EMG-12 Endmill Re-sharpening module

[Michael CheckleyParticipant @michaelcheckley34085]

As Muzzer says the corners got some use during the stepped roughing operations so if there was an issue with the newly ground edge is should have shown up here. I agree with Jason that a test cut compared to that of a new cutter would be useful.

Just minutes ago the same cutter was used to reduce the thickness of the profile. I had to remove 0.55mm from the top and bottom face so did 0.3 then 0.2mm DOC at 40mm/min and then a final 0.05mm DOC at 20mm/min.

[Harold Hall 1Participant @haroldhall1]

Seeing the test cuts taken by Owain some readers may like to visit my website where the process is discussed in depth. Do look at the photos, (6 and 7), of my similar test pieces, viewing them enlarged to view the results at the highest definition. The article can be seen here

Harold

[doubletopParticipant @doubletop]

Posted by Ketan Swali on 26/05/2015 14:41:29:

What is the maximum weight limit before a product is classed as 'a one off heavy itme' under the NZ import prohibition list.?

Ketan at ARC

Ketan

Apologies for the delay in replying.

There's no restriction on the weight of any import to NZ other than how much you are prepared to pay to get the goods shifted from one part of the world to another. So lathes and mills may as well be purchased locally rather than try in import them as a one off. The heaviest single item I've imported was 50Kg from China, it came by UPS, and it arrived without problem. Smaller items, collets, chucks, boring heads, QCTP have all been directly purchased at far lower prices than the local suppliers. Just check out some of the NZ supplier prices available online and compare them with what you charge and you'll soon see why we do it. Including buying stuff from ARC.

The other factor, which may well change, for tools and equipment GST isn't collected on a total sale price of less than $400 (200 quid) so removing the 20% VAT, including shipping and $0 import duty/GST makes small items viable. Of course that wouldn't apply in the case of an EMG-12.

regards

Pete

[Ketan SwaliParticipant @ketanswali79440]

Thanks Pete,

To avoid taking the thread off topic, I have sent you a PM.

Ketan

[Anonymous]

Here are the results of a quick milling trial. Material is, I think, EN1A. Both slots are 1.6mm deep and 10mm width, taken in one pass. Top slot is with a worn and chipped three flute carbide cutter running at 1500rpm and 375mm/min. Bottom slot is with a nearly new, and used mainly on the side flutes, four flute carbide cutter running at 1500rpm and 450mm/min:

Clearly the top slot is rougher, and the sidewall finish is iffy. I took three surface roughness measurements in each slot. Results were:

Top slot: 2.16 2.16 3.31 Average 2.54µm Ra

Bottom slot: 3.40 2.41 3.25 Average 3.02µm Ra

Not an intuitive result.

Andrew

[Howard LewisParticipant @howardlewis46836]

It's very sad when a thread descends into abuse mode. That is NOT what the Forum is about in my view.

There is a lot of interesting info supplied, and name calling does no good at all, other than putting off people, especially newbies.

I respect Ketan for his open minded and honest comments on this thread, and others elsewhere. Yes, I am a customer, but he wouldn't live for a day on the profits from my purchases!

I would love to have an EMG12, or larger, but 1) lack the space to store it, 2) cannot justify such a purchase, which leads onto my questions.

Presumably John Stevenson has an EMG 12, as has Bog Standard 2.

QUESTION 1

Whereabouts in U K are you two gentlemen? (Probably a couple of hours drive away from me?)

QUESTION 2

Would you be prepared to sharpen End Mills for folk who brought them to you, (for a consideration)?

Obviously, this would have to be either, by appointment, or on a "leave/collect later" arrangement, so as not to interfere with the "day job".

You can see where I'm heading, (probably along with a lot of others).

Howard

[Ketan SwaliParticipant @ketanswali79440]

For those who do not subscribe to the MEW in some way, here is a link to the article on our website, published with the kind permission of John Stevenson and Neil Wyatt – editor Model Engineers' Workshop Magazine:

**LINK**

Also, a small note to say that we sold out of these machines last Friday, and new stock is expected back in around early August 2015.

Ketan at ARC

[Ketan SwaliParticipant @ketanswali79440]

Howard,

PM sent to you, Ketan.

[John Stevenson 1Participant @johnstevenson1]

"What amazes me is that no-one has started to build a home brew version yet.

:0)

Martin"

With apologies to Martin Kyte but I caught delete instead of quote post, as a low level moderator I can see it but can't reinstate it, my apologies.

To answer this it would not be easy.

The holders are very easy but the cams and there are 21 different ones, would take a lot of reverse engineering. The changes between each one are that subtle. If you had a pattern and popped it on a CCM machine then you could get all the information but would then require a CNC to make full use of said information.

So by the time you have done all the cams and move onto the machine with it's many different angles it would be cheaper to buy one.

Howard,

I cannot speak for John Moore but I am situated mid way between Derby and Nottingham, about 3 miles from the M1 Junction 24 or 25 Post code NG10.

[Martin KyteParticipant @martinkyte99762]

I was actually being a little tongue in cheek given our general propensity to do things the hard way rather than buying a machine. I do include myself in that statement too.

Martin

[Harold Hall 1Participant @haroldhall1]

With regard to Martin's comment about a home brewed version, now to be seen in John's comments, my offer, to be seen here may be of interest to some. It is of course very much simpler but in my estimation works adequately for most home workshop tasks.

I will now be away for around 5 weeks but on my return it is my intention to start adding videos to my website and this is one of the first that I intend to attempt, my quick change lathe tool holders being another.

Harold

[John HaineParticipant @johnhaine32865]

Musing on how this works and noting the comments made about the "striations" on the ground faces, I had a close look at one of the photos.

I've superimposed some arrows that indicate ground lines visible on 3 of the 4 teeth (and probably on the 4th but there isn't much reflected light). They are in virtually the same position on each primary clearance and also line up on the secondary clearance. I would guess that these are due to a slight prominence of a diamond on the wheel surface? It indicates I think that the action of turning the cam advances the cutter directly onto the wheel surface, so small irregularities in the wheel get transferred "negatively" onto the tool. This of course doesn't matter at all since its only the end of the teeth that cut, but it helps to explain the action of the machine.

By contrast, on a grinder of the Quorn / Clarkson type, the face is ground by stroking it across the wheel until it sparks out. Any prominence on the wheel effectively acts like a little "flycutter" and you can get almost a mirror surface. It's maybe because people got hung up on designing TCGs that would hold the tool to permit this kind of action that it took so long for this new design to appear.

Edited By John Haine on 01/06/2015 21:55:36

[Michael GilliganParticipant @michaelgilligan61133]

Useful analysis, John

MichaelG.

[Harold Hall 1Participant @haroldhall1]

The idea of plunging the end of an end mill into a rotating wheel is not new, I first saw it in issue 14 of MEW. I then published a more detailed version (drawings, etc.) in issue 170. This now being the subject of the link I mentioned earlier.

If you did not see my earlier comments this would have been because my contributions again went AWOL (absent without leave) for some reason, do go back a read my comments if you have missed them. Note, I will now be away from the PC for the next five weeks.

Harold

[John Stevenson 1Participant @johnstevenson1]

I think Harold and many are missing the point.

Not everyone who comes into either this hobby or starts a small business or uses machines to follow another hobby like vintage bikes and cars are born with 6 fingers on each hand and have all the time in the world.

Because someone is able to think up an idea and even get it into print doesn't mean to say that everyone can follow it, has the skills to replicate what has been shown or even the time.

I have seen pictures uploaded of the generic 4 position toolpost and someone wants a drawing ????

Chances are it won't fit their lathe, tool is too high, central bolt is the wrong size and by the time they have modified this they have designed their own, but tell them to design their own and they will tell you they can't.

There are a myriad of tool and cutter grinders out there, there are hundreds more of jigs and fixtures to do all this work. The authors of who think theirs is the best thing since sliced Hovis but they can't all be right can they ?

What they do have in common is needing time and skill to build them and the same time and skill to operate them.

There are far more users lacking either of these skills than users who do. If they have one skill they are probably lacking in the other or lets be honest, can't be bothered.

The ratio of Quorns sold to Quorns built and finished must be 10:1

Where the EMG- 12 scores is it does what it says on the tin, It's quick, its easy and it can be used by people with no tool making or grinding skills and time. And that believe me is a higher percentage of people than those that who build jigs and fixtures.

Nothing wrong with jigs and fixtures, just that this thread is about the EMG – 12.

I have heard back for 5 people who have bought one of these. All are very pleased with it. None of them visit this forum as they don't build models and are not interested in posting comments, more interested in doing what they do.

[Ketan SwaliParticipant @ketanswali79440]

On the subject of the EMG-12, here is an email response sent to me by Bill in Australia. It does not specifically cover the questions raised, but still, I am posting it here. I am finding it difficult to persuade others to post. They have their own reasons, but I have obtained permission for this message to be posted. (Thank you Bill)

Before reading the comments, please note that this is only being posted to address certain attributes of the EMG-12 from a user of the product. ARC has the greatest of respect for other T&C grinders – home built or commercial. We have no axe to grind with anyone or any other T&C Grinders, all of which have their own attributes and/or additional features. For the record, I get on well with Ivan Law (the respected gentleman responsible for the Quorn) and Derek (DAG) Brown, both of whom I meet at the Harrogate Show recently, where Derek was showing/demonstrating his Quorn T&C Grinder. Glad to see that both are in good health

"Hi Ketan,

Having said my bit in the early stage of the discussion, I would like you to know how much I appreciate the opportunity to have been able to buy an EMG-12 from you and have you ship it out to me in Australia.

I bought it with the anticipation of it meeting 3 criteria which are important to me.

1. I wanted it to recover and produce sharp end mills repeatedly.

2. I wanted it to do that quickly?

3. I wanted it to be easy to use so even I could get the desired results.

I am happy to report that it has achieved 100% in each criterion.

All my end mills, 1/2" and less, both metric and imperial, are razor sharp. I have tested each one and they cut as well as when they were new. I will now not use or need to use larger cutters other than to enlarge 13mm holes in the lathe to accommodate a boring bar.

I must admit the add in MEW did not attract my attention until I read the review. It was the concept of being able to quickly sharpen a cutter after use in readiness for its next job that really appealed to me. I have been using a Quorn T&C grinder for years. I think I can say that I became frustrated every time I used it. I always had blunt cutters and it would take me a whole session in the workshop just to sharpen the ones I needed at the time. I will now sharpen my few large end mills on the Quorn as they wont t get a lot of use and my smaller end mills will always be razor sharp. At 77 I don't want to waste any of the time I have left getting frustrated.

Thank you again. I hope those last 3 EMG-12s have been sold and that you are getting more in because I am sure model engineers will eventually see the real benefits of the machine and then they will "justify" the purchase of one.

Bill Adamson"

Ketan at ARC

[Neil WyattModerator @neilwyatt]

An observation on Andrews 'counter-iintuitive' result:

Posted by Andrew Johnston on 31/05/2015 12:33:00:

Here are the results of a quick milling trial. Material is, I think, EN1A. Both slots are 1.6mm deep and 10mm width, taken in one pass. Top slot is with a worn and chipped three flute carbide cutter running at 1500rpm and 375mm/min. Bottom slot is with a nearly new, and used mainly on the side flutes, four flute carbide cutter running at 1500rpm and 450mm/min:

<I won't waste room reposting the pic>

Clearly the top slot is rougher, and the sidewall finish is iffy. I took three surface roughness measurements in each slot. Results were:

Top slot: 2.16 2.16 3.31 Average 2.54µm Ra

Bottom slot: 3.40 2.41 3.25 Average 3.02µm Ra

Not an intuitive result.

Andrew

1500 rpm at 4 flutes is 6000 cuts per minute. At 450mm per minute that's a feedrate 0.0.075mm or about 2 thou per cut. Halving the feedrate might noticeably improve the finish and reduce the surface roughness with the new cutter.

But why is the 'blunt' cutter better? – It seems it's either acting like a lathe tool where you stone off the end or burnishing the work (I suspect a combination of the two, with the 'bright' areas being more burnished. As this is a raher rough and ready approach the visual appearance is poor and less consistent (variation in roughness readings 1.15um with the blunt tool, 0.99um with the sharp one).

Lesson learned? Possibly that, if your main use for end mills is using the ends to clean up flat surfaces, having a few endmills with the corners neatly ground off may give the best results, but if you use sharp ones, drop the feedrate on the finishing cuts.

Your thoughts, gentlemen?

Neil

[SteveMParticipant @stevem36008]

Howard,

there's a guy called Geoff Josey who'll sharpen your end mills for a small fee. He regularly puts an ad on the Home Workshop site.
The fee is actually a donation to Farleigh Hospice, which is a damn fine thing I reckon.
This is a link to it

**LINK**

Steve

[Anonymous]

Posted by Neil Wyatt on 02/06/2015 20:15:20:

Your thoughts, gentlemen?

I've been called many things, but a gentleman wasn't one of them; nevertheless you're still going to get my thoughts.

I'm not entirely sure I believe my surface roughness measurements. It's a bit of a black art, or so it seems. The finish with the nearly new cutter certainly looks better. Spot on, I did the calculations in my head based on 2 thou per tooth. That's pretty conservative, I'm happy to run faster. As JohnS has pointed out endmills and slot drills are slightly hollow ground, but only by about 1°. So for a 2 thou advance that's a height difference of about 35 microinches or about 0.86µm. That's rather less than I am measuring? I am measuring Ra, which is an average. The conversion to a peak to peak measurement (Rz) is rather fuzzy, but generally somewhere between 10 and 20 times?

A facet of finish that is often neglected is uniformity. As well as aiming for a 'good' finish I try and achieve a uniform finish, even if it is a bit rougher. It's no good if the finish starts off looking like a babies bottom and then reverts to looking like a badgers rear end.

When I really need a good, smooth, finish (sub-micron) I use cutters with a radius ground on them.

Andrew

[Anonymous]

Botheration, I've missed my 1957th post, the year of my birth. This post will be my 1960th post, the year my brother appeared.

Andrew

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Neil Wyatt on 02/06/2015 20:15:20:

Lesson learned? Possibly that, if your main use for end mills is using the ends to clean up flat surfaces, having a few endmills with the corners neatly ground off may give the best results, but if you use sharp ones, drop the feedrate on the finishing cuts.

Your thoughts, gentlemen?

Neil

Tubal Cain in "Milling Operations in the Lathe" (WPS 5) comments on corner rounding spoiling the cut and how this may be stoned to improve surface finish. He goes on to say "Naturally, if the cutter is required only for surfacing, you can put a deliberate bevel here, with great advantage to both cutter life and finishing"

By the way, don't be fooled by the title of this book, it is an excellent general treatise on the action, use and maintenance of milling cutters – much better IMHO than Arnold Throp's "Vertical Milling in the Home Workshop" (WPS 2) .

Cheers,

Rod

[John Stevenson 1Participant @johnstevenson1]

Well yesterday I had to buy a new milling cutter, a sharp one

What !!! buy a new cutter when I had all these resharpened ones kicking about ????

Yup because it was a special one in a size I didn't have or close to it and also outside the reach of the EMG _ 12

£74.12 each including VAT It's a 3 flute 25mm Tiain coated rougher, the one with the serrations on the sides for chip clearance and guess what this one has deep grooves in all three cutting faces, two in each for breaking the chips up.

However at 10,500 rpm and a feed of 1 metre per minute and 12 mm depth of cut in some alloy plate the bottom finish is like a mirror. Side finish does show striations as you would expect from the chip serrations on the side.

Perhaps Ketan should advertise the new lot as having advanced chip clearance. I know the EMG – 12 won't do these on size but I'd could buy a machine for the price of 11 cutters.

This same cutter in 12mm which I thought about getting but cycle time would have been too much is £38.83 and that is with all my discounts so that's only 20 cutters.

[Martin KyteParticipant @martinkyte99762]

With regard to end mills for surfacing. I have a 3/4 inch cutter (bought second hand) which I ground the corners at 45 degrees (Quorn TCG) to give about 2 mm depth of cut without cutting on the side of the cutter. This is the cutter I use most. The 135 degree corner angle gives me a robust cutting edge similar to a roughing lathe tool which does not overheat easily and means you don't have to regrind the flutes. It produces a good finish and removes material quickly (Myford VMC mill). I would recommend this to anyone who has the facilities to regrind as described.

I'm sure this is not a new idea at all. In fact I copied it off the telly. (Old Fred Dibnah Video)

[Clive HartlandParticipant @clivehartland94829]

One has to bear in mind that the function of a milling cutter is to remove metal! Re-sharpening a cutter on the end lips is the easiest way of refurbishing, in many cases the flute edges get damaged and re-sharpening the flutes is a different thing again. Small size cutters need to be thrown away or converted for other use but large cutters are worthwhile recovering due to initial cost as JS has just stated. The machine covers the middle sizes used by model engineers but not the larger engineering sizes. If you have justification or need one then buy it. I cannot justify it at my lower scale of engineering so a Worden is all I need to sharpen the lips which will take up to 18 mm in my case. Making adaptors to suit all my size cutters in both metric and imperial. The only down side is the secondary clearance which on the Worden means adapting the motor mount to be raised to accomodate angle/height problem.

Clive

[JasonBModerator @jasonb]

Well it touched down yesterday, will report my findings in a day or two

[Author]

Posts