Unlike modern printers, Pen Plotters (Aka Drafting Robots) are awesome to watch (especially with the cover off). Unfortunately, they hit their peak of popularity in the 1980's and are becoming less common every year. I have always had a problem with standard plotter pens, they are expensive, they dry out quickly, and they are getting harder and harder to find. This hack is one solution! While the idea of adapting standard ink pens to plotters is not new, this Instructable may be the fastest and cheapest way to change your favorite brand of pen into a plotter pen. It was quick and easy and best of all, I made it at TechShop! (http://www.techshop.ws)
Step 1: Gather Materials
For this project you need:
Writing Pens (I used the Pilot V5 Precise and Faber-Castell Pitt)
Fiber Washer (Varies based on the pen chosen)
Old Plotter Pen
Step 2: Choose a Pen
You will need an adapter for each type of pen you choose to use. For this Instructable I chose the pilot v5 ballpoint Gel pen and a Faber-Castell Pitt artist pen. The Sharpie would not fit in my model of plotter. I chose the V5 and Pitt pens because my plotter has a through hole in the head, and those pens pass through the hole. If you have a later plotter without the hole, you can use virtually any pen of roughly the same diameter as the original plotter pens. In my experiments, the best results came from the Pilot V5 Precise Gel Pen. These pens also come in colors, which gives us more output options.
Step 3: Choose a Fiber Washer
I took my chosen pens to my local Home-_____ store and found the parts area containing fiber washers. They had quite a few, so I tried various sizes until I found one larger than, but close to, the diameter of my pen top. For both pens the choice was the 7/16.
Step 4: Trim the Pen Cap
The pens cap does a great job of holding the pen, so it is perfect for a holder! Remove the cap,and wrap a piece of tape around it so you have something to write on. Measure up 1-1/2 inches from the opening for the V5. Carefully score and cut the top as shown. Keep the remainder! On some pens you may be able to use the leftover portion as a pen cap! This keeps it from drying out when not in use. Unfortunately the V5's left over parts weren't usable.
Note: How much you cut varies with the type of pen. If you have success with another type of pen, contact me and I will add the details here!
Step 5: Mark the Washer's Location
So where does the washer go? If you already have a dried up plotter pen, you can use it as a reference! Align the tips and mark the location of the HP pens support ring. In my two-pen plotter I also needed to check the clearance to assure the cap would fit. This is not required in most plotters. Luckily, It did, so I moved onto the next step.
Step 6: Shim the Washer
On some pens the washer fits snugly, on the V5 the cap is a little small. We want the washer as close as possible to centered, so we have to create a temporary ledge for it to set on. Here is a trick to make it easier. We can use tape to support and shim the washer! This works amazingly well with aluminum tape, but for this Instructable I will use blue painters tape (Because that's what they have a TechShop! :)) Carefully wrap tape around the cap until the washer cannot slip over it. Now we can use our dried up pen for a reference a second time. With the pen in cap, align the points. Mark the tape where the lower part of the fiber washer should sit. Do this several times around the circumference and connect the lines.
Following the lines, carefully slit the tape. Try not to cut all the way down to the pen top. You often need a little tape to prevent the thin part from moving.
Now Turn the cap over so it is tip-up. Peel off the thin section you just cut. Note! You want to tear the tape away from the side next to the tip, not the opening! I didn't, and had to put more tape on to hold it. Why? Because the pen cap is tapered, so the washer needs to slide in from the smaller end. Now, tear a little tape off, check to see if the washer fits. repeat the process until the washer just slips over the tape. Score and remove the tape above the washer. It should look like the first picture. See the ledge? Check it again with the dried up HP pen to assure everything is where it should be.
Step 7: Epoxy the Washer
For this cap I used metal reinforced epoxy. I have used cheap two- part epoxy in the past, but I was out of the cheap stuff so I used something a little 'better'. I didn't see a significant difference. Time will tell of one type is better than the other. Mix the epoxy according to the instructions and spread it around the top of the washer. I put on more than I needed and wiped away the excess with a Q-Tip and a paper towel. The goal is to get a smooth fillet where the washer and cap meet. Be sure not to leave too much, it will interfere with the pickup mechanism on the plotter. Let it set for at least 8 hours. Turn the top over, remove the tape, and repeat the process. If you can't get all the tape out, leaving the little bit under the epoxy is fine. Now let holder sit for 24 hours to fully harden.
Step 8: Testing and Tweaking
Some plotters try to stow the pen between plots. This may cause the pen to hit the cover and could possibly damage the machine. It wasn't an issue on my plotter. If it will be on yours you can take the cover off for the test, or cut a slot in the cover for the pen to pass through. Do which ever you are most comfortable with.
Caution! Part II
If your plotter tries to stow the drawing pen between plots it may bend the tip. This is fixed by relocating the spring so the cap part hangs down out of the way.
If everything was measured carefully you should be able to use it in your plotter. Place it in the carriage and press the pick up pens buttons several times.
On my plotter, it would occasionally drop the holder. It seems the washer had a much larger diameter than the pen so it wasn’t fitting snugly. I fixed this by mounting it in a drill, spinning it and carefully placing a file or sandpaper stick on the spinning edge of the washer.
Note: I mounted it directly in the chuck, but I was worried I would hit the drill with the file, so I chucked the pen instead. If you do this, be very careful! If you break the pen you WILL regret it. All the ink will make an ink stripe on the wall of your shop! This is a low tech way of turning down the washer to a workable diameter. Now you know why I chose a fiber washer! It would not have worked with a metal one. Additionally, my preference is to not to make the holder match the diameter of the HP pen. They sit loosely in the holder, and that seems less precise to me. So I turned it until it fits snugly in the holder and didn't fall out.
The second thing that went wrong was in the Faber-Castell is the plotter would sometimes not pick up the pen holder. This worked perfectly on the V5, but the barrel on the Faber-Castell was too small. So, I increased the diameter with some aluminum tape. Tip: You can often find rolls of aluminum tape at your local 99 cent store. Big rolls at home centers can be pricey.
And finally, if you aren't happy with the results remember you can slow down the plot! In HPGL it is the velocity command embedded in the file. "VS#' Programs like InkScape give you a dialog when you choose 'Save As-> HPGL'
Step 9: Use It!
The basic steps to get an old plotter up and running is an Instructable on my 'To-Do' list, so stay tuned! But if you already have a working plotter, here is a tip. Place the holder in the carriage at the proper pen location for the HPGL file you will be using. Manually select the pen with the holder/cap with the plotters pen buttons. Now start your plot. On my machine at least, it doesn’t try to put a pen back before it starts ifthe pen it needs is already in the holder. The way plotters handle pens will vary based on model and year, so test your holder without a pen first to make sure.
Step 10: Bonus!
If you use the Faber-Castell drawing pen, you gain the advantage of an ultra-fine fiber tip pen that uses standard Indian ink. Some people are even refilling this pen! It is a little harder to find, but it is an awesome pen for this project. I found it in a craft store, but art supply stores ofter have it.
The good news is, the washer is the perfect size to slide over the cap! (no shimming the inside diameter) The bad news, the pen cap is shorter and doesn't hold the pen as well. To adapt, I added a little piece of aluminum tape on the pen to help it lock into the cap more securely.
Thanks for checking out my Instructable! If you modify a pen using this method, Send me a image and the details and I will add it here! Sharing is Caring!