How do I make my own gear hobs? (Gear cutting)

That was the clearest, most concise explanation of basic gear theory I have ever seen.

Excellent! 25 years in a machine shop and I now know more about hobbling than ever.

A book's worth of knowledge in thirteen minutes. Thank you.

Thanks for going through the theory on gear design and gear standards, this is very helpful for understanding the engineering behind the standards.

Thanks for going through all the calculations, makes the process even more interesting when you can get a better grip on it!

Awesome video, everthing was very well explained. Now I need to watch the other video about the build of the gear hobbing attachment.

You are a teacher more than a machinist ..thank you sir for sharing your knowledge.

Whelp... this is just the first of MANY times I'll be watching this.. So much valuable info here. Awesome work! Thank you!

Goes to show how important mathematics truly is. Thanks for sharing such an awesome video!

This was a great video! Prior to watching this and the two attachment videos I understood that hobbing existed but not what it entailed, and I've come away with a great appreciation for the mathematics, planning and applications of the process. I'm not a machinist, so it's always fascinating to learn about the techniques that are part of the manufacturing of precision components.

Wonderful explanation. Lots of time and energy went into this one!

I think you don't take into an account something. I would prefer to be wrong here, but... Consider making a spur-gear having PA = 20°. That means that the toothed rack complementary to such gear would have trapezoidal profile of tooth with also 20° angle between trapezium s sides and axis of symmetry. If you going to cur the gear using the rack as a cutter, no problem: you have to move cutting rack towards the gear in direction parallel to gear axis. With the hob things change: to compensate for helical "nature" of gear hob, you make an adjustment of milling machine axis and you mention that at 11:30. Now projection of the cutting edge (of its contour) of the hob to imaginary vertical plane will differ from its real contour — it will be compressed in by vertical axis by the factor of cos(helix_angle). If the scaling transformation has different scaling factors on X/Y axes, that transformation does not preserve angles. Thus you'll get slightly decreased PA on your gear. You probably don't notice that the gears you make have decreased PA because with helix angles as low as 5° or 10° the cosine of helix angle is ~ 0.99619 or ~ 0.98481 respectively, which means one-axis scaling to a factor of 99.6%/98.4%. So depth of the groove you cut isn't affected, but the width of the groove is about 1% less than required. Also, if you making two gears that should couple to each other, they will mate perfectly even if it's PA angle is unintentionally decreased. However, you are getting non-standard and modified profile of your gear teeth, so it won't mate perfectly with the gear manufactured somewhere else. However, all this considerations become not actual if at the stage of thread cutting (07:17) you tilt you cutter by the angle matching the helix angle of you thread. Which isn't the case as far as I can see.

Thanks, a lot of knowledge wrapped up in this video - very helpful!

Best video ever. I'm not kidding. Thank you for ALL the details!

You, sir are an excellent instructor. I was so focused during the math bit, I think I fainted for a second or two🤯🤣

Now I learned the basic of gear making, thanks for sharing this video…

Brilliant work in After Effects; you've cleared up some long-standing uncertainty for me.

Very nicely done, Andy, very enjoyable-thank you very much ✅👍

Nicest explanation,thank you my teacher,....this trick is for my retire,if my wife will permits to take my my mill and lathe in garage

fantastic video I been cutting gears 30+ years in work and I learnt something from it Thank you keep up the geat work