Sharpening End Mills At Home (probably?) - Acute Tool Sharpener Conclusion

This episode on Blondihacks, I’m working on a tool sharpener! Exclusive videos, drawings, models & plans available on Patreon!

Official Eccentric Engineering videos for this system:

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[Blondihacks]

Lots of folks asking how this compares to the D-bit grinder. Main thing is this kit has more options for tool holding. The D-bit grinder only holds round tools of a couple of specific sizes because it is designed for D-bits. There are head attachments for grinding square tools and other things, but they are expensive, and in the case of my vintage Kuhlmann, unobtainable. Is a D-bit grinder better if you have all those attachments? Of course. It’s a $2000 machine. This is a hobby kit you can build for a few bucks worth of steel. It fills a niche since most hobbyists don’t need or want a full tool and cutter grinder.

Also, FYI, this is not a sponsored video. I wanted to try the kit so I did. This is my honest impression of it.

[RonCovell]

Congratulations, Quinn, for finishing a rather complicated project. I didn't understand how all the components worked together until now, and it does seem clever and well-designed. I always appreciate your thorough and un-biased analysis of tools like this.

[bobblaine]

I've taken to 3D printing caps for my end mills that I take off once it's in place on the mill and put on before I take it off the mill.

[fromjunknewstuff]

I have built mine about 6 years ago and I really like it. Like most tool grinding machine they are a bit tricky to use and you need to refresh how to use them, unless you use them on a regular basis. So I usually set aside a few cutters and after doing one, the rest is pretty easy.
I found that a CBN wheel help me get a more consistent and accurate finish. When first setting up a new grinding angle, I initially only rotate the CBN wheel by hand a few turns and then verify the cutter end bluing to see if my set up is near perfect or way off and make the correction. Using this technique helps to to find and match the manufacturing original grind and duplicate it. Using this gentle approach to the grinding wheel help me a lot to understand and setting the angle to many other cutting tools. Powering the grinder and have a go at it, almost always removed to much material to then realized I have gone to far and lost my manufacturing reference grind.
I have resurrected quite a few endmills and have been quite please with the cutting edge I have achieved using the acute tool sharpener.
I like the table rest so much, I built a second and it gets used way more than the acute sharpener. The acute sharpening system is wrapped in a dust cover which will keep it grit free and running smooth next time I need it.

[paullehmor]

I experienced exactly the same issues with my first attempt to sharpen a two flute 10 mm end mill. Warning: The front of the tool block gets hot! I burnt my finger tips and now have to cure them before trying again. I also made a round 6 mm tool bit for my boring head from round HSS tool steel bar stock, and a 8 mm square tool bit for the fly cutter. The surface finish on aluminium turned out excellent in both cases! Tip: If you fasten the angle gauge in the slot of the setting block with the grub screw, and then set the block on top of the slide (or work head), you will have both hands free to adjust the table. This is why there is a cutout at the bottom fitting the locking peg on the slide (and similarly on the work head) and a magnet to hold the block in place. It's not mentioned in the videos, I got the tip from Gary. 🙂

[pointerish]

I’ve been enjoying your channel for a while now. Thank you for making these videos. Someday I’ll have the room to own a lathe!

[firbolg]

Very cool! I sharpened a lot of HSS drills but most of the mills I worked with were not easily sharpenable since I mostly machined heat treated steel and stainless. We used HSS drills for really large bores but everything else was with tungsten and other sintered alloy tools with even fancier coatings (every time I broke one I felt like shit but that was a rare event and then again my CNC hadn't been serviced properly ever in its 18 years of life).

We would usually send mills for sharpening and re-coating to a specialist company. Regarding brands, can't go wrong with Sandvik Coromant! Very expensive but equally very good! And you're absolutely right, low rpms and high pressure are the proper way to drill using HSS drills. Thanks for another great video! Fascinating to watch!

[warriorchrist]

I'm glad you feel all your little blunders it helps us to maybe not make the same mistakes

[LaraCroftCP]

Resharpening endmills is very interesting. I dont own a propper mill but i had to mill a 6 mm slot in a piece of steel and i only had one bad old 6 mm endmill. So i took a oilstone and freehand the geometry and to my total surprise it worked excellent. Good cuts in steel but because i used a modifyed Drillpress it took a lot of time so i made a custom cold chisel to clean the rest and chiseled the slot by hand, that was so much fun and i got even square ends of the slot like i prefered for the application.
But the sharpening System you build is impressive, some practice and you will can sharpen your Endmills without problems. Even your first try cuts so it only can get better.

[JohnGrindley-em]

Hi Quinn, I purchased the plans and built my own, don't beat yourself up, he makes it look a lot easier than it is, I'm sure with a lot of practice it will do a good job, I have a handful of old cutters I use to try with but not had any more success than you. Best regards John UK.

[joeybobbie]

Hi Quinn, This was a really interesting series. I’m looking forward to Building one to use for Sharpening Lathe Tools. It looks like a fun build. Thanks for the Videos. I’ll definitely be coming back to them.😁👍👍

[BrianFullerton]

The end mill geometry is fun to think about. Until it hurts:)
Prior to cutting the primary, and after cutting the secondary, do you need to reset the angle of the mill in the holder using the gauge block? Thinking "maybe" as the material removed works the bottom cutting edge up the helix, and it will matter if a lot was taken in the secondary vs a little. Cutting the secondary back "rotates" the cutting edge of the mill relative to the grinding wheel, no?

[joergengeerds]

re: endmill sharpening: there are a great many deal of shops that offer endmill sharpening. they have a big advantage since they use CNC diamond wheels: any number of flutes and helix angles are possible, especially modern carbide low helix with variable cutting edges (limits vibrations). given the cost of a good 1/2in carbide endmill of about $50 usd, the sharpening costs around $10 for those, so well worth it. the other advantage is rehabilitation, when flutes are chipped, the endmill can be shortened, or ground down to a smaller diameter. plus you get to choose a corner radius. I had a handful of endmills that I had ruined in the beginning, due to beginners stupidity. getting them fixed got me back tools that were far better than when they came from the factory.

[JustGuyMetalworks]

That was a fun project 😊. It's kinda hard to sharpen mills when all you have is straight geometry to work with.
I recently made a quick n' dirty chamfer mill (ended up to be left handed 😂) but I found it to be a little tricky getting the appropriate reliefs. I'm gonna have to revisit that one 😏.
Great vid as always 😁.
Cheers!

[backi]

Quinn that Rant about "being the Drillpress" .. love it ! 😎

[EngineerRaisedInKingston]

Congrats on finishing this colossal project, Quinn! What a clever bit of engineering that is. Really admire your ability to tackle these projects in tandem with your locomotive build as well. Can't wait to see what's next!

[DJMateo]

We generally won't resharpen an endmills from customers unless they are large diameters because of 2 reasons;

1 being that the deeper you regrind, the more and more the endface will be offset from the gash due to the helix and the hook angle will no longer be straight so the endface technically has positive rake.
2 is as you can see, it essentially ruins the center cutting ability since the gash falls away from center the deeper you go. Not a big deal for a home machinist, but it can no longer plunge as well as it did with a true center cut

[guye]

I made one of these about 12/12 ago. Probably not as well as you did but my end experience was exactly the same. I buy end mills and use it for lathe tools. It was well worth it overall.

[ulrichs.]

I will admit that "8 degrees and 5 degrees makes 13 degrees" is the one part that I understood and I shouldn't be trusted with anything more mechanical than a Lego brick, but I appreciate being able to come here every Saturday night local time and watch you know what you're doing. Thank you!

[johnapel]

That turned out great! I wondered how it would actually work. Neat!
Thanks, and Meow to Sprocket.