A Wallaby of my own.

[steamer]

Yes Custom made Unobtainium steel gears crafted by the trolls of the Swiss alps....somehow sounds pricey to me.......

Dave

[Don1966]

Gear up as they say, go thing you do know how to make another. Tough luck Dave, but practice makes pefect like Vince said. So I guess it will be awhile before the pinions get done. So show us how you make another cutter, that would be interesting.

Don

[steamer]

Sure Don....tomorrow.   I should get through the gears then also....famous last words....

Dave

[tel]

OUCH! I only run at about 350/400 rpm for gear cutting, and that's with commercial cutters!

[Maryak]

I more or less take the recommended fpm for carbon steel with a HSS cutter so for Drill Rod halve it. I don't reckon any of my machines are rigid enough for production cutting speeds. Then again I'm just a nervous nellie.

Best Regards
Bob

[steamer]

Ya I know guys  .....see responses above....I added some oil...but NO WAY!....at least not in steel

40 fpm ....is real!

Dave

[steamer]

OK

Gashing the gear first makes a big difference!   I took a .020 saw and gashed the teeth.  Then made up a new cutter with a cutter radius of about .38".

I set the speed to 250 rpm...which is 3.14159 x 2 x .38 x 250 / 12 = 49 fpm.

It seems very happy taking full depth of cut of .0707"....

I'll let you know how I make out

Dave

[steamer]

It's manual feed....and slow....I left the tool dead hard....I didn't draw the temper...I suspect the first pass would do that just fine.....
I have a copious supply of oil on it while cutting .....

Dave

[zeeprogrammer]

Hope you don't mind the questions...

What is 'gashed the teeth'?

To 'draw the temper'...is that to make less hard?

Thanks

[Dan Rowe]

A slitting saw was used to cut a gap before the profile cutter so the home made tool will survive a full trip around the gear if all goes well.

I hope all goes well.
Dan

[tel]

I think he meant 'gnashing the teeth makes ......' I know it helps when I do 'em!

[steamer]

That's what I meant Tel....

Here's some photos

The Gnashed teeth as I started to finish them with the flycutter


The finished product.




You'll notice the ring is removed.....

Dave

[tel]

Yeah, I knew what you meant. Nice job on the gears tho - gashed or gnashed!

And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth.
Matthew 13:42

[steamer]

Hope you don't mind the questions...

What is 'gashed the teeth'?

To 'draw the temper'...is that to make less hard?

Thanks

I think I answered the gnashed teeth question.
Drawing the temper is something you usually do with a hardenable steel.   In this case ...0-1

When first quenched, the hardness is considered "full hard" and is about 64 Rc.....harder than woodpecker lips!
It is also, generally speaking...brittle at this hardness.   So generally you draw the temper.

To draw the temper, one generally polishes the newly hardened part to bright finish.  Then , using a torch or an oven, the part is slowly heated and the change in color of the part....specifically the cutting edge of the part!...is noted.   It will start with a very light straw, to straw and progress to blue as the temperature rises.   As this tempering temperature rises, the hardness of the part decreases and the toughness increases.

For a cutting tool, A light straw at the cutting edge is correct.    Here's the problem though

This part is made of .187" diameter drill rod.....It will change temperature VERY rapidly...and if you go too far, the tool is too soft to use.  You can get a couple of trys....but that's about it.

In this case, the section of the tool is fairly stout....the cut is not deep, if I go easy the increase in temperature in the cut zone will be enough to temper the part, so I just stone the edge and use it as is.

Horses for courses....and some tools you really can't get away with this...but I figuired I could with this.. and it worked fine.

Dave   

[zeeprogrammer]

Thanks Tel and Dave.
Yep, understandable.
Yep.