Worm gears are very useful if you have low-speed, high-torque applications that do not require reverse drive. [Let's Print] Decided to see if they can print their own worm gears, which can actually be used in practice. This test is instructive for anyone who wants to use 3D printed gear sets. (Video, embedded below.)

The test involves printing a worm wheel on the FDM machine at different positions on the printing bed to determine the effect of layer orientation on performance. The materials used are ABS, PLA and PETG. Test conditions include running pairs of worm gears and worm gears at different speeds to determine whether the plastic parts will heat up or otherwise fail during operation.

The main result of the test is that in the unlubricated condition, the gears of each material failed within two minutes at a speed of 8,000 RPM. However, with adequate lubrication of plastic safety grease, each gear set can run at a speed of 12,000 RPM for more than 10 minutes. Given the high friction typical in worm gear designs, this makes sense. However, it is worth noting that there is almost no load on the gear train. We would love to see the drive do some real work to complete the test again.

It's also worth noting that worm drives usually don't run at 12,000 RPM, but hey-it's actually fun to watch. We have also shown some 3D printed gearboxes before and achieved some impressive feats. Video after the break.

It will be interesting to see the price of nylon without lube

Good idea, but because the gear is used idling, the result is limited.

Limited but not non-existent. Maybe they can be used for some kind of display. Maybe attach the number to the wheel and place it behind the cutout so that you can only see one number at a time when the wheel turns.

Adding load sounds like a great follow-up video to me.

It is very unusual that the worm wheel and the worm wheel are made of the same material. Industrial gearboxes (such as David Brown Radicon) use bronze wheels and steel worms. This is also the combination on the rear axle of a vehicle with a history of more than 100 years that I occasionally drove. It is pure and in perfect condition.

I think a 3D printed wheel using a short steel lead screw might be a practical (and easy to manufacture) solution. The worm gear must be generated with a pressure angle of 29 degrees to match the lead screw, but this should be a parameter in the design software.

The ACME is 29 degrees and the metric trapezoid is 30 degrees. sorry.

In fact, it is half of the pressure angle. Oh, an edit button.

Yes, it will be fine, isn't it. If there is any comfort I understand what you mean, it's good and very clear, let's face it, the angle of any thread you use is a defining factor, so putting a number on it really doesn't matter.

I like the idea itself, you can choose a variety of threaded rods according to the required ratio and gear ratio. The only real limitation is how small you can 3D print the features/strength of those small teeth, so the fine pitch threaded rod may be outdated, but there are still many options. I think you can even 3d print oversized teeth, and then use files to refine the teeth. The 3d printer will let you get the correct tooth contour most of the time, allowing you to have cuts in the wheels to reduce weight, so you save effort …

To be honest, when the feature size is small (<2 mm), I very much doubt that the difference between the 29 degree and 30 degree pressure angle is measurable in the printed worm drive pinion, especially when it has time to run in

Considering the real small scale, maybe you don’t want 3D printed teeth at all, just use a small threaded rod with an interference fit and apply the appropriate force on the softer plastic fdm wheel-no feature required, threaded rod It will either end up "cutting" (perhaps a combination of wear and deformation) its own teeth into that gear, or it will slowly shatter it. However, either way should provide such a small part with a beautiful gearbox under any load within a period of time, without any real complexity.

You can use a threaded steel rod and cut a narrow slit in it with the dremel tool, or even make a worm gear/wheel pair from aluminum. When you press the rotating rod on the aluminum plate, it will quickly eat it.

The difficulty is to create the correct number of teeth on the wheel, because as the diameter of the wheel shrinks, it will continue to erode and destroy the teeth you make. You must know when to stop.

This is sometimes called free hobbing. https://www.youtube.com/results?search_query=free+hobbing But if you have already started making worms and running stepper motors, you may be able to synchronize these motors and force the ratio to be correct.

>A copper wheel and a steel worm

Essentially, this combination is to reduce friction with bronze as a replaceable wear item. Over time, the bronze will be shaved off to better match the shape and/or mechanical fit/tolerance of the stronger steel.

In addition, in order to limit wear. In high-pressure sliding applications, some metals tend to microscopically transfer some surface materials back and forth when sliding over the same type of metal, which eventually leads to surface pitting, then friction, and then destruction.

Because nature does not like that we have beautiful things, two of the two most common engineered metals, steel and aluminum, are particularly vulnerable. Especially aluminum, can wear with surprisingly low forces.

This can be avoided by using different metals, or at least minimized by carefully selected alloy combinations and extensive lubrication, which inhibits atomic bonding across the surface.

This is about the surface structure of the material. Think of the surface as having some kind of sandpaper particles, and if the other components (in this case the wheel) are the same as the material, you will get the greatest engagement from the surface particles, because the spacing of the pits and grooves is very similar, and therefore , The peak of one component easily falls into the valley of another component. The result is the greatest friction and wear. Different materials have different sizes and this inherent "grain" spacing, so you won't get as many joints as possible, thereby reducing friction and wear.

Open any optical drive made of nylon

Nylon is an excellent material for low-power gears. It has a usable surface finish outside the mold (so you don't have to use bulk materials for hobbing), and it has amazing strength (McMaster says 11,000psi).

In addition, it is a bit slippery, has little wear around it, and can be used well with various long-lasting lubricants.

Listen to the sound it makes...something was wrong from the beginning. Sounds like a pepper grinder out of the box: P

Agree, in my experience (model train), grinding occurs when the worm is directly seated on the worm wheel instead of in the space between the teeth. This can cause greater friction until the gear is embedded or damaged. Leaving a little gap between the worm and the wheel can reduce friction and stop the vibration as in the video. It also allows lubrication, as we know, it is not used in the video.

>It is also worth noting that worm drives usually do not run at 12,000 RPM

why not? Worm gears are a simple way to provide huge deceleration + increased torque.

12,000rpm is what you expect from the unloading speed of a small DC brushed motor. They don't have much torque, but the speed is what you get. You need to reduce the speed in some way.

If your religious beliefs require you to 3D print everything, you must deal with wear and tear at high speed.

"If your [r] religion requires [s] you to 3D print everything..."

Obviously, not everything is best made of plastic. But people have been pushing the boundaries of 3D printing. I think it's amazing how much has been done so far. Only by trying to go further can you discover the true limits of what is possible.

For people with a well-equipped metal processing workshop and decades of experience, this may not make much sense. Not everyone has time, space, money, etc. But 3D printing is very easy to obtain. It is not a bad thing to allow more people to be able to create things they can imagine in their heads.

If you see a design for printing plastic on the Internet, please feel free to recreate it with metal, wood, ceramics, diamonds or any material of your choice. Maybe we will read it here eventually.

He forgot to test it under load. A pulley should be installed on the shaft of the output wheel, a rope should be tied to it, and then a winch should be used to lift the heavy object. Then he will find that when high torque is required, the steps and ridges inherent in 3D printing will start to get stuck. Even in theory (motor stall torque) * (worm gear ratio) >> mass * radius, this will still happen. Planar involute and planetary printing gearboxes will not suffer from this type of interference because all parts can be printed on the same plane.

In fact, 12,000 rpm is not unreasonable. Model railway locomotives usually use worm gear drives. HO and larger engines usually use motors of approximately 10,000 rpm. N scale is about 15,000. Brass worms and plastic gears are the most common, but plastic/plastic gears are not unheard of.

I have printed a worm and gear for use on my model train to trigger a trigger every quarter of a revolution of the drive wheel to trigger a puff of smoke and crackling sound. The gears are lubricated and adjusted, but they still wear out quickly, and the worm wears more. I will look for this plastic grease to see if it helps. Great video test results.

Please be kind and respectful to help make the comment section great. (Comment Policy)

This website uses Akismet to reduce spam. Learn how to handle your comment data.

By using our website and services, you explicitly agree to the placement of our performance, functionality and advertising cookies. learn more