Sharpening end mills

[Pete.]

I got a pile of end mills and slot drills of which probably there were 1/3 scrap 1/3 ready to use and the remainder in need of sharpening. I have a Clarkson tool and cutter grinder but never got any collets with it so I figured I would use what I have and make an adapter for R8 milling collets which I have a fair few of.

So I got a piece of steel, bored it to .950" and turned a taper in the front for the collets. This is 1.5" OD to fit the Clarkson work head I already had. The retaining coller comes off the original sleeve that came with the tilting head.

I had an ally disk that came off a stepper motor which had 8 index holes in it, so I decided to use that as a basic indexer. I bored the back of it to clamp the R8 collet.

One of the tooth rests acts as a stop and a close-fitting drill bit as an indexing pin.

And that's it - ready to sharpen end mills. I read up on clearance angles atc and got sharpening. These are staged photos BTW I always have the guard fitted.

Here's a typical end mill that's been used too fast. The tips are scorched but most of the cutter is fine.

A quick go-around on the primary and secondary angles and now it's so sharp you have to be careful how you handle it.

Now to protect these nice cutting edges.Following Andrew Mawson's idea I bought a 0.5L deep fat fryer off eBay:

And a couple of bars of Crocell.

Melted the Crocell in the fryer and used it to coat all my newly-sharpened cutters. A tip here - slice the Crocell up into little flakes or you'll burn the first bits and fill your workshop with smoke

 

[slim_boy_fat]

Impressive sharpening result there!!

Can you make chips in the Crocell.....?

 

[jsf55]

That's just take me back 45 years to when I was an apprentice and actually got to do stuff like that, nice job

 

[Richard.]

You don’t fancy a cash paying job of doing a few for me do you Pete. Drills I do daily but end mills I cannot get successful.
What’s the smallest size you can do?
Can you do ones I’ve had a go at and made worse?

 

[awemawson]

If you go out and buy a deep fat fryer for this application, make sure it is the type with the element bonded to the outside of the tank, not immersed in the tank, as some are, as it makes clean out nigh on impossible

 

[eLuSiVeMiTe]

If you go out and buy a deep fat fryer for this application, make sure it is the type with the element bonded to the outside of the tank, not immersed in the tank, as some are, as it makes clean out nigh on impossible

Whats the melt temp.
Would a wax pot work. (Leg waxing. )

Heating pots are removable too usually with a lid to prevent contamination

 

[Shox Dr]

Whats the melt temp.
Would a wax pot work. (Leg waxing. )

Heating pots are removable too.

Oh, now..you got me thinking...that would do for melting bismuth type stuff

 

[Pete.]

If you go out and buy a deep fat fryer for this application, make sure it is the type with the element bonded to the outside of the tank, not immersed in the tank, as some are, as it makes clean out nigh on impossible

This little £26 unit is ideal it has the element housed under the base of the pot in a raised relief so you can clean out the pot easily enough and there's quite a large heating area so it all gets hot very quickly.

Crocell needs 130-160 degrees so the 130-190 temperature range for this pot is ideal for it. Sadly it's not got the minerals for melting bizmuth, or at least not without modification which would probably kill the element.

Richard, yes I can sharpen your end mills, even ones that have been savaged. I have to be honest - once you set the rig up it's ridiculously easy to make a good looking cutter. I did some trials on some really rough ones that didn't matter if they got totally ruined and got quite a respectable cutter out of them. Currently I can't sharpen the flutes but that's my next project, making an air bearing to sharpen the flutes of end mills and reamers.

 

[eLuSiVeMiTe]

Oh, now..you got me thinking...that would do for melting bismuth type stuff

Quick Look suggest about 200 max so nope.

Something like that maybe
https://www.ebay.co.uk/i/2212754358...4%26rvr_ts%3Dc05ac94b1630ab6ad561bbc1fffb2c02

 

[Shox Dr]

Quick Look suggest about 200 max so nope.

Something like that maybe..

I’ve just had a look, and think a kettle with a rheostat fitted would do the job; builtin spout, and it’ll keep it warmer instead of decanting. Its for WS8 resin, simular to bizmuth but with a lower melting temp.

...aaaand we already have a kettle. Better tell her she can buy a new one

 

[Richard.]

This little £26 unit is ideal it has the element housed under the base of the pot in a raised relief so you can clean out the pot easily enough and there's quite a large heating area so it all gets hot very quickly.

Crocell needs 130-160 degrees so the 130-190 temperature range for this pot is ideal for it. Sadly it's not got the minerals for melting bizmuth, or at least not without modification which would probably kill the element.

Richard, yes I can sharpen your end mills, even ones that have been savaged. I have to be honest - once you set the rig up it's ridiculously easy to make a good looking cutter. I did some trials on some really rough ones that didn't matter if they got totally ruined and got quite a respectable cutter out of them. Currently I can't sharpen the flutes but that's my next project, making an air bearing to sharpen the flutes of end mills and reamers.

When you have time Pete no rush at all pm me an address and some payment details and I’ll get that over without delay. No rush at all to do the job though. I wrecked a few on my lathe tools bringing them down to centre height when I first got the lathe.
Edit I’m still up for the lead screw I’ve just gotta get round to stripping it out.

 

[RichardM]

Looking good Pete, Here's where I'm at at the moment having just got back from holiday:

bought a cheap finer wheel at Doncaster just to try out. Smoother finish but cutters need to be cooled when grinding.

Need to look at changing my design so I can accurately re-cut the centres of milling cutters. Probably just a bolt on plate so I can offset the cutter mounting move it across onto a cutting disk

20mm 20mm 8mm 8mm

I did make a guide tip (6mm cap head turned to 2mm diameter tip) for grinding the sides, but the movement was not smooth at the start so am thinking of revising it to a bigger radius piece of spring steel.

 

[ukracer]

I got a pile of end mills and slot drills of which probably there were 1/3 scrap 1/3 ready to use and the remainder in need of sharpening. I have a Clarkson tool and cutter grinder but never got any collets with it so I figured I would use what I have and make an adapter for R8 milling collets which I have a fair few of.

So I got a piece of steel, bored it to .950" and turned a taper in the front for the collets. This is 1.5" OD to fit the Clarkson work head I already had. The retaining coller comes off the original sleeve that came with the tilting head.

View attachment 143296

I had an ally disk that came off a stepper motor which had 8 index holes in it, so I decided to use that as a basic indexer. I bored the back of it to clamp the R8 collet.

View attachment 143297
One of the tooth rests acts as a stop and a close-fitting drill bit as an indexing pin.

View attachment 143298

And that's it - ready to sharpen end mills. I read up on clearance angles atc and got sharpening. These are staged photos BTW I always have the guard fitted.

View attachment 143299

Here's a typical end mill that's been used too fast. The tips are scorched but most of the cutter is fine.

View attachment 143300

A quick go-around on the primary and secondary angles and now it's so sharp you have to be careful how you handle it.

View attachment 143301

Now to protect these nice cutting edges.Following Andrew Mawson's idea I bought a 0.5L deep fat fryer off eBay:

View attachment 143302

And a couple of bars of Crocell.

View attachment 143308
Melted the Crocell in the fryer and used it to coat all my newly-sharpened cutters. A tip here - slice the Crocell up into little flakes or you'll burn the first bits and fill your workshop with smoke

View attachment 143303

View attachment 143304

How about a video of your set up and process??
i always see end mill sharpening as mega money to buy the right tool..

 

[Shox Dr]

@Pete. Would you post up your build, on the air bearing. I’ve a spin indexer I like to see if would convert

 

[Pete.]

Looking good Pete, Here's where I'm at at the moment having just got back from holiday:

bought a cheap finer wheel at Doncaster just to try out. Smoother finish but cutters need to be cooled when grinding.

Need to look at changing my design so I can accurately re-cut the centres of milling cutters. Probably just a bolt on plate so I can offset the cutter mounting move it across onto a cutting disk

20mm View attachment 14334020mm View attachment 1433418mm View attachment 1433428mm View attachment 143343

I did make a guide tip (6mm cap head turned to 2mm diameter tip) for grinding the sides, but the movement was not smooth at the start so am thinking of revising it to a bigger radius piece of spring steel.

What machine are you using Richard?

I also need to work on my centre gashing technique. I can get passable results by eyeing it in on the edge of the cup wheel but I'm going to read up on how to do it properly.

Looking at your pics I would say the wheel needs dressing. Do you have a dressing diamond? If you're dressing the wheel then I would say that it's simply too hard.

 

[Pete.]

How about a video of your set up and process??
i always see end mill sharpening as mega money to buy the right tool..

I've never done a how-to video but I guess I could. The only trouble would be that it would only pertain to my own setup, which is not at all usual, most grinding is done using a finger rest/hook rest. I'm missing the parts to use a hook rest so I came up with this simple direct indexer.

 

[RichardM]

What machine are you using Richard?

Looking at your pics I would say the wheel needs dressing. Do you have a dressing diamond? If you're dressing the wheel then I would say that it's simply too hard.

Machine - home made adaptation of a tool post grinder, current below.

It's a composite green wheel, not ideal as it will be for TC rather than HSS and too fine a grit. Yes the wheel probably needs dressing and I have a diamond. It was only a £1 purchase to try the design of a smaller diameter wheel to see if it was feasible way to get over the gash issue.

I think it would be easier to rig up a narrow wheel for the gash and jig the cutters differently, I may use the one currently fitted. When I have worked it out I'll post up a couple of pics, but may not be for a month or two as I have some other stuff that needs doing before.

The colour is from a marker pen used to highlight how much material I had removed / width of primary grind, and due to wheel rotation is ground the opposite way to yours (away from the edge, not the best I know). I may do a bit of re-positioning of the slide, put it behind the cutting wheel and extending the length.

 

[Bill Edwards]

Currently I can't sharpen the flutes but that's my next project, making an air bearing to sharpen the flutes of end mills and reamers.

That'll be an interesting one to see

 

[Pete.]

Machine - home made adaptation of a tool post grinder, current below.

It's a composite green wheel, not ideal as it will be for TC rather than HSS and too fine a grit. Yes the wheel probably needs dressing and I have a diamond. It was only a £1 purchase to try the design of a smaller diameter wheel to see if it was feasible way to get over the gash issue.

I think it would be easier to rig up a narrow wheel for the gash and jig the cutters differently, I may use the one currently fitted. When I have worked it out I'll post up a couple of pics, but may not be for a month or two as I have some other stuff that needs doing before.

The colour is from a marker pen used to highlight how much material I had removed / width of primary grind, and due to wheel rotation is ground the opposite way to yours (away from the edge, not the best I know). I may do a bit of re-positioning of the slide, put it behind the cutting wheel and extending the length.

View attachment 143450

I found that my green wheel glazes really quickly when using it on HSS, as in grind one tool and you have to dress it. I have a few cup wheels, silicone carbide, aluminium oxide and a CBN one that I got used which is also badly glazed and rounded on the edge but I haven't found a way to dress it yet.

Getting rid of that green wheel for a nice AlOx wheel will make a huge difference for you.

 

[Pete.]

@Pete. Would you post up your build, on the air bearing. I’ve a spin indexer I like to see if would convert

I will of course. I have started it actually, it's a scratch-built unit rather than a spindex conversion. I've spent a couple of evenings reading up and come up with a plan for a small distributed-orifice unit based on some induction-hardened rod in a cast iron liner but I don't have a sensitive drill to drill the tiny holes so I might have to go for bigger holes and suffer the extra air consumption.