Hobbing a Helical Gear (Differential Method)

[@ActiveAtom]

Nice topic, we love and very much appreciate your focused knowledge on the gear cutting and usage topic, good to see learn a lot about how the machine cuts these hob gears and it is a real joy to be here with you, hello to the beach please from the high-desert.

[@EvolventDesign]

Glad you enjoyed it!

[@EvolventDesign]

The beach said hello

[@TheKnacklersWorkshop]

Hello Andrew, Many thanks for this video... I find the whole gear cutting process extremely interesting... Take care. Paul,,

[@EvolventDesign]

Glad you enjoyed it

[@OldIronShops]

Very nice video Andrew love the history to bring up.

[@EvolventDesign]

Thanks very much, I enjoy learning about the very interesting history surrounding machining in general and share... Glad you like it.

[@OldIronShops]

@@EvolventDesign I'm on board with you there.

[@dizzolve]

beautiful machine, nicely refurbed

[@EvolventDesign]

Thank you very much!

[@Mike40M]

Some fifty years ago, I worked teaching machine tools at university level. One test was to using trigonometry calculate how to make helical gears. When the math was done, they had to set up and run a hobbing machine, possibly a Pfauter. Very easy to tell if they passed the test. If they had made the math wrong, it started looking good but ended with a smaller diameter blank.

[@EvolventDesign]

That is awesome! Thanks for being a teacher. Class work and shop work - thats the most effective way to teach and learn

[@RRINTHESHOP]

Nice machine, thanks for sharing about it.

[@EvolventDesign]

You bet, fun to do. It is an interesting project and the process is fun on these machines setup.

[@richardbradley961]

THANK YOU . REGARDS RICHARD.

[@davidcerven5072]

1:02 is it just me or I see a difference in gear teeth thickness ? Can gear hobbing generate helical teeth, which are the same thickness as straight teeth ?

[@EvolventDesign]

Good eye. Yes, they should be the same thickness and can run on each other. The helical properties are on the transverse plane (90 from the teeth not the shaft).

[@davidcerven5072]

@@EvolventDesign Is it possible to hob helical teeth, which have same thickness as straight/spur gear teeth ?

[@thomasutley]

Super overview. I’d be curious to learn how you determine the helix angle of a gear you’re replacing. Seems like it would be tricky to measure!

[@EvolventDesign]

You can measure the helix angle using some simple metrology tools(sine plate etc), but to test the gear completely for runout you need some special arbors on a gear tester (Vari-Roll). It is definitely a next level measurement.

[@elanjacobs1]

With some not quite simple math and a healthy amount of educated guesses. You start with the number of teeth, OD and pitch (just getting to the pitch and pressure angle can be a bit of an exercise when half the teeth are worn away). Once you have those details, you can work backwards to what the helix angle should be, then you physically measure the part and see if it matches up. If it doesn't (not uncommon), you have to then figure out what the addendum correction factor is. Sometimes, when parts are badly worn, the only way to be confident is to calculate a diff gear train, set it up in the machine and run an indicator over the part and measure how far off you are and re-calculate the gears. It can quite literally take a couple of hours to get to the answer in some cases.

[@seimela]

​@@EvolventDesign Do you think feed affect helix angle..? I am currently rebuilding my Liebherr L800 gear hob being electrical engineer I don't much I use KZbin to learn kinamatic of machine and I will build a PLC based on working principle.. Thank you

[@dannywilsher4165]

WOW, very interesting. I like learning about anything mechanical. Thanks for sharing!

[@EvolventDesign]

Thanks for watching. Glad to hear from you.

[@sarahdelacruz5208]

I have a question. You said that the scallops go away after running the gears for a little bit. Is that why certain machines recommend changing the oil after the break in procedure? Metal from the gears and other various machined parts contaminate the oil and thus require an oil change ?

[@EvolventDesign]

Yes, but it is just one reason to flush the gearbox. There are also deburring debri, and other potential shop dust that can get into a gearbox if left open for much time. For higher quality gearboxes the gears are ground and should not have any scallop debri. It is good practice all around regardless of the quality of gears used.

[@johnwenzel9252]

Interesting. Thanks for sharing!

[@EvolventDesign]

Thanks for watching!

[@TheJohndeere466]

Do you know how to calculate the measurement over pins for a helical gear?

[@EvolventDesign]

yes

[@TheJohndeere466]

@@EvolventDesign I need to make two 12 tooth 6dp 20 degree Pa helical gears with a helix angle of 13.398 degrees and they need to operate at a center distance of 2.200" I got a calculator from zak gear but my calculation always comes out too small and the gears have excessive backlash. One thing the calculators asks for is the normal arc tooth thickness on pitch diameter. To calculate this I multiply 2.200 x 3.1416 and divide by 24 since the gear has 12 teeth. Is this correct?

[@EvolventDesign]

Send drawing with your plans , contact info and phone number to: [e-mail]

[@EvolventDesign]

James-send me an email so I can get with you on the solution.

[@umerramzan3375]

Thank you dear, sir

[@EvolventDesign]

So nice of you

[@bobanppvc]

Is differential powered directly from motor or from feed gear i cant see?

[@EvolventDesign]

They are both powered from the motor. The order is Motor, Index Change Gears, Feed & Diff are linked behind the gearcase, then the power is split. One shaft goes to the platter worm gearbox, the other goes up the spindle to the hob. The truly interesting part is the diff connects back to the shaft that is connected to the motor before the Index Change gears.

[@amirhossein.b5471]

How i can find my machine constant??(its pfauter R01)

[@EvolventDesign]

kzbin.infovXuO0fzb-YY?feature=share

[@amirhossein.b5471]

@@EvolventDesign thanks for your reply. Does this constant work for helical gear?? And does this method work for old models like RS01?

[@EvolventDesign]

Yes, should work for the index drive train to set the tooth count. If your machine has a differential gearbox it works differently. The methods to solve this require you know the constant and have access to other solvers like the ones found here: gearcalculators.com/

[@GULF-NEPAL-EUROPE]

Very Informative Guru I want to know what are the difference setting for cutting right hand and left hand helical gear cutting settings to be done on Hobbing machine. Also when to use the lead angle given in Hob cutter? Please reply me sir, i want to know this very soon please.🙏🙏

[@EvolventDesign]

Thanks for watching. There are many different machines out there-It is spelled out in your owners manual.

[@GULF-NEPAL-EUROPE]

@@EvolventDesign Thanks for your reply. I hope to know just as a example for your machine so that it may somehow relate to other machine setup process.

[@EvolventDesign]

Yes, that will be a future video. Please support me on Patreon. www.patreon.com/evolventdesign

[@GULF-NEPAL-EUROPE]

@@EvolventDesign Ok sir, sure. I promise you I will support you. Right now i am on short travel to abroad.

[@mabmachine]

Some really great information in there. I find gear making fascinating. So far I've only cut spines on shafts which are essentially very long spur gears, but its been fun none the less. I'm curious if you know how this machine compares to the old Gould & Eberhardt or Brown & Sharpe US made hobbing machines? Thank you for sharing. -Mike

[@EvolventDesign]

Both share the same drivetrain, have not seen differential mechanisms on the G&E's. The G&E's that I know are very solid and reliable with massive cast iron bases. Have not seen a B&S hobber to know. But I do know B&S as a very technically solid machine tool builder and they likely have the differential. Pfauter had the patent on the differential, but I am not sure when it lapsed and others could use it. It took until the early 70's before CNC entered the hobbing world - much later than in mills and lathes.

[@EvolventDesign]

After looking through my history books, I found the earliest example of a B&S hobbin machine (horizontal) in 1915. This was apparently their first attempt, and they had studied the Pfauter machines extensively. Pfauter's patent in 1900 and manufacturing of machines significantly pre-dated the B&S efforts. The 1915 B&S machine does not appear to have a differential.

[@kompas3d.nxsolidworks.cadc83]

Hello, I have an interesting question for you. If a servo motor is used to do all the movements instead of a differential, what is the differential calculation formula to create a helical gear?

[@kompas3d.nxsolidworks.cadc83]

I am waiting for your answer. I have some formulas, please check them too.

[@EvolventDesign]

Depends on the machine you are using.

[@kompas3d.nxsolidworks.cadc83]

@@EvolventDesign Hello friend, I want to make a lathe on a CNC machine. Can you help me?

[@kompas3d.nxsolidworks.cadc83]

@@EvolventDesign ?

[@EvolventDesign]

If there are gears in your lathe let me know with drawings and we can help. We manufacture gears

[@likeit173314]

I Have An Old Hobbing Machine Niles RF-4 Can You Tell Me The Helical Constant Of Machine I Don't Have Any Manual If Machine

[@EvolventDesign]

I have only ever heard of a Niles RF3, but no manual. Not sure of a method either. Let me find the RF3 info and get back with you-it may be in German.

[@likeit173314]

@@EvolventDesign Thanks For Your Reply ! Yes it may Be RF-3 Or RF-5 Please Try For Me I am Waiting Your Reply Thanks Once Again

[@bhupender3799]

Sir wat is pfouter rh2 lead formula

[@EvolventDesign]

Hope this answers your question for the RS2 Machine Index Constant = 24 (from Becher and Korner Example 11 pg 23 GE edition) The Lead Angle is scribed on the end of the HOB.

[@bhupender3799]

@@EvolventDesign sir wat is lead formula plz tell the answer

[@fareshammoudi9187]

Thanks Sir for the clarifications, Are you familiar with the Y3150 Machine? I bought one recently and I was told that I need to connect a different Bushing (Bigger) for helical gears?

[@EvolventDesign]

Possibly, I think that machine looks and operates very much the same as the Pfauters. I could not say about the bushing, you would need the owners manual as that may be machine specific. For the all hobbers i have seen, it must be equipped with a differential in the drive train to make helicals.

[@dattatrayapundalik8315]

Please give me differnsiyal gear formula to orijinal pautar machine

[@EvolventDesign]

kzbin.info/www/bejne/jJ3UgJWEiJ6XgqM

[@adrian33799]

Hi Andrew. I have a question about the differential mechanism highlighted in green. Do you have more knowledge on this? As I am struggling to cut helical on my machine..and suspect this part to be the problem. Question, if the diff lever is activated, with machine off, should it be possible to stop rotation of the diff gear train by hand if I turn the input shaft(f) of the rotation gear on the index side? Is the diff(included/excluded)lever suppose to lock the diff mechanism's worm gear onto main index shaft(f) inturn turning the worm on diff shaft(D) rotating the diff gear train.

[@EvolventDesign]

Adrian- Short answer is I think you are correct in your conclusions above. The differential is a cluster arrangement of 4 mitre bevel gears (°45). The order of power transmission is: 1) Power input 2) Differential 3) Output from differential has a worm gear on the shaft 4) But it also becomes the input shaft to the INDEX change gear box. 5) then abcd for the INDEX gears 6) the output shaft has a worm on it that ties to the feed and differential gearbox 7) There is an engagement knob that ties to the output shaft of the differential gearbox and it engages a worm back to the wormgear in #3 above. 8) If it is not engaged, it will not function to make a helical. The function of the differential is to slightly slow or retard the relative motion of the INDEX ratio> To add a partial tooth. You then must tilt the hob head to the correct angle and it will generate the desired helical gear. The setup seems a little complex the first time around, but the more your do it the more it makes sense how things are working. Hope this helps. Andrew

[@EvolventDesign]

kzbin.info/www/bejne/jJ3UgJWEiJ6XgqM

[@haythamdraz9800]

How you convert from spur gear to helical gear pls

[@EvolventDesign]

For manufacturing > watch our spur gear videos and you can see how they are done vs this video for helicals. For design, that is a very different question and one new issue with a helical is the side load that will require some sort of solution/bearing for the thrust they create. Thanks for watching.

[@haythamdraz9800]

@@EvolventDesign thank you for your interest sir but i mean thise machine cause i have typical one wfzw mwm500*5 my problem is not how to calculate the helical but how to adjust It on this machine cause even i adjust the angle and all the calculation it also make spur not helical so may i have not connected the differential or i hv something i dont know. If you can offer me the manual instruction i will be glad

[@EvolventDesign]

The machine needs to have a differential gear train It is calculated in this video kzbin.info/www/bejne/jJ3UgJWEiJ6XgqM

[@sanjaydeshmukh5404]

28teeth cutting helical gear Helix angle15 How to change gear

[@EvolventDesign]

What machine do you have? Does it have a differential? Do you have the owners manual?

[@sanjaydeshmukh5404]

Gear hobbing WMW

[@EvolventDesign]

It might have the same constants from the video - try them on a test blank

[@jetenginethrust863]

Nice, thanks for sharing. I'm trying to find out the pitch/Module/DP or a gear I have from a power wheelchair motor gearbox. I thought it was a 1.5 Module but I was wrong, so now it's back to square one. I need some metric and inch helical gear teeth gages like a set of thread or feeler gages. McMaster-Carr has some but they are very expensive approx $300.00 for the inch & $280.00 for the metric just to use prolly once, no thanks.

[@EvolventDesign]

Yep, here’s a way to come close. Hopefully you have some good calipers or micrometers to measure the OD. If so make the measurement, count the teeth and the you can use our calculators trial and error to make an educated guess. Link in bio to our website and calculators.

[@sachinbsotari4396]

Differential constant value how calculate

[@EvolventDesign]

kzbin.info/www/bejne/jJ3UgJWEiJ6XgqM

[@nevinloop4726]

😎👍

[@learnsolidworksfree492]

How to calculate a helical gear

[@teguhjayatehnik5969]

Sip

[@dattatrayapundalik8315]

Please give me

[@dattatrayapundalik8315]

Sir muze orijinal pauthar ka diffransiyal gear nikalne ka formula batao

[@EvolventDesign]

kzbin.info/www/bejne/jJ3UgJWEiJ6XgqM

[@sachinbsotari4396]

how to found differential gear constant value method anyone mission gear hobbing

[@EvolventDesign]

Depends on your machine - It should be in your owners manual

[@EvolventDesign]

What is the specific machine and model number?