Sharp end mills

[Steamwhisperer]

I saw this little gem in one of Harold Halls books and thought I would give it a shot. Gotta say it works well and only needs an offhand (bench) grinder with a flat work rest that is height adjustable.
It is very easy to put both primary and secondary clearances and can also do slotting drills as shown but with a shim placed between the tool holder and the adjusting block to facilitate the uneven cutting edge lengths.

Phil

[Anorak Bob]

So Phil,

I take it that it is an adjustable depth stop and that the tool holding block is hand held against the stop and you require a block for each diameter cutter?

Looks dead simple.

BT

[Steamwhisperer]

So Phil,

I take it that it is an adjustable depth stop and that the tool holding block is hand held against the stop and you require a block for each diameter cutter?

Looks dead simple.

BT

Spot on Bob.
That's exactly how it works and before you say anything I am going to neaten it up. Give it the Bob treatment you might say.

Phil

[tongleh]

A lot simpler than a tool and grinder cutter, but how does the block with the spring and plunger interact with the one that holds the end mill?

[Steamwhisperer]

The block with the spring and plunger is an adjustable stop so you can gradually feed the tool into the wheel.

Phil

[Ueee]

Hi Phil,
It is a very simple and elegant way to sharpen the ends of cutters....but i must say it is always the flutes that i blunt before the ends. Does it really need the BT treatment? it has a nice solid "industrial" look as it is.

[Steamwhisperer]

Hi Phil,
It is a very simple and elegant way to sharpen the ends of cutters....but i must say it is always the flutes that i blunt before the ends. Does it really need the BT treatment? it has a nice solid "industrial" look as it is.

Hmmm I like the sound of solid "industrial" but Bob has set the standard and at the very least I 'must' try. :D

Phil

[fxst]

Which book was it Phil looks like a quick and simple fix to my blunt end mills.
Pete

[Steamwhisperer]

Which book was it Phil looks like a quick and simple fix to my blunt end mills.
Pete

Hi Pete,
I am still struggling to find which book it is in but it is featured in the Model Engineers Workshop number 170. I am confident I have a copy if you can't locate one.

Phil

[WCD]

I am still struggling to find which book ....

The book is Harold Hall's Tool and Cutter Sharpening - page 53.

Bill

[Anorak Bob]

I'm looking at page 53 and I reckon Phil's version is an improvement on Hall's. With Hall's, infeed is provided by means of his grinding rest and its integral feed mechanism. Phil's version is far more simple and can be used on a plate attached to a bench grinder's standard rest. I like it very much and have enough knackered end mills and slot drills to warrant lashing out and making my own.

I might be able to wring some usefulness out of the Hercus T and C grinder after all. A plan is hatching.

BT

[Steamwhisperer]

I'm looking at page 53 and I reckon Phil's version is an improvement on Hall's. With Hall's, infeed is provided by means of his grinding rest and its integral feed mechanism. Phil's version is far more simple and can be used on a plate attached to a bench grinder's standard rest. I like it very much and have enough knackered end mills and slot drills to warrant lashing out and making my own.

I might be able to wring some usefullness out of the Hercus T and C grinder after all. A plan is hatching.

BT

HI Bob,
I found it very easy to use and it does a great job. All I did was work out what angle was created as the table height was raised in reference to the wheel. That way the primary and secondary clearance angles could be set.

Phil

[fxst]

Thanks for the info ...Now I can look for it :D
Pete

[Anorak Bob]

Hey Phil,

Is cross feed involved in the sharpening operation or only "plunge" grinding? If cross movement is a feature of the sharpening process, how are you achieving it?

And is there anything that you would change about the design?

Bob.

[Abratool]

Phil & Bob
Thanks for the idea of sharpening end mills.
I think it can be done by holding the end mill in an indexing fixture, mounted on a surface grinder & traversing the end mill past the side of the wheel to a predetermined stop.
I will give it a try.
The ideas on this Forum never stop. One idea leads to another.
regards
Bruce

[Anorak Bob]

Phil & Bob
Thanks for the idea of sharpening end mills.
I think it can be done by holding the end mill in an indexing fixture, mounted on a surface grinder & traversing the end mill past the side of the wheel to a predetermined stop.
I will give it a try.
The ideas on this Forum never stop. One idea leads to another.
regards
Bruce


Along these lines? (see below)

I have another question. Some of my cutters are badly chipped. To remove the damaged section entirely before resharpening the end, how does either cutting the section off with a thin slitting wheel like those that fit a Dremel ( the ones that go puff when the disintegrate :o ), or sanding it off with a coarse disc on a faceplate sander sound? I have a pair of unused Charkson end mills that lost their corners in transit from the UK. The larger is about an 1 1/4" in diameter. The rest of the cutters have suffered from misadventure in my hands. :doh:

BT

[Michael G]

I'd vote for the thin cut off wheel in an angle grinder.
With respect to the cutter with the chipped corner, it may be better to grind all four corners with a deliberate chamfer. You won't get a square corner out of the cutter but it will stop the corners being further damaged. I've seen cutters sold like that somewhere.

Michael

[Steamwhisperer]

Hey Phil,

Is cross feed involved in the sharpening operation or only "plunge" grinding? If cross movement is a feature of the sharpening process, how are you achieving it?

And is there anything that you would change about the design?

Bob.

Hi Bob,
Plunge cut is the method used. I dress the wheel first and set the stop so the end mill is just kissing the wheel. I grind the primary clearance first then raise the table to the appropriate height and grind the secondary clearance.
The only real modification was to make a detachable, larger diameter, head for the stop so I could sharpen slotting drills as well. I had to do this because of the different length cutting edges of a slotting drill. The inside end of the cutting edge has to be in line with the outside of the wheel. When the holder was rotated 180 deg, I needed to place a spacer between the holder and the stop mount to realign the inside end of the cutting edge. The original specs meant that the holder missed the stop. With the larger head on the stop it didn't interfere with anything when grinding either cutting edge. Of course with an end mill, all four cutting edges are the same length. Just going out to the shed to take some pics.

Phil

[Steamwhisperer]

Here are some pics.
First one is the larger head and the second one is the plate that mounts to the grinder work rest.

Phil

[Steamwhisperer]

Another couple of pics. One showing the setup and the other the adjustable work rest for the grinder.

Phil

[Abratool]

Along these lines? (see below)

I have another question. Some of my cutters are badly chipped. To remove the damaged section entirely before resharpening the end, how does either cutting the section off with a thin slitting wheel like those that fit a Dremel ( the ones that go puff when the disintegrate :o ), or sanding it off with a coarse disc on a faceplate sander sound? I have a pair of unused Charkson end mills that lost their corners in transit from the UK. The larger is about an 1 1/4" in diameter. The rest of the cutters have suffered from misadventure in my hands. :doh:

BT
Bob
Identical, in every detail to what I had in mind.
Even to using the Hercus Indexer, & even the colour is the same!
regards
Bruce
ps I will get to set up some photos again, just been having trouble getting them across from the Computor File. Cannot figure it out, but hoping Sue can help.