Author Topic: Quite a set of gears!  (Read 8850 times)

Offline websterz

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Quite a set of gears!
« on: April 26, 2009, 10:35:17 AM »
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"In the 60's, people took acid to make the world weird.  Now the world is weird and people take Prozac to make it normal."
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Offline sbwhart

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Re: Quite a set of gears!
« Reply #1 on: April 26, 2009, 11:03:02 AM »
Ho that's given me a head ace  :hammer:

Stew
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ja2on

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Re: Quite a set of gears!
« Reply #2 on: April 26, 2009, 12:55:27 PM »
Now that is art  :bugeye:

Offline Stilldrillin

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Re: Quite a set of gears!
« Reply #3 on: April 27, 2009, 03:21:41 AM »
By `ek!!!  :bugeye:

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

bogstandard

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Re: Quite a set of gears!
« Reply #4 on: April 27, 2009, 04:08:25 AM »
Todd,

There is another one very similar to that, again I think of Chinese origin, but it shows partial gears being used to give wierd and wonderful movements.

I have searched hi and lo to refind it, but to no avail.

If you come across it, could you post another link.

Here is a short one that you would think was impossible to do.



Bogs

Offline PTsideshow

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Re: Quite a set of gears!
« Reply #5 on: April 27, 2009, 06:37:29 AM »
Very cool, Bogs I think you have found Wes's next project  :D
glen
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Offline Weston Bye

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Re: Quite a set of gears!
« Reply #6 on: April 27, 2009, 03:27:40 PM »
Gulp.  :bugeye: The irregular gears might be a ways off.  I need to do regular gears first.  The "cubular" gears might be doable before the others.

Weston Bye
Practitioner of the Electromechanical Arts.
author of The Mechatronist column
Digital Machinist magazine

Offline raynerd

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Re: Quite a set of gears!
« Reply #7 on: May 15, 2009, 03:01:18 AM »
Wow that one at 18s is fantastic - has anyone ever come across the plans that were shown. I wouldn`t mind saving a copy - I`m 10 years off making one but would love to have a look at them. Talking of gears - are there any good "how to" gear cutting links online?

Thanks for the post webby.
Chris

Online John Hill

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Re: Quite a set of gears!
« Reply #8 on: May 15, 2009, 04:58:33 AM »
Chris,  I have read a few techniques for gear cutting but unfortunately I didnt keep a record of the sites.  However the information was not difficult to find.

How to do it seems to depend a lot on what equipment you have!  These are the techniques I recall:

With lathe..
   Gear blank held on a vertical axis with the blank below the spindle centreline at the start of the cut.  The vertical axis must be able to move upwards (mounted on a vertical slide for example) and the blank must be able to rotate with index stops.  The lathe tool is ground to the profile of the tooth and the blank is slowly raised until it is completely above the spindle axis which completes the cutting of one tooth.

With a shaper..
    Again, the blank is held on an axis that must be able to rotate and is indexed for each tooth.  There is a technique described on-line where a wire is wound around a drum on the axis and rotates the blank automatically by the action of the shaper cross feed.

With a mill
    Well, I dont have a mill so I never looked at this option..
From the den of The Artful Bodger

Offline Bernd

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Re: Quite a set of gears!
« Reply #9 on: May 15, 2009, 09:27:11 AM »
Chris,

It depends on what type of gears you want to cut. John has hit on some of the high lights for simple gear cutting such as spur gears. The more complicated the gear the more complicated the machine. You would not be able to cut a set of ring and pinion gears for the final drivr of a car. The machines that do this cost in the 100's of thousands of dollars. I know this because I worked for a world leading gear cutting machine manufacture.

The simple spur gear can be cut on a mill with the proper cutter and a dividing head (and I don't mean Ralph  :lol: )

I'm sure if you do a google search you'll get many hits. Off hand I can't come up with any links at the moment.

Bernd
You can't fix "STUPID".

Online John Hill

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Re: Quite a set of gears!
« Reply #10 on: May 15, 2009, 08:46:50 PM »
Chris,  one of the interesting facts I learned is that most of the simple gears we use, such as the change gears on our beloved lathes, are actually compromises, all to do with something called 'involute' gears. Obviously every gear is different in tooth shape to gears of the same set but a different number of teeth but is it not required to have a gear cutter for each size of gear as there is a range of sizes that are designated 'acceptable'.  If you use the shaper method (and I suppose there is an equivalent lathe method) the gears are actually shaped by the blank revolving in respect to the cutting tool and it is possible for the amateur (maybe even me?  :scratch:) to cut spur gears that are more accurate than the commerically available ones!


I hope gear cutting will be an interesting and rewarding experience when I manage to get to that stage.
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Offline usn ret

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Re: Quite a set of gears!
« Reply #11 on: May 15, 2009, 11:30:14 PM »
Wes, :coffee: I stumbled on this some time ago and filed it away for posterity.  Well posterity is here, gear making, :smart: www.atmsite.org
the link as typed didn't work. If interested, go to the site and do search by author,  that works.
You've got mail :thumbup:

Cliff :coffee:
« Last Edit: May 15, 2009, 11:41:48 PM by usn ret »
If it isn't broken your not looking hard enough!

bogstandard

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Re: Quite a set of gears!
« Reply #12 on: May 15, 2009, 11:53:38 PM »
Chris,

I have done a little bit of gearcutting when I made new gears for an old Myford lathe. I had to make a new bull gear and another one for the back gearing setup.

For Horology (clocks) they usually manufacture their own flycutters and gearcutters to make the gear setups, and that is all usually done on a small lathe with a milling spindle setup.

http://www.csparks.com/watchmaking/WheelCutting.html

For involute gears, which is the normal type we use, and the ones I made, you buy your cutters ready made. Usually the sets come with eight cutters, to cover the whole range of teeth required. I just bought the ones that were needed.

http://rdgtools.co.uk/acatalog/INVOLUTE_GEAR_CUTTERS__SET_S_AND_INDIVIDUAL_.html

They are fairly easy to do if you have the equipment. The major bit is either a rotary table (and you need to know how to use it correctly to obtain minutes and seconds of a degree), or like I did, a dividing head, which makes it a lot easier. A very rigid arbor to hold the cutter, and a set of tables (usually in engineer tables) to give you the correct diameter of blank and depth of cut for each tooth. Once you have it all set up, it is just a normal milling procedure. But usually a rather tedious one with no disturbance required. Make a mistake, and it is start all over again.

If you want a lot of the same size, you could cut the gear profile along the length of a bar, and part off as required.

For one off's it is better that you use a gear stockist and buy individual ones, as to buy all the gear cutter sets to do every type and size of tooth form would cost a fortune.

Unfortunately, the ones I wanted were not produced, so I had no choice but to make my own.


John


Offline raynerd

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Re: Quite a set of gears!
« Reply #13 on: May 16, 2009, 03:30:52 AM »
thanks for your replies - some years ago I drove to Bradford to talk to a enthusiast/hobbyist horologist who was cutting some amazing gearing using the same lathe/mill as me at the time (unimat 3). He was using a modified dividing head accessory that can be purchased for the unimat, he then held his gear blank in a mandrel in the chuck and used the milling machine attachment with a fly cutter with gear profile to cut a gear notch. He then rotated the dividing head and therefore work piece to the next "click" and cut another gear...and so on. He was basically using the chuck on the "lathe" headstock to hold the work and then the mill to cut the notch. 

When I first posted earlier in the thread I had totally forgot what I had seen and it reminded me as I was reading your replies, espcially Johns first link. It made some really amazing gearing for such a relatively simple setup.

Earlier last night when I was reading through this post I made contact with him again and he has offered me a visit a week on Tuesday. Perhaps a bit advanced for me right now, gear cutting, but I`m not going to refuse and he has said I can take a camera to snap some pics to help me remember.

Anyway - sorry I have gone well off the original topic!

Chris

Offline Weston Bye

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Re: Quite a set of gears!
« Reply #14 on: May 18, 2009, 07:52:14 PM »
Wes, :coffee: I stumbled on this some time ago and filed it away for posterity.  Well posterity is here, gear making, :smart: www.atmsite.org
the link as typed didn't work. If interested, go to the site and do search by author,  that works.
You've got mail :thumbup:

Cliff

Cliff,
Thanks for the link.  Worm gears don't bother me.  Indeed, my "Time Machinery" article features a clock with a single 60:1 worm drive to derive minutes from seconds motion.  Hours were accomplished with a spiral cam and a 12 step ratchet.  Very unconventional.  The link is a good one though, a keeper.  Thanks again.

I haven't tried making spur gears yet, and my next clock still won't have any gears, worm or otherwise.  Will report after it goes to press.

Wes
Weston Bye
Practitioner of the Electromechanical Arts.
author of The Mechatronist column
Digital Machinist magazine