Spur Gear Design 2 - Involute of the circle

Рет қаралды 116,590

4 жыл бұрын

How to calculate the involute of the circle for gear tooth design.
This video follows on from part 1 which details how gears of different diameters interact or mesh, identifies which characteristic control the gear ratio and why the module is important. The relationship between addendum and dedendum in terms of clearance is also discussed. This video details characteristics of gear design including the top land, face, flank, bottom land, gear tooth profile, pitch circle, circular pitch, dedendum, addendum, whole depth, addendum circle, clearance circle, root circle, base circle, pressure angle, line of action and angle of interaction.

Пікірлер: 49

@csbanki Жыл бұрын

This is perfection, thank you very much for the simple explanation!

@flangemonk4547 2 жыл бұрын

Mesej yang jelas, struktur yang jelas, mudah difahami, terima kasih

@chasemarangu 3 жыл бұрын

Explained better than Wikipedia!

@PDWCreative 3 жыл бұрын

Thank you. It’s good to know the videos are helpful!

@vilivont4436 3 жыл бұрын

Thank you

@TeHo672 6 ай бұрын

This is very helpful because there is so much misinformation about drawing involute gears on the internet, but I do have a question. To get the circular pitch, you divide the base circle circumference by the number of teeth as you state. But you then add that it can be found by multiplying the module by PI, which gives a different answer. Or am I wrong?

@Asatruction 3 жыл бұрын

Amazing! I've been trying to figure out how one would be able to potentially sketch out a spur gear by hand (simply because I love to learn the fundamentals of things, and doing things by hand really does it for me) for a while now, and apart from three descriptions of Unwin's approximation, each of which tells a slightly different story, I didn't manage to find anything about it, let alone how to do it with true involutes. The previous video and this one really helped a ton, connecting everything in my head. Since I'm doing this for a hobby and have little reference material but want to learn as in-depth as possible, could you maybe recommend resources on the web or even books (possibly even what's used in university) to learn mechanics and more engineering topics from?

@PDWCreative 3 жыл бұрын

I'm glad you like the videos. There is allot of literature out there on the web but books tend to have a more complete description. Most general mechanical engineering text books should have a section dedicated to gear design. Try shigleys mechanical engineering design to start. Its very useful

@slicktires2011 2 жыл бұрын

I have a question: in the final drawing at 2:50 , it looks like only the first 2 circular pitch lengths are being used for the tooth profile, the others don't seem to be doing anything... Why do you have to draw 6 lengths?

@PDWCreative 2 жыл бұрын

You can use less than 6 lengths. For this video I'm primarily trying to show that the tooth profile is formed using an involute curve. You can shorten the process.

@doggoluvr133 Жыл бұрын

If you're drawing the arc by eye then the increased lengths make it easier to curve the arc accurately

@nayanmipun6784 2 жыл бұрын

Divide 360 into the double the numbers of gears, draw inner circle for the depth of the gears, alternate would be the gears peaks and the middle would be valleys

@PDWCreative 2 жыл бұрын

Remember the pitch circle is not the mid point between peak and valley

@jeyasoorya 2 жыл бұрын

Sir, these Videos are very useful to design a spur gear. I have a question, can we make helical gear by providing twist angle using these procedures shown in your video?

@PDWCreative 2 жыл бұрын

I think there is a little more to do than twisting the extrude. I'll need to do a video soon

@PointerGo 2 ай бұрын

So is the pressure angle calculated or just chosen? The angle is needed before the diameter of the base circle is calculated, right? This is the part that is confusing to me.

@vincentlee2460 2 жыл бұрын

How do u draw the blue involute curve smoothly? You need more circular pitch tangents to guide the drawing of involute otherwise it will look chunky

@PDWCreative 2 жыл бұрын

Add more guides or try the method in Spur Gear Design 3

@joshuakelly2665 2 жыл бұрын

This doesn't seem to work for low teeth # gears. I have an 8 teeth gear with a modulus of .5 and an outside dia. of 5 mm. I calculate the pitch circle dia. as 4 mm , the base circle dia as 1.476066, and the Circular pitch as π/2 or 1.57079 mm. When I draw my involute, though, my curve seems to be no where near where the actual tooth would be. Thoughts?

@PDWCreative 2 жыл бұрын

Try video 3 in the series. This is a very small gear. When I modelled the CAD based on your requirements I dont think the combination is practical. The teeth look weak and may break easily. You need more teeth and a smaller module. Think how far you can take the design before it becomes impractical. Also consider if the module is too small will the gear slip?

@joshuakelly2665 2 жыл бұрын

@@PDWCreative This is a real gear called a 082A, not one I'm designing or printing, and pretty common in toys and small devices. I'm just trying to layout the gearing in SketchUp to build a case for my device and it's easier to design it when I can see everything first. And yes, it is a rather small gear, but I need to go from 6000 RPMs to 60 and I need the size as small as possible. Another commenter suggested an online calculator, which I used instead, and the results came out very close to the actual gear. Thanks for the video though, you did a good job on a lot of you explanations.

@PDWCreative 2 жыл бұрын

@@joshuakelly2665 There is an alternative method in Video 3 for forming the involute. Video 2 really is just an involute explanation. The third video gives a practical demonstration

@MrDrake333 Жыл бұрын

at 00:45 you talk bout base cirkel bu according to your part one, the drawing is showing that the circel you makred as base circle is the "pitch circle" wich one is the right circle name?

@PDWCreative Жыл бұрын

The tooth arc starts at the base circle. There are other ways to create the involute. For arc construction points you could just use equal unravelled sections of the base circle circumference. It’s explained better in the rack and pinion design video I made.

@rbffr 2 жыл бұрын

When pressure angle is 20 then maximum number of teeth is 41.above it the base circle falls below dededendum circle. can you tell me how gears with large number of teeths are made. Are they involute or any thing else.

@PDWCreative 2 жыл бұрын

Try a different pressure angle and module combination. There are lots of different tooth profile types. Involute is one of the more common

@joseantoniolopez3113 3 жыл бұрын

good please go go

@alexanderli5987 3 жыл бұрын

isn't the circular pitch the pitch circle divided by number of teeth? Why is it that in the diagram, it's labeled on the base circle?

@PDWCreative 3 жыл бұрын

Your calculation is correct but the curve starts at the base circle. The base circle moves around significantly as the module and pitch circle change with differing gear designs. Some combinations lead to slightly impractical spur gears.

@alexanderli5987 3 жыл бұрын

@@PDWCreative thanks!

@PDWCreative 3 жыл бұрын

I see why there is some confusion. You don’t have to use the circular pitch to draw your lines to make the involute curve guide. You could just divide the base circle circumference into equal sections. It will still work

@alexanderli5987 3 жыл бұрын

@@PDWCreative ahhhhhh ok that was what i was looking for. just finished designing a mechanical arm and it was awesome! Thanks for the video