Tips

This is the tips section of the site, here you will find tips and some trick for RC cars and trucks.

T-Maxx Brakes

The Bellcrank adapter was made from .064 alu sheet stock. The throw diminsions were left as stock. But note the brake arm is now advanced (rotated) toward the rear of the truck. This allows engagment of the brake lever sooner in the servo rotation and keeps the arm from going past center and losing leverage. This advancement can be seen in 2 of the pics. The sketch is to scale and you can get the angle off the screen by tracing it.

The brake jack screw plate is made from 3/4" x 1/8" alu. The screw I used was a 6-32 hex head cap screw. The screw is about 5/8" long. Make sure that the one you use isn't so long that it will hit the inline drive "U" joint. The lock nut is NOT a nylon lock as it isn't needed. Just use a standard nut. When tightened it jams the screw up tight.

The mounting of the plate, to the servo support, is done by using Scotch Brand double sided gel tape (beats foam tape anyday) of two (2) lb's holding force. The top of the plate is located 3/8" down from the top of the servo mounting support, not the servo mounting flanges. What I did was to put 2 strips of tape on the support and after placing the plate in place I then trimed off the excess. Make sure that the head of the screw is as lined up with the center of the brake cam push pin as possible.

The bellcrank was mounted to an old servo bellcrank. The stock one will do. With the servo in netural and the holes drilled in the new alu bellcrank, place it on top of the servo arm. Drill the center hole large enough for the bellcrank mounting screw to attach the same as the stock one. What I'm talking about can be seen in the last pic. Mark where you will drill the attachment holes. I used 2-56 screws for this and tapped the old bellcrank. Then cut off the excess servo arm so the brake and throttle will not hang up during rotation. The brake linkage will give you more problems that the throttle. I made sure that the brake linkage would stay put by jamming it with 2 collars and a piece of tubing. All of the slack is now at the brake arm. Make sure you use a stiffer piece of tubing to pull against the brake arm. The standard tubing is too soft and deforms too easily.

Then adjust the Jackscrew up against the stationary brake pad. All you want is for it to be just touching the plate without pushing it off the 2 mounting screw heads. If you apply the brakes you can see if the plate deflects or not. The maximum brake is when there is no deflection. To back off on the brakes then run the jackscrew in towards the plate. This will allow the plate to deflect. You will also note the brake disk deflects as well. This deflection asorbs all the braking energy and leaving only little for braking. The jackscrew insures that it all is used for braking.

You can, its optional, move the brake arm out as far as it will go and still be in the hole. This adds leverage to the system. It's not a lot but every little bit helps.

If you really want or need stronger brakes and/or faster brakes, then swap out the servo with one of over 100 oz in and a fast response time.

After getting it all done, you will have to pattern your throttle/brake finger. I wish the transmitter had an end point adjustment. Well I'll work on that next.

Home Anodizing

Sulfuric acid is very toxic and dangerous, it releases hydrogen which is flammable. Use proper venilation. Wear all the required safety equipment.

Anodizing at Home
Based on the number of companies selling, and people looking for, anodizing services for aluminum parts, I wanted to provide this info to the R/C community. Often anodizing is considered and/or presented as a difficult and expensive procedure. As it turns out, it really isn't that hard or that pricey.

Supplies Needed:
The first thing to do is to get the following things together: First on the list is the most expensive item: a 6 to 12 volt battery charger. They run from $45.00 to $110.00 depending on model, functions, etc. While it may seem like a lot, it does have other uses. (You could charge a battery, for example.) =) The next item, though not that expensive, will take some effort to find: battery electrolyte, a.k.a. sulfuric acid. This should be available at a battery wholesaler for about $2.00/gal. To make the negative ground, you will need some aluminum ground wire and aluminum-foil. The wire can be found at an electronics store for about $35/spool, and you should have the foil in the kitchen. If you happen to be out of foil, you can pick up some more at the store when you go to buy the last item for this project.

No super-special chemicals or solutions necessary to make the colors; just plain-old fabric dye. (Something like Rit dye, for about $5.00.) Rit offers something like 30-40 different colors, so you have quite a number of choices for what color you want your parts to be. An optional item is nitric acid: about $25.00/2.5 L. (This is used to clean parts prior to anodizing, but there are some cheaper alternatives. See end notes.) This is available at chemical supply stores. Should you not be able to find any, you can try to get on the good side of the high school science teacher. He may help you out since you only need a few ounces.

Safety Precautions:
There are a few precautions I want to go over to help keep you from blowing up the house or trashing the garage. First of all, do not mix or store your anodizing solution in a glass container. Something could happen to make it break, and most households are not equipped to deal with that kind of spill. You also don't want to knock over the container, so a stable, rubber bucket makes a good choice. You will also need to be certain that the part you want to color will fit in the container without sticking out of the solution, and without touching the negative ground in the bottom of the container. Any acid that you don't use, keep in what it came in, or an old plastic bottle, like a bleach bottle. You can also store your used solution this way for doing more parts later.

(Make sure that there is absolutely no bleach left in the bottle. Acid and bleach make chlorine gas. Very bad. Don't breath. Poisonous.) Safety also applies to the nitric acid, but in a different way.

It is imperative that you label and keep track of this stuff, as it is a stronger acid than sulfuric, and more dangerous. The breakage/spill problem is not as likely since you won't have that much around. (Unless you bought more than a few ounces from the chem store.) The last note about the acids is to mix properly when adding acid and water. Always pour acid into water, never the other way, and do so slowly, being sure to mix in well. There is a reaction taking place and it releases a lot of energy. During the anodizing process, you will be running electricity through a weak acid solution. This creates hydrogen (just like charging a battery) which is very flammable.

This stuff burns at the speed of thought when ignited, so do be careful. (Read as Remember the Hindenburg?) Make certain that there is some way to ventilate the project area, and DO NOT let any sources of ignition near the project area. Other precautions you should take include safety glasses, rubber gloves, and maybe some sort of drop sheet under the area.

(Editor's Note: I also recommend not using a glass container, I highly recommend use of glass within a plastic container to help keep the acid from eating through plastic, but keeping the glass less breakable in the event the container falls over.)

Preparations:
One of the most essential things you need to do in order to get even color over the whole part is to be sure that the part is absolutely clean. You want it free of all contaminates, from dirt to the oils in your skin. This is where the nitric acid and some rubber gloves will help. A solution of 1-2 ounces of nitric acid in a gallon of distilled water will allow you to clean the surface in preparation for the anodizing. Aluminum oxidizes very quickly when exposed to air, so the easiest way to keep it clean is to clean it just before you are ready to start working on the piece. (You should rinse the part with distilled water before you put it in the next acid solution.)

Other options are carburetor or brakes cleaners, or other similar degreasers. Soap and water will work also, or cleaners like Simple Green. These are cheaper, a nitric acid wash is the best. (You decide, it's your money.) Make your negative ground with the aluminum wire and foil. Shape the end of the wire into a paddle shape and cover the round part with the foil. What you want to do is create a flat, round shape to sit on the bottom of the bucket, with a lead that comes up out of the bucket. You will clip the battery charger's negative lead to the wire that comes out of the bucket. When you are ready to start, you will want to mix up your immersion solution. In your rubber bucket, combine the sulfuric acid and water to come up with a solution that is about 30% water. (1 part water to 2 parts acid.)

Place the paddle in the bucket and attach the negative lead. Then attach the positive lead to the part, making it an anode, and immerse it in the solution. (Remember that the two leads the paddle (cathode), and the part (anode) should not touch.) This is the best time to turn on the charger: once the part begins to fizz, leave it in there for about 10-15 minutes. After about this time the part should no longer conduct electricity. (You can also use an ohmmeter to check conductivity, but this is not needed.)

Turn off and disconnect everything, and rinse the part in cold water. Don't use hot water! You will find out why in the next section.

A couple of notes:
It may take some trial. It wouldn't be a bad idea to get some scrap aluminum and play with it before you start anodizing your Wanted parts. You can check out the above, as well as pick the colors you like best. If you test out some colors, you will also learn just how long or short you need to work with the color solution.

Color:
So now it doesn't conduct electricity, and is ready for color. It's been rinsed and waits eagerly to change to a new look. Don't wait too long to do the color, due to that oxidizing thing again. You want to mix up a strong solution of dye and water, in a container that can be heated. The solution needs to be at low heat, such as on the stove, so bread and cake pans work well. Again, you need something that will fit the whole part, but it's okay if it touches the bottom this time. I would recommend turning parts every few minutes just to make sure that you get all-over color. Inform your mom or wife that the pan can (and will be) washed out. It is important that the heat be low enough. If the solution gets too hot, you will seal the surface, and it will no longer take any color. (See, told you to rinse it in cold water!) Leave it in the dye until the part is slightly darker than you want it. The next step is to seal the surface of the metal in clean, boiling water. This will leech a bit of color from it, thus the slightly darker color in the previous step.

End Notes:
It is important to realize that the process described above will yield only one color on your part. At this time, I haven't found out how to do any of the splash type of anodizing. Also, this process is for aluminum. I don't know how, or if, it will work on other metals. (I doubt it.) Anodizing only works well on rock metal like bar or sheet stock, as opposed to castings. If it was forged or machined, it should have the density to take color through this process. I figure this shouldn't be too big a problem with many r/c parts, but just thought I should let you know about it.

Something to consider when looking for a charger, are how many amperes it puts out. Without getting into any mumbo-jumbo, anodizing relies on 10 to 40 amperes per square foot. For small brackets and such, this is no problem. The larger parts however, may need the higher levels of amperes. The other note about part size, has to do with how long you leave it in the solution. Above it said 10-15 minutes, but that is for a smaller part. The larger parts may not only need higher amperes, but more time as well. I would recommend an ohmmeter, but again, I have one already.

So there you have it. Quick, fairly easy, and not too expensive. If you don't have the charger, then your first anodizing session could cost a lot. But, then you can do it again for much less. Or do your buddies stuff. Or talk them into chipping in on a setup for all of you to use. We all know ways to help make things cheaper.

The above is from MaxxTraxx