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Author Topic: Gear cutting end mill search  (Read 21305 times)

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Gear cutting end mill search
« on: March 20, 2010, 11:05:44 PM »
I came across the video below of a guy using a endmill to cut gear teeth into a brass blank. Very cool, but I am looking to do the same thing and I can not find a end mill like the one used in the video. I can find gear tooth milling cutters galore but not end mills with gear tooth profiles. Can any one point me to where I might find them? Or what are they called to search for them.

http://www.youtube.com/user/John5tevenson?aia=true#p/u/7/fps0OR1eF_s

THanks
Scott

Offline Tweakie.CNC

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Re: Gear cutting end mill search
« Reply #1 on: March 21, 2010, 04:23:48 AM »
Hi Scott,

You may find this of interest. http://www.patentstorm.us/patents/6591715/description.html

Tweakie.
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Re: Gear cutting end mill search
« Reply #2 on: March 21, 2010, 11:26:35 AM »
That is exactly what I am looking for.
Does any one sell these style of cutters?

Thanks
Scott

Offline Tweakie.CNC

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Re: Gear cutting end mill search
« Reply #3 on: March 21, 2010, 01:03:47 PM »
Hi Scott,

I think you are going to have to make your own cutter.

It would seem that until such time as Paul Avis licenses or sells his patent, no one else can manufacture and sell these without the risk of patent infringement.

Tweakie.
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Re: Gear cutting end mill search
« Reply #4 on: March 21, 2010, 10:21:44 PM »
It is a shame if he is not moving to produce them. To just sit on a patent is kind of senseless but who knows what is going on.
I was thinking of making one but I am a little stumped as to how to machine the exact profile without a CNC lathe or grinder of some sort.
I  dont have a vertical CNC controlled axis on my mill yet. I do have a X and rotational CNC axis setup though. Maybe this is the need that will get me to work on one.
I would be interested in hearing from anyone who has made such a gear cutting endmill to see what angles were used in creating it.

Scott

Offline Tweakie.CNC

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Re: Gear cutting end mill search
« Reply #5 on: March 22, 2010, 11:58:23 AM »
Hi Scott,

I think that although the endmill gear cutter is a brilliant device it is in many ways very impractical to market. A supplier could, for example, hold a thousand in stock and yet it is unlikely than any one would be suitable for the particular gear a manufacturer is intending to make. This is because the gear tooth profile and, more importantly, the shape of the gap between the teeth (and therefore the final shape of the endmill cutter) will be different for any given diameter / number of teeth and the contact angle of the gear (the portion of the involute curve forming the tooth profile is always linked to the pitch circle diameter of the gear). The picture below, perhaps rather extreme, shows to illustrate the difference in teeth profile between two gears which both have the same D.P. but differing number of teeth and therefore diameter. The endmill gear cutter could, I think, only really be a product ‘made to order’ once the size and parameters of the gear has been established and then another endmill gear cutter would have to be ordered for the meshing gear (if it was not identical to the first) and so on.
If you are up for a challenge and plan to try making one of these endmills then just as a suggestion:- An online gear profile generator can be found here http://woodgears.ca/gear_cutting/template.html once you have entered your parameters download the gear in HPGL. From the resulting file delete the first part (up to the second instance of SP1) it can then be opened into LazyCam. By deleting the unwanted chains and entities you will be left with the profile of ½ a tooth – from which you could produce the GCode toolpath for the exact shape of the endmill cutter. Milling it is another task (but not impossible) then cutting the flutes and creating the clearances from the cutting face could then be accomplished (4th axis would be nice here) followed by a hardening process. Sounds like quite a major project but it would not be beyond the grounds of possibility.
Incidentally I am no expert on gears, my only experience comes from profile cutting countless gears and escapement wheels for a friend of mine who has an insatiable appetite for designing and building wooden clocks and mechanisms.
Best of luck with the project.

Tweakie. 
KEEP SAFE !
Re: Gear cutting end mill search
« Reply #6 on: March 23, 2010, 08:16:56 PM »
I see your point on needing one for each gear if they are not the exact same dia & # of teeth. Thanks for the link to the gear tooth profile generator. I think I had come across it awhile back. My best bet for ease might be to just use a small dia end mill /router bit and just mill the entire gear profile. I just need to get my CNC router completed.

Thanks for all the great help and advice.

Scott

Offline RICH

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Re: Gear cutting end mill search
« Reply #7 on: March 23, 2010, 11:31:39 PM »
Scott,
Here is a link which shows some gear cutters that i have made and used. There are actualy two posts and the first post shows how the bit was set and cut. They work fine but it does take time to make them.
Guess it's better than spending $25 a crack when you need one.
There was an arcticle on how to make the ones that that guy is seeking a patent for ( Pracatical Machinist Magazine some time ago )

http://www.machsupport.com/forum/index.php/topic,8118.msg51321.html#msg51321
http://www.machsupport.com/forum/index.php/topic,8120.msg51325.html#msg51325

FWIW,
RICH
« Last Edit: March 23, 2010, 11:36:48 PM by RICH »
Re: Gear cutting end mill search
« Reply #8 on: March 24, 2010, 12:07:26 AM »
Cool idea! I never thought of fly cutting them. Nice pictures.
I wonder if I could make one to fit a small fly cutter that could be mounted in a router. Slowed down a lot of course.

Scott

Offline Sam

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Re: Gear cutting end mill search
« Reply #9 on: March 24, 2010, 01:52:30 AM »
I would advise against putting any tool into a router that is not perfectly balanced.
I would also advise against slowing down a router with a rheostat.
http://www.machsupport.com/forum/index.php/topic,13270.0.html
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