Helical Gear Cutting Lathe Attachment

[Captain Jerry]

Chuck th_wav

Congratulations. That is a helluvan accomplishment. The simple way that you solved what seems to be an impossible problem makes my jaw drop. It is a real gem.

A couple of questions if you don't mind. From the pics, it looks like the tool spindle is directly beneath the lathe spindle, and that a left hand rotation of the knob at the end of the spindle pulls the blank into the cutter path producing a right hand helix. Does the mating gear need a left hand helix? How?

Is rigidity an issue? If you are like me, you are already designing version 2. I hate to offer suggestions to a genius but would it help to shorten up the distance from the tool body to the gear blank, even relocating or eliminating the spring if possible/necessary?

To add a little drag to help control feed rate and to take up wear, would it help to split the tool body and add clamp screws to close it around the spindle?

More congratulations on an amazing job!

Jerry

 

[tel]

AHA! The penny has duly dropped - the disc thingy on the back, that carries the indexing arrangement is turned by hand! Might have been obvious to some, but I completely missed that.

 

[cfellows]

Chuck th_wav

Congratulations. That is a helluvan accomplishment. The simple way that you solved what seems to be an impossible problem makes my jaw drop. It is a real gem.

A couple of questions if you don't mind. From the pics, it looks like the tool spindle is directly beneath the lathe spindle, and that a left hand rotation of the knob at the end of the spindle pulls the blank into the cutter path producing a right hand helix. Does the mating gear need a left hand helix? How?

Is rigidity an issue? If you are like me, you are already designing version 2. I hate to offer suggestions to a genius but would it help to shorten up the distance from the tool body to the gear blank, even relocating or eliminating the spring if possible/necessary?

To add a little drag to help control feed rate and to take up wear, would it help to split the tool body and add clamp screws to close it around the spindle?

More congratulations on an amazing job!

Jerry

Thanks, Jerry. Here's the answers to your questions:

1. Since the two gears will operate at 90 degrees to each other, both will have the helix angle in the same direction. However, the sum of the two angles must equal the angle of interaction. So, in this case, the mating gear will have a 10 degree helix angle, relative to the axis, to mate with this 80 degree helix angle.

2. Rigidity is not an issue, at least with a brass gear blank. I need the spindle to have some distance so it doesn't interfere with the cutting tool. I wanted to allow for cutting helical gears up to 1/2" wide.

3. Don't think any drag is required. I want to keep it pretty free turning and the spring holds the bearing against the aluminum template. I do need to get a stronger spring, however.

Indexing is a bit of a struggle. Counting the holes to move the indexing pin is difficult. I need to rethink that part of the setup. May replace this part with a worm gear indexer.

Thanks again for the kind words... Chuck

 

[Maryak]

Chuck,

That's very clever :bow: :bow:.....................your not just a pretty face are you. ;D

Best Regards
Bob

 

[cfellows]

Chuck,

That's very clever :bow: :bow:.....................your not just a pretty face are you. ;D

Best Regards
Bob

I keep telling my wife that, but she just looks at me like, "What makes you think you even have a pretty face?"!

Here's a picture of some updates I made. I moved the indexing plate to the back so I could see better to count the holes when moving the detent pin. I remade the template carrier in a little bit larger size and knurled the edge to give me a firmer grip. Just about ready to try another gear.

 

[John S]

Chuck,
What about a handle that goes over the rear boss and the index screw goes thru that ?
Give a bit more leverage and control ?

John s.

 

[ksouers]

Wow, Chuck!

Somehow I missed this. Amazing stuff!

It's going to be fun watching you work out all the bugs.

 

[cfellows]

Here's a couple of pictures of a finished gear. Looks great! Got video of me cutting this gear following as soon as I get it uploaded to youtube.

The gear was cut with a #1 40DP gear cutter. The blank is aluminum, 6 teeth, pitch diameter of .864, overall diameter of .914, the gear face is about .25" wide and the shoulder is also about .25" wide.

 

[4156df]

Chuck,
That's very impressive. I'll be happy when I cut my first spur gear much less a helical gear. This is a very interesting post.
Dennis

 

[cfellows]

Thanks to all for the kind and encouraging comments. Here is a video of me cutting the aluminum gear pictured. Hopefully this will answer any remaining questions.

[ame=http://www.youtube.com/watch?v=oSeMX9SZXXY]http://www.youtube.com/watch?v=oSeMX9SZXXY[/ame]

Notice in the video I say to watch the spindle and it will move left. Actually, it moves to my other left, or should I say right... :-[

Note to self: Turn the lathe off when changing the indexing pin in the indexer between teeth!

By the way, John, I thought about adding a handle, but I like the sensitive touch of just the 2" knob. I think the only other change I need now is a longer and perhaps stronger spring on the spindle nose. I'm taking a full depth cut of around .056" and there is virtually no tendency for kickback. Might be a different story if the gear blank were steel, but I plan on only using brass, aluminum, and plastic.

Chuck

 

[larry1]

Chuck, This is an really great tool.really waiting to try this. Larry1

 

[zeeprogrammer]

Very nice Chuck. I really enjoy videos like that. Helps us newbs understand so much.

P.S. You can't help but look good when you have such a smile as you do in your avatar. Wifey needs to be careful...there's women (and others) out there who'd like to grab such a fine fellow. :big: When my Dad was 81 he was 'accosted' by a woman. Made him feel good until he realized that Mom wasn't worried. :big:

 

[cfellows]

Very nice Chuck. I really enjoy videos like that. Helps us newbs understand so much.

P.S. You can't help but look good when you have such a smile as you do in your avatar. Wifey needs to be careful...there's women (and others) out there who'd like to grab such a fine fellow. :big: When my Dad was 81 he was 'accosted' by a woman. Made him feel good until he realized that Mom wasn't worried. :big:

Thanks, Zee! I am definitely one of the friendlier folks around and the wifey does keep pretty close tabs on me.

 

[SAM in LA]

Chuck,

What a great tool.

The video does a good job showing how your new tool works.

Thanks for sharing.

SAM

 

[doubletop]

Chuck

I'm not going to even attempt to look at the maths involved in this. I'm surprised Marv hasn't chipped in yet.

Hopefully this isn't egg sucking time but did you anneal the ally before you bent it? I read somewhere some time back how to successfully anneal ally without melting it. Cover the whole sheet in liquid soap and heat it with the torch until the soap goes black, take it off the heat and (now I forget whether its quench or not). You'll be able to bend those spirals round the former with your fingers.

Pete

 

[arnoldb]

Well done indeed Chuck :bow:

I noticed in an earlier post you asked about a single-point cutter, but I think the multi-tooth cutting wheel might be better in your "hand driven" application - just a thought from a novice though.

Thanks for showing!

Regards, Arnold

 

[tel]

Just watched the vid Chuck - Brilliant! Just one question, how do you deal with height adjustment, or doesn't it matter?

 

[cfellows]

Just watched the vid Chuck - Brilliant! Just one question, how do you deal with height adjustment, or doesn't it matter?

The cutter fixture mounts in my lathe milling attachment which has vertical adjustment. I mount the cutting fixture with gear blank into the milling attachment vice then raise it until it just touches the gear cutter. The screw on the milling vice is a 3/8 x 16tpi so each full turn raises the gear blank by .0625. There is a hex head on the milling vice height adjustment so each flat will raise the vice by about .010".

Chuck

 

[cfellows]

Well done indeed Chuck :bow:

I noticed in an earlier post you asked about a single-point cutter, but I think the multi-tooth cutting wheel might be better in your "hand driven" application - just a thought from a novice though.

Thanks for showing!

Regards, Arnold

Thanks, Arnold. The next challenge will involve cutting a 10 degree helix gear to match the 80 degree gear I just made. That will involve running the gear blank in at a much steeper angle which means more overhang to avoid the cutter hitting the fixture spindle.

Chuck

 

[tel]

That was quick! Thanks matey.