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John Stevenson
12-29-2013, 04:39 PM
Sorting the design out for a job.
Oh how things have progressed. Did the design work and drawing yesterday.
'Made' 4 gears today on the 3D printer to prove the concept on a simple jig. Two seperate gears and one double pinion made all in one.

The production gears will be separate gears pressed on a shaft but easier to print together.

http://www.stevenson-engineers.co.uk/files/encoder%20gears.jpg

OK doesn't look anything special but the ratio needed has to be accurate to 3 decimal places, no plus or minus.

100 year old gear book gave me the ratios

Gearotic gave me the options using two different pitches. Now here is where it gets fancy. None of the 4 gears are standard, the two finer teeth ones are corrected so they fit fixed centres that are written in stone.

Of the two courser gears one is standard for the pitch, one is corrected but both have the pitch corrected to fit the same centres.

Anyone know where I can get a 44.53 DP gear cutter ? http://www.model-engineer.co.uk/ckeditor/plugins/smiley/images/wink_smile.gif

Zadig
12-29-2013, 05:09 PM
The fundamentalists in Derbyshire are still using clockwork timers then?

doctor demo
12-29-2013, 05:21 PM
Anyone know where I can get a 44.53 DP gear cutter ?

Print one out on that fancy printer that made the gears, duh.

Steve

John Stevenson
12-29-2013, 05:55 PM
The fundamentalists in Derbyshire are still using clockwork timers then?

Subtle ....................

Steve, Tried that but it melts when i try to sharpen it. :p

doctor demo
12-29-2013, 06:01 PM
Tried that but it melts when i try to sharpen it. :p

Sharpen the printer and then print a sharp cutter.

Steve

Mike Nash
12-29-2013, 06:11 PM
Gearotic gave me the options using two different pitches. Now here is where it gets fancy. None of the 4 gears are standard, the two finer teeth ones are corrected so they fit fixed centres that are written in stone.

Of the two courser gears one is standard for the pitch, one is corrected but both have the pitch corrected to fit the same centres.

Anyone know where I can get a 44.53 DP gear cutter ? http://www.model-engineer.co.uk/ckeditor/plugins/smiley/images/wink_smile.gif

That is just evil. Pity the poor slob that has to source replacement gears someday. I seriously doubt they would ever figure out why nothing worked like the original.

Arthur.Marks
12-29-2013, 08:04 PM
Hmmm... Since we're already irrationally mixing the old and new, why not make a gear hob on one of those digital gearbox HLV-H type lathes? :) Then make Ivan Law's Eureka Form Relieving Tool to use on the same. Haha. Any better ideas?

mike4
12-29-2013, 08:19 PM
Yes , change the design to use readily available gear cutters .

By the way Mohammed , how is your camel taking to the cool climes?

Michael

John Stevenson
12-29-2013, 08:29 PM
Michael,
I can't change the design to use standard cutters.

I have a fixed ratio I have to keep and a semi fixed centre distance between the two gear shafts.
Because there are 4 gears in two different ratio's if I make one a standard set of gears the other ratio is way out.
It's took about 3 hours of spreadsheet work and using Gearotic to come up with what i have so far.

There are two more ratio's that will give me the final one needed but the disparity between the two trains is that big they can't share a common idler shaft.

I can do it easier with internal gears but I don't have the room for big numbers.

mike4
12-29-2013, 08:36 PM
John ,
Thanks for the extra info that makes you dilemma a bit clearer.

How many of these do you have to manufacture, small lots could be approximated by grinding an end mill to the pitch and cutting them .
I have repaired a couple of smaller ones that way for a machine thats no longer made.

The end mill was a learning curve , by that I had never ground a taper and sharpened the flutes to make them cut steel again , its some where in the workshop under a mountain of other crap.
Michael

Don Young
12-29-2013, 09:32 PM
I would think that the button method of making a gear cutter would be suitable for any pitch as long as you do the math correctly. Cutting a helical hob should be doable if you can get the lathe to do the right lead. Cutting a straight rack type hob should be very easy.

I would not be surprised to learn that there are more 'non-standard' gears in the world than 'standard' ones.

Zahnrad Kopf
12-29-2013, 10:12 PM
Anyone know where I can get a 44.53 DP gear cutter ? http://www.model-engineer.co.uk/ckeditor/plugins/smiley/images/wink_smile.gif


I would not be surprised to learn that there are more 'non-standard' gears in the world than 'standard' ones.

Quite so, actually.

John, you're getting deeper into the world these days such that it might interest you to investigate a book recently authored by Alex Kapelevich, titled "Direct Gear Design". You're venturing into that area now, where the application dictates gear tooth geometry instead of artificial standards. He's wonderfully intelligent man, very generous with his knowledge and advice, but has a business to run, like anyone else. I've had the pleasure of being involved in projects he was also involved in and always came away learning more than I expected. Might I suggest you read his book and the white papers he's made freely available? As to your question, regardless of the rhetorical humor possibly intended, I've done exactly this a few times in the recent past with WEDM. :) Let me know if I can be of any assistance, Old Sod.

Sparky_NY
12-30-2013, 07:22 AM
Anyone know where I can get a 44.53 DP gear cutter ? http://www.model-engineer.co.uk/ckeditor/plugins/smiley/images/wink_smile.gif

Don't need no stinkin gear cutter when you have gearotic, just take a small ball endmill and go at it !

JohnAlex141r
12-30-2013, 07:38 AM
Quite so, actually.

John, you're getting deeper into the world these days such that it might interest you to investigate a book recently authored by Alex Kapelevich, titled "Direct Gear Design". ...

Gear Head;

Thanks for the pointer to Alex Kapelevich; interesting site.

Another JohnS.

John Stevenson
12-30-2013, 09:58 AM
Quite so, actually.

John, you're getting deeper into the world these days such that it might interest you to investigate a book recently authored by Alex Kapelevich, titled "Direct Gear Design". You're venturing into that area now, where the application dictates gear tooth geometry instead of artificial standards. He's wonderfully intelligent man, very generous with his knowledge and advice, but has a business to run, like anyone else. I've had the pleasure of being involved in projects he was also involved in and always came away learning more than I expected. Might I suggest you read his book and the white papers he's made freely available? As to your question, regardless of the rhetorical humor possibly intended, I've done exactly this a few times in the recent past with WEDM. :) Let me know if I can be of any assistance, Old Sod.


Many thanks for that but I do have a copy.

Sad bastard that I am i probably have over 100 books of gears and gearing.
problem is most contain the same info so distilled down those 100 will probably make 5 or 6 unique books.

Trouble is there is always a loose gem in most of them.

Alistair Hosie
12-30-2013, 12:29 PM
John do you remember a short time ago a female teacher was threatened with death for allowing a student to call his little teddy bear mohammedIit caused quite a diplomatic explosion at the time it is funny how angry some muslims are over such things but there we have it. Alistair

Rich Carlstedt
12-30-2013, 12:33 PM
Anyone know where I can get a 44.53 DP gear cutter ? http://www.model-engineer.co.uk/ckeditor/plugins/smiley/images/wink_smile.gif

John, you need one more machine for your shop, a CNC Shaper :)
A machine where all things are possible !

Rich

lakeside53
12-30-2013, 12:33 PM
Changing his name to "little teddy bear" might cause even more problems at the local pub ;)

Timleech
12-30-2013, 12:37 PM
Many thanks for that but I do have a copy.

Sad bastard that I am i probably have over 100 books of gears and gearing.
problem is most contain the same info so distilled down those 100 will probably make 5 or 6 unique books.

Trouble is there is always a loose gem in most of them.

Have you got any of the American Gear Manufacturers' design manuals?
I've got section three, on helical & spiral gears, could lend or sell it to you if of interest.

Tim

John Stevenson
12-30-2013, 02:31 PM
If it's the set in 5 parts then got them all.
Trouble is often times a reprint carries a different name.

Got two books here with different names and covers but the text is the same in both.

Timleech
12-30-2013, 02:42 PM
If it's the set in 5 parts then got them all.
Trouble is often times a reprint carries a different name.

Got two books here with different names and covers but the text is the same in both.

Dunno, it only mentions 'Section 1' which is mainly mathematical tables relevant to gear design, and 'Section 2' which covers spur and internal gears.

Written by Earle Buckingham, Cambridge, Mass., Industrial Press, 1937

Edit - looks as though it's still available:-

http://www.amazon.com/Manual-Gear-Design-Holbrook-Horton/dp/0831131160

Tim

Zadig
12-30-2013, 04:57 PM
John, I took your request for help as a rhetorical one, are you actually looking for specific info?

John Stevenson
12-30-2013, 06:28 PM
No think I'm sorted on this one, need to talk to the customer after the holiday