7:18 You got it wrong - "the segment distance between first two points" should actually be "the segment distance of base circle between first two points". Difference might seem irrelevantly small but actually it makes your profile significantly different from involute gears.
This is outstanding, exactly what I was looking for. I knew there had to be a way to draw a proper gear with nothing but geometry and math within the CAD tool being used. So many other tutorials rely on external calculators, spreadsheets, importing coordinates… This is the way.
For those who need the equations: 1. Pitch Diameter (d) = given (you choose) 2. Number of Teeth (n) = given (you choose) 3. Pressure Angle (p) = given (you choose; typically is 20 deg) 4. Diametric Pitch (dp) = n / d 5. Dedendum Diameter (dd) = d - ( (1/dp) * 2) 6. Adendum Diameter (da) = d + ( (1/dp) * 2) 7. Base Diameter (db) = d * cos(p) 8. Tooth Width (tw) = pi / (2 * dp) 9. Half Tooth Width = tw /2 10. Tooth Width Angle (ta) = (tw / d) * (180 / pi) Hopefully these are correct. Correct me if I'm wrong. AM 8/26/2020
The tooth width formula is referring to the topland distance of a tooth? Where did u get this formula, machinist handbook? What is the formula in Module? Thanks
@@vincentlee2460 Hello, I'm late to the party, but the formula in module is simply (1.57 * module). I got this from Norton's Design of Machinery. This is the tooth width, not the top land. You can obtain the top land width multiplying (0.25 * module).
Update: GCSW - Free Gear Calculator from KHK gears - get a DXF output of any gear profile which can be imported in SW to make the gear in 3D. Just did this, works great in no time at all.
I like the information on the involute profile and how to draw it. What I didn't so much like is modeling practices, especially in SW, So for others learning always mirrors the sketch if you can it is far far more efficient to solve and you're going to be patterning also so it's really important to keep your features light. If he were to do a whole gearbox his system would slow to a crawl trying to solve a mirror pattern on a few thousand features. also and this is more if you ever plan on working for others give variables names that make sense and if you're going to use a shit ton of construction geometry either name it in the sketch or name them in the variables for a teaching aid I would add the name in the dim text. lastly, add radios using the feature. you will find that relief radi changes depending on how something is machined it's far easier to change the radius feature named gear relief than to undo a double tangent constraint. I would have also defined most of the calculated values in the equations but that is just my preference, I would also have put the 3 diameters in their own sketch and described the involute curve in another. I may have been so inclined to put the extrude geometry on top of the theoretical curve just to keep it clean and understandable then there would be an argument to define the relief in the sketch.
Great tutorial. I am reverse engineering some pretty interesting gears from a lathe gearbox - actually there are gears with different numbers of teeth working on the same center distance (slide gears). For example, there's a 30 and a 33 tooth gear, both with the same OD, that work with a 24 tooth counter gear. I have calculated the gears to be DP 12, with a +0.4 profile shift on the 24 tooth gear and yet to be determined positive/ negative profile shift on the 30/ 33. With the given center distance these can be accurately calculated. The SolidWorks modeling is great for checking. I plan to get the actual sample (damaged gear) on a profile projector and get a 1:1 image from that which I then will be able to check against my SW constructed profile. This should be sufficiently accurate. Thanks again for the video.
I think you're a little off on your involute profile. The variable radius lines should equal the arc length along the base circle and not the line segment between the two points. The error is growing for every sequential radius calculation.
I think the author is correct. If the base sectors have equal angles, then successive tangents will have length twice the preceding ones.if a circle is divided into 4 parts, then every tangent at the 4 points will have a length equal to 2 times the preceding one. The last will be the full circumference of the circle and is 4 times the length at the second tangent. The second tangent is just 1/4 of the circumference.
Is this how to Create a SolidWorks Part Model of a spur gear using ‘Unwin’s Construction Method? if yes thanks you so much...if no...pls could you direct me to the appropriate video link
I am trying tp create my involute curve with the following sized gear: Picth Dia. = 330 Module = 3 No. of teeth = 110 Pressure Angle = 20° My base circle Diameter (134.67mm) is much smaller than the pitch diameter and also the addendum. This presents an issue when I create the involute curve connecting the segments. the involute curve does not intercept the pitch diameter. Has anyone modeled larger gears?
Thanks so much for the HD version. Need to learn this manual way to draw a gear based off some old pdf as the automatic methods aren't giving me the exact same result.
It's a great job! I got a question with using lengths of equally segmented lines instead of those of equally segmented arcs to creat the points of involute spline.I know it does not matter that much, for there must exist lengths of arcs equal to those of lines.For someone who cant figure this out, it might bring themselves brain racking how this work how it can be, not in a serious way for some aspects. Thanks again.Great Job!
...There is a possibility of using parametric equation. X= dbase × cos(t) + dbase × t × sin(t) Y = dbase × sin(t) - dbase × t × cos(t) dbase = base diameter t = angle radians Good luck.
im making my own gear. i have a diametric pitch or mod of 15. The gear i made has a pitch diameter of 1" and 15 teeth which works out fine. However, I am trying to make another meshing gear that is 3x larger. So for that gear I have diameter of 3" with 45 teeth; however, that gear provides a smaller base circle than the dedendum diameter. I don't get it. I'm stuck. Any help will be much appreciated!!
![Digital Circus Episode 4 [TRAILER]](http://i.ytimg.com/vi/abZtsmMUbJo/mqdefault.jpg)
7:18 You got it wrong - "the segment distance between first two points" should actually be "the segment distance of base circle between first two points".
Difference might seem irrelevantly small but actually it makes your profile significantly different from involute gears.
This is outstanding, exactly what I was looking for. I knew there had to be a way to draw a proper gear with nothing but geometry and math within the CAD tool being used. So many other tutorials rely on external calculators, spreadsheets, importing coordinates… This is the way.
For those who need the equations:
1. Pitch Diameter (d) = given (you choose)
2. Number of Teeth (n) = given (you choose)
3. Pressure Angle (p) = given (you choose; typically is 20 deg)
4. Diametric Pitch (dp) = n / d
5. Dedendum Diameter (dd) = d - ( (1/dp) * 2)
6. Adendum Diameter (da) = d + ( (1/dp) * 2)
7. Base Diameter (db) = d * cos(p)
8. Tooth Width (tw) = pi / (2 * dp)
9. Half Tooth Width = tw /2
10. Tooth Width Angle (ta) = (tw / d) * (180 / pi)
Hopefully these are correct. Correct me if I'm wrong. AM 8/26/2020
The tooth width formula is referring to the topland distance of a tooth? Where did u get this formula, machinist handbook? What is the formula in Module? Thanks
@@vincentlee2460 Hello, I'm late to the party, but the formula in module is simply (1.57 * module). I got this from Norton's Design of Machinery. This is the tooth width, not the top land. You can obtain the top land width multiplying (0.25 * module).
Update: GCSW - Free Gear Calculator from KHK gears - get a DXF output of any gear profile which can be imported in SW to make the gear in 3D. Just did this, works great in no time at all.
Thank you Michael. It's a very nice tutorial.
Thank thank you so much. This was so well done and calmly and clearly explained.
I like the information on the involute profile and how to draw it.
What I didn't so much like is modeling practices, especially in SW, So for others learning always mirrors the sketch if you can it is far far more efficient to solve and you're going to be patterning also so it's really important to keep your features light. If he were to do a whole gearbox his system would slow to a crawl trying to solve a mirror pattern on a few thousand features.
also and this is more if you ever plan on working for others give variables names that make sense and if you're going to use a shit ton of construction geometry either name it in the sketch or name them in the variables for a teaching aid I would add the name in the dim text.
lastly, add radios using the feature. you will find that relief radi changes depending on how something is machined it's far easier to change the radius feature named gear relief than to undo a double tangent constraint.
I would have also defined most of the calculated values in the equations but that is just my preference, I would also have put the 3 diameters in their own sketch and described the involute curve in another. I may have been so inclined to put the extrude geometry on top of the theoretical curve just to keep it clean and understandable then there would be an argument to define the relief in the sketch.
Great tutorial. I am reverse engineering some pretty interesting gears from a lathe gearbox - actually there are gears with different numbers of teeth working on the same center distance (slide gears). For example, there's a 30 and a 33 tooth gear, both with the same OD, that work with a 24 tooth counter gear. I have calculated the gears to be DP 12, with a +0.4 profile shift on the 24 tooth gear and yet to be determined positive/ negative profile shift on the 30/ 33. With the given center distance these can be accurately calculated. The SolidWorks modeling is great for checking. I plan to get the actual sample (damaged gear) on a profile projector and get a 1:1 image from that which I then will be able to check against my SW constructed profile. This should be sufficiently accurate. Thanks again for the video.
I think you're a little off on your involute profile. The variable radius lines should equal the arc length along the base circle and not the line segment between the two points. The error is growing for every sequential radius calculation.
This is an excellent video tutorial for learners in middle level. According to the definition of an involute curve BilletBenny's remark is correct.
A wanted to comment the same! It is important, when you make a part where precision is priority.
I think the author is correct. If the base sectors have equal angles, then successive tangents will have length twice the preceding ones.if a circle is divided into 4 parts, then every tangent at the 4 points will have a length equal to 2 times the preceding one. The last will be the full circumference of the circle and is 4 times the length at the second tangent. The second tangent is just 1/4 of the circumference.
Did you say The tooth width is 7.85 inches AT VIDEO 14:02 or u meant 0.785? Thanks
Same question.....
Where does the pressure angle come in or did I miss that part?
Thank you so much. Great video
Is this how to Create a SolidWorks Part Model of a spur gear using ‘Unwin’s Construction Method? if yes thanks you so much...if no...pls could you direct me to the appropriate video link
I am trying tp create my involute curve with the following sized gear:
Picth Dia. = 330
Module = 3
No. of teeth = 110
Pressure Angle = 20°
My base circle Diameter (134.67mm) is much smaller than the pitch diameter and also the addendum.
This presents an issue when I create the involute curve connecting the segments. the involute curve does not intercept the pitch diameter.
Has anyone modeled larger gears?
Thanks so much for the HD version. Need to learn this manual way to draw a gear based off some old pdf as the automatic methods aren't giving me the exact same result.
It's a great job!
I got a question with using lengths of equally segmented lines instead of those of equally segmented arcs to creat the points of involute spline.I know it does not matter that much, for there must exist lengths of arcs equal to those of lines.For someone who cant figure this out, it might bring themselves brain racking how this work how it can be, not in a serious way for some aspects.
Thanks again.Great Job!
How about when the base diameter is the smallest
Can you please send the file
...There is a possibility of using parametric equation.
X= dbase × cos(t) + dbase × t × sin(t)
Y = dbase × sin(t) - dbase × t × cos(t)
dbase = base diameter
t = angle radians
Good luck.
Great!!! work on involute profile
why do i get my base circle diameter smaller than my dedendum diameter???
im making my own gear. i have a diametric pitch or mod of 15. The gear i made has a pitch diameter of 1" and 15 teeth which works out fine. However, I am trying to make another meshing gear that is 3x larger. So for that gear I have diameter of 3" with 45 teeth; however, that gear provides a smaller base circle than the dedendum diameter. I don't get it. I'm stuck. Any help will be much appreciated!!
nvm i calculated wrong
nvm it still doesnt work
@@The_Engineering_Boost I hope you figured it out
Solidworks is a bizarre program because you can't natively rotate an assembly. Once you draw it on a particular axis, it's there for life.