Gear Cutting

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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Dustin_WWP
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Joined: Tue May 14, 2019 8:17 am

Gear Cutting

Post by Dustin_WWP » Wed May 15, 2019 6:35 am

Hey everyone
I am new hear and fairly new to machining but the place I work at we just recently bought a lathe (Clausing) and a CNC mill (ACER). We had an instructor come from our collage to teach us a little of the basics, now we are on to cutting gears on our mill. We have cut several now and they have done really good on the machines we are making them for. The only problem I am having is I want to cut more than one gear at a time to try and gain more production but I have not been able to find any sort of mandrel to put multiple gear blanks on. I just wanted to see if anyone had any ideas on where to find one or possible has anyone made one to cut multiple before?

Thanks

DavidF
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Re: Gear Cutting

Post by DavidF » Wed May 15, 2019 9:16 am

depending on the size of the gear you may want to consider purchasing gear rod stock and part of the thickness of gears you need..
https://www.mcmaster.com/gears

Russ Hanscom
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Re: Gear Cutting

Post by Russ Hanscom » Wed May 15, 2019 9:46 am

Several options; depending on the size and specifics of the gears you are making.

One has been mentioned. Another is to take round rod and cut multiple gears on it them part them off, Use a set of soft jaws for boring and finishing the gears.

Yes, you can stack multiple blanks on a mandrel and cut them all at once - just depends on the sizes involved. You may want/need to make up your own mandrel.

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SteveM
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Re: Gear Cutting

Post by SteveM » Wed May 15, 2019 11:07 am

OK, this is off the top of my head (and this is an expansion of Russ's comments):

Let's say the gear you are working on needs 2" diameter stock.

Start with a slightly oversized piece of stock long enough to make several gears.
Bore / ream a hole to the internal bore of the gear, let's say 1"(on the mill, not on the lathe - tailstock alignment can mess with your reaming).
Take a piece of rod slightly larger than 1", put centers in both ends to make an arbor.
Turn the center of it to 1" for the length of your gear blank stock.
Thread the ends to some thread smaller than 1"
Install the gear blank and use nuts on both ends to clamp
(note that you could leave a shoulder on one end and only thread the other end, clamping the blank against a shoulder)
Install that back on the lathe and turn down the gear blank material to 2".
Now you have a long piece you can mount between centers on your dividing head on the mill and you can cut the tooth profiles for the full length.
Once you have the tooth profiles cut, put it back on the lathe and run a parting tool to cut it into gears.
Only run the parting tool down to leave them all connected because if you cut into the arbor, you could crash (also, this allows you to re-use the arbor).
Take the semi-parted blank gears and either saw the remaining diameter, or put it into a chuck and do the final parting.
Using soft jaws to hold each blank, take facing cuts to true them up as needed and to get you any shoulder you need.

The downside I can see to this is that if your internal bore is small, the arbor might not be stiff enough, but if you use good thick hardened washers on the ends, the clamping will increase the stiffness of the entire assembly.

Steve

Dustin_WWP
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Joined: Tue May 14, 2019 8:17 am

Re: Gear Cutting

Post by Dustin_WWP » Wed May 15, 2019 1:39 pm

Thanks everyone for your help, I took what you all said and just made my own mandrel and it worked out great. I cut out some aluminum gear blanks to practice with before I done them in steel. I cut 3 of the aluminum blanks and they turned out great and fit very nicely on the machine, so now that I have it all worked out I am going to try to do 3 steel blanks tomorrow. I will try to send some pictures tomorrow as well. Thanks again!!

Dustin

Conrad_R_Hoffman
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Re: Gear Cutting

Post by Conrad_R_Hoffman » Mon May 20, 2019 10:09 pm

FWIW, I make most of my gears out of Delrin. They hold up great, can be cut faster and the gear cutters stay sharp longer. I'm sure there are places where you really need steel, but maybe fewer than people think.
Conrad

1947 Logan 211 Lathe, Grizzly G1006 mill/drill, Clausing DP,
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bandsaw, lots of measurement stuff, cutters, clutter & stuff.


"May the root sum of the squares of the Forces be with you."

spro
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Re: Gear Cutting

Post by spro » Tue May 21, 2019 1:05 am

The mysterious half helical gear of the thread dial, for one.

Wolfgang
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Re: Gear Cutting

Post by Wolfgang » Mon Jun 03, 2019 7:46 pm

Conrad_R_Hoffman wrote:
Mon May 20, 2019 10:09 pm
FWIW, I make most of my gears out of Delrin. They hold up great, can be cut faster and the gear cutters stay sharp longer. I'm sure there are places where you really need steel, but maybe fewer than people think.
Agreed, plastic gears, and especially cloth reinforced phenolic gears are much stronger in use than most people realize. When cutting phenolic material for gears be sure to use flat sheet for the blanks and NOT round rod. Anyone care to guess why? w

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GlennW
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Re: Gear Cutting

Post by GlennW » Mon Jun 03, 2019 9:19 pm

It's all about the grain in the phenolic laminate.

I had to make a batch of hydraulic pistons from phenolic and it would have been simple to part them off of phenolic rod, but I had to cut plugs from sheet using a hole saw to make then from to get the required strength due to the grain.
Glenn

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

spro
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Re: Gear Cutting

Post by spro » Tue Jun 04, 2019 10:16 pm

Good flyin point, Glenn! I was amazed back some years replacing the timing chain on a slant six. Tweren't no chain. It was a big phenolic helical gear. That thing had worked a Long time.

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