Difference between revisions of "WaterColorBot Troubleshooting"

Revision as of 02:14, 17 November 2013

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WaterColorBot: Hints for troubleshooting

This page contains some collected tips and hints for making happy WaterColorBots, addressing known things that can go wrong.

Motors "cogging" (skipping steps)

There are a bunch of different things that need to work correctly for the WaterColorBot to move the brush smoothly from point A to point B. When the motors can't move the brush-- because it's stuck for any reason --it will often cause one or both of the motors to make a "cogging" noise.

So, if you find that your WaterColorBot is...

• Making a sound like Cah-Chunk-Chunk-Chunk-Chunk-Chunk-Chunk!
• Losing position while painting, or
• Running into the walls,

then it is likely that the motors are "cogging" that is, skipping steps on the motors. With one notable exception (forgetting to begin with the carriage in the upper-left START corner), this will never happen on a properly tuned WaterColorBot. Unfortunately, there are a few different things that can go wrong and cause this, particularly on a freshly-built WaterColorBot.

What to do when cogging happens

If the WaterColorBot begins cogging-- for example running into the wall while painting --the first thing that you should do is to stop the plot, so you can see what's going wrong.

The way to halt a plot in progress depends on the environment that you are painting from.

• In RoboPaint RT, press the PAUSE button to halt painting.
• In RoboPaint, press the PAUSE button to halt painting.
• When painting from Inkscape, press the PRG button on the EBB to pause a plot in progress.

No matter what environment you are plotting from, any of the following actions will also stop a plot in progress:

• Disconnecting power from the EBB by pulling out the cable from the power supply
• Disconnecting power from the EBB by unplugging the power supply from the wall
• Unplugging the USB cable from the EBB
• Pressing the RST (reset) button on the EBB.

Possible causes of cogging

Cogging happens when the motors want to turn, but are prevented from doing so for some reason. Here are some of the possible reasons that the motors might not be able to turn:

You drove into a wall

That the motors cogs and "skip steps" when the WaterColorBot carriage is driven into one of its side walls is a safety feature. (When industrial robots come to something in their way and don't stop, things can go very wrong.)

• If a newly built WaterColorBot always drives into the wall when you start painting, it is possible that one of the motors is wired backwards, which would cause the motors to drive it the wrong way. Check the wiring.
• The most common cause of driving into the wall is not starting in the Home (Upper left, "START") corner. WaterColorBot software assumes that the carriage is at the home corner when you start your painting, and acts accordingly-- and if it wasn't there to begin with, it could end up hitting a wall.
• Another possible cause of driving into the wall is that the WaterColorBot has lost track of where it is. That can happen if the motors skip steps (cogs) while running and you don't notice.

There is too much friction

The motors can only exert a certain amount of force. If that force is insufficient to overcome the friction from the spectra cord and moving the carriage, then the motors will not be able to move.

To check the level of friction, raise the brush and turn off the motors, so that you can turn the winches by hand. When you try to turn the winch, it should turn easily, and move the carriage when you do so. If it does not turn easily, then you need to figure out why.

The most common cause of high friction is if the two steel rods are not square to the chassis. You can check this by moving the carriage to the home corner, and making sure that all four rod-end sliders line up evenly against their stops.

A second thing to check is to make sure that the Spectra cord is routed through the grooves on the three ball bearings.

Third, check to make sure that you have not over-tightened the spectra cord. If you plug the string, and it sounds like any musical instrument other than a string bass, you probably have too much tension.

There is too much slack in the cord

If there is too much slack in the spectra cord, the cord can get caught under itself at the winches, effectively tying a little knot, and cause the motors to cog. You may need to tighten the cord to correct the issue.

You are driving too fast

Sometimes, the best solution is to run the WaterColorBot a little slower. In RoboPaint and in Inkscape, there are speed controls that let you set how fast the motors move. Speed values of around 70% are typically a good balance between painting speed and reliability. In RoboPaint RT, you can press the numbers 1 through 9 on your keyboard to control the speed. (The speed value will only be remembered until you quit the program.)

Motors get hot

Your motor current is set too high. Adjust the current setpoint on the EBB.

Motors make funny noises

Does it sound like chunk-chunk-chunk? If so, your motors are cogging. Read the section about that earlier.

Does it sound like an angry whistling/screaming/hissing creature? If so, your motor current is set too high. Adjust the current setpoint on the EBB.

Motors are apparently too weak

If all of the following are true:

• Your motors are not generating enough force to move the carriage
• You can easily overcome the motor force, turning the winches by hand
• The motors are not getting hot

Then it is likely that the motor current setpoint is too low. Adjust the current setpoint on the EBB.

Servo motor (Brush-lift motor) makes a buzzing noise

The servo motor can sometimes make a mild buzzing noise. This is usually not harmful, but if it sounds loud and angry, it may be the case that you are operating outside the area that it is comfortable to operate in. In Inkscape and RoboPaint, you can use the preferences to adjust the servo endpoints. If you go higher (or lower) than the servo can move, it will stress the servo motor, and make noise doing so.

Painting quality issues

Paintings are sloppy: Poor reproducibility

When properly set up, the WaterColorBot is capable of making one painting after another with remarkably fine reproducibility between copies.

• Check that brush is tight in holder (this matters much more than you think!)
• Check that string is not too loose - it may need to be tightened after its initial stretching
• Check that rods are perpendicular
• Check that paper is held tightly in place.

Paintings are sloppy: Too much water

• Put less water in the water dishes
• Change brush position so that it does not dip into water as far
• If you are painting in a mode that performs a water dip after getting paint, turn off that mode.

Painted image is distorted at edges

If your drawing calls for the brush to move past the edge of the page, it may end up distorted when the carriage changes trajectory to stay within the bounds of the page (especially when painting from within Inkscape). The solution is to check your drawing, and ensure that it fits entirely within the printable area of the WaterColorBot.

Paper is warping when it gets wet

Paper tends to warp as it gets wet, particularly with uneven wetting and lower grades of paper. Methods of dealing with this include pre-wetting and stretching paper, as well as holding paper down with tape or in blocks. Watercolor painting is an old art, and people have been solving these problems for hundreds of years; you may want to read up on the subject online or in books.

One of the most common methods of dealing with warping is to paint on a "wet canvas" (really, wet paper). If doing so, you may prefer to use the PVC plastic spoilboard (available here, rather than the wooden one.

Spare and replacement parts

Something broke! Help!

Please use the Evil Mad Scientist contact form, and let us know how we can help.

Purchasing spare parts (for replacement or for hacking)

Replacements and spare parts for every component of the WaterColorBot are available. Not everything is listed on the web site, so please use the Evil Mad Scientist contact form, and let us know how we can help.

Spills

I spilled paint/dirty water on my spoilboard, now it's covered with ink!

This happens; it's okay. Let it dry. Everything will be fine, and it will have more character in the morning. (There is a reason that it's called the spoilboard....)

If your spoilboard has taken too much abuse, replacements are available from Evil Mad Scientist. (Coming soon to the web store-- please use the contact form in the mean time.)

I spilled paint/dirty water on my WaterColorBot Frame, now it's blue!

Do the best that you can to wipe up the paint or water while it's wet, either with towels, napkins, or paper towels. Let the frame dry thoroughly and evaluate the damage (if any). You may want to sand affected areas lightly, especially the inner grooves where the rod ends slide, if the grain of the wood has been raised by the water.

I spilled water on my EBB!

Umm... please don't do that.

Unplug it from power and USB, remove all the water as best you can, and let it dry for a couple of days. The "classic" trick of letting it dry in a container with dry rice is a pretty good idea.

At absolute worst, replacements are available for purchase.

I spilled water on my motors!

We've never actually seen this happen, but it is bound to happen someday. We certainly do not recommend experimental tests of this situation. What we can suggest is to unplug the EBB from power and USB-- as soon as possible --remove all the water as best you can, and let it dry for a couple of days.

At absolute worst, replacements are available for purchase.

When Robots Attack

Runaway WaterColorBot (on its way to destroy Tokyo...)

If you need to halt painting for any reason, there are gentle ways to do so, depending on which environment you are painting from:

• In RoboPaint RT, press the PAUSE button to halt painting.
• In RoboPaint, press the PAUSE button to halt painting.
• When painting from Inkscape, press the PRG button on the EBB to pause a plot in progress.

No matter what environment you are plotting from, any of the following actions will also stop a plot in progress:

• Disconnecting power from the EBB by pulling out the cable from the power supply
• Disconnecting power from the EBB by unplugging the power supply from the wall
• Unplugging the USB cable from the EBB
• Pressing the RST (reset) button on the EBB.

I'm concerned about using the WaterColorBot around young children

Well, so are we! The WaterColorBot is not designed to be operated by young, unattended children. There's water and paint that can get spilled, and potentially pinch points around the winches and where the carriage moves. If the latter is your concern, you might consider turning down the EBB current, so that motion stops more readily when interrupted.

Media Issues

Can't find exact replacement paints

No worries. We are compiling a list of other brands of watercolor paint palettes that can be used with the WaterColorBot, that fit in the cutout of the standard spoilboard. A better solution is often to use tube-based watercolors in the existing (Crayola) palette. Tube based colors are easy to find and available in a wide range of grades.

See our Paints page for more information.

Can't find exact replacement paper

No worries. The WaterColorBot works with a wide range of paper qualities and sizes, including US letter and A4.

See our Paper page for more information.

International Issues

Can the power supply run on Europe voltage?

Yes. The power supply included with the WaterColorBot works with worldwide voltages. You will need a plug-shape adapter to run in certain countries, but it does not need to adapt the voltage.

New sections, yet to be added

- Cable guide catches on the rivet on the upper right (near point G)

- Brush catches on edge of water dish or paint pans

- Brush isn't washing very well

- Failing to actually dip into the water, to re-wet the brush. - Allow longer period of time for brush to move up and down In Robopaint: Settings > Basic Settings > Duration -