idraw-H - I Draw Monkeys

iDraw H Pen Plotter: Overview and Tips

I got to test drive an iDraw H A1, and I am sort of obsessed.

When I first got the iDraw H a couple weeks ago, I was hesitant because I knew its whole selling point was it was really fast. But I had my own large pen plotter based on the OpenBuilds Acro system, and my machine could also go fast, but the speed came at the expense of accuracy. So yeah, it could go fast but not in a useable way. Additionally people I knew with the special order large format AxiDraw all told me they ran much slower than the A3 machine.

Due to all this, I had the idea that if you scaled up, you had to give up speed. And to be honest, I didn’t really think the iDraw would prove that wrong. Well, it did.

This article is part review and part tutorial, including tips I recommend to people who have just gotten an iDraw.

Setting Up The Machine

The machine came semi-assembled. It took me a very leisurely 15 minutes to put it together.

It was about eight screws (Allen wrenches are included so no screwdriver necessary) and plugging in a few labeled motor and limit switch cords.

There is a video on how to assemble, and I watched it sort of, but the whole thing felt pretty intuitive so I didn’t pay full attention. However, once I tried to fire up the machine, I realized that I had missed a couple connections, so I do suggest that you actually follow along with the video as you put it together.

Pen Holder: A Real Difference

One thing that makes this build stand apart from the other builds I have encountered is that it uses a stepper motor on the z-axis for the pen holder instead of a servo. The advantages of this are:

Much quieter. Servos have to be honest an annoying sound. These stepper motors, in comparison, are much less noisy.
Will last. Servos are cheap and pretty easy to replace, but they die easily and often. In fact, when I was trying to compare the new iDraw for this article, I was plotting the same file on my AxiDraw and mid-plot the servo died.
Faster. Much, much faster.
Downward pressure. With the servos usually the only downward pressure exerted is gravity. You can add weight (a glass, for example) on the top of a pen to add downward pressure but it is difficult. This pen holder uses springs, and while the pressure isn’t too much (this is a good thing) you could potentially change out the springs to increase pressure which might be something if you were using pencils or paint pens that need to be pumped.

Before You Start Plotting: Quick Tips to Optimize Accuracy

When I fired up the iDraw for the first time, I was immediately impressed by how quiet it was and its speed. However, when I started printing some Hershey text which is really good for spotting any inaccuracies, I noticed the letters were a bit warped. I knew from building other machines that there were some mechanical things I could do to optimize the accuracy and after doing these two things made the warped letters become almost perfect. I suggest you do these as well before beginning to plot. It is an extra couple minutes and made a huge difference:

Step 1: Tension the belts. Going one by one, locate the four belt tensioners at the end of the y-axises (see picture to the right). Use included Allen wrench to loosen (don’t remove) the grub screw. Pull the belt hanging off the end tight—it might only feel like it moves a millimeter or two but that is enough to make a difference. While holding belt taught, retighten grub screw fully.

Step 2: Square up the machine. This is shown in the assembly video but once the whole machine is finished, it can help to redo this step. Loosen the screws slightly at the end of the two y-axis. Pull the x-axis square and fully against the plates on the y-axis and while the x-axis is there re-tighten the screws. This is to make sure that the corners are square. Repeat on the other side

As you do these two steps, it might feel like you are almost doing nothing, but I promise it makes a big difference. Check out these letters I plotted with the iDraw before I tensioned or squared up the machine (images are slightly englarged)::

After tensioning of step one, you can already see how much things improved:

And this was the final result after tensioning and squaring things up, as you can see these steps make a huge difference:

Beginning Plotting: Things to Know

First step: install software and plug-in. The plotter uses an Inkscape plug-in based on the open-source AxiDraw plug-in in order to drive the machine. You can find the plug-in and instructions on how to install here. Note: the iDraw H uses the iDraw Control 2.0.

Inkscape is an open-source editor for vector images (SVGs). It is also complete free. Inkscape can be frustrating when you first start using it—some things are not quite intuitive—but as I’ve used it more and more, I have grown to love it. It is a very powerful tool especially for managing SVGs. I almost never use Adobe Illustrator now and fully prefer Inkscape.

Second step: home the machine. Once you fire up your iDraw, before you do anything open up the iDraw Control 2.0 extension and navigate to Options > Config > iDraw model and select the correct size of your machine. You must do this before homing or it won’t work correctly.

Next, navigate to Manual > Command and select AUTO HOME from the menu.

The home position is in the corner shown in the picture below. If you draw a landscape drawing, the home corner will be the upper left hand of the page. If you have a portrait-oriented drawing, the home will be at the top right corner of the page.

Third step: insert pen by going to the Setup tab of the software and clicking to lower the pen. Once in the down position insert the pen. Click raise the pen to raise the pen back up. Sometimes, I like to add a bit more to the down position as pages rarely are completely flat. With the iDraw, I add 0.1-0.2mm. And then you are ready to plot! Navigate to the “Plot” tab and click Apply. Note: Inkscape will plot anything that is visible in your document.

Special hint for plotting: in Inkscape, always work in Outline view. This will help you always know what is going to come out of the plotter as the plotter reads the paths only (not internal fills or varying stroke widths). You can find outline view under View > Display > Outline.

Performance Tests and Comparison to Other Machines

When I first started exploring pen plotting, I was using an A3 sized AxiDraw. I plotted for a couple weeks, thinking everything was fine and dandy until I found Arnaud Pfeffer’s contact sheet and sent it to the plotter. I hadn’t even noticed how my AxiDraw was really out of whack (we had taken it apart for a plane ride). The contact sheet helped me tune it back up and get it accurate again.

So when I got the iDraw, I revisited the contact sheet (which on top of being quite beautiful is a magnificent tool) to evaluate the machine.

After doing the first plots, I realized it needed a bit more tuning (see the steps above). But those were quickly done, and then I could speed/accuracy test it against my other machines.

And this is where I started to get excited because I realized that those iDraw speed claims were true—and most importantly, the machine was fast AND accurate.

Here is the contact sheet printed at max speed (100%) on the AxiDraw A3 verus 7500 speed (max speed is 10000) on the iDraw H. Both use a Muji 0.38 gel pen and are optimized for path order but to preserve directions o the lines. The time on the AxiDraw print was 19 minutes. The time for the iDraw H was 10 minutes 24 seconds.

That means the iDraw was almost 2x as fast on a plotter with a print bed that is 3x the size.

I then plotted the same on my OpenBuilds self-build machine (1.5m x 1.5m) . And this is where I realized I think more than anything not only is the iDraw fast, but I have some tuning and figuring out to do on my self build to speed it up (which may involve purchasing an iDraw board to run my machine on). A large part of the OpenBuild’s slowness (since it is also an H plotter just like the iDraw) on this file in particular has to do with the circles. My Gcode circles do not go fast. So it is at least partly a software problem. However, on my OpenBuilds machine it took 1 hour 😳 and I think isn’t even as accurate.

Note: The pen was also dying so some errors are simply due to that.

Trying To Go As Fast as Possible

Next, I tried to max out the speed completely. I ran the iDraw at 10,000 and fully optimized the plot, meaning that it reversed path directions.

Here, there are some accuracy issues and a couple artifacts that have to do with the pen having a downward pressure, but the speed is insane: Just under six minutes.

Adjusting Speed Depending on Purpose and Drawing

It is amazing to have such a fast machine, but you wouldn’t always want to be plotting at max speed. Often on my plots that I do in layers, I know where accuracy is of primary concern. If a layer contains small text, for example, I will slow down the machine. If I have lots of long straight lines, I will max out or if it is a lot of scribble lines where fraction of millimeter differences don’t matter. The iDraw lets you go super fast but also can slow down when tip top accuracy is important. It is just nice to have the choice.

Text at Different Speeds

Text is always a good way to test accuracy. I wanted to plot the same sentence at different speeds on the iDraw H to see how different it is at slow speeds and fast. Below is the result. I put a ruler next to it for scale.

Important to note is that the from 5000-10000 the speed was actually quite similar. They all took 24 seconds to plot. This is due to acceleration putting a cap on how fast the machine can go. As these are all short paths, the speed was throttled from reaching max.

There is a place in the software to change the acceleration speed. However, I will leave it as standard as acceleration can hugely affect accuracy. (Tip: for hyper accurate plots, adjust both acceleration and speed down).

At the 500 speed, the sentence took 37 seconds.

Interestingly, when I plotted the same sentence on the AxiDraw at its max speed, it took 42 seconds.

Repeatability Test

I wanted to check the repeatability of the iDraw. I took two lines of Hershey text (the bottom line is tiny, the small letters are just under 2mm high). I placed it in the middle of the top of the page and plotted it five times having it return home between each. If I didn’t tell you this was five layered plots, I’m pretty sure you would think it was only one slightly thicker pen. So it completely passed the repeatability test. Accurate to fractions of millimeters.

Acrylic Pen (Requiring Pressure)

Because the pen holder exerts a certain downward force, I wanted to test if it would allow an acrylic pen that typically must be pumped ever so often to last longer than if in a pen holder like the AxiDraw. In the end how long it lasted was similar on both machines but you can see the quality of line is much different. I do wonder about swapping out the springs for stronger ones to test if you could get it to exert enough pressure to keep it flowing longer. It is something to explore later.

Fun Part: Drawing + Watercolor

So, I had a large format pen plotter before I got the iDraw H A1, and I loved it, but often would default to the AxiDraw because it was faster, and frankly, I am an impatient person.

But another thing is that I love to play with watercolor with the pen plotter. And water color takes time because the brush must return to the water dish over and over. And if it must travel long distances slowly, the water can dry up before it gets to where it should be.

So the iDraw H’s speed offers a solution to both my impatience and water drying. I was excited.

I used some code that I had used to make a recent set of postcards and enlarged it for a 65x50cm size paper which fit with ample room on the plotter.

How To Turn Your Robot into a Watercolorist

The number one thing that people DM me to ask is how do you program the plotter to do watercolor. And the answer is really simple. You need no special technical skills. You only need to set up your Inkscape SVG in a specific way. You just need to put a little circle where the water dish is and intersperse that in the z-order of the paths for when you want the brush to go get water. Then—this is very important— make sure to set optimization in iDraw software to: None.

Why Speed Matters: Almost a Kilometer

For this particular drawing, I program in the visit to the water bowl when I make the drawing in Processing. (You can find more resources for learning creative coding—or faking it—on my resources page).

I let the iDraw do its thing. In between each line, it would return to the water bowl. The one thing I noticed is that the range of the pen up/pen down is not as large as I am used to. This would be perfectly fine for any pen drawing but specifically for watercolor, I needed a bit more clearance to get into the water dish. Since I didn’t have it, I got some interesting drips. I have plans to fix this in my next plots either by raising the paper or by 3d printing a new plate for the pen holder that would offer me more range.

It finished the watercolor layer in 2 hours and 32 minutes. And while the length of path drawn was 53 meters, the total distance traveled (back and for to the water dish) was 847.92 meters!

And Done!

I plotted a few more layers and was finished with the whole drawing in under four hours. This is fast for a drawing of 50x65cm including a water color layer. The lines are indiscernible compared to the same code plotted on my AxiDraw. I couldn’t be happier.

Final Thoughts + Additional Resources

When Uunatek offered to send me an iDraw H A1 to review, I was excited to check out a new drawing robot. But honestly, I didn’t expect to like it as much as I do. Primarily, I didn’t think it was possible to be as fast and accurate as it is at the scale that it is at. Having this new machine opens up a lot of new possibilities for me.

Highlights:

Quiet: the machine is really quiet compared to all my other machines.
Fast and accurate: do I have to say it again?
Seamless Plotting from within Inkscape: the ability to use the plug-in based on the open source Axidraw plug-in just makes everything so much easier.
Stepper motor pen lift: Faster, more quiet, and less prone to malfunction than servo based pen lifts
Light and simple build: this is a lean machine. It will be really easy to transport.

There are a few things I would change. I do wish the pen up/pen down had a larger range in order to easily accommodate water dishes. I also wish I could adjust the home corner to a different spot relative to the drawing as it just wasn’t ideal for my workflow. The list price is also a bit high, but they do offer discounts often.

Overall, I think it is a pretty awesome machine if you are looking for a large format plotter, and I definitely recommend it!

Links:

You can buy an iDraw here. If you use the code LIZVIP you can get 15% off. They offer it in A2, A1, and A0. The company also has other drawing robots in smaller sizes.

There is a Facebook group for iDraw users which is a helpful place to get more information.

This is the link to download iDraw software and additional documentation.

Thedotisblack did a great review and tutorial video that can help understand the machine better.

And Dan Catt also did a similar video that is worth checking out.