custom gears

[studysession]

Hi -
I own a CNC Mill and a Lathe that is not CNC. I am currently using these to make custom RC parts. I want to make a custom transimission for my RC cars.

Where can i find a tutorial to show me how to cut custom gears for my cars?

I would like to make gears like shown in these photos:



Thanks in advance for the help!

[DareBee]

Most straight cut gears you use a gear tooth profile cutter (this is a horizantal mill or arbour type cutter) and then you need an indexing head to mount your part into. For the helical gears you will need a true 4 axis full motion CNC setup.
I dont have a tutorial and my search engine works the same as yours.

[studysession]

Yeah - I was searching google when I came accross the website where I pulled those pictures from. How big of difference is it for a 4 axis mill?

Right now I have a 3 axis setup.

Thanks!

[scott m]

May I suggest a copy of "Machinery's Handbook" if you don't already have one. The information on gears and cutting them is invaluable. If I were you and wanted to start into gears, I would pick a spur gear/pitch, work out the equations, buy or make a cutter and then produce one. These are the easiest gears to cut and will give you confidence to try others. That's quite a selection of gears you have there. Scott.

[HuFlungDung]

For helical gears, a 4th axis cnc setup will also require some kind of a swivelling head attachment, to set the cutter parallel with the helix.

FYI, you can machine helical gears most easily on a universal horizontal milling machine (a manual mill). What sets this machine apart from regular horizontal mills, is that the table can swivel up to 45 degrees in either direction. However, a universal vertical head can also attain the correct angle, its just a matter of where the cutter is positioned: on top, or on the side of the blank being cut.

If you can find some pics I posted in my gallery on this forum, I show some action photos of the process all set up. You've gotta love gears to do these, though, and I'm talking about the gears that you use to connect the universal dividing head to the table. The table needs to drive the dividing head rotation, so it is very nice to have a power feed on that axis.

[HuFlungDung]

Straight groove timing pulleys I have often cut with a couple of slitting saws spaced appropriately on an arbor. It usually works out okay if you cut the opposite sides of adjacent (not the same) teeth (tooth). The exact width of the space is not as critical as you might first assume, because the belt teeth merely need a clear space to fall into. A little bit of corner rounding helps belt life, of course. The pitch diameter of the timing pulley is critical: that would be the top surface of the tooth. If that is machined incorrectly, the belt will want to "climb" all its life. Browning was nice enough to print a big fat book with the correct dimensions in it. Now don't everybody order their gearing catalogue all at once

[HuFlungDung]

If you are serious about gear making, a hobbing machine is the epitome for this type of work. But, because gear hobs are expensive, and the machine is only good for making any kind of toothed wheel, that's why they are not commonly found in a regular shop. That's not to say that used ones are expensive, though. I've seen some hobbers priced right that tempted me to buy.

[studysession]

Thanks for all the replies -
As for making my own cutters and stuff. I have no clue what all is involved yet. I ordered a book off EBay. Should be here in a week or two. Hopefully it will give me some insite. Was hoping to find something online to give me a step by step understanding and what all is involved. This is all new to me. Only had the lathe for less than a month now and just got the mill earlier this year.

Any help and info would be appreciated.

[scott m]

Maybe I should not have mentioned making your own cutters. By hand it is entirely hit or miss as far as accuracy is concerned. I am sure there are machines and fixtures but that may not be cost effective depending on your needs. There are ways. I only mentioned this because that is how I started, however..... my gears are for my own purpose and they serve them well. Hobbing machines are nice. I still would suggest beginning with a spur gear to "cut your teeth on" . Scott.

[studysession]

I want to make a custom gear box for a radio control car. I want to cut custom gear for it.

Problem is - I do not know what tools I need or how to do any of the work required. I made this post hoping someone would post a link to a tutorial. I do not know where to begin. Figure other people make them for different projects, I should be able to figure this out.

The book I ordered off EBay is: Gear Wheels and Gear Cutting How to Book
Chapters Include:
First Principles Explained
Proportion and Form of Teeth of Gear Wheels
Lantern or Pin Wheels and Racks
Bevel Gears
Worm Gears
Helical Gears - Spiral Gears - Chain Gearing - Epicyclic Gears - Special Form of Gear Wheels
Definitions and Calculations for gear Cutting
Gear Cutting on Milling Machines
Cutting Spur Gears in the Lathe
Gear Generating Methods

Hopefully it will be enough to get me started.

[HuFlungDung]

Put it this way, some gears are within grasp without a lot of trouble. But many different machines exist to deal with complexities of each type of gear. Bevel gears are difficult to cut properly on anything but a gear shaper.

I've picked up what I know from various machine shop study texts. Most likely, that book you have ordered will give you a good start in the information department.

You can easily spend a lot of $$ getting set up just to cut one type of gear, let alone all types.

For the hobbyist, you might check a source like Sterling Instrument for gears for your rc car.

[scott m]

Gear cutting can be a mystery when you first start out but you will find it is like any other machining operation. I will include some helpful links. First here is a picture of cutting a spur gear on my lathe. The index gear on the end came from my lathe. The only accurate gear you can cut this way is a spur. Scott.




Gear Forum
http://www.communitypc.com/wwwboard/wwwboard.html

Bevel:
http://members.cruzio.com/~lehrian/B...ocs/index.html

Worm Gears:
http://bedair.org/Worm/Worm.html

Hope this helps. Scott.