? How to use really small end mills to mill really thin slots

[Chris333]

Max, I have a side business for you, cutting keys!  I have a Honda and the metal part of the key is molded into the plastic handle. The plastic cracks and the key snaps off. One of my keys broke long ago and the other was on it's last leg. I bought 2 blank keys on ebay. Today I had them cut. It was $100 to cut 2 keys. They didn't swap out my remotes. They didn't swap out my immobilizer chip. Just cut the keys.

In the end it was way cheaper than going to the dealer, but still! 

They didn't have this machine, but it gives you an idea of what they had to do.

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[peteski]

Using Max's manual milling machine, it would cost much more than a $100 in his time spent first on calculating all the movements and then on very carefully (manually) cutting the patterns.

[mmagliaro]

Yeah, that's nuts.  If ever there was an application for CNC, it would be key cutting.   If you
had a catalog of key patterns, you could put the blank in the machine, select the correct pattern,
and just let the machine do its thing.  I will not be manually cutting car keys any time soon.

[Chris333]

In the video it is CNC. They can cut the key with just your VIN number. I think the place I went had some sort of duplicator that just traced my original key, sorta how regular keys are made.

A VW key is similar, but instead of cutting both sides you cut right up the middle:
http://cdn1.bigcommerce.com/server4100/q0hpod6/product_images/uploaded_images/imag1948.jpg

[mmagliaro]

Well, this ends on a happy note.

It turned out to be easier than I thought.

I used a 3/64 2-flute carbide cutter, and tested it cutting some .093" thick brass.
I was easily able to cut a sideways slot into the brass, taking only .015" of depth per pass
with the mill running nearly full-out (about 2500 rpm).

Then I figured, what the heck, and tried milling the whole slot in one pass (depth of > .093, so it just
cut sideways through the brass, making a slot).

It worked perfectly.  No broken bit, no chattering, no mishaps.  I think my calculation from the speed/feed
calculator said 1/2" per minute or so.  I was feeding much slower than that.  I just used two hands on
the handwheel and tried to keep it steadily rotating without any jerking in the motion.   I cut a slot
about 1/4" across in several minutes.

Since I am apparently able to make this cut with a relatively slow mill and a full cut not requiring multiple passes,
I know I can do this without much hassle. 

[narrowminded]

NICE!!!