Hello everyone! Starting from this post, we proceed to working on our Mustang. You can follow the release of all issues if you now subscribe to the telegram channel.
Let’s start with the body.
Ways of creating car body
As I said in the previous post, we had two options. The first option was to buy the original body parts. The second option was to make the body by ourselves.
There was also the third option – we could buy a body from those people who were engaged in manufacturing Kit Car sets, but the disadvantage of such variant was that these people make their bodies in cross-sections.
They divide the 3D model into cross sections. These sections are arranged in such a way that there are 5 cm gaps between them.
Then foam plastic is put there.
After that everything is cut and polished being later covered with filling paint.
After that the matrix is removed.
But there is a very high possibility that in the process of creating bodies in this way, some details might move and there will be a distortion.
People do not notice this. As a result, it turns out that the parts, let’s say the left and right ones, the right rear wing and the left rear wing, differ from each other by their proportion, symmetry and even size.
We faced this problem when we bought the Lamborghini body. We were working on the rear and front wings having to level them out, because there was a very big difference between them.
In order not to deal with such a problem in this project, we decided to make the body by ourselves. Although we made it with the usage of a CNC machine, but not on the basis of sections.
We will make the entire model of the car from foam polystyrene. To do this, we bought 8 packages like this and spent about 10 thousand rubles (approximately $140) on it.
Well, it’s hard to believe that in about 10 days this pile of foam plastic will turn into a full-sized model of Mustang.
3D model to help
We took the 3D model of Mustang. We used a 1967 model as the basis.
It differs from the Shelby version by its air intakes, tail light panel, trunk, and also by the front position lamps.
These body parts are original. Therefore, we will remove them from the model and will work only with the main part of the body.
We will adjust the model to the original size of the car.
As the basis, we will take the length and width of the wheelbase; check the resulting model by the width of the hood. We have the original size.
After that, we begin to divide the body into segments.
Blocks of the same size are created together with 10 cm thick foam plates.
Later they should be arranged in such a way that they will fill the entire model along the surface of all the body elements.
By doing this, we cut the body into the layers. From each layer like this we get several elements that are retained as separate models.
Then these models need to be cut out. Once they are ready, it will be necessary just to assemble them. There will be something like a construction set.
Today we start sawing the Mustang’s body and we begin doing it with these two elements, the parts of a front wing.
Now we set the program for cutting these parts with the help of the CNC machine.
To do this, we use the ArtCAM program. Here we need to enter the sizes of the operating field. After that we should choose a 3D view and download the 3D model.
We need to place the wing in the center. Then we need to lower it down to the operating field so that in the upper part it would still be possible to place a small element in order to save the material and a little bit of time.
Well, it’s all right. We got a wing like this. Now we should take its upper part and place its operating area in the same way. Then we need to raise it above the wing. We got the operating area like this.
Now we need to carry out programming. We select the milling cutter, all the parameters are entered. A few passes need to be done along Z. Since we have a 10 cm milling cutter, or, more precisely, 12 cm, the cutting part of it seems to be 72 mm.
And if you immediately move it 100 mm down, then the upper part of it will melt down the foam plastic. To do this, we need to make two passes.
Then we will calculate the project. The program has created a visualization of how the body will be cut.
It could be programmed in such a way that it would move along two axes, first along X, and then along Y. But then everything will be cut for a very long time and it won’t improve the quality that much.
Of course, it will be better, but it won’t be worth spending extra 3 or 4 hours.
Starting the CNC machine
Next, we will run the program of milling cutter control.
Now we need to install the foam plastic sheet in the working area of the milling cutter. We set to “0” and run the program.
We are installing the sheet in the working area.
We also put 2 cm thick plastic foam under the sheet. This is done to prevent the milling cutter from breaking by the hard base of the machine if it suddenly moves down and if “0” is set incorrectly (this happens sometimes).
Then we need to strongly fasten the sheet of foam plastic. For this we use screws. Along the edges of the sheet, where cutting will not occur, we need just to screw it in.
Details about milling cutter
A few words about the milling cutter. We have an ordinary three-axis CNC machine.
In fact, we have the fourth axis, but it is used to create some balusters or legs. We will not need it, so we have removed it for now.
I guess its operating area is 1250×950. Z-axis height is 300 mm. Now let’s set it to “0”. We will enter zero in the lower left corner. And if you look from the other side, then we will have it here.
We launched the spindle and the program. Well, we can start.
Let’s do it!
The cutting process will take about 3 hours.
During this period, it will be necessary to approach and clean the waste and sawdust from time to time, so that everything won’t wind on the milling cutter.
Top view of cutting process
Detail is ready
Take out the item
So, 3 and a half hours later, the milling cutter finished its work and cut out our details.
Now we need to get them out polishing them with sandpaper. Since these are the parts of the same element, in this case of the front wing, they can be glued together.
Polishing the surface
After cutting, the surface of the parts is ribbed. This is due to the fact that when the cutter moves like a snake, then grooves remain on the details.
You can get rid of them by taking sandpaper with the soft base and just polish all this.
But you may not worry about the fact that it will be polished too much and the detail itself will be affected, since when the program for the CNC machine was set, then there was a special 0.5 mm space set in order to polish the extra part.
Gluing the elements
So we glued the two elements together. This is nearly 2/3 of the front wing. In general, the process of how we will make the rest of the details is clear to you now.
It will take us about a week to cut the other details. Also, we will immediately glue them together, in two or three parts. Then from these parts we will assemble a full-size Mustang model.
I like this way of manufacturing the body because today we made the left wing and tomorrow, when we will be making the right wing, I can rest assured that it will be perfectly symmetrical with the other one.
Another big plus of it is that it involves the minimum of manual labor and it has the high speed, which is very important.
Well, that’s all for today.
There will be a lot of interesting things!