# Sharpening end mills in lathe



## MRA (Mar 24, 2016)

Hi Folks

I'm in the process of making a tool-post grinder, and it struck me that I might be able to use it to reclaim worn-out end mills from work.  If the cutter was held in the headstock it could be indexed using the lathe gears, and the grindstone aligned by setting over the top slide and perhaps also using a vertical slide (which I have, though it needs modifying to fit my 'new' lathe) or packing pieces.  Anyone given this a go?

As usual, the motivation is partly saving money on a cutter grinder, but more so saving space - I work at home in a small, overflowing 12x8 shed, so making tools perform several functions (sometimes rather badly, or at least rather slowly) is the only way to go.

cheers
Mark


----------



## goldstar31 (Mar 24, 2016)

Having 'been there', might I ask why go to the trouble of making a tool post grinder? I made mine by taking the additions around a wood router and fitting it to the lathe using a 43mm collar. Mine was a Bosch POF45 and I've written about many times! Others have written about using them on separate home made machines.  Off hand, the Brookes was written about in in MEW issues 16 and 17. 

As for using a vertical slide, one is used on the Stent. 

Going back to the holder for 'doing end mills', it was well covered in the 'Cannon' described in MEW. The grinding department was the cheap and not really too nasty 6" DE grinder available in many outlets.

The reason for MY comments are that your present ideas introduce a GRIT situation which is hardly acceptable on a lathe.

For what my opinion is that you could make something like a Tinker which will do a surprising amount of things and can, or it is claimed, made in a week.

My opinions but others may also comment


Norman


----------



## Blogwitch (Mar 24, 2016)

Mark,

Almost anything can be achieved as long as you think about the final product and it is safe to use.

There are a couple of things to note.

Milling cutters nowadays come in all shapes and flavours, 2, 3 or up to maybe 12 flutes, especially from a production workshop as you are hoping for. All these different types will require a different setup, even if it is just angle orientated. That is why cutter grinders have so much adjustment on them, they can be set up for the correct angle for the cutting face (including the clearance angle from tip outer to tip inner) and then the relief angle behind the cutting tip.

Two flutes will require some sort of gashing device to give one cutting face longer than the other, I used to do it manually with a small Dremel, while multi flutes have one cutting edge longer than all the others to achieve the same effect. For the old fashioned end mills, that is not required as the cutting faces don't go all the way to the centre.

I would suggest you get hold of some old cutters of the type you are hoping to regrind and give them a good dose of looking at, to see whether it is feasible to attempt to get all those varying angles on your setup.

You just might also find that on the ones that come out of a production workshop will have their flutes worn as well, if that is the case, you will have to shorten the cutter to get back to unworn flutes and totally reshape and grind new cutting tips on them. Not a job for the feint hearted.

I think there is a bit more to it than you first thought, but if you think you are up to doing it, go for it and show us the results.

John


----------



## MRA (Mar 24, 2016)

Thanks folks.  I'm mostly interested in small-ish 4 flute end mills and 2 flute slot drills.  

The router body is a good idea - high speed, built-in collet chuck, lots of them about.  They're probably a brushed 'universal motor' too, so possible to make a gizmo to slow them down to suit a given wheel.  My router is not easily adaptable without destroying it - lots of moulded-on extraneous bulk - so I think I'll have a look for something more useable from the normal sources.  

Grit - I know.  Well, I guess this is not going to be a large part of what I do in the shed, and with enough rubber sheet applied over the right places...


----------



## goldstar31 (Mar 24, 2016)

Mark
           As you are probably intending to use 2 and 4 lip cutters, you can probably index using  tool holders bored from square stock.
i.e. bored 1/2" or whatever and locked correctly for one lip, and turned 90, 180 and 270 degrees to do perhaps the 1st  and then the table tilted for the 2nd grind.

Looking back a bit, this is what tools like the Worden, the Kennet and several other designs utilise.

Doing old fashioned  'ends' as suggested, is a pretty crude affair. It's the blasted grit that is always the bugbear unless you have a flat bed grinder of some sort- speaking as an owner of an unused Quorn.  Heigh ho!

Norman


----------



## goldstar31 (Mar 24, 2016)

As age takes its toll( Ugh), why not lash out and buy- I think £17- for the drawings of the Acute Tool Sharpening System by Eccentric Engineering. It's an Aussie firm but his sister lives in the UK.  I bought the drawings, incidentally.


There is a UTube or whatever on the 'net. Worth a look

Regards

Norman


----------



## SmithDoor (Mar 24, 2016)

Yes you can sharping in a lathe end mill and reamers
The down side is after you sharpen the end mill it is a new size typical not the size you need. 
The cost of end mill is so cheep why use a odd size that makes more work.
If you need special size end mill or ream just use one with centers in both ends of the cutter. Set your compound to 83 or 87 deg for feed to the 0.0001. use centers in both the head and tail stock. make a finger for the flutes use the bolts for the follower rest. :fan:

Good luck
Dave



MRA said:


> Hi Folks
> 
> I'm in the process of making a tool-post grinder, and it struck me that I might be able to use it to reclaim worn-out end mills from work.  If the cutter was held in the headstock it could be indexed using the lathe gears, and the grindstone aligned by setting over the top slide and perhaps also using a vertical slide (which I have, though it needs modifying to fit my 'new' lathe) or packing pieces.  Anyone given this a go?
> 
> ...


----------



## GLCarlson (Mar 26, 2016)

MRA said:


> Thanks folks.  I'm mostly interested in small-ish 4 flute end mills and 2 flute slot drills.
> 
> The router body is a good idea - high speed, built-in collet chuck, lots of them about.  They're probably a brushed 'universal motor' too, so possible to make a gizmo to slow them down to suit a given wheel.  My router is not easily adaptable without destroying it - lots of moulded-on extraneous bulk - so I think I'll have a look for something more useable from the normal sources.
> 
> Grit - I know.  Well, I guess this is not going to be a large part of what I do in the shed, and with enough rubber sheet applied over the right places...



Check out PreciseBits for advice on collets, router bodies, etc. Ebay sometimes has just the body (eg, a Dewalt 611) for <100 bucks, which is trivially easy to mount - just a clamp to fit your QCTP. One caveat- watch the speed. Wheels can explode.

Try Al foil, not rubber sheet to protect your ways. Foil tears if caught (safety feature), holds tight, and is cheap enough to wad up and toss, trapping all the grit. With a little judicious taping, it can be a flexible way cover. Not a very durable one, but for one-time use, it works.

All that said, I'd be very leery of _routinely_ grinding on a lathe. Once in a while, with care and careful cleanup, sure.


----------



## bazmak (Mar 26, 2016)

End Mills are normally ground many times on the end only,so reduced size
never becomes an issue.Grinding the flutes does reduce the size but is only done when a damaged or badly worn cutter can no longer be ground solely on the end.These are usually marked and used for rough milling where the dia of the cutter is not critical.Reamers are not usually ground on the flutes but always on the end cutting chamfer.Occationally the flutes will be precission ground to a reduced known size etc


----------



## Blogwitch (Mar 27, 2016)

Mark,

I have no idea what country you come from, but if it is from the US, Little Machine Shop sells toolpost grinders for maybe little more or even less than it would cost you to make a decent one. Plus all you would need to make is an internal grinding holder for it's spindle.

If you are only going to be using 3mm (1/8" at a push) mounted points, then it would be easy to fit something like a pin chuck (with collets) or pin vice (different sized units) onto the spindle.

Grinders plus accessories

http://littlemachineshop.com/products/product_category.php?category=-1731696149

Pin vices

http://www.ebay.co.uk/itm/Heavy-Dut...101352?hash=item3ce5c79a28:g:BZUAAOSwd0BVzxCy

Pin chuck

http://www.ebay.co.uk/itm/Expo-Adap...549887?hash=item25b4e2c2ff:g:lRcAAOSw34FVB30K


John


----------



## Owen (Jul 3, 2016)

What negative answers to a very simple question why all the references just make a suggestion like covering the bed of the lathe to ensure that the ingress of grit is avoided, I personally think that you are just trying to be smart.

QUOTE=goldstar31;278839]Having 'been there', might I ask why go to the trouble of making a tool post grinder? I made mine by taking the additions around a wood router and fitting it to the lathe using a 43mm collar. Mine was a Bosch POF45 and I've written about many times! Others have written about using them on separate home made machines.  Off hand, the Brookes was written about in in MEW issues 16 and 17. 

As for using a vertical slide, one is used on the Stent. 

Going back to the holder for 'doing end mills', it was well covered in the 'Cannon' described in MEW. The grinding department was the cheap and not really too nasty 6" DE grinder available in many outlets.

The reason for MY comments are that your present ideas introduce a GRIT situation which is hardly acceptable on a lathe.

For what my opinion is that you could make something like a Tinker which will do a surprising amount of things and can, or it is claimed, made in a week.

My opinions but others may also comment


Norman[/QUOTE]


----------



## goldstar31 (Jul 3, 2016)

I can only apologise if my comments appear 'negative'. Perhaps the site owners will delete them.

Regards

N


----------



## Blogwitch (Jul 3, 2016)

Owen,

For the amount of times a toolpost grinder is used (and I have been at this game for over 50 years) I think you can dismiss any comment about grit unless you are doing it every other day and using the lathe on the second days, then MAYBE you might see a tiny bit of wear on your slides caused by the grit produced  after many years.
I tend to just drape paper towel over the ways. The only time you will produce a lot of grit is when you are dressing the wheel, so I change the paper afterwards. As long as your slides are well lubricated, you could even use wet paper towel to catch every last bit of grit.

BTW, what is the difference between using your lathe and a dedicated tool grinder? What you are saying, about the grit problem, your tool grinder will wear away just as much as your lathe, or surface grinder. Do you want us to stop using those as well?

Now back to the real world.

What speed does a router run up to? Maybe someone could let me know, as I don't work with the brown stuff except for making the odd base, which I can do on my mill.
I would be worried that a router can exceed the grinding stone burst speed. My commercial toolpost grinder, using a 2" external wheel can only reach around 15K RPM for external and 20K RPM (by pulley and belt system) for internal grinding using 1/2" mounted points. I consider anything over that to be classed as taking your eyesight into your own hands. They run a lot faster than an offhand grinder because of the smaller wheels.

I have just  had delivered a couple of days ago, one of these, for fitting to my mill and if I buy another, my future CNC mill.

http://www.aliexpress.com/item/NEW-...30193.html?spm=2114.10010108.1000023.4.cainW3







For the cost, about 90 UK pounds (including postage and a 4 pounds customs charge), you get a powerful enough motor, a full set of ER11 collets, a mount plus a power supply that is variable speed, plenty fast enough for what we do, in fact, if I didn't already have a toolpost grinder, I would be making myself one out of this bit of kit. 
BTW, it is a sealed motor, the air fan cools the outside, so no need to worry about GRIT ingress.

John


----------



## MRA (Jul 6, 2016)

That's a neat suggestion John - thanks.  I think earlier you wondered where I was - just up the road in Manchester.  

I looked at die grinders but your suggestion comes in under even a second-hand one, unless I was very lucky, and with a much wider range of collets.  

Initial motivation is to true the hard jaws on an otherwise nice 3-jaw chuck I have which runs out.  After that - I might like to try gear cutting in the lathe, indexing using change wheels.

cheers
Mark


----------



## Blogwitch (Jul 6, 2016)

It's nice to know you live so close Mark.

I am in Manchester tomorrow evening for a 40th birthday party.

You should gear yourself up for a visit to my bombsight shop, but bring a list of what raw materials you require and I will see if I can fill it for you.

John


----------



## goldstar31 (Jul 6, 2016)

I realise that I'm going Off Topic a bit but now tool and cutter grinders are relatively inexpensive. My Clarkson was £100 and I made much of the tooling or used dividing head stuff or whatever on the thing. However, this new design- no not really new- from Eccentric Engineering seems pretty easy to make and perhaps a cheap DE 6" Grinder would suffice for most people.  As for tool post grinders- on a lathe? Not me.

A word about truing 3 jaw wear with a tool post grinder. It is an old subject that has been flogged and flogged in the past. Doing a tidy up of a  otherwise unworn chuck is feasible but if there is other wear in the scroll etc, all that will happen is that ONE diameter can be ground accurately.

Sorry but that is my experience

Norman


----------



## RonGinger (Jul 6, 2016)

John, I have looked at that spindle motor several times, but was concerned about the runout of the collets- it looks like the holder is simply held to the motor shaft with a set screw. Does it seem good to you? Have to measured runout?


----------



## Blogwitch (Jul 7, 2016)

Ron,
As of yet, no runout check done, but I think I read somewhere that it should be a max of 1 thou.

When it will be used on my mill, full checks will be carried out and if necessary the collet holder will be ground in position, a thing I have done with all my collet holders, including ER32, ER16, MT3 and R8, and over time, three 5C collet chucks as they all had runout, some as much as 4 thou. 
After having their noses reground or very finely turned on the inside, runout could hardly be detected when collets were tried in any of them.

http://www.homemodelenginemachinist.com/showthread.php?t=24123

That is a warning to people who think that their collet holders are guaranteed to run true, I have yet to find one that does, except the ones I have made myself from scratch.

If there is only a small amount of runout, for a toolpost grinder, I wouldn't even bother, as dressing the wheels will bring things into acceptable parameters that the normal home machinists would never know. 

John


----------



## DJP (Jul 7, 2016)

I have shared this before and I tend to agree that grinding wheel dust on my lathe was what motivated this approach. For my needs sharpening the ends of  milling cutters is sufficient to get extra use and for special jobs I keep a set of new cutters.

A separate machine for any grinding is preferred and doing this work in a separate welding shop is even better, in my opinion. The risk of failure is high when assembling engine bearings in a dirty environment.

My thoughts for your consideration.


----------



## Blogwitch (Jul 7, 2016)

You can go on forever trying to come up with the perfect solution.

As I have a surface grinder, I started using one of these for tip sharpening, mine is 5C not ER like the one shown, but I do have John S's original ER holder that fits mine, so I can use either type of collets.

http://www.arceurotrade.co.uk/Catal...t-Fixtures/Stevensons-ER32-Sharpening-Fixture

You can buy tool holders that are used on a surface grinder for sharpening flutes, but are rather expensive for what they do, plus once you touch the flutes, you are actually making the cutter a smaller size, so you could easily end up with a cutter that is neither here nor there so will have to be used as a rough jobbing cutter.

http://www.amadeal.co.uk/acatalog/End-Mill-Sharpener-AMA_OT_287_6350TD.html#SID=79

I have actually taken things a little further and invested in the smaller one of these.

http://www.arceurotrade.co.uk/Catal...g-Module/EMG-12-End-Mill-Re-Sharpening-Module

Very easy to use and will sharpen cutters from 2mm to 12mm, but only on the tip. If you chip the edge of the cutter, just grind it back to a flat on the end and this will recut a new set of faces on the end in only a couple of minutes. It doesn't do the flutes BTW, but I don't need to do that anyway. 
I just need to make a set of imperial cutter holders (very easy) then I am ready to sharpen almost anything. I do use a lot of 16mm 6 flute carbide, which this one can't do, so for those, I use the first one I showed and it does a great job.

No more thrown away cutters, unless of course you are like me and drop carbide ones which duly snap in half as they hit the floor, but I do up-cycle the shanks.

Why don't I invest in a tool and cutter grinder?

No room for one in my shop, and I don't fancy fiddling about setting things up to do just one grind. With my surface grinder, I can grind almost anything as I already have the fixtures to grind lathe tools and slitting saws as well, and they only take a few seconds to set up.

John


----------



## MRA (Jul 8, 2016)

Goodness, that's quite a fixture!

Hope you enjoyed your party John, and thanks for the invite.  I'd like to come and see what sound like your extensive facilities some time.  I make my stuff from scrap - I work in a workshop attached to a university lab, and there is a lot of scrap (not all of my making!) - hence my interest in recycling and making-do.  In fact I get a bit paralysed by a blank sheet and new materials (not to mention working accurately from a drawing, though I'm getting a little better there)  - but thanks for your offer!


----------

