How to determine the Pitch or Module of a Gear

Repairing old gears? Incorporating a gear into your project and need to make a meshing mate? Designing a new transmission? This video has some super valuable and handy information to get you started.
Chapters
0:00 Pitch or Module
0:24 The Answer
1:10 Tools
1:58 Gear Templates Get a Paper Copy Here
evolventdesign.com/collection...
2:15 Dot-Dash Tooth Counting Method
3:20 Measuring OD with a caliper
3:44 Calculating Pitch - DANG!
4:24 Calculating Module - CORRECT!
5:15 ODD Tooth Pinion Counting Teeth
5:35 ODD Tooth Pinion OD Measurement
6:49 ODD Tooth Pitch Calculation - CORRECT
7:13 The Answers
To learn more Check out our paper gear template
evolventdesign.com/blogs/hist...
When doing maintenance, repairs and restoration. Here are some of the tools that make a difference:
Expendable Products used for restoration work - Amazon
Brownells OXPHO-BLUE amzn.to/3o4iPHd
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CitriStrip Paint Removal Gel amzn.to/3MwrlsB
Tools
Wire Brush set for cleaning holes amzn.to/411Qe3Q
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Products that are hard to find that just need a shout out. These are not found on Amazon. Small companies that have a good product:
Acro Tool and Die Works www.acrolaps.com/
Lapping Tools for the ID of holes. I get a huge amount of value from this specific set
SET-2-TH
The Parkson has many pinned connections. Cleaning all those small tapered holes and getting them to have a good finish and fit with the pin - PERFECT
IOSSO Mold and Die Polish iosso.com/products/mold-polish/
Cant go wrong with this stuff. Clean rigorously after for any sliding ways then oil.
NLGI #2 Grease
evolventdesign.com/collection...
Love this product. It was used on the cam to lock the main anvil. Makes it slide nicely where it counts and otherwise lock on a separate surface. Your operator will appreciate it.
A bottle of patience. Take your time on old equipment, soak the bolts and connections in WD-40. Leave it for a few days. Clean the threads and screw slots BEFORE your first attempt so your screwdriver has a chance. Soak and wait some more. Your hardware will be reuseable, your effort will decrease and - in the end - your project will be that much more enjoyable.
Please SUBSCRIBE 🔔 We have developed useful content to help the machinist community with gears and gear machine tools. With our free resources centered around skills/tools/knowledge, you are now enabled to make any high quality gear you would ever need.
The history of gears is surprisingly interesting - the process of milling and hobbing gears plus the transmission of torque and movement all find a place here. We will open the "Secret Gear Case" to YT as well through this channel - a personal mission
evolventdesign.com​
To learn about lubricants for your machines
oilviscositychart.com​
/ villagehobber
Disclaimer:
evolventdesign.com/policies/t...

[@kwaaaa]

Informative and practical, another video saved for the brain bank. Thanks for making this, extremely helpful in making sense of all this as an amateur machinist.

[@lord_scrubington]

0:35 thats how you do a youtube video, less than a minute in and all the formulas you need are right there, with he explanation FOLLOWING. Other tutorial channels should be taking notes

[@cgordon1103]

THANK YOU SO MUCH!!! Have been looking for this for a while and you've explained it simply and well.

[@sky173]

This is the video I've been looking for! Thanks for sharing!

[@richardmills5450]

That was fabulous. All the answers to all my questions cheers

[@TheKnacklersWorkshop]

Hello Andrew, Great video. Enjoyable viewing, thank you... I feel sure I will pop back to this video from time to time. Take care. Paul,,

[@OldIronShops]

My favorite gear channel had a blast at the bash gear School.

[@freestyla101]

Absolutely brilliant video.

[@AzeemUddin-ii8xb]

Thanks for valuable information 😊

[@TheAyrCaveShop]

Great info Thanks !

[@babcockcopper]

Awesome! Thank you

[@donaldlane6282]

Very useful video. I bought an old lathe, and needed to figure out the change gears to see if I had a complete set, and if not, the specs for making replacements. Used the formula, and created a gear with Fusion 360, then 3d printed it. Came out perfectly. I wanted to get the tooth count for some of the gears that were currently installed without removing them, so I transposed the formula to T=(Pitch*OD)-2, which worked perfectly. Thanks for a very clear and well done video!

[@EvolventDesign]

Glad it was helpful!

[@OldIronMachineWorks]

Always enjoy your videos, just wish there were more of them. It was great seeing you at the bash. Gary

[@EvolventDesign]

Thanks for this kind comments-and for watching

[@sarahdelacruz5208]

oh man this made my weekend. this is bad ass.

[@EvolventDesign]

That’s great

[@davidjames1007]

Thank you, to the point with no waffle. Needed this as I want to start learning how to do this.

[@EvolventDesign]

Glad it was helpful!

[@zumbazumba1]

Thank you for this video ,it explained things ,its very easy to understand .

[@EvolventDesign]

Great-that’s the goal

[@charleskutrufis9612]

Thank You, another informative video.

[@EvolventDesign]

You bet

[@petergoose8164]

Clear and to the point.

[@EvolventDesign]

Thanks for watching - gears are everywhere

[@bswargo]

Really great simple video for figuring this out. I was an electronics engineer, not a gearhead, lol - really really appreciate the help.

[@EvolventDesign]

Glad you liked it!

[@bondie9150]

Top video Andrew. Have just spent the last few hours getting baffled by other web sites that retreat into complex geometrical and theoretical explanations . No doubt they mean well but your explanation cuts through the BS and gives me a practical method that i can use. Well done.

[@EvolventDesign]

Glad it was helpful!

[@EvolventDesign]

Pure Theory is great, sweat and job shop work crunch theorys down to the absolute minimum requirement

[@kevindanahy4665]

Thanks, great video!

[@EvolventDesign]

Glad you liked it!

[@pointer7pl]

thank you

[@hlaingphyowai2460]

very very good. Easily solution. Thank you

[@EvolventDesign]

Glad it helped and thanks for watching

[@starshipengine]

This is really helpful. What if the gear is an inner ring gear, how does the formula change? Thanks

[@martinjosealvarez]

Thanks

[@plasmarc9]

Thank You!

[@EvolventDesign]

You're welcome!

[@EverettsWorkshop]

You make it look so easy - at some point I want to get to gear making, so this is helpful in making it in terms a layman can understand, lol!

[@EvolventDesign]

You can do it next time you need to make a gear. Great to hear from you

[@jameslezak7882]

How do you determine a gear size if you have a rack but no pinion? How do you determine the rack pitch or module? Thanks for your time and sharing!

[@EvolventDesign]

A rack is a gear with infinite teeth. The easiest way is to measure the number of teeth per inch. Then using this calculator you can find out if it is one of three different pitch measurement systems: evolventdesign.com/pages/pitch-calculator For instance use 8 TPI and you get this from our calcuator" ---------------------------------- Inputs Threads per Inch: 8.000 1/in Outputs Module: 1.011 mm Diametral Pitch: 25.133 1/in Circular Pitch: 0.125 in Threads per Inch: 8.000 1/in © 2022 Evolvent Design, 11-Mar-2023 evolventdesign.com/pages/gear-pitch-calculator --------------------------------------------------------------------------- So it could be a circular pitch gear if your numbers are VERY GOOD and they are exactly 8. But if you are off a little, it could be a DP of 25 or a module of 1. Gears and racks are pretty exacting when it comes to pitches. You could also download our gear identification templates to compare with: evolventdesign.com/collections/all/products/copy-of-dividing-head-reference-chart-digital-download Then you can get closer by using this calculator and figuring out a pin and measuring again. evolventdesign.com/pages/gear-rack-calculator At this point, determine the pin to use and then measure across the longest span possible to increase the accuracy of your TPI measurement. It may take an iteration or two, but you can usually figure it out.

[@miasnieuwoudt8952]

Nice vid!

[@EvolventDesign]

Thank you for watching

[@mickyas1000]

Thank you, trawled the net for ages for a simplistic explanation, with examples, without success...until now, but you Americans do like to waffle on.😉🤣 Thanks again.

[@tsstn]

Thank you thank you. Thank you. Thank you. Thank you thank you. Thank you. Thank you. Thank you,thank you. Thank you. Thank you. Thank you,thank you. I think you get the point thanks again.

[@pitovid]

Nice work Do You Have Any Formulas And Explained on Elica ,,Helicals Deg gears woking it out

[@impactodelsurenterprise2440]

I have come across 2 scenarios where OD used to calculate gear module/DP can not be relied upon. For example in sliding gears sometimes the OD has to be been trimmed down to allow for the gear to slide over another. Another case take for example a lathe feed box which typically has 8 change gears between two shafts for different threads that requires an exact ratio per gear pair in order to produce a correct thread pitch. Now it is quite impossible to design two shafts sharing a center distance that these 8 gears can mesh with their respective mating gear if we only make them with available modules and DP. So what most manufacturers typically do is use a close enough module or DP a cut a gear that has a substantial accumulated pitch error, and then cut again but on the opposite flank to make the gear symmetrical and then trim the OD so that the gear pairs can now mesh. I think the most fool proof yet simple method to determine module/DP is by measuring the two shafts center distance and counting the number of teeths of 1 of the gears. The rest can then be determined.

[@EvolventDesign]

Yes, you are right. There are many types of gears that do not work with this method, the ones you mentioned as well as any corrected or altered gear with a profile shift. Also many automototive gears tend to have "Non-Standard" industrial pitches for their specific designs.

[@manojkolhapure6714]

Thanks for video sir Please guide how to check or calculate spiral bevel gear and pinion module if i don't have a drawing and also how to check angle of spiral means helical gear check with protector but in spiral gear thats not possible please guide. thanks

[@EvolventDesign]

Ok I will try

[@zumbazumba1]

I got several questions: 1.How do you cut tapered gears like in angle grinder gear box ? 2.Could you make a video about tooth profile and gear cutting on the milling machine ? 3.Also how do you make a new gear if old mashing gear is worn? How do you determine module/pitch ,tooth profile ,od etc if gear is worn out and get them to engage properly? (obviously best would be to change both , but we all know we don't live in a fairy world ,in a machine with a lot of gears it would be too expensive to change all until they fit perfectly) 4.How do you cut a worm gear ? Thank you for all the information you provide !

[@EvolventDesign]

1-they are called bevel gears-high quality ones are generated on a specialty machine 2-We have a 3-part series on gear milling to answer your second question 3-if you know the center distance between the shafts it will help narrow the possible tooth counts/size

[@EvolventDesign]

4-worm gears. Yep. That one is on our list. Stay tuned and thanks for watching

[@mitchelle05]

Hi Sir, Do you have a tutorial video on how to know helix, lead, angle etc. of a helical gear from sample, for example someone bring you broken helical gear, how do you get the info from the sample?

[@EvolventDesign]

Not yet. It is most accurately done with a lead checker. There are some other methods- we will put it on the list.

[@pyromedichd1]

We still need to know how to determine the Pressure Angle of the gear without using gauges. Do you have a method for that?

[@EvolventDesign]

Gauges are free and easily made with our .DXF Generator found here: evolventdesign.com/pages/spur-gear-generator You can get the output in a very universal file format ".DXF" and then print it to scale. It is a paper gauge, but as long as you can see the outlines it will work. Finer pitches are difficult.

[@pyromedichd1]

@@EvolventDesign Thank you.

[@piecetoyou8285]

How do I know what missing gear I need, I own a old jewelers rolling mill, on the very top there would of been a T handle, at the bottom of the T stem there would of been a tooth cog, on the left and right so either side of this tooth cog there is bigger cogs, When turning the cog in the middle this would turn the left and right cogs, when all cogs are turning this would raise the gap between the rollers for what ever metal needed rolling, So my question is , as the cog is missing to the T bar is there a way to determine what size cog and how many teeth and what pitch? i need to buy,

[@EvolventDesign]

Most likely yes. All of these gears/cogs mesh when they are at a certain center distance of their shafts. Measure them all, then compare their pitch lines which must be tangent to each other. The pitch lines, outer diameters and tooth counts are inter-related.

[@KhlaBaiTong]

Wow 😚

[@christiangreen612]

im trying to model a daihatsu feroza gearbox, and the gears dont seem to be metric or imperial.for 2nd gear countershaft i have a module of 2.6667, and diametral pitch of 9.58. have you ever seen that before?

[@EvolventDesign]

Automotive and motorcycle gears tend to be non-standard modules. Since they are mass manufactured, they can make a better custom product.

[@christiangreen612]

@@EvolventDesign thanks for the info brother! im guessing aftermarket manufacturers like quaffe would use standard tooling? so i would have to design a gearbox according to standard metrics?

[@EvolventDesign]

The custom gears made by Daihatsu are far superior to standard gears-in other ways. They typically have profile shifts.

[@bertyjustice]

I am building a model IC engine, the plans call for a pair of spur gears, ration 2-1 DP48 60 teeth and 30 teeth. I only have DP 32 cutters, if I cut a 60 teeth and 30 teeth with the DP32 cutter obviously the ratio is still 2-1 but does it make any difference the fact that the gear diameters are slightly larger or would it perhaps throw the timing out? If you have the time any help appreciated thanks

[@EvolventDesign]

Timing Should still work . Your center distance will change, weight will likely increase-might impact performance if heavier

[@bertyjustice]

Wow! what a fast reply. I'm very gratefull as I have spent days trying the find a answer on the net. This video is also excellent for us amateur engineers. I have now subscribed.

[@awaisrafiq1366]

i have a gear with following measurements. But i am confused whether to Pick Metric or Imperial in Designing. because both give different OD. • N = 28 • Face Width = 48.50mm | 1.875in • OD = 262.5mm | 10.334in • Module = 262.5/30 = 8.75 (in Solidworks Design with Mod = 9 - OD = 269.54) • Pitch = 30/10.334 = 2.903 (in Solidworks Design with Diametral Pitch = 3 - OD = 253.54 ) How do I know whether it is Metric or Imperial Gear? Which one to prefer in design? Because I am not getting same size in design as in real.

[@EvolventDesign]

I prefer metric when designing from scratch. Your gear may be non-standard. What machine does it go to?

[@EvolventDesign]

Many automotive gears are non-standard

[@yeetmeister0704]

only if i could use the dot dash method on counting teeth on a 1 1/4 od gear with 80 teeth

[@EvolventDesign]

YES, that is a very common problem. Stay tuned, I have a method to count fine pitch teeth.

[@EvolventDesign]

Here is a method: kzbin.info/www/bejne/mHOrn2yhqNWYq8k

[@Casualgaming763]

The standard unit of measure prettt much wordlwide is in kilometer, meter, milimeter. I dont get why we use inches, yards etc. Seems to just make things more complicated

[@EvolventDesign]

No sweat, either way works just fine.

[@abdulkhalegalghamdi6635]

👍💐

[@freestyla101]

Hey sorry if you explained this, it’s been a minute since I watched the video, but why do you add 2 to the number of teeth? I posted my calculations in a machinists group and I got a bit of push-back for not measuring the pitch circle. I can’t really explain what the two is for so I’m hoping you could help.

[@EvolventDesign]

Measuring the pitch circle is ideal - But for most with few tools it is less practical. So usually the well intended “equation guys with clean hands that don’t work in a shop” will say this sort of thing. Both methods work and can be derived from first principles of gear equations that relate OD or pitch circle to tooth count. Measuring the OD with calipers is practical and doable by most people. If you want to measure the pitch diameter or pitch circle go to our MOP calculator and get some pins. But the solution is iterative, because to choose a pin that works you need to know the pitch-see what I mean. Or get some $$$$$ measurement tools. It is easy to spot the different advice you get from a practitioner vs “equation jockeys”

[@freestyla101]

@@EvolventDesign haha well said. Ok I get what you’re saying, but how exactly does the 2 compensate for the fact that you’re not measuring the pitch circle? Obviously if I don’t add 2 to the tooth count, the module will be wrong. Following your guide my result was exactly 1.25 which made me happy, but I’m still curious as to the why.

[@EvolventDesign]

I can do the math too. But as far as the numbers go, it is in the “Standard” aka AGMA 917 and for coarser pitches it is also standard. Take the definition of pitch diameterPD=T/DP. Then substitute it into the definition of the OD equation OD=PD + 2/DP re-arrange and you get the equation in this video…EXACTLY!

[@freestyla101]

@@EvolventDesign right. So either you know the pitch circle and divide it by teeth to get module, or you only know the OD and you divide by teeth + 2 to get the exact same result? Is that correct?

[@EvolventDesign]

@@freestyla101 yep

[@chippyjohn1]

Imperial gears haven't been made since about WW1. It's been all module/metric for a long time. Why use obsolete measuring tools also?

[@EvolventDesign]

When given the chance-I prefer Module gear design because the numbers are simpler etc. But the English Pitch System is very much alive with 14.5 degree pressure angle gears. This was standard for so long that it exists and persists today and probably for a long time into the future to maintain equipment and even for select new designs. Boston Gear makes a pretty good company selling Imperial gears - its all they do.

[@andrewmerafuentes6683]

Thanks for this great content. My testosterone levels went up just by listening too.

[@EvolventDesign]

Great to hear!

[@fritzyberger]

I cut a lot of 3dp20pa gears

[@EvolventDesign]

Thanks for watching.

[@kalinkar7441]

Why all the formulas dont mention those additional +2 teeth?

[@EvolventDesign]

They are in the AGMA equation definitions: It is in the “Standard” aka AGMA 917 and for coarser pitches it is also standard. Take the definition of pitch diameterPD=T/DP. Then substitute it into the definition of the OD equation OD=PD + 2/DP re-arrange and you get the equation in this video…EXACTLY! In other words if both equations are part of the difinition, rearranging with math yields the equation showing the +2 teeth. Also from practice, the OD is always spelled out as a key reference number on drawings and thus manufacturers cut the OD as close as possible to this diameter. Hence from the definition and the practice - it works. Most seasoned gear manufacturers and engineers will know this relationship.

[@shetheyithe8894]

I used it for Solidworks and you can't correct it.

[@dennisrech9149]

Why did the first calculation come out wrong? You left that hanging.

[@EvolventDesign]

Dennis, thanks for watching and joining the conversation. The wrong calculation was purposeful to show that you need to check both Module and Pitch calculations and units. If you don't know whether it is pitch or module to start with, you need to check both.

[@hugovinueza103]

Traducir aespañol

[@EvolventDesign]

Prueba esta configuración youtube-espanol.googleblog.com/

[@EvolventDesign]

Gracias por ver

[@impactodelsurenterprise2440]

Why add 2 to teeth?

[@EvolventDesign]

Great question. The equation for Diametral Pitch(DP) that also relates to tooth count(N) and a Diameter (Pitch Diameter)(D) is a very simple equation: DP = N/D But when you have an unkown gear the outside diameter (OD) is easiest and most practical to measure. And in that case the equation becomes DP = (N+2)/OD Basically, it is just math combined with the knowledge that the OD of a gear is typically called out as a reference diameter on plans and is machined precisely. This equation makes the reverse engineering of most gears simpler with fewer tools.

[@EvolventDesign]

Plus precisely measuring the pitch diameter directly is difficult and usually requires pins or wires to estimate.

[@impactodelsurenterprise2440]

@@EvolventDesign thanks!