EMG-12 Endmill Re-sharpening module

[Neil WyattModerator @neilwyatt]

Thanks Jason,

Neil

[VicParticipant @vic]

I wonder why these aren't seen more often over here?

http://www.ebay.co.uk/itm/MR-13D-NEW-2-13-MM-GRINDER-DRILL-BITS-SHARPENER-GRINDING-MACHINE-100-135-ANGLE-/111545794583

Under £300 inc postage.

[Harold Hall 1Participant @haroldhall1]

Something that I feel is very often overlooked is that for an endmill it is only the extreme tips of the end cutting edges that are required to cut metal. For a four tooth endmill this will be one quarter of the feed rate per revolution, I would think, no more than 0.05mm even for a roughing cut in the home workshop.

The requirements are for the four tips to be at the same level and the edges to be ground so that the overall result is concave. I have on my website a very simple device for achieving this.

Slot drills are of course different as they required to plunge like a drill, but the device above will still sharpen these also. However, as one edge is longer than the other it needs a little different approach. Both edges are first sharpened as for an end mill but then the device is set so as to create a slightly greater concave result when only the inner section of the longer edge is ground. This makes the edge slightly bent but maintains both tips at the same level.

It will only take about 3 hours to make and this can be reduced if the alternative mounting method is adopted.

Harold

[Ketan SwaliParticipant @ketanswali79440]

When I placed the advert in ME, I thought that the time gap between the advert in ME and the MEW would be short. I failed to take the digital issue into consideration. With hindsight I should have advertised in the ME after the review came out in the MEW, to avoid some of the misunderstanding.

Ketan at ARC

[John Stevenson 1Participant @johnstevenson1]

Vic,

Believe me, some of these manufacturers don't know what is needed, one company makes one and every one copies, including the mistakes.

The one you linked to grinds a drill like this.

Which is very handy for cordless drills with fast reverse

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bogstandard2 on 13/04/2015 10:02:01:

But just as a teaser, what is shown on the outside is nothing compared to the inside working bit.

.

I'm perfectly happy to wait for the review … but I do hope it includes some explanation of the inner-workings.

MichaelG.

[Michael CheckleyParticipant @michaelcheckley34085]

I hope this machine does get reviewed, as already said it is always good to see how different people tackle these problems and how new pieces of equipment are designed and made. It would be nice to see more commercial kit reviewed in the mags.

[brickyParticipant @bricky]

Hi

I made and use the cannon type sharpening jig that was serealised in MEW about 3 years ago.It does not sharpen the flutes but makes a good job of the cutting edges it,s worth a look.

Frank

[VicParticipant @vic]

Posted by John Stevenson on 13/04/2015 10:33:11:

Vic,

Believe me, some of these manufacturers don't know what is needed, one company makes one and every one copies, including the mistakes.

The one you linked to grinds a drill like this.

Which is very handy for cordless drills with fast reverse

I saw that graphic in the link I posted but I really don't believe it's even possible to grind a bit like that with this device.

A poor description or misplaced graphic is not enough to discount a device, we just need a dealer to obtain a unit and see if it works or not.

[duncan webster 1Participant @duncanwebster1]

I hope this isn't too stupid! If using and end mill correctly it is actually cutting on the side. Apart from restoring the corners, sharpening the ends seems like only half the story. Surely I want to sharpen the sides.

[jim’Participant @jim11037]

My thoughtss too.

[John Stevenson 1Participant @johnstevenson1]

No it's not a stupid question and yes Duncan and Jim are both right – to an extent. Because of the range of cutters this machine does the cutters are limited to reasonable light work.

Start hogging and you want the big ripper cutters that Bogs has mentioned.

In most cases and we will take a say 8mm cutter it's plunging and then making a groove, be it open sided or closed.

In steel which is liable to wear the cutter most max depth will probably be about 4mm deep so we have the end flutes, corners and 4mm of the side doing the work. The majority of this work is done by the ends and corners as they take most load. The sides will wear to an extent but it's easier to waste 4mm off the end and finish up with a cutter that's a standard size than keep taking all the flute down as you even have to remove unused side flute to keep parallel. That is both wasteful and time consuming doing side flutes.

In practice that side wear isn't such a problem unless you are working on something like carbon fibre, tufnol or glass fibre which are very, very abrasive.

Worst case scenario is you chop the worn end part off and start again, in some ways this is also useful as you end up after a while with short dumpy cutters which are brilliant for doing things like keyways as being short on the flutes they are very rigid and forgiving. Makes you wonder if all beginners should start off with stubby cutters? and this isn't being derogatory.

I grind brand new centre drill back so the small diameter is only half of what it was when new. Sounds wasteful reducing the life of a tool but it stands more chance on ending it's life after a few regrinds than getting killed early on when it breaks.

The long pip is a throw back to when we used to use dead centres, the hole produced was a reservoir for the white lead lubricant. Now we are onto revolting centres we only need enough of a hole lead so the tip doesn't bottom and that isn't a lot.

[Ketan SwaliParticipant @ketanswali79440]

Posted by Michael Gilligan on 13/04/2015 10:35:38:

Posted by Bogstandard2 on 13/04/2015 10:02:01:

But just as a teaser, what is shown on the outside is nothing compared to the inside working bit.

.

I'm perfectly happy to wait for the review … but I do hope it includes some explanation of the inner-workings.

MichaelG.

Now that the MEW 228 is out on digital and print, I believe that most of the questions on here have been answered.

With regards to MichaelGs question, here are two pictures from the manual:

This is the inside of the top part of the housing:

This is a picture of the top part removed, exposing the grinding wheel fitted to the motor which is fitted inside the bottom part of the housing.

Unfortunately I do not have more detailed drawings for the inside, but hope this gives the idea.

Ketan at ARC.

[Michael GilliganParticipant @michaelgilligan61133]

Thanks, Ketan

… Much appreciated.

MichaelG.

[John Stevenson 1Participant @johnstevenson1]

Michael,

Although Ketan has posted pics of the inside I don't think other than curiosity it would be much help.

 

When using a proper conventional Tool and Cutter grinder such as the Clarkson etc., they are very versatile but take a lot of setting up and using. That is where the skill is involved and the time taken to set up.

 

This little Module can only do the ends of cutters, which in all fairness is the most common wear point but it does it exceeding fast, with next to no skill.

 

The skill level has been removed from the operator and built into the machine.

 

I would hate to have to try to reverse engineer one. The design changes from size to size and even flute to flute are very subtle.

Take say the cam for a 3 flute cutter which has 3 lobes on it, not all the lobes are the same, they are to look at them but one is subtly different so it allows a longer cutting edge for over centre cutting. Same on the 2 and 4 flute cams.

 

The second hole that grinds the primary cutting edge, isn't a hole if you study it well, it's a slot but very slightly curved. On a 3 flute two of the cutting edges are ground normal but the slight difference in the other cam lobe means one tooth, the master,  describes a curved path which throws the edge over centre.

 

A lot of work and design has gone into this so it can be operated very quickly by an unskilled person.

Edited By John Stevenson on 22/04/2015 09:28:00

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Stevenson on 22/04/2015 09:25:56:

Michael,

Although Ketan has posted pics of the inside I don't think other than curiosity it would be much help.

…

A lot of work and design has gone into this so it can be operated very quickly by an unskilled person.

.

Thanks for the info. John

As you will know from my interest in old patents, etc. It's largely curiosity on my part; I just like to understand how things are done. … Most unlikely to ever try building one of these though.

MichaelG.

[CirclipParticipant @circlip]

Posted by John Stevenson on 22/04/2015 09:25:56

Take say the cam for a 3 flute cutter which has 3 lobes on it, not all the lobes are the same, they are to look at them but one is subtly different so it allows a longer cutting edge for over centre cutting. Same on the 2 and 4 flute cams.

The second hole that grinds the primary cutting edge, isn't a hole if you study it well, it's a slot but very slightly curved. On a 3 flute two of the cutting edges are ground normal but the slight difference in the other cam lobe means one tooth, the master, describes a curved path which throws the edge over centre.

Hmmmmmm I just might then

Regards Ian.

[Neil WyattModerator @neilwyatt]

I got rung up by a reader today who asked a very valid question – where does the grinding dust go?* He feared it would gum up the delicate mechanism inside.

I explained there was noting inside but a specially shaped grinding wheel BUT where does the dust go? Do you just lift the lid off at the end of a session and vacuum it out/brush it on the floor?

Neil

*It's a very good question. Back in the 80s a friend of mine worked at a place that serviced BBC computers. They took the lid off a Master and found the space below the spring-loaded hatch for the ROM cartridges full of fag ash and dog-ends.

[John Stevenson 1Participant @johnstevenson1]

Yes good question Neil and because there hasn't been a picture of the rear then it isn't obvious.

 

 

That port is 20mm diameter and I just push a 20mm plastic conduit elbow into it, nice snug fit, and a pipe going down into a bean can.

 

For the show I'll bring the de-luxe model which has a small computer fan as on extractor and a chilli con carne tin for added flavour

The machine also comes with a 1" paint brush to brush the  crap out.

Edited By John Stevenson on 22/04/2015 13:06:22

[Neil WyattModerator @neilwyatt]

I might stick those pics in the next issue,

Neil

[Karl LangshawParticipant @karllangshaw22965]

Moved to this thread to keep things together.

Karl have a read of what Ketan and John S have to say and then maybe it won't see as expensive.

 

 

Please tell me that I am not the only one who was left picking my lower jaw off the floor when I saw the price of this item from arc eurotrade. £800 quid for a device that can ONLY sharpen end mills, they have got to be having a laugh????

I think I will be sticking to my homemade device which cost a few quid and does a perfectly good job.

Edited By JasonB on 27/04/2015 09:56:57

Edited By JasonB on 27/04/2015 09:58:38

[John Stevenson 1Participant @johnstevenson1]

Posted by Karl Langshaw on 27/04/2015 09:20:42:

for a device that can ONLY sharpen end mills,

.

Karl, with a slight modification it can be altered to sharpen a pencil………………….

[Another JohnSParticipant @anotherjohns]

Regarding the price – I think that this is a great machine, and a boon to those who focus on construction speed over costs.

There are many ways to view costs; say if you:

– Divide the cost of the machine over the lifetime in years; it'll most likely be quite low;

– Compare the costs to the cost of the end mills that get used at work – it would pay for itself in a few months if not less;

– Compare the costs to lost time waiting for end mills to come in from a supplier;

– Add the cost in to the cost of building say a large traction engine or a large locomotive – it would get lost in the pocket change if one kept an accurate record of building and fitting out all the tackle for a large locomotive.

Me? I've completed a Worden for my sharpening needs, but I can certainly see the utility of this machine. Also, I'm focusing on 3-1/2" gauge, so material and tooling costs are much lower.

Just some random thoughts whilst waiting for the bus to take me to work…

John A. Stewart.

[Neil WyattModerator @neilwyatt]

You could make all the same arguments about a drill press – it only does one job, you can make do with a hand drill, lathe or a mill instead, or you can buy a cheap one (as many of us do) yet there are still plenty of people willing to spend the thick end of a grand on a drill press – because it suits their needs and their way of working.

Neil

[Involute CurveParticipant @involutecurve]

I have a Clarkson with most of the bells and whistles, when I first got it I used to regrind all my cutters inc the sides, however I quickly got bored with that, and now only sharpen the ends which is much easier and quicker, and to be honest most of the time its all that's required.

My cutter cycle goes like this.

I use em until the corners get warn or chipped.
At which point I knock the corners off with the grinder, this cutter then last ages and I use it for roughing.

Sometimes I make them Tips radiused for 3D interpolation!!

Next I cut 2-3 mm of the length and resharpen.

This cycle then repeats until the sides go, at which point I bin em

I use a lot of cutter, so I will be looking at one of these if they are on display at Harrogate.

I would probably get rid of the Clarkson if its no longer used.

How much are the replacement wheels? and how often do they require changing? also can the wheel be dressed?

Shaun

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