# A little more gear cutting



## joeby (Feb 2, 2010)

This week has been clean-up week for me, I have a pile of little jobs on my bench that I need to get out of the way. This is not exactly an engine related project......yet.

 I had thought about adding to Dean's excellent post on gear cutting, but I decided to start a new thread, as this is just a little bit different machine and method.

 I have a lathe in my shop that I have been working on that had some gear problems. One of the back gears had shed a few teeth, and the tumbler gears had some problems as well ( one missing, one completely worn out). This lathe was built in the late 1800's, so finding parts has been a little more than difficult.

 The first problem to get taken care of was turning the tumbler gear shafts to true them up again. Not at all concerned with size, I'll make the gear bores to suit, but the shafts were not going to let themselves be removed, so.......





we turn 'em with the boring head.

 Now I need gears. The blanks were turned up and an mandrel made in the same manner as Dean had done. The gears I am working on are a bit bigger and I'm using my horizontal mill. Getting the dividing head set up for this takes a little bit of time, and the following is just the manner in which I set up, not by the book...maybe not even correct according to some; but it works for me.

 I had to transfer the mandrel from the lathe to the dividing head, so it needs to be trued up in the dividing head. I indicated it on center close to the chuck, and at the tailstock end by using the adjustment screws in the chuck and tapping the end around with a brass hammer. Once it was running true, I aligned the dividing head with the table.




 By setting the indicator this way, I can crank the knee up and down to locate the highest point on the mandrel, which is center, and keep track of the reading. Then by moving to the other end of the mandrel, and again finding the high point, I can bump the dividing head around until I get the same reading on both ends.

 Now that I'm aligned with the table, I need to get the vertical alignment.




Same method, just running the saddle in and out to locate my high points. The alignment done, the tailstock is slid into position and clamped.

 This gear is 24 teeth, and this being a 40:1 dividing head, the plate needs to be fitted for the correct spacing. 40/n gets you the numbers you need, so 40/24 = 1 2/3. That's one full turn and 2/3 of another. A hole circle divisible by three is the one to use, so I can use 10 holes in a 15 hole plate, 12 holes in a 18 hole plate, 14 holes in a 21, etc. I decided on an 18 hole circle (third row in from the outer edge) to keep the crank handle as long as possible for easier turning.




Then by setting the sector arms so there are 13 holes between them, I don't have to count off my 12 holes for the 2/3 turn.

 I'm going to "gash" the teeth first to take some of the load off of the gear cutter, so on goes a 3/32 slitting saw.




 Just a tip here, don't attempt to tighten the arbor nut at this point, very easy to bend an arbor by doing this.




With the arbor support in place and clamped, now the arbor nut can be tightened.

 Finding the center of the gear blank on a horizontal can be a problem, the cutter is too small to reach down the side of the gear blank, and there isn't any room to get to the mandrel. Got some of those cheapa$$ 1-2-3 blocks? Here's a use for them.




With those set up against the gear blank, and knowing the gear blank diameter and the saw thickness, a little simple math will tell you the distance the side of the cutter should be from the 1-2-3 block. That figure, a depth micrometer, and three hands will tell you where you actually are.




The correction to get you on center is easily done by dialing it off on the cross slide handwheel.

 I like to set the depth of cut at about .002" and go around once to check my setup for correct spacing. If everything is as planned, I'll wind up with 24 teeth gashed in,




like so.

 Comments and criticisms are welcome.

 Thanks for looking.

Kevin


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## Deanofid (Feb 2, 2010)

Comments for sure, Kevin, starting with "Thanks!"

I really like seeing the set-ups that others use.  It seems pretty common for me to pick up a hint when watching someone doing things that I already do on a regular basis. Even more common to have the lazy parts of my brain awakened. Like, "why don't I use my 1-2-3 blocks more often?".  They're a great tool for things like you show here, and I forget to use them!

Nice to see a project using a horizontal miller, too. 

Now, waiting for part two.

Dean


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## tel (Feb 2, 2010)

Some good information there - a karma point for your effort


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## ariz (Feb 2, 2010)

a most instructive post joeby, thanks for sharing

karma from me too


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## SAM in LA (Feb 2, 2010)

Thanks for the lessons in how to set up for gear cutting.

The methods you used for locating the stock with your test indicator I had not seen before.

My poor brain is being stretched and reshaped by all of the new to me information.

Thanks once again.

SAM


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## rog/tn (Feb 2, 2010)

:wall: Setups with round stock drive me crazy!
Thanks for sharing your indicator method. 
I plan on using it today to set up some indexing on my 4th axis.
rog


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## black85vette (Feb 2, 2010)

Nice use of the 123 block!  :bow:


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## joeby (Feb 4, 2010)

Thanks everyone.

 The last few days have been busy, so I haven't made any more progress on this job. This is one of those things that, once a step is completed, I won't continue until I have the time to do the next step in entirety.

 I did have a little time to dig through the parts boxes and get some of the pieces to this project together.

 As I mentioned in the first post, one of these two gears was missing and one worn out. I had two gears already done.





 Nice running fits on the shafts and all; but a major goof.





 I mistakenly assumed that since the worn gear was 26 teeth, the missing one probably was also, seemed to make sense that since the purpose of these gears is to reverse the lead screw.

 I got out the Machinery's Handbook and looked up the formula for shaft center distance and filled in the blanks. Simple enough. One formula is the sum of the teeth of the two gears divided by twice the diametral pitch equals the center distance. I knew the center distance from direct measurement of the shafts, I also knew the diametral pitch and the tooth count of the worn gear. A little calculating and I came up with 24 teeth for the missing gear.

 I decided to make the 24 tooth gear first this time so I can check it on the shafts with one of the 26 tooth gears I had already made. I plan to remake the 26 tooth gear also because it is slightly undersized on the width.

 The gear on the left in this pic is the driving gear for the tumbler gears. 





 I made it and it's neighbor a while back.

 I'm rather anxious to see how well it all fits together.

Kevin


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## Deanofid (Feb 5, 2010)

That's kind of a drag, Kevin! 
From the appearance of the gears you've already made, it doesn't look like you need
any extra practice. I guess you're going to get some, though. Sorry about your little mix up.

The upshot is, you have a nicely made 26t gear to build an engine around.
: )

Thanks for keeping us posted.

Dean


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## joeby (Feb 5, 2010)

Dean,

 Thanks, I can always use the extra practice though.

 Looking at the rest of this machine (built in the late 1800's) I have a lot of practicing to do. The attention to fits and finishes amazes me, it's something that you don't see on a lot of the things we have today. All done without CNC!

 Not to worry about the two extra gears. I have been keeping up with some of the projects others on this site are working on and a few uses come to mind, a sheet metal roll maybe?

 They are a little big for an engine project I think, the 26 tooth gears are 1" wide and 2.333" diameter ;D

Kevin


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## Deanofid (Feb 5, 2010)

joeby  said:
			
		

> They are a little big for an engine project I think, the 26 tooth gears are 1" wide and 2.333" diameter ;D
> 
> Kevin



Oh. Well... big enough for a flywheel, then?

Jussst kidding. 

Dean


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## joeby (Feb 6, 2010)

Dean, might make an interesting flywheel at that!

 Did a little more work on the gears tonight, first pic shows the start of the gear cutting,





 Nothing new, just a cutter change. Note that I didn't use the depth micrometer to check the center, the gear cutter measures .305 wide, the saw was .094, a difference of .211. .211 / 2 = .1055, so I just moved the cross feed by .1055 according to the dial and left it there. 

 Simple matter to touch off on the OD of the gear, keeping in mind to mark the hole in the plate that you were last in so you can return to it after moving the gear blank to a spot you can touch off on.

 I didn't take the whole depth in one pass, I left .030 for a final pass.

 First trip around,





 Second, and final pass,





 This pic shows the finished 24 tooth gear next to one of the mating gears. The gear to the left is the original 26 tooth gear, you can see how pointed the teeth are starting to get from wear. At the top is one of the 26 tooth gears I made previously that are being replaced.





 Next job will be cutting the new 26 tooth gear to match.

Kevin


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## Deanofid (Feb 7, 2010)

Looking very good, Kevin.
What kind of lathe are you restoring? 

Dean


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## Twmaster (Feb 7, 2010)

Kevin,

That's really terrific stuff. Seeing other folks methods and setups is always a treat. Leaves me with ideas for my own workshop projects.

Like Dean I'm curious what lathe you are making parts for. 

Also, is the boring head shown in the first post one of Andy Lofquist's design?

I'll be watching this thread.


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## joeby (Feb 7, 2010)

Dean, Twmaster,

 The lathe is a 16" swing Pratt & Whitney.





 Rescued from my Grandfathers shop a few years ago as a rusty, dirty lump. 

 Twmaster, yes, that is one of Andy's design. I bought the castings and set of drawings from him a long time ago, I've gotten a good bit of use out of it since!

Kevin


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## Maryak (Feb 7, 2010)

Kevin,

That is one beautiful piece of Old American Iron - I'm envious. :bow: :bow:

Your gear cutting brings back many memories, you are using exactly the same method with a horizontal mill that I was taught as an apprentice except we did the full depth in one pass after the index proving nick.

Best Regards
Bob


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## joeby (Feb 7, 2010)

Maryak,

 Thanks, yes I think the older machines had much better looks than the modern ones, but it's very easy to become spoiled by geared headstocks and quick changes!

 Here are a couple of pics taken before the lathe was moved to my shop.









 It had to be completely disassembled and carried out in pieces. Except for the bed itself, of course. I guesstimate the beds weight at near 1000 lb..

 By the way, yes, I have also cut gears at full depth and one trip around. This mill is an old Nichols, probably capable of much more that I give it credit for, but the rise and fall spindle gives me nervous fits when taking heavy cuts!

Kevin


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## Deanofid (Feb 7, 2010)

Beautiful old machine, Kevin. Lovely massive bed. I'll bet that ol' boy can put on a cut!

Dean


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## joeby (Feb 14, 2010)

Got in a few hours shop time today. Valentines Day, I know, but I gave the Wife some free time for herself instead of being underfoot!

 I finished up the 26 tooth gear, made a bushing for it and put the tumbler back together to check the gear mesh. Everything looked good, so I made up two new retainers and a new screw to replace the one that's living with the missing gear.





 The cone pulleys had gotten a little rough looking from a slight coating of rust, (my shop gets a bit damp during the spring and fall) so I wanted to do a little clean-up on them before re-installing the spindle. Gave the little Atlas a workout!





 Gives an idea of the size difference between the Atlas 12" and the 16" P&W.

 Next will be a little run-in to get the spindle bearings adjusted and see how the new gears like their home. 

Kevin


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## Deanofid (Feb 15, 2010)

Little Atlas? Naw. _I_ have a little Atlas. 
I've got the same line of oil on the wall behind mine, though. On more than one shirt, too.

The new gears look great nested in their places. Just plain nice work, Kevin.

Dean


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## Twmaster (Feb 15, 2010)

joeby  said:
			
		

> Dean, Twmaster,
> 
> The lathe is a 16" swing Pratt & Whitney.
> 
> ...



Cool beans! That is one dead sexy old P&W lathe. I so very much lust after it's little brother the P&W #3. 

I thought I recognized Andy's design. He's a great guy. I've exchanged much communication with him. Even have his tool post plans.

Now, about that 'little' lathe.....


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