Coloring a Robot

Technical Technical Discussion
1

This is the first year my team has actually found the time to color some parts and i was wondering what methods teams have used in the past and how well they worked. I’d also like to know how hard some things are and how expensive they can be. I hear paint chips and scatches easily and that powder coating can be heavy. We’re pretty much interested in coloring our frame and some of the sub compenents, all of which are alluminum. Would anodizing work well? Any pictures would be great.

Thanks,
Ben Van Selous

2

Spray painting is light weight, easy and most important cheap. it can get messed up a bit but doesn’t that just show character?

3

We always powder coat our frame and some of the bigger parts of the robots. It will add about 3 pounds to the robot, but thats just an estimation. Also with powder coating, it adds about ten-thousands to the dimension to whatever it is on. So if you have close tolerances then that might be a problem. Anodizing is very nice. It is extremely light-weight and doesn’t chip or scratch. But the only problem is that you can only do it to small parts.

4

Do u send your parts out for powder coating? I’ve seen kits in Northern tool. Do you think its something a team could handle on their own? If you do send the parts out to a shop is powdercoating an expensive thing to have done?

Thanks,
Ben Van Selous

5

Not necessarily - if you have a big enough anodizing tank and a large enough power supply (you need somewhere in the neighbourhood of 4-12 amps per square foot of part surface area) you can anodize anything. We are going to be anodizing most of the aluminum on our robot this year - it’s very durable, looks great, is relatively inexpensive, and is fun to do. The only hitch is that most of the stuff we use like extrusion and angle comes already anodized but not dyed, so it takes a bit more work to de-anodize first.

6

Is this something you do yourselves? If so I’d really like to learn how to do it. Could you post an overview of the process? I really appreciate your help.

Ben Van Selous

7

Yeah we send out for powder coating. We are lucky becuase our school is in a manufacturing district. Actually the second largest in the nation. We also get it done for free. I don’t know if you know how powder coating works but you will need the powder and sprayers. You will also need a place to do it and you will need to be able to electricly charge the part you are coating. If you can do that then are set.

8

We have a powder coat with high gloss. Black and gold of course:)Getting it painted should probably be done by a professional. If you have problems with runs and drips, you could get it on the robot in places where space can be vital. Of course, the problem with getting it painted is that if you ever have to drill, cut or work it up, your going to be very reluctant to mess up such a nice paint job.

9

Sure, no problem.
Please keep in mind that this is a very general overview, since we only started doing this ourselves this year, and haven’t quite perfected the process yet.

First off, it may be obvious, but you can only anodize aluminum. Any other kind of metal simply won’t work with this method. The part should be really well cleaned before, and keep in mind that the anodized layer is so thin that if you leave a bad finish before anodizing, it will show through afterwards.

The first step is to immerse the part in a basic solution (2 molar NaOH will do the trick) for a short amount of time. This is known as “etching”, and the idea behind this, I believe, is that it increases the surface area of the part on an atomic level, making the aluminum more receptive to the oxygen later on. If your part came already anodized, like extrusion, then leaving it in the basic solution for half an hour or so will remove the anodized layer, if you help it along by wiping every few minutes.

The next stage is the actual anodization, in which the part is immersed in a sulfuric acid solution (1.5 molar H[sub]2[/sub]SO[sub]4[/sub] is what we use). This is done usually by suspending the part with aluminum wire (having any other type of metal in the solution will cause the electricity to flow through it instead of the aluminum). The part gets attached to the positive terminal of a power supply, which is why it’s called “anodization”. You also need a cathode, which usually is an aluminum plate at the bottom or side of the anodizing tank, hooked up to the negative terminal. We use a 35A manual 12V battery charger as our power supply. The power supply gets turned on, and should be set so that it supplies 4-12 amps per square foot of the surface area of your part. At this current, it usually takes about an hour and a half to anodize a part. What happens during this process is that the water in the solution is electrolyzed, and the hydrogen is released while the oxygen bonds with the aluminum at the anode to form a porous aluminum oxide layer.

The following step is to dye the oxide layer to whatever colour you want. Ordinary fabric dye works fine for this, mixed at twice the normal concentration. This takes 15 minutes to half an hour, and during this stage the dye is absorbed into the pores of the aluminum oxide layer.

The last stage is the sealing, during which the pores are closed, trapping the colour inside. Some people will use special chemicals to seal their parts, but immersing them in boiling water for a few minutes works just fine.
The result of all this is a colourful, slightly matte layer a couple thousandths of an inch thick.

If you’re considering trying your hand at anodizing yourself, there are some excellent websites which you should consult, such as this one and this one.

Good luck with your robot colouring! :slight_smile:

10

Is that allowed? I thought there was some kind of rule against chemically treating materials for your robot. If this is allowed I will definetly have to try it.

11

You cannot paint your robot any color that is on the field. So MOE, what are you guys going to do, since green is the color of the vison tetras?

Our robot is going to black/gray. Personally I would want something like bright orange or pink.

EDIT: I am looking for the exact rule now…

12

From the Q&A:

I read this Q&A as saying that you can paint your robot whatever color you like.

13

<R33> states that plating and anodizing are legal.

14

Ah, thanks. Sweet, Im gonna try this today on some scraps. Assuming I can get my hands on some chemicals :smiley: .

15

The camera is set to read the colors of the field, therefore a robot that is colored the same color as a part of the field would be considered distracting…

That how I read it, but where is the rule, cause it doesn’t fall under <G26>, thats the entanglement rule.

16

No you are right!

Q: Clarifying Q. 981: Even if the intent is not to distract the robot? Since the cameras can be calibrated to sense many different colors, must some colors (& if so, which) be avoided by teams in decorating their robots and themselves?

A: No.

17

does anodizing interefere with welding? would it be better to do it before or after you weld, say your frame together? Does grinding or buffing the metal before hand (or even after) affect the outcome of the color when you anodize?

18

Anodize AFTER you weld. If you anodize before you weld you’ll have to clean off the anodize where you’re planning on welding. Once you have ALL metal work done then it’s time for anodizing. If you start grinding afterward you’ll just remove the anodizing (grind through).
The experience I’ve gotten at work with anodizing (stuff we sent out) is if the metal was buffed or grinded before hand the color doesn’t change drastically but the sheen will be different.