3D design course in 360. Simple mechanisms right away! – Lesson 5

This is the fifth edition of the Autodesk Fusion 360 design course. In previous months, we discussed the main features of the program: creating simple solids, cylindrical and rotating solids. We have developed a ball bearing - completely made of plastic. We then developed the skills to create more complex shapes. This time we will deal with the angle gears and gears.

Some elements of mechanisms like to break often, this also applies to asterisks. brings a solution to some problems - for example, with a missing gearbox.

Movement

We start with something simple. Gears are usually cylinders with cut or welded teeth. We start the sketch on the XY plane and draw a circle with a radius of 30 mm. We stretch it to a height of 5 mm - this is how a cylinder is obtained, in which we then cut the teeth (thanks to which we get better control over the diameter of the created gear).

1. The basis for creating a rack

The next step is to sketch out the template that was used to shape the teeth. On one of the bases of the cylinder, draw a trapezoid with a base 1 and 2 mm long. The program allows you not to draw a longer base of the trapezoid - we can determine its length thanks to the points at the ends of its "shoulders". We round the corners on a shorter basis using the options on the sketch function tab. We cut the created sketch around the entire cylinder and then round off the sharp edges. The place for one clove is ready - repeat 29 more times. The option mentioned in previous editions of the course will come in handy, i.e. repetitions. This option is hidden under the name Pattern on the tab where we select the version.

2. A hole is cut into one notch

By selecting this tool, we select all surfaces of the created cut (including rounded ones). Go to the Axis parameter in the auxiliary window and select the axis around which the cut will be repeated. We can also select the edge of the cylinder - the end result will be the same. We repeat the repetition 30 times (we enter into the window visible on the working field near the model or in the auxiliary window). When creating gears, you need to practice a little to get the right tooth size.

Movement ready. Adding a hole to mount the wheel on the axle should not be a problem at this point in the course. However, when creating such a circle, the question may arise: "Why not draw the teeth in the first sketch instead of cutting them into a cylinder?".

3. A few repetitions and the rack is ready

The answer is quite simple - it's for convenience. If there is a need to change the size or shape, it is enough to change the sketch of the tooth. If this had been done in the first draft, a complete revision of the sketch would have been required. It is proposed to use the repetition operation, already acting on the model, duplicating the operation performed or the selected faces of the object (1-3).

Angle gear

We come to the slightly more difficult part of the lesson, that is, the corner transmission. Used to change direction, most commonly 90°.

The beginning will be the same as in the gear. Draw a circle (40 mm in diameter) on the XY plane and draw it up (by 10 mm), but setting the parameter to 45°. We make a sketch of a template for cutting teeth, as for a regular circle. We draw such patterns on the lower and upper planes. The template on the bottom face should be twice as wide as the sketch on the top face. This value is obtained from the ratio of the upper and lower diameters.

4. Basis for the preparation of the bevel gear

When creating a sketch, it is recommended to enlarge it so that it protrudes slightly from the base to avoid planes with zero thickness. These are model elements whose existence is necessary due to an incorrect size or inaccurate sketch. They can hinder further work.

Having created two sketches, we use the Loft operation, from the bookmark. This step was discussed in the previous sections for merging two or more sketches into a solid. This is the best way to make smooth transitions between two shapes.

5. Cut from two sketches

We select the mentioned option and select both thumbnails. The cut out fragment of the model will be highlighted in red, so we can constantly monitor whether unwanted shapes or planes are created. After agreement, a notch is made on one clove. Now it remains to round the edges so that the teeth easily fall into the cutout. Repeat the cut in the same way as with a normal gear - this time 25 times (4-6).

6. Finished Corner Rack

Worm gear

The worm gear is still missing from the gear set. It also serves for angular transmission of rotation. It consists of a screw, i.e. worm, and relatively typical rack and pinion. At first glance, its implementation seems very complicated, but thanks to the operations available in the program, it turns out to be as simple as in the case of previous models.

7. The rod in which we will cut the gears

Let's start by sketching a circle (40mm diameter) on the XY plane. Pulling it up to a height of 50 mm, we create a cylinder from which the snail will be cut. Then we find and select the operation from the tab, then the program tells us to run the sketch and draw a circle, which will be something like the core of the spiral we just created. Once the circle is drawn, a spring appears. Use the arrows to position it so that it overlaps the cylinder. In the auxiliary window, change the parameter to 6 and the parameter. We will definitely cut and approve the operation. A worm has just been created, i.e. the first element of the reducer (7, 8).

To the worm made earlier, you also need to add the appropriate rack. It won't be much different from the rack at the beginning of this tutorial - the only difference is the size and shape of the prongs, which are based on the shape of the notch on the cochlea. When both models are positioned so that they are next to each other (or even slightly overlapping), we can draw the corresponding shape. Repeat the cut as in the previous cases and cut a hole for the axle. It is also worth cutting a hole in the snail for attaching the axis.

9. Visible elements are two independent bodies.

At this point, the gears are ready, although they are still “hanging in the air” (9, 10).

10. Worm gear is ready

Presentation Time

The created gears will be mounted in various mechanisms, so they are worth testing. To do this, we will prepare the walls of the box in which we will place the gears. Let's start from the very beginning, and to save material and time, we will make a common rail for the first two gears.

Start the sketch on the XY plane and draw a 60x80mm rectangle. We pull it up 2 mm. We add the same element to the XZ plane, thus creating an angular section on which we will mount the created gears. Now it remains to cut holes for the axles located on one of the inner walls of the corner. The holes must be more than 20mm away from other components so that the 40mm stand has room to pivot. We might as well add axes for the gears to turn on. I leave this model without a detailed description, as at this point in the course it would be more of an unnecessary repetition (11).

11. Shelving rack example

Worm gear we will install it in a kind of basket in which it will work. This time the square doesn't work out very well. So, we will start by making a cylinder in which the screw will rotate. Then we add a plate on which we will mount the rack.

We start the sketch on the YZ plane and draw a circle with a diameter of 50 mm, which we extrude to a height of 60 mm. Using the Shell operation, we hollow out the cylinder, leaving a wall thickness of 2 mm. The axis on which we will mount the auger must have two points of support, so now we will restore the wall removed during the "Shell" operation. This requires you to redraw it - let's take advantage of that and make it a stub. This element should be slightly moved away from the main one - the already considered functions will help with this.

We sketch a circle with a diameter corresponding to the diameter of the cylinder, and draw it 2 mm. Then add a flange at a distance of 2,1 mm from the created wall (we do this in the sketch phase of the flange). We stretch the collar by 2 mm - the snail will not allow more. In this way, we get a stably mounted screw with its easy assembly.

Of course, do not forget to cut holes for the axle. It's worth exploring the inside of the rig a bit - we can do that with a straight cut. On the XZ plane, we start the sketch and draw a face on which we will place the rack. The wall should be 2,5mm from the center of the cylinder and the axial space should be 15mm from the surface of the cylinder. It is worth adding a few legs on which you can put the model (12).

Summation

The production of gears is no longer a problem for us, and we can even present them beautifully. The models will work in home prototypes and, if necessary, will replace the damaged part of home devices. The gears have larger teeth than the factory ones. This is due to the limitations of the technology - the teeth must be larger to obtain the required strength.

13. Printed worm gear

Now we just have to play with the newly learned operations and test different settings (13-15).

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