By continuing to use this site, you agree to our use of cookies. Find out more

Member postings for brian jones 11

Here is a list of all the postings brian jones 11 has made in our forums. Click on a thread name to jump to the thread.

Thread: cutting spur gears on a mill
25/09/2021 15:48:26

Read their history

A protectionist cartel to dominate the Gear technology and its direction since 1916

Its not a government organisation like ANSI or BSI/ISO

So read between the lines and form your own impression

and remember - just cos Im paranoid doesnt make me wrong

Like I said, we can live with DP so long as we recognise that its a size factor and not to be confused with CP

ISO got it right with Lets make Addendum = Mod as a convenient design preference

and DP = 1/Mod in their relevant units (profiling shifting and truncating excluded of course)

Its not related to geometry just an international agreement

IMHO its rubbish not to come out and be frank about this - thats the bit I dont understand

One thing that has come out of this huff puff is how hugely complex making power xmission gearing can be

Its seems industry, as has been said, treats gears as components and hands the requirements over to specialist suppliers

That didnt work too well initially for wind turbines as the technology was carried over from Marine gearing

How many designers have you encountered in your career who were what we used to call Catalog Engineers

Maureen has my secret weapon in her jaws I must get on



OBTW SOD  thanx for the heads up on FreeCad, got it loaded with FCgears from Workshop and exported a dxf of and involute, useful bit of kit even a SBP can manage

Looking at the Crown and bevel pinion, without the benefit of CNC how does one make those pieces


Edited By brian jones 11 on 25/09/2021 15:53:17

25/09/2021 13:25:30

Ah the reactionary armchairs of protectionist AGMA

Another jaundised view on how blinkered stupidity is maintained cast in concrete

link courtesy Duncan Webster above


25/09/2021 10:55:21

Here is a typical example of how industry and teachers present these gear calcs to us

2021-09-25 10_30_35-c29 755-821 technical - 27.48-27.60.pdf ? mozilla firefox.jpg

Just slipped in amongst other credible bits of algebra - 2nd from the bottom

No explanation or qualifier - btw its a fudge factor we use for convenience so that OD is (N+2)/DP

It falls down when Profile shifting is used to reduce undercut and if peaks are truncated as in stub gears

No mention of this

and the whole industry and educators are perpetuating this algebraically illiterate myth

Addendum = Module

and furthermore the word "pitch" should never been attached to "Diametral" as a descriptor for a gear size factor

Its wholly misleading - call it Diametral Factor" great no problem

Europe opted for Module equivalent to 1/DP and set Addendum = Mod in mm. Thats the teutonic mind for you

Thats sorted then

Another first for MEW


25/09/2021 10:11:33
Posted by Neil Wyatt on 25/09/2021 09:22:16:

Posted by brian jones 11 on 25/09/2021 01:15:05:

why Addendum = 1/DP

Convention. There's no absolute physical law that says it should be any value, but this just happens to give well proportioned teeth. Much longer and undercutting affects even large gears, much smaller and teeth don't engage enough to run smoothly.

Well Neil point taken and I can live with that

Its just the industry and indeed teaching texts present this as and algebraic certainty without any qualifier ( like this relationship is chosen as a convenience for standardisation)

Whats so hard about that, why try and bluff about it.



25/09/2021 08:55:26

Yes MG a nice description

BUT why oh why does the industry seek to cover up the fact that algebraically mod (or 1/DP) is NOT equal to Addendum - its a fudge factor and indeed it can be 0.8*mod for stub gears)

Why dont they just say "for standards we make mod equal to addendum"

We can live with that - its honest

But no, the carpetbaggers driven by AGMA have sought to skate over the issue of geometrical correctness

This deceit gummed up my gear box for some time as I couldnt make the connection in strict algebraic terms yet all the texts state Addendum = mod never once qualifying it with "by convention"

Its quite scandalous really and I hate being lied to. Its as bad as Clinton denying he had ykw with Lewinski

Could not pass GO and collect £200



Spare a thought for the gear boxes used in wind turbines, These a predictably unreliable

look at the specs

sun and planet gearing up ratio 100:1 from 15rpm to ca 1500rpm

xmit 2000 hp

weight 20t

Shaft torque 700,000 ft lbs

Large sudden variations in loading, gusts, start up, emergency stop

Must be changed every 4-5 years

Thats something the green lobby dont like to talk about

AWS Wind energy is a long way from being a cheap renewable and is heavily subsidised by the taxpayer (levy on energy providers)

As for offshore conditions OMG

Thought for the day

from the desk of


Edited By brian jones 11 on 25/09/2021 08:57:13

25/09/2021 01:15:05

Many thanx AJ for your enlightenment

But can you show me algebraically why Addendum = 1/DP

I cant find any explanation except Google sources say thats what it is

I have even proved it to 6 places on the Dr's gear calculator

But why????????????????? What have I missedembarrassed

Stupid boy Pike (ready for punishment)

24/09/2021 18:19:33

Calling AGMA weird????????????

Wow its like insulting the Grand Wizard of the gear hobbers masonry

SIAS suck it and see what gear snobs do as a last resort

You see you are given one small gear lots of teeth

What do you know

you measure the OD, count the number of teeth and then start guessing

For the benefit of the Armchairs hereinotwithstanding , todays youth have their own lingo used on phones.  Here is a list of some 1500 acronyms for you to learn while you've got nothing on (in this hot weather)

My great grand kids try and catch me out






I got caught out on Maureen's toolpost, I thought it was 7/16 BSF

I had a suitable nut but it wouldnt got on more than 4 turns, so i thought the thread was damaged and started using a die on it. Didnt feel right so I checked my tables

bsf 18 tpi .438 od

unf 20 tpi .438 od

the naked eye did not see the difference

So imagine that issue x 100 in complexity - welcome to Gear World

Obtw a wheel nut off a mini was repurposed



Edited By brian jones 11 on 24/09/2021 18:30:45

24/09/2021 16:13:28

I think the article by Jannick referring to Base Pitch is meant to be what we call the CP

His Base Circle is what we call the Pitch circle or defined as PCD

I think this was before AGMA got involved

SIAS means you cant actually measure the PCD once youve cut a gear and need another one to mesh before you can deduce PCD with confidence - all the rest is gear snobbery

but thats my junior opinion, what do I know - not a lot as has been amply shown


Edited By brian jones 11 on 24/09/2021 16:15:39

Edited By brian jones 11 on 24/09/2021 16:16:27

24/09/2021 14:41:58

All you needed to know about CP and the Base Bitch

this past post went into the problems of measuring a gear (as opposed to calcs + suck it and see)

You cant just use calipers / disc mic and measure PCD just like that

If you have two gears meshed together you can deduce the pcd from distance between centres

then there's the eyeball method

pa 14 vs 20.jpg

23/09/2021 16:40:17

Agreed, you are measuring chordal pitch slightly less than CP

So how did they actually measure gears in late victorian times with simple tools

I think someone had some actually gear design books from that or edwardian period

23/09/2021 14:22:16

Tremendous magnum opus, 14 years longer than most marriages then.

Is it the sort of m/c to make special gear hobs?


23/09/2021 11:58:05
Posted by John P on 18/09/2021 11:40:12:

Somehow doubt if BJ 11 would be interested in cutting a rack.
This one here took over 5 hours to cut the 159 teeth.

milled rack 1.jpg

Was definitely a "OMG what a painfully slow process as you mill each one"

You see I knew you were doing it wrong

you need a cycloid profile for rack and pinion,_Function_and_Manufacturing_Compared_to_Established_Gear_Designs/

That why I suggested a motor bike chain

fascinating stuff

Whack a Mole

23/09/2021 11:26:35

Don't confuse quantity with quality.

Sounds like the motto of Tesco

or perhaps

Millionaire Alan Sugar and his egregious Amstrad rubbish

IMHO there have been numerous high quality insightful postings on this thread

May the freedom to rattle cages and shake the trees be long fruitful and may we be tolerant enough to sweep up the dummies spat out on the floor

Now Maureen needs my attention - Wimin

OBTW have we got any members of the err opposite gender on this board? They were good at making bullets in WWII

23/09/2021 10:50:53

The full credit must go to Duncan Webster above for his "Fuse" link and his fascinating tale of bigotry by AGMA (my instincts were right about the mafia)

Its a book for the armchair Kobo, you can down load EPUB

Horologists OMG have they got their own closet on this board somewhere? I cant imagine their x30 world and desktop lathes and they wouldnt countenance free hobbing

I need a man's lathe

notice elf n safety - he should be in a boiler suit, not a flappy shop coat.


sometimes I feel its whack-a-mole time

12000 views have we gone viral - like Covid?

Certainly given the fustian Mew Board a throgging

Edited By brian jones 11 on 23/09/2021 11:07:30

Edited By brian jones 11 on 23/09/2021 11:11:38

23/09/2021 04:08:55

In 1890 they knew a thing or two and armchairs hadnt been invented

22/09/2021 11:12:37

does this help

22/09/2021 09:25:45

Kind of missing the point here MC

this thread has opened up a treasure chest of valuable insights from experienced members sharing their knowledge

The noob to this complex sphere has to battle through all manner of rubbish from google and YT

For example there is the self style expert on Gears sponsored by AGMA

Browse the Fundamental Laws of gearing at the beginning and you will get the picture

I do appreciate the Japanese link from Dave S


I did produce a perfectly serviceable plastic gear for modellers with light duty use in mind. Might work even better in Delrin. If it helps some modeller knock something up quickly then maybe it has a use despite the sceptics


OBTW its a pity we cant rate these posts because some of them really are 5* solid gold

You cant make an omlette without breaking eggsdevil 

Edited By brian jones 11 on 22/09/2021 09:30:39

22/09/2021 07:54:21

Not sure what you are trying to do with your head on it's side and a large dia cutter? Can't you tilt the work

Think of it as a metal saw

goto 10.00 to see action

Dave S

Is profile shifting  the same as changing the PA? ie


Edited By brian jones 11 on 22/09/2021 08:00:03

Edited By brian jones 11 on 22/09/2021 08:00:46

22/09/2021 00:14:45

Thats fantastic MG

those animations are what I have been looking for. explains it all

This should be a sticky for all young shavers to understand gears

profile shifting has really done my head in

21/09/2021 23:16:34

Now here's a silly question from SBP

How are gear teeth made with an undercut root?

The SCR CNC wallahs need not stir from comfy chairs

This is strictly old school

AFAIK it could only be done by shaping after roughing out?dont know

OMG you gotta see this

Edited By brian jones 11 on 21/09/2021 23:50:13

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
rapid Direct
walker midge
Eccentric July 5 2018
JD Metals
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest