# Gear Cutting Components?



## RVJimD (Jan 17, 2015)

Good Morning,

i ordered a mill the other day so now I'm shopping for tooling.

the one thing I can't seem to find on Enco is the tooling I need for cutting gears.  I don't know enough about it yet to even put in the right search criteria.

I'm looking for the arbor and cutters to make small bevel and spur/pinion sets.  I ultimately want to try making some differentials and transfer cases for my RC construction equipment.  From my reading here and elsewhere I thought I would find a set of cutters and an arbor.  What else would I need to get started. Sorry for the noob question, it's okay if you roll your eyes!

thanks

jim


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## Bill Gruby (Jan 17, 2015)

First off you need to learn the nomenclature for a gear, ie.  diametral pitch etc. The cutters you are searching for are called "Involute Gear Cutters". The standards are 1-7. You will need to know the formulas to figure out which one you will need. There is a lot more to gear cutting than just buying a cutter, mounting it and making a gear.

 "Billy G"


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## RVJimD (Jan 17, 2015)

I agree.  Is there a favorite reference people use?

jim


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## Bill Gruby (Jan 17, 2015)

I'm lucky, I have a Gear Shop close and the owner is a good friend. If you have a Machinerys Handbook it's a good place to start. I will see what I can find for you on the net.

 "Billy G"


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## Bill Gruby (Jan 17, 2015)

Here is one, just scroll past Servo Motors.

http://www.efunda.com/designstandards/gears/gears_nomenclature.cfm

 "Billy G"


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## jpfabricator (Jan 17, 2015)

Mark leclure on you tube has a down to earth video of the fundamentals making gears. 

Jake Parker


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## RVJimD (Jan 17, 2015)

I hadn't thought of looking at Marc's videos yet, I really like his presentations!

here is the book I thought I would start with.  It is written by Ivan law.

http://www.amazon.com/gp/product/08...&pf_rd_r=0DPRF7GM0TNSAZB0KN7P#customerReviews

Jim


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## DMS (Jan 17, 2015)

The book [h=1]Gears & Gear Cutting (Workshop Practice Series 17)[/h]
Is a good general resource. You will also need an indexing fixure, like a spindexer, or dividing head.


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## RVJimD (Jan 17, 2015)

I have a rotary table and indexing plates and tailstock.  

Jim


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## rgray (Jan 17, 2015)

I have that Ivan Law book, it is pretty good info. I got most of my gear cutters on ebay. usually can get them under $25.00

If you need a specific one and can't find it on ebay, ...Travers is about the only machining catalog I've found them in.

A gear cutter set is 8 cutters. I have a few sets of 8, but you will probably find that you do not often need all 8. Once you figure out what sizes of gears you need to cut you can get cutters that cut those specific sizes.

English system is DP (diametrical pitch)  
Metric gears are modual

DP gears have larger teeth with a lower number. 6DP tooth is much bigger than a 14DP.
Modual gears have larger teeth with a larger number.  1 mod is much smaller than 5 mod.

If that's not confusing enough...the DP cutter numbers and the modual cutter numbers are reversed (#1 DP cutter cuts 135T-rack and a #1 modual cutter cuts 12-13 teeth same as a #8 in DP)

Lots to learn when it comes to gears. If you want to cut helical you might find that easier with a dividing head that can be tilted. You can tilt the mill head but I refuse to do that.


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## rgray (Jan 17, 2015)

www.cage-gear.com ...then click on tools. Great calculators etc here.


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## Baithog (Jan 17, 2015)

You will need some way to tilt your rotary table if you want to cut bevel gears.

I get my cutters on Ebay. They also have the mandrels to mount the cutters, although you could turn your own.

You didn't say how big these RC vehicles are, but cutting exact tooth form gets less critical with little, low power applications.


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## RVJimD (Jan 17, 2015)

Thanks for all the tips guys!

the vehicles are 1:14 scale and pretty slow running so no worries about noise or perfect mesh, or super human strength.  I may ultimately buy gears but since I need to justify owning a mill I HAVE TO TRY IT!

for me, a lot of the fun doing something like this comes from the learning process up to the point of actually cutting metal.

Jim


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## xalky (Jan 17, 2015)

I cut my first gear a few months ago. It was just a straight 113 tooth spur gear, but I learned a lot about gear cutting and sizes and calculations and gear standards. If I could have bought the gear,I would have. The gear cutters and arbor set cost as much as the gear would have, if I could have found one. I enjoyed the challenge and the satisfaction of making it. But I think I would just buy gears if they were available. The smaller gears are so reasonably priced that it almost makes no sense to cut them unless you have to.


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## acourtjester (Jan 19, 2015)

There are a few thing that may help
There is a program called GearDFX by forest moon the will do all the calculations for you.
You can also download Inkscape (free) and there is a section in there that will draw a gear for you.
I just completed a electronic dividing head (web info Chuck Fellows youtube) that used a Arduino to do all the movements for you. 
:jester:
I bought the cutters on Ebay.


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## benmychree (Jan 19, 2015)

rgray said:


> I have that Ivan Law book, it is pretty good info. I got most of my gear cutters on ebay. usually can get them under $25.00
> 
> If you need a specific one and can't find it on ebay, ...Travers is about the only machining catalog I've found them in.
> 
> ...


Add to the complication; bevel gears take a whole different set of cutters than spur gears, and take at least three separate cuts with offsetting of the cutter to arrive at a finished tooth width at each end.  Spur gears are quite simple to cut, for normal work, all that needs to be known is the depth of the tooth, and that is stamped on the cutter.
I assume that hey are still in business, and they have EVERYTHING in the way of gear cutters, that is Ash Gear Company; they are located in the Eastern USA.


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## benmychree (Jan 20, 2015)

benmychree said:


> Add to the complication; bevel gears take a whole different set of cutters than spur gears, and take at least three separate cuts with offsetting of the cutter to arrive at a finished tooth width at each end.  Spur gears are quite simple to cut, for normal work, all that needs to be known is the depth of the tooth, and that is stamped on the cutter.
> I assume that they are still in business, and they have EVERYTHING in the way of gear cutters, that is Ash Gear Company; they are located in the Eastern USA.



So far as helical gears are concerned, it is not tilt of the dividing head that is required, but an angular feed of the table, wherein the table of the (universal milling machine or other such homemade fixture) is swiveled to the spiral angle of the gear teeth, and the (universal) dividing head is geared to the table screw so that as the gear being cut is fed into the cutter, the dividing head rotates and creates the spiral tooth gash.  I have cut many spiral gears this way on my Brown & Sharpe #2 universal mill (light type), and have done other similar spiral milling, such as a valve actuating cam for a Sullivan steam driven wet air pump on the steam yacht Cangarda;  Google it, it was a fantastic restoration of an 1901 steam yacht about 125 ft. length and 18 ft. beam with triple expansion engine and all original steam driven auxillaries.  The yacht was also featured on the PBS aired documentary "Ultimate Restorations".


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## janvanruth (Jan 20, 2015)

http://www.bostongear.com/pdf/gear_theory.pdf


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## rgray (Jan 20, 2015)

benmychree said:


> So far as helical gears are concerned, it is not tilt of the dividing head that is required, but an angular feed of the table, wherein the table of the (universal milling machine or other such homemade fixture) is swiveled to the spiral angle of the gear teeth



So many gears so much terminology...I thought helical was just an angled spur gear. I have cut and used a few of them. Are they just called angled spur gears?

I got in to wikipedia and read but still didn't find an answer.
Spiral bevel, and hypoid sound like they need the movement you refer to.


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## Bill C. (Jan 20, 2015)

RVJimD said:


> Good Morning,
> 
> i ordered a mill the other day so now I'm shopping for tooling.
> 
> ...



You need a dividing head and tail-stock for the arbor.  What size of gear do you plan to make? 


Good luck with your project


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## awander (Jan 20, 2015)

Check out Gearotic.com, for gear and gear-train design software from Art Fenerty, the inventor of Mach3 CNC software.

I use it and like it. It will not only help you design and animate your gearboxes, but also output CNC code for involute gearcutting using regular endmills and a rotary axis.


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