# Made a gear cutter from scrap



## alb (Aug 29, 2013)

This was an old cast iron boss from a lawn mower 
Being Scottish I hate thing going to waste ;-)

Alb


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## alb (Aug 29, 2013)

My first try at cutting a gear



Alb


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## Ray C (Aug 29, 2013)

Good going...  You'll be hooked now, gears are fun.


Ray


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## Walt (Aug 29, 2013)

Did you purchase the cutter or did you make it? If you made it, I'd like to hear how you did it.

Walt


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## Dave Smith (Aug 29, 2013)

very good job!!!


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## alb (Aug 30, 2013)

Thanks All,

This cutter was made from an old cast iron boss that was cut off a lawn mower (the end of the shaft that holds the blade on) 
I just turned it down to a nice finish then milled out the slot for a 6mm cutter then milled a flat so I could get the three clamping screws in
But I am going to make another out of a harder steel c45 I am a bit worried that the cast iron may be a bit brittle 
I will get a build log on the next adventure

Thanks 
Alb


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## Walt (Aug 30, 2013)

Nice work!

The 6mm cutter though, did you grind it? If so, how did you determine the geometry? If not, where did you purchase it?

Walt


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## alb (Aug 30, 2013)

Walt
No I just ground it on the bench grinder green grit wheel and used a old gear for reference 
Not very technical I know but if it works don't knock it 

Alb


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## DAN_IN_MN (Aug 30, 2013)

alb said:


> Walt
> No *I just ground it on the bench grinder green grit wheel *and used a old gear for reference
> Not very technical I know but if it works don't knock it
> 
> Alb



Is the cutter bit carbide?


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## benmychree (Aug 31, 2013)

I have made flycutters many times to make gears that I did not have a "real" cutter for; one thing is that if you grind a cutter from another gear as a sample for the form, it should have a number of teeth fairly close to the number of teeth to be cut; a good guide as to how close the sample should be to the number of teeth to be cut is the range of numbers of teeth for a regular set of single tooth gear cutters; the lower of number of teeth, the more important this is, as the form of the teeth changes much more radically at the minimum numbers of teeth, and less as the numbers increase.
Carbide would be my last choice for a cutting tool for this purpose.


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## alb (Sep 1, 2013)

Thanks for the info
The gear I was making is just for my lathe so I can do some thread cutting.
The tool is cobalt so very hard but I am only going to cut nylon,plastic and brass gears so abut over kill

Alb


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## Tom Griffin (Sep 1, 2013)

Nice job cutting the gear. Gears _are_ a lot of fun.

Making a hob is another way to do it that closely replicates an involute gear form. Here's a link:

*Making a Gear Hob*

Tom


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## alb (Sep 1, 2013)

Thanks Tom

That looks great I will investigate that a bit further 

Alb


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## BRIAN (Sep 1, 2013)

Nice job. 
Another way of making a cutter is to turn the profile on a piece of silver steel then halve it and harden it like this.



Its easy and works well.

I will be in St Andrews  for a holiday and to see the family next week, so dont use up all the sunshine.
Brian.


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## alb (Sep 2, 2013)

BRIAN said:


> Nice job.
> Another way of making a cutter is to turn the profile on a piece of silver steel then halve it and harden it like this.
> 
> View attachment 59896
> ...



Thanks Brian,

That looks great I will try that method out next
Enjoy st Andrews it's beautiful even in the rain.


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