Author Topic: First attempt at gear cutting  (Read 613 times)

Offline Steve Crow

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First attempt at gear cutting
« on: December 29, 2020, 07:11:21 PM »
After what seemed like an age acquiring cutters and making arbors, a centreing micrometer and other bits I finally got round to cutting some gears.

They are Mod 0.3 bevel gears, and spares, for a differential Im making.

They still need parting and cleaning up.



There are 6 x 12 tooth mitre gears, and 2 x 40 tooth crown wheels with matching 16 tooth pinions.

It wasnt entirely a success though. I lost the top of one tooth after turning the rotary table before Id retracted the tool enough (back centre on photo).  Stupid error but thats why I made spares.



I used the parallel depth method from the Ivan Law book and everything was straightforward once Id got my head around the maths.

A lengthy process though. The 10 gears I made needed a total of 552 separate cuts. (Each tooth gap is cut 3 times). This is my excuse for making the error a mixture of tiredness and complacency.

They look fine under magnification and seem to mesh well (even the bit with the half tooth).

I will report back when they are finished and assembled.

Steve

Offline Bearcar1

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Re: First attempt at gear cutting
« Reply #1 on: December 29, 2020, 07:43:38 PM »
That is a good looking lot of gears. Bugger you messed up that one tooth but I have to say the rest look very good for a first attempt. I have yet to cut any gears but have been interested in doing so and will keep watching here.


BC1
Jim

Offline pgp001

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Re: First attempt at gear cutting
« Reply #2 on: December 29, 2020, 07:59:09 PM »
Dont throw that one with a missing tooth in the bin.

You could make a couple of bevel gear quadrants from it, you know the type for balancing brake pull rods or that type of thing.
I made something similar for the brakes on a model Clayton steam wagon years ago.

Phil

Online crueby

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Re: First attempt at gear cutting
« Reply #3 on: December 29, 2020, 08:13:01 PM »
Very nice job on the gears! Module 0.3 is pretty small, well done!

Offline Flyboy Jim

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Re: First attempt at gear cutting
« Reply #4 on: December 30, 2020, 12:07:07 AM »
Those are some nice gears. I'd love to see some pictures of the process sometime.

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline Jo

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Re: First attempt at gear cutting
« Reply #5 on: December 30, 2020, 07:32:33 AM »
Well done on cutting those gears, Steve.

Now that you have made the first ones you will have no worries about cutting some more  :)

Jo
Enjoyment is more important than achievement.

Offline simplyloco

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Re: First attempt at gear cutting
« Reply #6 on: December 30, 2020, 09:34:46 AM »
Never mind a first attempt, those are excellent!

Offline Roger B

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Re: First attempt at gear cutting
« Reply #7 on: December 30, 2020, 09:50:17 AM »
Very nicely done  :praise2:  :wine1: Gear cutting of any sort is on my things to learn one day list.
Best regards

Roger

Offline Laurentic

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Re: First attempt at gear cutting
« Reply #8 on: December 30, 2020, 11:11:33 AM »
What is even more impressive is that they are bevel gears - I fretted enough just cutting straight spur gears!

Well done, excellent effort

Chris

Offline Steve Crow

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Re: First attempt at gear cutting
« Reply #9 on: December 30, 2020, 12:03:08 PM »
I didn't take many photos of the set up - I always forget to.

Here is one showing the micrometer for centering the cutter.



And a couple from cutting the crownwheel.





Steve

Offline Don1966

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Re: First attempt at gear cutting
« Reply #10 on: December 30, 2020, 06:10:34 PM »
Very nice gears for first time you should be proud of your accomplishments. Should you want the spreadsheets for calculating the gears so you avoid the math an errors that might produce PM me you email address and I will forward you the calculation spreadsheets on all the gears. Your email is safe with me it will not be shared. 


Regards Don

Offline Steve Crow

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Re: First attempt at gear cutting
« Reply #11 on: December 30, 2020, 10:45:44 PM »
Thank you Don,

I've already checked out all your useful spreadsheets and used them to double check my maths for these gears.

Cheers

Steve


Offline kuhncw

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Re: First attempt at gear cutting
« Reply #12 on: December 30, 2020, 11:24:15 PM »
Steve,

Very nice work on the gears.  Thanks for posting the photos as now I know what you meant by a "centering micrometer".

Chuck

Offline Steve Crow

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Re: First attempt at gear cutting
« Reply #13 on: December 31, 2020, 10:39:31 AM »

It took about 4 hours to set up.

I thought the only chance I had of doing these correctly was to have everything square and spot-on.

First I had rebuild the mill in horizontal configuration, something I hadn't done before. Then everything needed to be clocked on each axis before tightening. Then the angle plate had to be clocked square and the 8mm collet adaptor dead centred on the rotary table with a DTI.

Hours of tapping with a little rubber hammer.

After all that, when I went to centre my cutter I found out that the arbor was 5mm too short! (the angle plate screws fouled the column). So I had to remove the painstakingly clocked headstock, put it back on my lathe, set it over for morse taper turning (more clocking) and make a new, longer arbor.

This set me back the best part of a day so I didn't have much time to do the cutting as I had to give the kitchen table back!

In the end, I did all the cutting in one long session. It took about 6 hours including roll-ups, tea and sandwiches. That still works out one cut every 39 seconds.

I would have liked to split it up over a couple of days but it wasn't possible.

I was getting quite tired by the end of it, hence the error.

Steve

Offline simplyloco

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Re: First attempt at gear cutting
« Reply #14 on: December 31, 2020, 06:10:43 PM »
I know the feeling. When I was an Army Engineer I made replacement gears without the luxury of an involute cutter. Single point tools were the order or the day, ground up against the profile of the mating gear. Time consuming or what!
They might have been noisy, but they usually worked OK until the replacements arrived or the tank/gun/bulldozer got hit! :LittleDevil: Metaphorically speaking as I never went to war...