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11 comments

Simple End Mill Sharpening Jig

Posted September 04, 2018 9:15 AM by Del the cat

I've been having fun with my little mini mill, but I noticed the 10mm end mill was getting a bit worn where I'd been using it to improve the quality of my cheapo drill press vice by machining the faces.
I've bought a book about milling and it shows a really fancy sharpening jig with about 10 parts and springs and stops etc.
I thought it would take an age to make and I didn't have the right size material.
Most of you know my love of wood and simplicity, so I made a simple wooden jig, using a long lever to give a controlled feed rather than a screw.
I don't have a bench grinder as the fine wheel in the drill press, or the belt sander serves as well.
It didn't take long to make and it works a treat. It can be adjusted to give a honing angle too but I didn't bother as the edge it produced was already a vast improvement.


I gave it a quick try out facing a bit of steel and the finish was greatly improved. (The pic of the face was taken after the test)

I may produce an improved version, but why bother when it does the job?
Del

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#1

Re: Simple End Mill Sharpening Jig

09/04/2018 10:11 AM

PS. The cheapo drill press vice was a rough cast iron which still had a bit of a skin on it in parts which is why it blunted the mill rather quickly.
Del

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#3
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Re: Simple End Mill Sharpening Jig

09/04/2018 11:33 PM

I can't tell how you set the rotational position of the endmill, but the results speak for themselves.

If you did the same thing using the mill instead of the drill press, then you could use the table feeds to adjust your depth of cut.

For rough cast iron, you really ought to use a carbide endmill. To sharpen those, you need a diamond wheel of some kind. Fortunately, some of those are pretty cheap now.

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#5
In reply to #3

Re: Simple End Mill Sharpening Jig

09/05/2018 3:03 AM

The arm with the mill bit swings back and forth so I can pull it right back to rotate the bit, aligning it by eye then tightening the pinch bolt.
To start off I just touch it to the stationary wheel and then make a pencil mark on the base arm about 1 mm away from the edge of the movable arm.
Start the wheel, push the movable arm (to press the bit against the wheel), stopping when it touches the pencil mark. There's 4:1 leverage, so the 1mm movement at the end of the arm is 0.25mm at the bit, and any error is similarly reduced to 25%.
Here's a pic with the arm swung back.

Del

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#2

Re: Simple End Mill Sharpening Jig

09/04/2018 12:22 PM

What is it that 'they' say?

Perfect is the enemy of good enough.

Nice job!

There's a lot one can do with a little thinking and a little fiddling.

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#4

Re: Simple End Mill Sharpening Jig

09/05/2018 1:04 AM

Looks good.

I gather that you moved the the quill to grind the face and increased the cut with the wedge at the cutter end about a pivot at the furthest end (close in the picture). The clearance is produced by the radius of the grinding wheel. Am I correct?

  • How did you index the cutter through 90º?
  • Is the cutting face at 90° to the cutter axis or does it have clearance towards the centre?

Tony

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#6

Re: Simple End Mill Sharpening Jig

09/05/2018 10:51 AM

First of all, a very good innovative way to recondition the end mill. I used a similar setup when I started with a small benchtop mill. I would like to offer a couple of improvements to the existing jig.

First, switch to an aluminum oxide wheel that will cut more freely than what looks like a silicon carbide wheel you are using now. 60 to 100 grit will produce a better surface finish on the ground surface. K or L hardness on the wheel is good for grinding high speed steel without burning the steel.

Second, add a diamond dresser holder that can clamp to the drill press table and get a single point diamond dresser. There are several cheap imported single point dressers on the market that use anything from a 1/8 to 1/2 inch diameter shank. Some are available with threaded shanks to use for adjusting the dresser. I typically use a 1/2" diameter dresser shank. On my drill press, I added an x and y cross slide vise and used that to hold the diamond dresser, but it's not necessary and a block with a hole in it and a set screw is enough. You set up the diamond dresser at an elevation below the grinding wheel, use the quill feed to bring down the grinding wheel and set the diamond dresser just in light contact with the OD of the grinding wheel. Then, with the grinding wheel running, you move the grinding wheel up and down across the dresser using the quill feed. It dresses the grinding wheel to a true cylinder and makes for a very smooth ground surface. That will actually extend the life of the end mill cutting edge.

Last of all, you might want to consider putting a guard around the grinding wheel to catch or deflect chunks if the grinding wheel breaks and possibly to contain some of the grit it generates. The grit eats machines.

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#7
In reply to #6

Re: Simple End Mill Sharpening Jig

09/05/2018 12:44 PM

Cheers, V useful post. I'm struggling to find decent 75mm (3") grind wheels but I'll persevere.
Now I've proved the concept, I'll possibly improve it.
I do have a diamond dresser, not a single point one tho', so I may look into that.
Del

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#8

Re: Simple End Mill Sharpening Jig

09/05/2018 11:01 PM

Del, what was the name of the book, is there an online copy we can review?

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#10
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Re: Simple End Mill Sharpening Jig

09/06/2018 2:33 AM
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#9

Re: Simple End Mill Sharpening Jig

09/05/2018 11:08 PM

What method are you using to give the long lever a controlled feed ?

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#11
In reply to #9

Re: Simple End Mill Sharpening Jig

09/06/2018 2:35 AM

Finger, thumb pressure, the movement is only about a mm at the end of the lever.
Del

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