# Sharpening a milling cutter



## ecdez (Jan 17, 2017)

So I have one of these that's gotten a little dull.  I understand the sharpening process but I do not have a fixture for it and only a surface grinder to work with.  Is it even possible with what I have (and can make for a fixture) or is all lost and I should cough up the money for a new one.  Getting it professionally sharpened could be an option as long as it's not the same price as a new one but I'd prefer to do it myself if I can.  That's kind of the hobbyist slogan right?


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## T Bredehoft (Jan 17, 2017)

On the magnetic table of your surface grinder, (or remove it and bolt the following to the table) build an arbor, that will just slip in the bore of  your cutter, and hold the surface to be ground at the appropriate angle, leaving relief on the cutting edge. You might  wind up needing two fixtures (one for each side). Incorporate a spring loaded device/finger that will allow you to move to the next tooth and grind it just like the one  you just did. 
By grinding each tooth, one at a time, you ought to be able to sharpen the grinder, but be slow, don't try to take it all at once, you don't want to introduce any heat.
You could incorporate a ball bearing for smooth rotation. There are lots of possibilities.


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## 4GSR (Jan 18, 2017)

Go buy you another cutter.  You may destroy one trying to sharpen it.  They do sell a simple fixture for holding this type of cutter to sharpen.  It'll work for either a T & C grinder or surface grinder.  I just can't put my fingers on a picture of it at the monment.


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## rgray (Jan 18, 2017)

here's a couple of ideas:
https://books.google.com/books?id=c...#v=onepage&q=convex cutter sharpening&f=false

https://books.google.com/books?id=S...#v=onepage&q=convex cutter sharpening&f=false

I was thinking of a between center fixture on the surface grinder with a mandrel to hold the cutter and some kinda stop made to index the tooth. And a sine fixture or dress a wheel to the needed angle.
Between center fixture with table direction and cutter to be sharpened below wheel.


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## ecdez (Jan 18, 2017)

T Bredehoft said:


> you don't want to introduce any heat.



I'd only be skimming off a tiny bit and I have a small mist cooler so heat shouldn't be a problem but I'll keep an eye on it.




4gsr said:


> Go buy you another cutter.  You may destroy one trying to sharpen it.  They do sell a simple fixture for holding this type of cutter to sharpen.  It'll work for either a T & C grinder or surface grinder.  I just can't put my fingers on a picture of it at the monment.



If I'm going to buy a new one I'll definitely be trying to sharpen this one first. Only one way to learn.

I think this is the fixture you might be thinking of.









rgray said:


> here's a couple of ideas:
> https://books.google.com/books?id=cc8DAAAAMBAJ&pg=PA125&lpg=PA125&dq=convex+cutter+sharpening&source=bl&ots=DMorx8PaUt&sig=ICu5TbN3K7qVtm0JEsztWWAGseE&hl=en&sa=X&ved=0ahUKEwiTvaTqhs3RAhXK2SwKHWYfCAgQ6AEIMjAI#v=onepage&q=convex cutter sharpening&f=false
> 
> https://books.google.com/books?id=SryjBgAAQBAJ&pg=PA385&lpg=PA385&dq=convex+cutter+sharpening&source=bl&ots=sbXSYdvaKR&sig=MbZ7h4X1abbgQlzVkdvyIQhJOQ4&hl=en&sa=X&ved=0ahUKEwiTvaTqhs3RAhXK2SwKHWYfCAgQ6AEIPDAL#v=onepage&q=convex cutter sharpening&f=false




Excellent links, thanks!


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## Downunder Bob (Feb 11, 2017)

ecdez said:


> I'd only be skimming off a tiny bit and I have a small mist cooler so heat shouldn't be a problem but I'll keep an eye on it.
> 
> 
> 
> ...


That is a simple fixture that will work. But you might want to consider sharpening on the front face, with one single setting you will sharpen the circumferential face and the two side faces. You still may need to take many light cuts to avoid overheating. Most production machine shops use this method. It is quicker, therefore cheaper and requires less skill in the setup. It also allows the continued use of damaged cutters.

 When using either method you should take a light cut then index the next tooth take a light cut and continue right around, until you've done all teeth to be sharp. A very important advantage of this method is you are NOT altering the cutter profile. 

Also if you have one or two teeth that are chipped, you can grind them a bit further after the rest are finished, it will not affect the overall performance of the cutter. With this method it is not really important to take the same amount off each tooth, just enough to sharpen it. Whereas cutting the relief angle on the OD. it is critical to take exactly the same amount off every tooth  

Also if you ever have to sharpen  a profile cutter this is the only way to ensure you retain the correct profile, the best way to sharpen your "V"cutter.

Sometimes this type of cutter will have alternate teeth offset to either side, just do the alternate teeth in one setting and then adjust for the other side.

Happy sharpening and machining.


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