# Thread: Source for cheap(er) gear milling cutters needed.

1. ## Source for cheap(er) gear milling cutters needed.

I need to cut a new gear for my Enco 12x36 lathe. Enco wants \$50 for a new gear, but I'd like to try and make one myself. Since I've never cut gears before it would be a good learning experience.

I stripped out the original gear by having the leadscrew direction lever in the wrong position and ramming the carriage into the tailstock. Luckily the idler gear was made of a plastic material (acetal?) and it saved other more expensive parts I'm sure.

Anyway, MSC wants around \$135 for a milling cutter and that doesn't even include the arbor. So I'm looking for a cheaper milling cutter to do the job. It probably won't be used more than this one time, so it doesn't have to be the best of the best or anything. If it costs less than \$50 I'd be very happy.

I have a vertical knee mill and a cnc bed mill, so I need a cutter that can be mounted on a vertical mill, not a horizontal mill. I also have an indexing head that will rotate the material as it is being cut.

The gear specs are:

Major Dia = 4.830"
Minor Dia = 4.585"
Number of Teeth = 80

That means the diametral pitch should be around 5. I actually get 5.409 when I average the major and minor dias, multiply by 3.14159 for circumference, and divide 80 by that value. Correct me if I'm wrong, but here it is in other words:

Pitch Dia = (4.830 + 4.585)/2 -> Answer is 4.7075"

Circumference at pitch dia = 4.7075" * 3.14159 -> Answer is 14.789"

Diametral Pitch = 80 / 14.789" -> Answer was 5.409"

So I believe I need a milling cutter designed for a pitch dia of 5 and will cut a gear with 80 teeth correct?

Any sources for cheap cutters would be appreciated. I even thought of grinding one myself. I think I could get close enough to make it work.

2. About the only practical way of cutting a single gear for less then you can buy one is to use a fly cutter and grind up the cutting bit yourself.

How to use a Milling Machine

3. How about getting a gear from these guys and machining it to fit? Welcome to Boston Gear

4. Buy the new gear and get back to work. It is not worth even trying to make a gear for a new gear price of \$50 bucks. I make all kinds of part but when it come to gears we make the blank and send it out to be geared. There are special machines just for gear making and if you want you gear to run smooth get one of these guys to gear it for you. Just a tip.

Thanks and good luck
SP

• Originally Posted by smallplanes
Buy the new gear and get back to work. It is not worth even trying to make a gear for a new gear price of \$50 bucks. I make all kinds of part but when it come to gears we make the blank and send it out to be geared. There are special machines just for gear making and if you want you gear to run smooth get one of these guys to gear it for you. Just a tip.
You've got a good point, but I wanted to try making a gear for a practical situation. My lathe is running right now, I have a metal change gear that is identical to the plastic one. It's not as safe of course, but it give me some time to give it a try.

• Thanks to Andre' B and Packrat too. I'll be sure to check out the links.