Author Topic: A Simple End Mill Sharpener  (Read 1756 times)

Online cnr6400

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Re: A Simple End Mill Sharpener
« Reply #15 on: January 12, 2023, 04:34:09 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp:  :cheers:

Nice job Steve! That is a nice tool you've made there, at a fraction of the cost and effort of some of the more fancy tool / cutter grinder designs that are available. Thanks for sharing the details.

One key point about tool sharpening in general - minimal force is needed to sharpen the tool, whether someone is using the side of a grinding wheel for sharpening, or a disc sander, or anything else. I think people pushing against grinding wheels too hard caused some of the safety rules about grinding wheels to be needed! :thinking:

The disc sander approach is great because it will make a planar cut every time. For endmills, do you use a jig to check, grind, and re-check to get the lips all cut to the same end position?
"I've cut that stock three times, and it's still too short!"

Offline vtsteam

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Re: A Simple End Mill Sharpener
« Reply #16 on: January 12, 2023, 05:02:33 PM »
Ron, thanks kindly!  :cheers:  I made a lathe tool jig for the same sander, mainly for shaping and sharpening an Acme thread tool, since otherwise, like you, I tend to freehand regular lathe tools on the bench grinder.

The jig fits on the square side of the mill cutter guide strip (90 degrees to the table) and an additional strip. The lathe sharpening jig does have an adjustable angle. And the sander's table is tilted DOWN below horizontal for lathe tools, unlike for end mills)

Steve

Offline vtsteam

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Re: A Simple End Mill Sharpener
« Reply #17 on: January 12, 2023, 05:13:09 PM »
:ThumbsUp: :ThumbsUp: :ThumbsUp:  :cheers:

Nice job Steve! That is a nice tool you've made there, at a fraction of the cost and effort of some of the more fancy tool / cutter grinder designs that are available. Thanks for sharing the details.

One key point about tool sharpening in general - minimal force is needed to sharpen the tool, whether someone is using the side of a grinding wheel for sharpening, or a disc sander, or anything else. I think people pushing against grinding wheels too hard caused some of the safety rules about grinding wheels to be needed! :thinking:

The disc sander approach is great because it will make a planar cut every time. For endmills, do you use a jig to check, grind, and re-check to get the lips all cut to the same end position?

Thank you kindly cnr 6400! :cheers: I have to admit, I have only just free-handed the mills I've sharpened, not checked lip geometry at all, and then proceeded to mill. I have thought about rigging a simple stop to regulate cutting depth for both lips, but never got around to it. I'm a poor example to follow, and I think anyone with a brain would add that and be done with it. Or at least, as you say, measure the lips to make them even.

For some reason, the mills I've sharpened have not complained about it. I do, as you say, merely touch off the edges -- no serious grinding so far. I suppose a person might with minimum bother and more sense than me, hold a mill vertically on a small bit of plate with a light behind it to see if both lips touch at the corners. Hmm, maybe I'll do that........
Steve

Online Kim

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Re: A Simple End Mill Sharpener
« Reply #18 on: January 12, 2023, 05:33:38 PM »
Very cool little sharpening jig you made for your disk sander, Steve!

Thanks for taking the time to share it.  You do make sharpening an end mill look like a doable proposition!  Do you sharpen carbide end mills? Or just HSS?

Kim

Offline vtsteam

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Re: A Simple End Mill Sharpener
« Reply #19 on: January 12, 2023, 05:40:52 PM »
Hi Kim, thanks so much!  :cheers: I've never tried carbide, and I suppose you'd need a special abrasive for the sandpaper for them. I don't even know if that's available. I have owned so few carbide mills that it just hasn't occurred to me to try. but I do know you need the green abrasive wheels on a regular grinder.

My recent carbide mill loss was due to broken off teeth, so would probably need complete re-making of all angles, etc.
Steve

Offline vtsteam

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Re: A Simple End Mill Sharpener
« Reply #20 on: January 12, 2023, 06:56:49 PM »
A few post scipt thoughts for anyone interested in building something similar.....

1. A disk sander is easy to make out of an old motor. A 5" disk would be needed to fit standard sandpaper disks in the U.S, but if you have a lathe, it's pretty easy to make.

2.) A non tilting table set to 6 degrees can be just a block of wood clamped to a table, with a miter groove routed or chiseled into it. It is not traversed when sharpening end mills other than to just set the position of the mill, so it isn't a precision sliding requirement.

Six degrees yields a fairly robust edge, 5 to 9 is the reported range for steel and cast iron. I imagine lower would work better for brass and copper. The nice thing about sharpening your own end mills is you could tune them for what you need. If you are using a simple block for a table, make a few with different angles.

3.) Lacking a spot welder, or brazing equipment, I'm pretty sure a good epoxy would work fine for putting the slide pieces together, as long as the metal was well cleaned. JB Weld would seem suitable. There's really very little pressure on any of the parts when sharpening. the main pressure is downward towards the table, and cuts are very light. There's none of the danger of a bench grinder.

4.) Be sure to put the 1-1/2 degree angle on the correct face and in the right direction of a guide strip. It should cause the mill end to be concave, not convex!

5.) The less the sliding table thickness the better. That's why I used 1/8" material. Same for the holders. Ideally the mill should just touch the sanding disk on the same horizontal line as the center of the disk.

Mine doesn't, it's a little above, but it's okay. Too high, though, and the edge of the sanding disk will cross the center of the mill at an acute angle. You could angle the mill in its holder to compensate for that, but that isn't ideal, and takes some extra estimation. Ideal would be a slightly lower base table to compensate for the mill's center height-- and if you're making a fixed table out of wood, you can drop it down a little to make it perfect.

In my case the center of a mill is 1/8" plus 1/2" (table thickness, plus mill holder center height) or 5/8" higher than ideal. It works fine, but if I were building it from scratch, I'd lower it 5/8".

5,) I mentioned above that the relative lengths of the lips of the cutter could be checked against a bit of flat plate with a light behind it to see that the corners both touch. The corners on an end mill are longer than the center is. So it's the corners you are looking at, and the corners that do the bulk of the cutting.

Well, now thinking about it, even better than a plate would be using a combination or machinist square. Lay the mill vertically against the long thin arm, with the tip onto the wider base, and sight through that combo against the light. That keeps the mill square to the base. Look at the corners. Pretty much the same principle as a drill gauge.
« Last Edit: January 13, 2023, 02:52:46 PM by vtsteam »
Steve

Offline samc88

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Re: A Simple End Mill Sharpener
« Reply #21 on: January 13, 2023, 10:40:28 AM »
Great idea! Ive used my parkside cheap disk sander a couple of times for lathe tools, I think Ill have to have a go at making an end mill fixture

Offline ShopShoe

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Re: A Simple End Mill Sharpener
« Reply #22 on: January 13, 2023, 01:46:13 PM »
Just a note regarding disk sanders like the example shown, primarily sold for woodworkers.

I have one and one day  I decided it had a lot of hours on it and might benefit from a cleaning and adjustment session. I started wondering about the disk sanding surface and did a little testing and found it was not flat and not square to the shaft or the table. I ended up making a mandrill and then I chucked it in my lathe and refaced it.  I also "balanced" it with the help of my mower-blade balancing tool. The result turned out to run smoother and be easier to use.

Might be worth a try.

ShopShoe


Offline vtsteam

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Re: A Simple End Mill Sharpener
« Reply #23 on: January 13, 2023, 02:40:05 PM »
Mine doesn't wobble on the shaft. As far as being square to the table, that is adjustable since the table and guard are a removable unit and held down to the sander by screws in slots.

It's actually a nice combo, since I can easily remove the guard and pivoted table to change sanding disks, without disturbing the angle that the table is set at (6 degrees for my end mill sharpening)

BTW, forgot to mention above, another handy thing to have is a 84 degree gauge cut out of sheet metal for setting the 6 degree bevel on the sander. Or again, it could be made of wood. And other convenient angles can also be made up as gauges for lathe tool sharpening, or -- if like me you sometimes bevel wooden patterns for metal casting. A small disk sander is a very handy thing to have around.

I mention wood above for extreme budget builders, beyond even my "rat" mill sharpener, but of course far more beautiful and elegant jobs could be made of it in aluminum or brass even. I might some day pretty mine up, as well. Meanwhile, it does sharpen mills quickly and easily.
Steve

 

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