What are the main milling components to make gears?

A

awaqa909

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I get to work with CNC machines and manual lathes, but I never get to set them up. Much less know how to. I was thinking I could get a small mill and small lathe from Grizzly or similar and make some rc car parts. I was thinking it would be cool if I could make my own transmission for a rc car. But I have no idea how to make gears or what hardware/tools are needed.

So, what kind of hardware and tools would I need to manually make gears? The gears will probably all be under 3" diameter. I'm also looking for a cheap and not too hard method and can be done using a manual mill and lathe.

I have found that a dividing head is a way to make gears? Ebay cheapies are $300 and I'm not sure if they would fit on a small manual mill that I would like to get. (one of Grizzly starting lineup) I don't have too much garage space or $$.

Thanks,
Awaqa909
 
Gears can be made in the home shop using a rotary table or indexing head mounted on a milling machine table. Cutters come in a couple of different types, some of which you can make yourself. One thing to consider is that making gears is more complex than meets the eye, so you might want to educate yourself on the subject before getting too far. I would start out by obtaining the book "Gears and Gear Cutting" by Ivan Law. It is one of the Workshop Practice Series of books and can be purchased new for about $20. It covers gear nomenclature, design, cutters, etc. and also includes instruction on making your own cutters. I believe that this book is a must have if you plan to make your own gears.

You can also make your own gear hobs (another type of gear cutter) on your lathe using tool steel. Instructions for doing so are available on a 4 hour DVD by Jose Rodriguez and sold by Little Machine Shop for about $40. The DVD is titled "Making Gears the Easy Way". It is packed with good information, but I will warn you, the videos will tend to put a person to sleep. Mr. Rodriguez knows what he is doing and presents it all in his DVD, but the presentation could be livened up a bit. It's sort of like watching paint dry for lack of a better way to put it. Sorry, no disrespect meant against anyone, but watching someone else machine a part in a video without being sped up or abbreviated in some way just puts me to sleep.
 
terrywerm said:
I would start out by obtaining the book "Gears and Gear Cutting" by Ivan Law. It is one of the Workshop Practice Series of books and can be purchased new for about $20. It covers gear nomenclature, design, cutters, etc. and also includes instruction on making your own cutters. I believe that this book is a must have if you plan to make your own gears.
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I strongly agree. Gears can be cut using involute gear cutters. I have seen videos of people using a fly cutter ground to shape, but I have never tried it. There are also gear hobs but I don't have any so I haven't tried it. The picture below is from the book Terry mentioned. I would use a tail stock as well for additional support.

gear mill.jpg
 
More than one way to skin a cat, but my "minimal" set up is an arbor with an involute gear cutter and dividing head. The calculations for depth of cut and blank diameter are readily available, which means I don't remember the formulas off the top of my head . . . Important features are the diametral pitch and number of teeth. Involute gear cutters have a range for the number of teeth they cut for a proper tooth profile, something like 7 or 8 cutters in the series to go from 12 or so teeth up to a rack (infinite teeth).

You can gears by grinding a single-tooth HSS tool to match the gear tooth profile and mount it in a fly cutter. Indexing could be done with a rotary table if you don't have a dividing head.

Photos attached are of my typical set up using a vertical mill instead of a horizontal. L&W dividing head with a shop-made arbor between centers to hold the blanks. Arbor with the involute cutter is a step-sized slitting saw arbor from Enco. Involute cutter was from Victor Machinery for around $50.

Bruce


cutting P50s.jpg dividing head set up.JPG
 
Welcome to Hobby Machinist! If you can get away with only gears having tooth counts evenly divisible into 360, then a spin indexer can substitute for a dividing head or rotary table. A spin indexer costs about $50 and up, new, plus any needed collets. For gears made from aluminum, plastic, or other easy to machine material a tailstock can be optional, though it will require more thoughtful setups to attain enough rigidity for accurate work. With some creativity an existing gear might be used for indexing.

I do not want to discourage you, and your idea is quite doable, but please do note that making gears is not beginner work on the lathe and mill. It is more like journeyman work, to be done after a good amount of other basic learning. And that is a good thing, there are many rewarding lessons to be learned and satisfaction to be had along the way. If you are afraid of math and not willing to study and understand the details of gear cutting, you will not likely have success.
 
It is easier to use a super spacer or dividing head, but I think you can make most tooth counts with just a rotary table. I cut the 4 gears for my threading clutch with a plain rotary table. The hardest part was getting the chuck centered on the table. Keeping track of your progress is an exercise in repeated, total attention to detail. Spending hours cutting teeth, only to find the last one is half a tooth is disheartening. You can cut the kind of gears you are interested in on a mini-mill once you fix its inevitable flaws. A better choice for a multi purpose garage size shop is the G0704/PM-25 class machine. A rotary table for a mini-mill should be no more than 4". I have put my 6" table on my mini-mill, but it isn't very useful. A G0704 will take a 6" or bigger table. You don't want to go too big because you do have to pick it up and move it. Get a quality table. You can get by without a tail stock for small gears, but get one if you can.

The gear cutters mentioned above are the way to go. An ebay set of cutters will get you started for well less than a hundred bucks. Or you can buy them as needed if money gets tight. A cutter will last a long time cutting aluminum or acetal. Save the titanium gears for later :).

Of course we are assuming that you also have a lathe, or access to one, to make the blanks with.
 
You can also make gears with a shaper and some type of indexing tool as noted above. What material do you think you will be making the gears from?
 
Lindsay Publications has some great books on the subject. You can do it, but the details are challenging.
 
terrywerm said:
Gears can be made in the home shop using a rotary table or indexing head mounted on a milling machine table. Cutters come in a couple of different types, some of which you can make yourself. One thing to consider is that making gears is more complex than meets the eye, so you might want to educate yourself on the subject before getting too far. I would start out by obtaining the book "Gears and Gear Cutting" by Ivan Law. It is one of the Workshop Practice Series of books and can be purchased new for about $20. It covers gear nomenclature, design, cutters, etc. and also includes instruction on making your own cutters. I believe that this book is a must have if you plan to make your own gears.

You can also make your own gear hobs (another type of gear cutter) on your lathe using tool steel. Instructions for doing so are available on a 4 hour DVD by Jose Rodriguez and sold by Little Machine Shop for about $40. The DVD is titled "Making Gears the Easy Way". It is packed with good information, but I will warn you, the videos will tend to put a person to sleep. Mr. Rodriguez knows what he is doing and presents it all in his DVD, but the presentation could be livened up a bit. It's sort of like watching paint dry for lack of a better way to put it. Sorry, no disrespect meant against anyone, but watching someone else machine a part in a video without being sped up or abbreviated in some way just puts me to sleep.
Click to expand...
Since you know about some books, do you have a book in mind that I could use to get closer to becoming a machinist? I'm thinking a book that leaves out cnc stuff. More of a manual mill book.
I'm looking at buying some other books off amazon, thinking I should get a book on milling. Plus it should bring the total up, to get free shipping.

Lots of good info. But it is looking like I need to start with some kind of book, then get something like the "Gears and Gear Cutting" book. Probably start with a mill and turn aluminum into parts and then work my way up.
 
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