# Small Internal Grooves



## rake60 (Sep 3, 2008)

We recently finished up a job at work that had a small (.628") bore in one end.
The print called for two .090" wide shallow O-Ring grooves to be cut in that bore.

That part of the job fell into my coworkers shift.
The next day I went in and saw perfect grooves in that bore with no chatter at all.
Today he told me that he had cut the grooves with an end mill. ???

He did indeed! An end mill in a small boring bar holder.
Here's my rough copy of his mini internal grooving tool.







The flutes are simply ground away leaving one side with the top width needed for the
groove. The spiral of the flute makes it free cutting and the chip curls out of the bore
instead of binding on the tool.

And they say old dogs can't learn new tricks! 

Rick


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## Hexbasher (Sep 4, 2008)

i make tons of boring bars (as well as d-bits) from 8 dollar(cheapy's) 1/2 2 flute hss end mills at my new shop i work at

i hand grind simple single point boring out of old end mills all the time for boring heads (superior for aluminum IMO)

one time i had to do a weird gloove in a milled part on the cnc...i used our d-bit grinder like a cylindrical grinder and buzzed off the flutes so the endmill became a "t slot" culler thats 2mm high....it was an aluminum part and and only 1.75mm deep or something..easy...(o-ring seal around a pocket)


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## rake60 (Sep 4, 2008)

I happen to work with a guy who is an EXPERT tool modifier! LOL

We had a meeting with a tooling manufacture about a week ago and he was
telling the factory reps what he had ground and modified for a particular use.
The factory reps were laughing all the way.
*"We have this tool that is MADE to do that!"*

$200 for a tool you might use once a year.
A little hand grinding at a standard on hand tool works just fine.

$200 is nothing to a machine shop's purchasing agent, but if it's something you
don't really need in the first place because you've found a way to get past it, why
bother?

Machining work is 90% mental and 10% physical.

I have to be an expert since I've been referred to as being *"Mental"  * most of my life!






Rick


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## chuck foster (Sep 4, 2008)

where i work we use nothing but solid carbide end mills, when they break or get dull the boss says to just throw them away.
when broken i understand throwing them away, but when they are dull i would think you just send them out to be sharpened.
 since we throw them away i bring the smaller ones home and use the carbide for my boring bars. the bars i made have a round hole drilled at right angles to the bar and a set screw is used to hold the carbide in place. so i just sharpen the carbide to the shape i want and put it in the boring bar and off i go ;D

i hate to throw away stuff that can be used or recycled.

chuck


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## Hexbasher (Sep 4, 2008)

i save damn near every broken tap, endmill, whatever....

i have afew 'crashed' indexable tooling i've refurbish as well


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