So, I need a gear....

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GlennW
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So, I need a gear....

Post by GlennW » Fri Jan 08, 2010 7:28 pm

The stud gear on my lathe has a bit of wear on it, so I decided it was time to make a gear. I thought about buying a new one, but it is 7 weeks just to get a quote from the manufacturer as apparently, I'm the only one that has ever needed one!

I figured out what the gear was after a little calculator time, and it is a 1.5 Mod Pitch 20° pressure angle Metric gear (50 tooth). I bough a 12" length of Iron bar and then set out to find a 1.5 Mod Pitch Involute cutter for the tooth range I need.

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Turns out that Metric cutters have a Metric bore, so I don't have an arbor (mandrel?) for it. Chucked up some 1 1/2 round 4140 pre hard bar and turned it and threaded it to accept the cutter and a 3/4" 16 tpi nut. I decided to use a 1/4" pin for a key, so it will be reduced to fit the 6mm keyway in the cutter and will be a "0" fit into the hole. The manderl will be held in a 75 TG collet in a NMTB 30 tool holder and run in my vertcal mill as I don't have a horizontal mill.

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Needed a nut for the arbor, so I turned, bored and threaded one as well as machining two flats on it for a wrench.

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Faced it and counterbored it a little so the threads and face are concentric.

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Turned a 3/4 shank on it and put a couple of centers in it as I will grind it on centers so it is perfectly concentric. Both pieces screwed together and almost done. I guess I could have wiped the slimy finger prints off of it.

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I was going to make another mandrel (arbor?) for the gear blank, but I decided to just use an expanding mandrel I already had. So I guess the next step is to make a gear blank from the iron bar.

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To be continues as time permits....
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

Russ Hanscom
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Post by Russ Hanscom » Fri Jan 08, 2010 8:26 pm

Last time I checked, Travers Tool had metric gear cutters with english bores - I was looking for a 1.5 Mod too.

You might be past that point.

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GlennW
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Post by GlennW » Fri Jan 08, 2010 9:07 pm

Sure enough!

I think I checked everywhere but Travers. I used to buy quite a bit from them and get the sale catalogs regularly too.

Oh Well, too soon old, too late smart!

These projects are mainly excuses to run machines and make things anyway. (therapeutic value) :D

Thanks,
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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GlennW
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Post by GlennW » Sat Jan 09, 2010 5:14 pm

Ground the shank and cutter register, then installed the nut and ground it and the OD of the body.

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Pin installed to stop the cutter from rotating.

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Assembled and ready to cut. Nothing beats a ground finish. Probably would have turned it on centers and not ground it, but the grinder was set up for that center distance and the right wheel was on it so there was no setup involved.

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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

Russ Hanscom
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Post by Russ Hanscom » Sat Jan 09, 2010 8:32 pm

Very nice!

Jose Rivera
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Post by Jose Rivera » Sat Jan 09, 2010 11:02 pm

Glenn ... having an OD grinder makes me jealous 8) 8)
Last edited by Jose Rivera on Sun Jan 10, 2010 12:05 am, edited 2 times in total.
There are no problems, only solutions.
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Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa

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Lew Hartswick
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Post by Lew Hartswick » Sat Jan 09, 2010 11:56 pm

Can you say "gilding a lily"? :-) Beautiful but would work just as well
if it were just as "turned". I seem to always quit when I get it to the
"working point". On the other hand "eye candy" is good for the soul. :-)
...lew...

Harold_V
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Post by Harold_V » Sun Jan 10, 2010 12:01 am

Lew Hartswick wrote:Can you say "gilding a lily"? :-) Beautiful but would work just as well
if it were just as "turned".
True, but holding size, roundness and being straight are features that come almost with no effort with a grinder. There really is no substitute for finish grinding. Projects so finished can't be distinguished from those from the store.

Beautiful job, Glenn.

Harold

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DICKEYBIRD
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Post by DICKEYBIRD » Sun Jan 10, 2010 8:33 am

Man, that is some beautiful work Glenn. Can't wait to see pics of the gear making process.

Noob question: Can you post a pic of the machine you did the grinding on or is it just an attachment on your lathe?
Milton in Tennessee

"Accuracy is the sum total of your compensating mistakes."

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GlennW
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Post by GlennW » Sun Jan 10, 2010 10:26 am

Lew,
Glenn Wegman wrote:These projects are mainly excuses to run machines and make things anyway. (therapeutic value) :D
As you stated, it's good forthe soul :)



Thanks to all for the nice comments!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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seal killer
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Post by seal killer » Sun Jan 10, 2010 11:25 am

Glenn--

Your project is not only fabulous, it is very educational. Please quit doing everything else and concentrate all of your CPU cycles on this one thing! :)

I would like to see a picture of your grinder, as well.

--Bill
You are what you write.

Jose Rivera
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Post by Jose Rivera » Sun Jan 10, 2010 2:24 pm

Glenn Wegman wrote:Lew,
Glenn Wegman wrote:These projects are mainly excuses to run machines and make things anyway. (therapeutic value) :D
As you stated, it's good forthe soul :)



Thanks to all for the nice comments!
Glenn ... do you need a helper ? :lol: :lol:


There are cylindrical grinders and center-less grinder among a slew of others, including tooling grinders.
Do a search on eBay on these names.

Any finish requiring better and more precise finishes ... then the lapping machines come in, but one need a precision ground finish to even start meeting those goals.

Finishes beyond grinders are measures in the range of 8L to 2L.
Tolerances can be held to six place decimals (millionths of an inch).
Can only be accurately measure with super mics, precision gages and air gages.

Neat stuff, I had the opportunity to deal with such tooling in the Space Shuttles doing final machined parts QC and at McDonnell Douglas, QC also.

Now days some CMMs can measure to six place decimals. With them the limitations are only with the capacity of the machine.
With the previously mentioned tooling one is limited to far smaller size capacity of dimensions that can be measured.
There are no problems, only solutions.
--------------
Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa

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