Interesting note on the AxiDraw, the way it holds the pen at an angle and drags it around means it can work with a fountain pen where you need the nib held with a softer angle relative to the paper (both tines touching, ink flows out in between). The photo shows it with a Lamy Safari.

I don't think this is the case with regular pen plotters, which look like they hold the pen vertically and keep it fixed as it draws in different directions. Some pens will write vertically, but it's not ideal depending on the nib grind. The bottom corner of the nib is rounded to work at a range of angles, but the top might have sharper edges that would catch when dragging it upward.

EDIT - I suppose you could make an adapter for a pen plotter that would hold it at an angle though.

I tried putting a calligraphy pen in my plotter and it was definitely rough on the nib because of the angle. With continuous line drawing it would probably be ok, but too much up/down movement might get messy. Still fun to watch though! Here's a short video of it in action: https://www.instagram.com/p/BNCxyfLBh8_/

Those folks also sold “Sylvia’s watercolor not” which was designed around, well, water color painting via the same mechanism.

They also sell an “eggbot” for drawing on Easter eggs. Wonderful stuff.

dont forget you would have to prevent the modified regular pen plotter from dragging the angled fountain pen the wrong way

As long as it's not a particularly flexible nib (and most aren't these days) you can pretty much push it any direction once you have it at an angle. Lucky for me, otherwise I'd have trouble with down strokes (left-handed overwriter).

My wife uses a vinyl cutter at a local hackerspace, and I wanted to make the same comment. When I saw it, I realized it was a 2-d printer. Somebody else put in a pen to draw huge mazes. I wonder if the smaller cheaper pen plotters could be modified to cut vinyl?

Any recommendations on vinyl cutters? It looks like all the servo-controlled ones start at around $1k; are the stepper ones at all worth it?

I have an inexpensive stepper-based cutter and it has really impressed me. I had very low expectations when I bought it, but it's quite nice as a pen plotter.

With an 0.05mm fiber tip technical pen, the stepper movements are indistinguishable in the final drawing. I've also run the same drawing multiple times to check repeatability, and it's within probably 10 thou (10 * [1/1000 in]) at least at first glance with a small drawing.

Having a servo-based movement is probably important if you are cutting tough outdoor vinyl or stencil material, but if you are just moving a pen across paper, some of the advantages of servos don't come into play.

The only problem I've had with it is when cutting 4-5mil mylar for stencils. There, because of variations in the thickness of the mylar (I think), the machine sometimes fails to cut completely. It doesn't lose its place in the drawing, though, which makes me think that they are running the stepper motors in a closed-loop mode similar to how you'd use a servo. I am not 100% on that, it's just a theory I've developed after watching the thing at work for a while. I'm still enjoying just playing with it enough for the moment, so I haven't bothered to dig into its innards.

Lots of fun for under 200 bucks though, IMO.

"makes me think that they are running the stepper motors in a closed-loop mode similar to how you'd use a servo. I am not 100% on that, "

Do the steppers have encoders on them? If not, the machine can't do closed loop control. It can keep track of where the rotor should be based on counting the steps of coils it has energized, but it has no way of directly keeping track of the rotor. A large enough torque resisting the rotor's rotation can cause the rotor to skip steps, but this doesn't influence the energizing of coils in the stator so the machine has no idea that anything has gone wrong.

An encoder lets you directly measure what's going on with the rotor (and therefore the shaft of the motor). You basically keep track of where you should be (based on counting the steps delivered to the stator coils) then use the encoder to validate. e.g. 'I've sent 12 steps so I should be 48 degrees from where I started. My encoder is reading 26 degrees, so I must have skipped steps somewhere along the way.'

If you use an encoder to adjust your position, then you are a servo; you probably won't use a stepper motor because the main advantage to a stepper motor is that you don't need position feedback to estimate the position accurately, but a stepper motor with feedback is just as much a servomechanism as any other motor with negative feedback.

[edit]

Wikipedia tells me that there are some mechanisms that use stepper motors that run mostly open-loop with an encoder only for detecting stepper-miss. Whether or not this qualifies as a servo-mechanism is up for debate.

In any event, I seriously doubt that a sub $200 plotter is doing this, as the encoder adds to the BOM.

If the step distance is very small then many designs would tolerate a fair amount of stepper-miss before being noticeable. Might be easiest to see if you did half of a shape, then went somewhere else and finished the shape.

What's the part number for the one you have, please?

Unfortunately I can't say with confidence; mine is one of the servo-controlled ones that cost exactly $1K (new). I don't have first-hand experience with the stepper-driven ones. I will say, however, that 3D printers in the sub-$5000 space are pretty much all steppers, and those work great, so I doubt a stepper vinyl cutter would have positioning problems. The forces involved aren't high enough to make the drive system miss steps, skip belt teeth, etc..