One week more and I think I should upload what I have done until now. I am continiuing with the R/C car design, which is going to be printed using a 3D printer in plastic.
After the first post, I was working in the 3D design and linking the dimensions to the basic parameters that I need to buy or calculate.
Why that way? Is it not easier just dimension the model and change it when you have the dimension of the elements that you are going to buy?
Well, this is how the engineers work with the software Catia. Catia, apart of being a normal/good CAD, has the option of use parameter in the design; so then I will be able to modify the parameter value and then the whole model will change to the new dimensions.
In that way, I can check different configuration or options dependidng on which elements I like, but also change thickness to see the minimum one which is going to resists all the loads.
This is the process that I am finishing now, modify all the model to make it depend in few parameters according to de dimensions I have looked up in internet.
After that, I will have to buy the elements and measure to be sure that they are exactly the size that I wanted. If some are longer or bigger, I will change the parameter value in Catia, and the whole model will change and will be now ready to be printed.
Example of the parameter of catia, with a fx symbol in the constraint
The elements that I will have to print, and I will have to buy are the following:
-Electrical Motor: One of the most basic ones. It will move the rear wheels (in this model) and make the car move. In this case it's a Brushless motor with a KV of 4300, 900 watts of maximum power, 50000 rpm of maximum speed and a voltage less than 12 V.
-ESC: Electronic Speed Control. This device will be connected between the motor and the receptor and is the element which controls the speed of the motor, and then the power that it gives. There are mechanical speed controls, but latelly almost everybody uses one electronic (at least for electric cars).
-Battery: This is like the fuel of the car; in this case electric fuel. Normally the battery is one of the heavist and largest elements in a model and could be up to one third of the weight of the model. When you are going to take one, it is important that you look carefully the voltaje and maH of it, so the car will have the endurance and the motor that you desire.
-Receptor: The control or brain of the car. THe receptor will receive the orders from the Radio in your hands to control the car in different channels. It controls the motor power (throught the ESC), but also the direction control of the front wheels of the car (trhought a servo motor).
-Servo-motor: The servomotor is the element in charge of turning the wheels to make the car turn in one side or other. There are differnt kinds, which has to be study carefully and in detail.
Other servomotor will be neded to move the FPC camera up to 180º and let the driver look in different angles.
-FPC camera: Is one of the most expensive elements of the car and will be the last in being bouht (of course because the price) there are diffirent kinds. The desire features are light, with a good wireless range and real time video capacity to the googles (or monitor). Normallyare small, light and with a cost of 300 american dollars.
Now I start with some mehcanic elements:
-Wheels: Yes, I know. I could design and print the wheels. But they could be a little pain in the us since I have to design them in two parts for the inside part and the tyre apart. Also, they are cheap, les than 20 dollars the total.
The wheels I will use are 1/10 size and 1/8.
-Spur gear and pinion gear driver: the gears, will be designing and printed. The size and characteristics will have to be calculated in the excel software.
-Bearings: of course the bearings, they cannot be forgotten. Are very important to connect static elements with the shaft of the wheels. I will use two sizes (for the rear wheels and the front wheels). I don't design them because there are many in internet, metal ones and has to be done with accurate tolerances better that the ones I will use with the printer. I will use 2 per wheel, and I will explain other day how I will use them.
-Bolts and screws: THe other structure element, that I will use to fix the elements and as shafts. I would like t use the Metric system, although in USA is not so easy. My initial idea is using a long one M7 and some shorters M4. Also, I will need washers and nuts, many of them. The precise number will be known later in the project.
-Structure: This element I won't have to buy separaterly, is the one I will print. I include it in the list because it will be needed as part of the parameters to the 3D design.
This are the most important elements that I will have to look for and the ones I will have to configurate the design for.
The 3D model after some changes
comparative: left the new model, right the first design
Although both are very similar, I have done some changes in the model. The most imporant ones affect the rear wheels (bigger) the bearing casign, and the frame.
More changes will be appear while I am linking the dimensions with the prameters.
Sorry that this post is much more boring than others. The next one will be more interesting.
