What to make a gear from at home. Methods for manufacturing gears and gears. Required materials and tools

I tried to present it in as simple a language as possible.

Recently, a friend who was selling chocolate fountains in St. Petersburg came up with an unusual offer. The fountain was returned to him, where the screw that raised the chocolate did not spin. I love tasks like this, when few people can (or want to take on) repairing individual things and you need to rack your brains a little how to make rare spare parts with your own hands.

After disassembly it became clear that the problem was in the gearbox. One gear literally melted on the shaft (the quality of the components was simply excellent. Most likely, the gear slipped for a long time, then heated up. The fountain was turned off, the gear again stuck to the shaft with an offset center. Then it was turned on again and several teeth, unable to withstand the load, broke off) . It’s impossible to find the exact same gear, so I decided to make a new one from the equipment that was nearby.

Options creating gears there are a lot, I will tell you only about one of them. In my opinion, it is the simplest and most effective.

Step 1. Development of a gear drawing

You will need:

• any vector editor
• calipers
• gear generator (I used this online service)

So, we count the number of teeth of the broken gear. We enter all the parameters and take measurements.

Download the drawing file. I drew the inner star myself in Corel, because... I didn't find the required parameter.

When calculating the internal diameter of the gear, you need to maintain a delicate balance between spinning and cracking from strong tension.

Step 2. Making the gear

The material of the new gear is transparent plexiglass. Just search in a search engine laser cutting in your city and go there. It’s better to cut several with different parameters at once. I think one cut like mine shouldn’t cost more than $6.

Step 3. Launch and test the fountain

In general, adjacent gears are usually made from materials of slightly different densities. This way they will last longer. Most likely the manufacturer simply neglected this.

Lubricate, launch, rejoice!

Good luck in your work!

One of the most complex and yet widespread mechanical systems is a gear drive. This great way transfers mechanical energy from one place to another and a way of increasing or decreasing power (torque) or increasing or decreasing the speed of something.

How to make a gear with your own hands? The problem is always that creating effective gears requires quite a lot of drawing and math skills, as well as the ability to create complex parts.

For an amateur there is no need to have maximum efficiency, so we can get a much easier system to make, even with the tools at hand.

A gear is a series of teeth on a wheel. (Note in the diagram above, they labeled the wrong number of teeth on the gears - sorry)

Step 1: Formulas and Calculations

Formulas for drawing and making gear teeth can be found in abundance on the Internet, but for a beginner they seem very complicated.

I decided to simplify the problem and the solution works very well on both large and small scales. On a small scale it is best suited for machine cutting using laser cutters For example, very small gears can be successfully manufactured in this way.

Step 2: Easy way

So, the shape of the prong, to put it simply, can be a semicircle.

Step 3: Determine the dimensions

Now we can define the parameters to make the gear:

1. How big/small the gear teeth will be (diameter) - the smaller the gear, the smaller the teeth should be.
2. All the teeth that are assembled into the mesh (connected) must be the same size, so you need to calculate the smaller gear first.

Let's start with 10mm teeth.

I want a gear with 5 teeth so that the circle is 10x10mm (in circumference) = 100mm.

To draw this circle I need to find the diameter, so I use math and a calculator and divide the circumference (100mm) by Pi = 3.142.

This gives me a diameter of 31.8mm and I can draw this circle using a compass and then draw exactly 10 circles of 10mm diameter on its circumference using a compass.

If you have the option, it's easier to do everything using drawing software. If you are using software, you will need to be able to rotate the circles of teeth around the main circle, and you will need to know how far to rotate each tooth. It's easy to calculate: divide 360 ​​degrees by the number of circles. So for our 10 circles, 360/10 = 36 degrees for each tooth.

Step 4: Making a Scalloped Shape

Remove top part one circle and the bottom of the next circle. To do this you must have an even number of teeth

We have the first gear. It can be cut from wood or metal using basic tools, saws and files.

This process is easy to repeat for as many gears as you need. Keep the size of the circle consistent and they will fit together.

Step 5: Get the Gear

Since these semi-circular gears are easy to cut, you can make them using a tool and a jigsaw or saw.

I used to make a 9 or 10 tooth template on plywood and used that as a guide for my hand router and cut the gears without any problems.

If you have access to a laser cutter, they can be cut from 3 or 5mm thick acrylic and come in very small sizes.

This material is a general guide to designing and printing plastic gears on a layer-by-layer 3D printer.

The gear light switch is a clever example of something you can design yourself after reading this article.

Optimal materials for plastic gears

What material is the best? The short answer in terms of the quality of the finished gears is as follows:

Nylon (PA) > PETG > PLA > ABS

• Please note that the license is “Personal Use Only”, i.e. the result cannot be distributed, sold, changed, etc.
• When assembled, the structure is 15.87 cm in diameter. Largest printed part - 14.92 cm in diameter

Print all parts with at least 3 perimeters on all sides and bottom, 15% infill. We recommend a layer thickness of no more than 0.3 mm. Any material will work as long as it is possible to avoid distortions of parts, which will render the device unusable.

The handle part is the only one that will require supports.

Assembly instructions (read before starting work)

1. Use a razor blade to clean the teeth of the gears until they fit together well, then install them on the plate with the same direction of rotation as they were printed (center gear pin on the right, driven gear mesh top center).
2. Secure the main gear by inserting the pins into the holes.
3. Apply some dry glue (a glue stick works well) to the working end of the lever and install the lever on the side where the pins match. Glue is needed to secure the lever to the pins. The lever also presses the main gear against the structure.
4. Heat and soften the clamps. This is enough to open them. Align the edges of the clamps with the holes on the back of the plate and crimp the gear in a circle. (The holes on the back of the plate may require cleaning - a knife will help, it all depends on how good your printer is). Press the clamps until they harden. This ensures that everything will hold securely.

Special advantages of layer-by-layer printing and examples of the use of gears

So, what is the advantage of 3D printing gears over traditional methods how are they made, and how strong are the gears?

Printed plastic gears are cheap, the process is fast, and you can easily get a customized result. Complex gears and 3D variations are printed without problems. The prototyping and creation process is fast and clean. The most important thing is that 3D printers are common enough that a set of STL files from the Internet can supply thousands of people.

Of course, printing gears with common plastics is a compromise in surface quality and wear resistance when compared to cast or machined plastic gears. But if designed correctly, printed gears can be quite an effective and reasonable option, and for some applications, ideal.

Most working applications look like gearbox typically for small electric motors, handles and winding keys. This is because electric motors work great at high speeds, but they have problems with a sharp drop in speed, and it is problematic to do without a gear drive in this case. Here are examples:

Specific problems of layer-by-layer printing

1. Printed gears usually require little post-processing before use. Be prepared for wormholes and the fact that the teeth will need to be processed with a blade.

   Reducing the diameter of the central hole is a very common problem even on expensive printers. This is the result of many factors. This is partly due to thermal compression of the cooling plastic, and partly because the holes are designed in the form of polygons with a large number of angles that contract around the perimeter of the hole. (Always export gear STL files with a large number of segments).

   Slicers also contribute, since some of these programs can select different points to bypass holes. If the inner edge of the hole draws the inner edge of the extruded plastic, then the actual diameter of the hole will have a slight shrinkage, and it may take some force to insert something into this hole later. So the slicer may quite intentionally make the holes smaller.

   In addition, any discrepancy between the layers or the discrepancy in the width of the intended and actual extrusion can have a significant impact noticeable effect, “sealing” the hole. You can combat this, for example, by modeling holes with a diameter of approximately 0.005 cm larger. For similar reasons, and to ensure that the printed gears fit next to each other and can work, it is recommended to leave a gap of approximately 0.4 mm between the teeth in the model. This is a bit of a compromise, but the printed gears won't get stuck.

2. Another common problem is getting a solid fill, which is quite difficult for small gears. The gaps between the small teeth are quite common occurrence, even if the slicer is set to 100% fill.

   Some programs deal with this relatively successfully in automatic mode, but you can manually solve this problem by increasing the overlap of layers. This problem is well documented on RichRap, and there are various solutions to it in the blog.

3. Thin-walled parts turn out fragile, overhanging parts need supports, and the strength of the part is significantly less along the Z axis. The settings recommended for printing gears do not differ from the usual ones. Based on the tests already carried out, we can recommend a rectangular filling and at least 3 perimeters. It is also advisable to print in as thin a layer as possible - as much as your equipment and patience allow, because then the teeth will be smoother.
4. However, plastic is inexpensive, but time is precious. If the problem is critical or you need to replace a huge broken gear, you can also print with continuous filling, so as not to leave any chance for any other ambush other than wear.

Most Common Reasons for Printed Gear Failures

• Grinding teeth (from long-term use, see Step 10 about lubrication).
• Problems with fitting onto the axle (see Step 7 about fitting).
• Broken body or spoke (these are rare failures that usually occur if the gear is poorly printed, has insufficient padding, for example, or is designed with spokes that are too thin).

About the importance of the involute

Bad way to make gears

Quite often in amateur communities you can find incorrectly designed gears - gear modeling the matter is not so simple. As you might guess, poorly designed gears do not mesh well, have excessive friction, pressure, kickback, and uneven rotation speed.

An involute (involute) is a certain kind of optimal curve described along some contour. In technology, the involute of a circle is used as a tooth profile for wheels. gear transmission. This is done to ensure that the rotation speed and engagement angle remain constant. A well-designed set of gears should transmit motion entirely through rotation, with minimal slippage.

Modeling an involute gear from scratch is quite tedious, so it makes sense to look for templates before taking it on. Links to some of them will be given below.

Subtleties of tooth modeling. Optimal number of teeth

Think about it: if you want a 2:1 gear ratio for a linear mechanism, how many teeth should there be on each gear? Which is better - 30 and 60, 15 and 30 or 8 and 17?

Each of these ratios will give the same result, but the set of gears in each case will be very different when printed.

More teeth give a higher friction coefficient (the number of teeth meshing at once) and provide smoother rotation. Increasing the number of teeth means that each one must be smaller to fit the same diameter. Small teeth are more fragile and more difficult to print accurately.

On the other hand, reducing the number of teeth provides more volume for increased strength.

Printing small gears on a 3D printer is like painting fine lines in a coloring book with a thick brush. (This is 100% dependent on the nozzle diameter and the horizontal resolution of the printer. Vertical resolution does not play a role in the minimum size restrictions.)

If you want to test your printer by printing small gears, you can use this STL:

The printer we tested performed everything perfectly. top level, but with a diameter of about half an inch, the teeth began to look somehow suspicious.

The advice is to make the teeth as large as possible, while avoiding warnings from the program about having too few teeth, and also avoiding intersections.

There is one more point to pay attention to when choosing the number of teeth: prime numbers and factorization.

The numbers 15 and 30 are both divisible by 15, so with that many teeth on two gears, the same teeth will continually bump into each other, creating wear points.

More the right decision- 15 and 31. (This is the answer to the question at the beginning of the section).

In this case, the proportion is not observed, but uniform wear of the pair of gears is ensured. Dust and dirt will be distributed evenly throughout the gear, as will wear.

Experience shows that it is best if the ratio of the number of teeth of the two gears is in the range of approximately 0.2 to 5. If a higher gear ratio is required, it is better to add an additional gear to the system, otherwise you may end up with a mechanical monster.

How many teeth are there?

Such information can be found in any Mechanic's Handbook. 13 is the minimum recommendation for gears with a pressure angle of 20 degrees, 9 is the recommended minimum for 25 degrees.

A smaller number of teeth is undesirable because they will intersect, which will weaken the teeth themselves, and the problem of overlap will have to be solved during the printing process.

Subtleties of tooth modeling. Pressure Angle, and How to Make Strong Teeth

Pressure angle 15, pressure angle 35

Pressure angle? Why do I need to know this?

This is the angle between the normal to the tooth surface and the diameter of the circle. Teeth with a larger pressure angle (more triangular) are stronger, but have poorer grip. They are easier to print, but during operation they create a high radial load on the supporting axis, produce more noise and are prone to kickback and slippage.

For 3D printing good option is 25 degrees, allowing for smooth and efficient transmission in palm-sized gears.

What else can be done to strengthen teeth?

Just make the gear thicker - this will obviously strengthen the teeth too. Doubling the thickness equals doubling the strength. good general rule states: the thickness should be from three to five times the pitch of the gear.

The strength of a gear tooth can be approximated by considering it as small cantilever beam. With this approach, it is clear that adding an overlying solid wall to reduce unsupported area significantly improves the strength of the gear teeth. Depending on the application, this calculation technique can also be used to reduce the number of engagement points.

Axle mounting methods

Tight fitting on the axle with notches. This simplest method is not found too often. Here you need to be careful with the distortion of the plastic, which will worsen the transmission of torque over time. This design is also non-removable.

The axis is on the fixing screw in the plane of the gear. The retaining screw passes through the gear and rests against a flat area on the axle. The retaining screw is usually directed directly into the gear body or through a recessed nut through a square hole. Each method has its own risks.

Pointing the screw directly can strip the fragile plastic threads. The recessed nut method solves this problem, but if you are not careful and apply too much force during fastening, the gear body may break. Make the gear thicker!

Adding special screw-in thermal inserts will significantly improve the strength of the axle attachment.

Recessed hexagon - hexagonal insert in which sits a hexagonal nut for a hexagonal screw. You need to print enough solid layers around the hexagon so that the screw has something to hold onto. In this case, it is also useful to use a fixing screw, especially when it comes to high speeds.

Wedge found in the world of amateur 3D printing rarely.

The axle is a single unit with the nut. This solution resists torsional loads well. This, however, is very difficult to achieve on a printer, because the gears have to be printed perpendicular to the table surface, and any axes with this solution have a weak point in the Z axis, which manifests itself under high loads.

Some types of gears

External and internal spur gears, parallel helical (helical), double helical, rack and pinion, bevel, helical, flat top, worm

Spiral gear (herringbone). It is commonly seen in printer extruders, they are complex to operate but have their advantages. They are good for their high coefficient of adhesion, self-centering and self-leveling. (Self-leveling is annoying because it affects the operation of the entire structure). This type of gear is also not easy to produce using conventional equipment such as hobby printers. 3D printing knows much simpler methods.

Worm gear. Easy to model, there is a great temptation to use it. It should be noted that the gear ratio of such a system is equal to the number of gear teeth divided by the number of worm openings. (You need to look from the end of the worm and count the number of starting spirals. In most cases it turns out from 1 to 3).

Rack and pinion gear. Converts rotational motion into linear motion and vice versa. Here we are not talking about rotation, but about the distance that the rack travels with each turn of the gear shaft. It is very simple to calculate the density of the teeth: you just need to multiply their density on the rack by pi and by the diameter of the gear. (Or multiply the number of teeth on the rack by the tooth density on the pinion).

Lubricating 3D Printed Gears

If the device operates under light loads, at low speeds and frequencies, you don’t have to worry about lubrication of the plastic gears. But if the loads are high, then you can try to extend the service life by lubricating the gears and reducing friction and wear. Anyway all gear functions are more efficient when lubricated, and the gears themselves last longer

For objects such as 3D printer extruder gears, a heavy-duty lubricant may be recommended. Litol, PTFE or silicone-based lubricants are perfect for this. Lubricant should be applied by lightly wiping the part. toilet paper, with a clean paper towel or dust-free cloth, evenly distributing the lubricant, turning the gear several times.

Any lubricant is better than no lubricant, but you need to make sure that it is chemically compatible with the plastic. And you should always remember that WD-40 lubricant sucks. Although it cleans decently.

Tools for making gears

High-quality gears can be made using free programs alone. That is, there are paid programs for highly optimized and perfect gear connections, with finely tuned parameters and optimal performance, but no good is desired. You just need to make sure that the same mechanism uses gears made by the same tool so that the connections mesh as they should. It is better to model gears in pairs.

Option 1. Find an existing gear model, modify or scale it to suit your needs. Here is a list of databases where you can find ready-made models gears.

• McMaster Carr: Extensive array of 3D models, proven solutions
• GrabCAD: a giant database of user-submitted models
.
• GearGenerator.com generates SVG files of spur gears (These files can be converted to importable ones. However, some programs, such as Blender, can import SVG directly, without dancing with tambourines).
• https://inkscape.org/ru/ - free program vector graphics with integrated gear generator. A decent tutorial on making gears in Inkscape - and .

STL file editors

Most gear pattern generators produce STL files as output, which can be annoying if you require features that the generator doesn't offer. STL files are the PDFs of the 3D world, they are intricately difficult to edit, but editing is possible.

TinkerCAD. A good basic browser-based CAD program, easy and quick to learn, one of the few 3D modeling programs that can modify STL files. www.Tinkercad.com

Meshmixer. A good program for scaling original shapes. http://meshmixer.com/

Non-FDM 3D printing

Most people, even dedicated hobbyists, do not have immediate access to other 3D printing technologies for making gears. Meanwhile, such services exist and can help.

SLA- Great technology for professional gear prototyping. The printed layers are not visible, and the process can produce very small details. On the other hand, the parts are expensive and somewhat fragile. If you use this process to prototype a future diecast model, you won't have any problems retrieving it. Make the part solid, otherwise it will certainly break!

SLS- Very precise process, resulting in durable parts. The technology does not require supports for overhanging structures. You can create complex and detailed pieces, preferably with walls up to a quarter inch thick. The printing layers are also almost invisible... BUT, the rough surface (because the technology is based on powder printing) is extremely prone to wear. A very heavy duty lubrication is required and many do not recommend SLS gears at all for long-life applications.

Technology BinderJet good for detailed and precise multi-color decorative or not structural details. Good for getting crazy colored parts, but very brittle and grainy, so not what you need for functional gears.

Hello) Today, in the process of thinking about the meaning of all things, I asked myself the question of making a gear rack at home. I think some people have already encountered this problem - it is very difficult to find a ready-made gear rack, and cutting out each tooth with nail file is a very tedious task (it is quite difficult to maintain a constant profile and pitch). Of course, if the tooth module is not too small, and the length of the rack is short, then you can get confused)) But what to do if the module is, for example, 0.5 mm (tooth height 1.125 mm) or less, but the length is relatively long? In mass production, such racks are made on gear hobbing or gear shaping machines (sometimes by stamping), in individual production on universal milling machines finger or disc profile cutter. For home use, I suggest the following method (probably this will not be news to many, but maybe it will be useful to someone).

So, we have a gear (m=0.35mm; tooth height, respectively, h=0.7875mm)

Unfortunately, it will be necessary to sacrifice something ((The victim will be any other wheel with the same module (or at least close to it). The diameter does not play a special role here, the main thing is the compliance of the module. Here are two victims.


Let's check. Fit perfectly)


Next is a blank for the future rack, it was a plate from a clock mechanism (it’s clearly visible that I’ve already practiced on it).


We anneal it and secure it in a vice.
Next, we mint it with our sacrifice. To begin, make marks with light hammer blows on the gear.




Well, then we hit as hard as we can! slowly and carefully mint it to the height of the tooth.


The step will match perfectly. The profile, of course, is not perfect, but I don’t think that this method will be used for racks in some very important mechanisms))


After we have minted the blank to the required depth, we finish it with natfil. As a result, we get a site with a profile of very good quality)




Control.


After this, you can safely cut out the rail itself with a ready-made profile)) In this way, you can obtain fine-modular slats from non-solid metals. Was spent: two gears, half an hour of time (+ two experiments). Thank you for your attention)

Home workshop owners have many tools and devices that make it much easier manual labor and improve work efficiency. One such mechanism is a reduction gearbox.

It is mainly used to change the rotation speed of the output shaft downward or increase the torque on it. By its design, this device can be combined, worm or gear, as well as single- and multi-stage.

Many people make a reduction gearbox with their own hands.

What is a gearbox?

This mechanism is a transmission link that is located between the rotational devices of an electric motor or engine internal combustion to the final working unit.

The main characterizing indicators of the gearbox are:

• transmitted power;
• number of driving and driven rotary shafts.

To the rotational devices of this mechanism fixedly fix gear or worm gears, which transmit and regulate movement from one to another. The housing has holes with bearings on which the shafts are located.

Required materials and tools

To make a gearbox you may need following materials and tools:

• wrenches and screwdrivers of various shapes and sizes;
• files, drills;
• rubber gaskets;
• washers, pipe cuttings, gears, bolts, bearings, pulleys, shafts;
• inverter;
• caliper, ruler;
• pliers;
• vice, hammer;
• frame from an old gearbox or steel sheets.

How to make a gearbox with your own hands?

Most important detail The reduction gearbox is considered to have its housing. It must be designed and manufactured correctly with your own hands, since the relative position of the shafts and axes, the alignment of the seats for support bearings and the clearances between gears depend on this.

Industrial gear housings made mainly by casting from aluminum alloys or cast iron However, this is completely impossible to do at home. Therefore, you can select or modify a ready-made body to suit your needs, or weld it from steel sheet. Only in this case should you remember that during the welding process the metal can “lead”, and therefore, to maintain the alignment of the shafts, it is necessary to leave an allowance.

Many masters do it differently. In order not to bother with boring work, they begin to weld the body completely, and instead of sockets for support bearings, pipe sections are used, which are set in the required position and only after that are finally secured in place by welding or bolts. To facilitate maintenance of the gearbox, it is necessary to make a removable top cover at the housing, and a drain hole at the bottom, which will be used to drain used oil.

The gears are supported by the axles and shafts of the gearbox. Typically, in a single-stage mechanism, only shafts with rigidly mounted gears are used. In this case, both gears rotate together with their shafts. The axle is used when it is necessary to insert an intermediate gear into the gearbox.

She begins to rotate freely on its axis with minimal clearance, and so that it does not move sideways, it is fixed with a nut, a thrust collar or locking split washers.

Shafts should be made of steel, which has good strength and excellent machinability.

The bearings in the gearbox serve as supports for the shafts. They perceive the loads that arise during the operation of the mechanism. The reliability and performance of the gearbox depends entirely on how correctly the bearings were selected.

For the mechanism with your own hands best choice of bearings closed type , which require minimal maintenance. They are lubricated with grease. The type of bearings directly depends on the type of load.

When using spur gears, ordinary single or double row ball bearings will suffice.

If the mechanism contains helical gears or worm gears, then an axial load begins to be transmitted to the shaft and bearings, which requires the presence of a ball or roller angular contact bearing.

Another quite important part of the gearbox is the gears. Thanks to them, you can change the rotation speed of the output shaft. To make gears, you need special metal-cutting equipment, so to save money you can use ready-made parts from decommissioned devices.

It is very important during the installation of gears to set the correct gap between them, because the noise level that occurs during operation of the gearbox and the load capacity depend on this. It is best to lubricate the gears with liquid industrial oil, which is poured in such a way that it covers the teeth of the lower gear. The remaining parts are lubricated by spraying oil throughout the internal cavity of the mechanism.

Shaft seals prevent oil from leaking out of the gearbox. They are installed at the shaft outputs and secured in bearing caps.

To prevent emergency destruction of mechanism parts from heavy loads, a safety clutch is used. It comes in the form of a bellows, spring-loaded friction discs or a shear pin.

Installation process Bearing caps make them very light, which can be through or blind. They are selected from ready-made parts or turned on a lathe.

Scope of application of the gearbox

This mechanism is indispensable assistants V various fields human activity. Typically it is used:

• in industry;
• in automobile gearboxes;
• in electrical equipment and household appliances;
• in the gas industry and many other industries.

This mechanism is used very widely in industry. In various processing machines it is used as a rotary transmission part, increasing the speed of revolutions.

But in automobile gearboxes, the gearbox, on the contrary, reduces the engine speed. The smoothness and softness of the transport depends on how correctly its adjustment is done.

This speed reduction device is also used in household appliances and electrical equipment with electric motors. These could be mixers, washing machines, drills, food processors, Bulgarians.

Gearboxes are an indispensable part of ventilation equipment, treatment facilities, pumping systems. They help maintain optimal gas pressure in gas-flame installations.

The gas production industry also cannot do without this mechanism. Transportation and storage of gases is a rather dangerous process, so a reducer is used to block the access of gas or open its outlet by adjusting the pressure.

Assembling a gearbox with your own hands from available materials is quite a troublesome task, but not too difficult. With its help, the rotation of the output shaft is reduced and its torque is increased. The performance of the devices or machine completely depends on this part. This mechanism is used in a wide variety of human activities.

• Fedor Ilyich Artyomov
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