new pens.

[@CuriousMarc]

Nice! Thanks for sharing your experience! After a bit of research, it looks like these pens might have been water based, so simply soaking in water was a good move. Where did you procure new pens?

[@CraigPetersen12f36b]

@@CuriousMarc Greetings Marc, I ordered my pens from www.draftingsteals.com/ I have an order for some .3mm and .7mm pens. I found another site www.draftingfurniture.com/listings0/Plotterpens.html, however I haven't purchased anything from them. There are several eBay sellers who carry these pens but I would rather get them from more reliable sources. I appreciate the time and effort you put into your videos, I actually purchased a HP 59401A and the HP 2225A based off your videos, it's equipment I wouldn't even thought I would ever have a need for or even use, especially a HP 59401A.

[@CraigPetersen12f36b]

@@CuriousMarc Update: Got my new pens a few days ago, they work great! Zero issues.

[@CuriousMarc]

@@CraigPetersen12f36b Sweet, good to know there is a source of new pens! I will pin this comment thread!

[@calmissile1]

Thanks for the inspiration of finding a solution to refilling these dry pens. I used your idea but found a far easier way to remove the top. No lathe required (even though I have several). With a small set of wire cutters, pull the pen tip straight out. It comes out easy. Grab it as close to the pen body as possible. I then insert a small allen wrench in the hole. Hold the body of the pen in a pair of pliars at the ridge and tap out the top plug by tapping on the allen wrench. Presto, the top pops out and no damage to the plug or the pen. Just completed 12 pens and bought the multicolored Sharpie set for $9. Doug

[@note2tee]

thanks for the tip. i have no lathe, was thinking of drill a small hole and drip some ink in and cover up the with a screw

[@devlinmacpherson1069]

This was great advice!! I've begun my pen plotter journey and was able to revive an old hp pen thanks to your help: kzbin.info/www/bejne/nnqaq6yJjc-Ynqssi=5gFiTaio1OWaKESj

[@UriahHeep100]

Brilliant!!

[@DRAWINGAT]

OMG I did that back in 1987 with a HP Plotter! What a flash back!

[@UriahHeep100]

Thanks so much Marc! I have just resurrected my 7550A after about 20 years having been packed in my Sea Container, I'm now semi-retired so getting to play with some great new (toys) technologies (3D / Arduino / Rasp Pi etc. Still had many Pens sealed from new but all are pretty dry. I so appreciate your work here, the 7550A will still work with XP so I am re-installing it on an old desktop. Such a fantastic Plotter and so entertaining!!! Electronics & Communications Engineer from the days of Dec PDP's, Data General Nova, HP1000FX/MX....

[@martinstephens987]

In the late 1980s, we used the HP 7475a with stubby Rotring Isograph technical pens. They tended to dry up halfway through a long plotting job, so we each had our own system of nurture plus superstition to keep them working.

[@EzeeLinux]

Necessity is the mother of restoration. :)

[@RinoaL]

i really like the artwork you had it draw! tbh i've kinda overlooked plotters until now because its one thing i just never really find in the trash. this is really cool. Wal-Mart used to sell ink cartridge refill kits where you would drill a hole in the top of whatever contained you wanted to refill and squeeze ink into it. so what kinds of anime/manga do you like? i personally like Ghost in the Shell, Pokemon, Sailor Moon, Nichijou, Hetalia, and movies like Royal Space Force...and of course Akira and miyazaki films. :D

[@JerryWalker001]

I had a similar issue with an old HP A1 plotter. I turned some holders from aluminium that had the same outer profile as the original pens but had an internal bore that suited more modern plotter pens.

[@compu85]

Great how to! Using the lathe to shave the pen end down gives a clean result.

[@timthompson468]

Thanks. That is very useful information. I use old HP X-Y analog plotters with my analog computers and have the same problem, but the pens are smaller. I found some pens, but they’re about $10 ea. I might try to have an adapter 3D printed so I can use a standard felt tip marker. The HP 7015B mentions a “Universal Pen Holder.” Sounds nice, but I doubt it’s obtainable these days.

[@colinstu]

great work! can't wait to see the 7550 going again too, love those.

[@joeytavora1270]

i love this, we use modern pen plotting at work, we just made an adapter to put a bic pen in them. It's so satisfying getting to use up a kilometric in a day!

[@cumhachd]

Back in the early to mid 1990s I did a lot of engineering drawings on pen plotters, both a big HP E-size machine (which I couldn't keep but I found it a good home), and a 7475A, which I still have. You may cringe now, but back then we cut a chunk out of the case to accommodate much taller after-market drawing pens because we plotted so much the simple HP felt pens ran out too fast. The pens we used had large liquid ink tanks and a steel wire nib, so they drew much finer than the has, and lasted longer. That old plotter still works perfectly, but I sometimes regret the modification. Still, I'd never sell it, so nothing lost! Thanks for the lathe technique, I will definitely use that on my dried old felt pens - they are still much better for large area fills than the drafting pens.

[@johanwesselink2861]

The pen with less alcohol plots in strait lines. ;-)

[@johnpickens448]

I remember that space shuttle vector graphic was an HP demo for many years. I had an HP Pascal computer at work and that image was part of the boot display. The Pascal system used HPIB interfaces for disk drives, printers, plotters, and for controlling scientific test equipment. Way ahead of their competition.

[@thesteelrodent1796]

I remember the drawing being included as one of the demos in AutoCAD. They had the same demo drawings for well over a decade and were common sights on plotters at computer shows, but it is very likely that AutoDesk sourced them from somewhere else

[@edgeeffect]

Seeing you shuttle plot makes me wish I still had a plotter.... and a nice DXF of Space Station Mir.

[@TheBoyMechanic]

Thanks for this. I acquired a 7580A plotter from an engineering firm and most of the pens are dried. Going to have to try this

[@jazzlover10000]

We used to use a rapidograph adapter from another plotter with the same diameter. Then you could use rapidographs in pen 1 of your 7475a plotter! The only thing was that you needed to make sure to only address the PEN # that was currently in the tray. This worked ok in AutoCad and other things when you needed a B sized plot that looked professional enough to hand off to a machinst with a CNC lathe. I would have never handed my machinist a set of drawings printed in RED or on those large diameter (.3) pens! Anyway it's all just fun now... or is it? I could probably still use my 7475a plotter if I wanted to to deliver drawings. But this was how it was done back in the day for those of us too cheap to buy D size plotters... but still wanted to hand off decent drawings to machinists or architects. I probably still have my dried-out rapidograph with adapter in a box... somewhere. I just bought a 7475a plotter... for about the same price I sold mine for 30 years ago. Look forward to playing with it - probably will do so via BASIC or C programs on an IBM PC. Used to do that a lot. The commands are easy to issue over RS232C... unless you have the HPiB model of course. Thanks for letting us know about the 'lathe' method. Too bad I don't have a lathe. I do have a grinder but am reticent to work on the beautiful .3 plotter pens that came with my printer with such ruffian, bolshevik type tools!

[@waynedoe2486]

Just dusted off a 7475a that I bought 30 (40?) years ago. Have no idea why I bought it. Anyway, the pens are dry. My solution is to : 1)drill a small hole in the end opposite the writing tip 2) screw in a sheet metal screw that's a little larger that the drilled hole 3) use a miniature crowbar to lift up on the metal screw and the end pops out easily. 4) After refilling with sharpie, screw a short sheet metal screw in the drilled hole to make an air seal. This will allow for syringe refills in the future when ink starts to run low (?). (make sure the screw head will clear when the head is going back and forth) I am waiting to see if the new ink will indeed soak into the writing shaft.

[@nicholasmason8302]

Thank you! Just the information I needed, brilliant video.

[@campbellmorrison8540]

I some much regret having dumped my 7470A and the mountain of pens I had for it. I used to love watching it plot stuff but I ran out of room and justification so this was one of the casualty's.

[@Colaholiker]

"A little less alcohol next time". Who couldn't relate to this. :)

[@picsi-software]

Back when we were able to buy these new... they constantly dried out.. we didn't use the felt-tips, but the tech nibs and the speedballs.. Ultrasonic cleaners do a good job on the tech-nibs.. I still have a DraftMaster 2 :) If anyone has a takeup spool I'd love to talk to them

[@rampagerick]

I have a box full of sealed pens, I should get some details. I think they're mostly Rapidoplot brand in various lineweights. My grandfather had a Roland DPX-3500 that was in use up to about 2004. I believe the pens will interchange with some HP styles. We have a Weidmuller MCP Basic at work, I never got around to seeing if my pens would fit.

[@TroyeWelch]

I bet a little MEK (Methyl Ethyl Ketone) dropped into the back of these would get them going again. That was a common solvent for pens like these. The solvent is what has evaporated- the ink is all still there. If you live in California where MEK is banned, you can get it in Reno (Home Depot or Lowes) if you're ever going through there. The state (CA) cares more about fruit with bugs in it than organic solvents being brought into the state.

[@CuriousMarc]

Thanks for the tip. I read a bit more about it, I thought it was carcinogenic, but it is not. I believe MEK is banned for suspected toxicity as it absorbs through skin in the bloodstream readily. But the level of toxicity is apparently disputed, which is why CA has banned it but not NV. I think I'll keep refilling the pens with the Sharpies' insides ;-).

[@JohnDavidDunlap]

I'm actively looking for an IBM 7372 plotter(rebranded HP7475A) and this video answers a big question I've been asking myself. Namely, how am I going to get working pens? Thanks!

[@emdxemdx]

I recall seeing some 40 years ago someone with a Rapidograph adapter to use with HP pens.

[@jazzlover10000]

Oh I forgot. .. if you want to use the tall pens you can cut a bridge in the 7475a plotter to let the pens through. This was de rigeur back in the day... so I don't consider it to be vandalism. Then you can populate your carousel with rapidographs or whatever... as I recall anyway.

[@BobWiersema]

I know this is a old video but I still have some refillable .25mm pens from my HP7550 if you want them. Also have a few .3 in various colors that still work. Sadly the plotter is long gone. It was in perfect condition when I stopped using it. Great plotter for AutoCad.

[@CuriousMarc]

I'll sure take them. Contact me from my channel page: kzbin.info , click on the About tab, and then View email address.

[@RobSchofield]

I'm trying to work out how to do similar with the tiny little "ball point" pens used in Tandy and Toshiba plotters.

[@fedesartorio]

Cool video, maybe an ultrasonic bath could help with this?

[@AureliusR]

Could you not simply buy liquid ink (like from a pen store) and just re-soak the existing felt absorbers?

[@note2tee]

just drip few drops of ink jet refill ink to the sponge tube. You will need to rinse the tube clean. You can get those cmyk colour inkjet printer refill and you have 4 colour pen including black or you can mix the dye and get other colours to fill out 6 or 8 slot

[@scipanda4969]

Very crafty. nice job.

[@bzuidgeest]

I noticed that the curved lines seem to consist of multiple straight segments. I expected a device like that to be able to do smooth curves. Or is that asking to much?

[@CuriousMarc]

The 7225 sure has all the precision needed for very nice curves, but it is very slow (it's 1970's hardware my friend). For the purpose of making a live demo for VCF, I simplified the HPGL output (reduced the number of points) so it could be plotted in less than a minute but still looked good. The more recent 7550 isn't more precise, but it is immensely faster, I'll be able to do more complex plots in a short time. I hope I can make a video to compare the two.

[@AiOinc1]

Do you have the HPGL files you used for the plot of the girl or the space shuttle still? I have a plotter I am repairing and it is difficult to know when they are working correctly without a known image.

[@CuriousMarc]

You’ll find the shutlle on my website: www.curiousmarc.com/computing/hp-7475a-plotter File name is Columbia.hpgl. I have not released the anime girl.

[@BubblyGumm]

You can see the printer in motion at 8:00 if you are just here to show the kiddies what you used to use in prehistoric times!

[@Laracrafttrabant]

i made some 3d printed pen holders for different types of pens, i should make a video and share the files. I have two hp 7550a one working and the other one needs some love still. The longer pens also have a speed limitation cause of the higher point of mass. best regards Lara Craft

[@MSK_MKT]

Looking forward to it :)

[@pedro_8240]

Since you already have a lathe, why not machine some nice aluminium caps with something to facilitate removing them by hand, or better yet, whole pens with threaded caps, and just insert some new felt tips?

[@CuriousMarc]

Interesting idea. People do that for the Calcomp plotters, that originally had machined metal pens which you cannot find anymore. But here you'd have an issue of weight. The mechanism is really meant for a very light (and short) plastic pen. I found that machining adapters out of Delrin was a good solution.

[@kylehazachode]

Fisher Space Pen company makes plotter pens. I think you send them your plotter pens and they’ll replace the cartridge with their pressurized space pen cartridge

[@CuriousMarc]

Really? It says you have to email them at [e-mail]. I’ll give it a try. The format for HP pens is so unusual and it’s not meant to be a removable or refillable cartridge, so I have a hard time to believe this. I know that the Calcomp plotters used pressurized, removable cartridge pens, so I suppose that’s what they provide.

[@CuriousMarc]

So I checked. They do have plotter pens, but as expected, none that would work in an HP plotter. They are ball pens and require 250g (!) of force. Reference PSGM20BK, Fisher Plotter Pen.

[@gacherumburu9958]

👍

[@sherlockhomeboy4031]

Is this plug and play or do I need to download a software to upload my image?

[@edgeeffect]

I have a memory... but, considering how long ago it was, it might be a false memory... That the A3 flatbed HP I used at work had taller pens with it... like the standard HP design near the tip but with a normal pen's body height.

[@suppengroove]

a knowledge that i'm never gonna use :D but i feel smarter know. thanks

[@lezbriddon]

i just dumped a 7475a as no one wanted it. worked a treat, bloody shame but lack of space and being married......

[@hamiltonqkarl]

I literally just spent a hundred dollars on ebay for one. why oh why

[@SilverSpoon_]

back when refilling your HP was possible and inexpensive..

[@theelmonk]

Selling very small, sealed containers of ink at a high price ? I guess that's where they learnt the business model for inkjet printers!

[@paulscott3546]

Very Smart

[@AnalogThinker]

If anyone here has one, and is willing to get in touch with me, I'd love to design the 3D Model for a REPLACEMENT CAROUSEL, mine has gone missing. Would love to recreate a model based from a series of detailed pictures and measurements. For the community! I post all my retro parts on Thingiverse.

[@eugenijusjanuskevicius2292]

it's better to use ball point pen, as it will not drag or wear out.

[@DandyDon1]

Someday your house will be full, and then what will you do? :D

[@pmkleinp]

Buy up the houses surrounding him. /jk

[@JohnDavidDunlap]

Build a bigger house. The wife will be fine with it, provided that the size of her closet increases proportionately.

[@shunorrr]

anime? but why?

[@CuriousMarc]

Most people do sin(x)/x or locomotives. But why?

[@RinoaL]

+shunorrr because anime is fucking amazing

[@leisergeist]

Because it's the original intended purpose of the machine :)

[@JohnDavidDunlap]

Why not?

[@cumhachd]

Back in the early to mid 1990s I did a lot of engineering drawings on pen plotters, both a big HP E-size machine (which I couldn't keep but I found it a good home), and a 7475A, which I still have. You may cringe now, but back then we cut a chunk out of the case to accommodate much taller after-market drawing pens because we plotted so much the simple HP felt pens ran out too fast. The pens we used had large liquid ink tanks and a steel wire nib, so they drew much finer than the has, and lasted longer. That old plotter still works perfectly, but I sometimes regret the modification. Still, I'd never sell it, so nothing lost! Thanks fir the lathe technique, I will definitely use that on my dried old felt pens - they are still much better for large area fills than the drafting pens.

[@CuriousMarc]

Excellent, I saw a few demos which had the cut out on a 7475 and I wondered if it was original, as my 7550's certainly do not have it... Not a bad modification really. I am tempted to do that on one of my two 7550 cases, as the Pilot Bravo pens fitted with the ring really performed well.