PDA

View Full Version : Acute Tool sharpening



Kiwi
10-24-2015, 06:38 AM
I don't know if this has been covered before or not but does any one know or use this system http://www.eccentricengineering.com.au/ I'm thinking I'm haveing to improve on what I do at the moment that is by hand and eye and scribed lines on the bench grinder support I've tried those drill sharpening jigs didn't last very long wound up doing it with hand and eye again End mills have not met with much sucess as yet any thoughts any one ? (it looks a bit fiddly)

Sparky_NY
10-24-2015, 08:02 AM
Its a interesting fixture but I could not find pricing anywhere.

chucketn
10-24-2015, 08:10 AM
http://www.eccentricengineering.com.au/index.php?option=com_virtuemart&page=shop.browse&category_id=33&Itemid=3&vmcchk=1&Itemid=3

Too rich for my blood. I have Harold Hall's Deluxe Grinding Table, a simpler version of this, made by my tool and die guy buddy!

Chuck

Lew Hartswick
10-24-2015, 08:35 AM
If you have a mill it's pretty easy to make one (or several) :-)
...lew... http://home.earthlink.net/~lhartswick/Diamond-turning-facing/

alanganes
10-24-2015, 10:57 AM
I do love gadgetry and appreciate clever fixtures and all that, so I appreciate the use of the the parallel linkage to keep a fixed angle on the work piece while allowing you to move it around the table, etc. On the other hand, I'm not sure I'd spend the money and effort to make one of these simply for the sake of holding particular angles on my tool bits. Just seems a bit pricey for the capability it brings you.

Personally, I don't think that the angles are all that critical for most applications. So long as the required reliefs are where they need to be, if one of them is 7 degrees rather than 5, I'd doubt anyone could notice a performance difference. Most of us offhand grind our HSS tools to "eyeball tolerance" and they work fine. If you are making a tool to cut threads, then of course its being 60 degrees is important. But again, if it is 59.6, I suspect most of us could not tell the difference in the finished part.

I recall seeing a link someplace (it was likely posted here) to an interesting study where someone asked experienced machinists to grind some tools to specific relief and rake angles, and then accurately measured them in comparison to what the guy grinding it thought he was making. Turned out most were off by a significant amount, but it generally made no significant performance difference.

Things like end mills or other multi-surface cutters are a different animal, of course, as holding uniformity from one cutting edge to the next over many edges by hand/eye is pretty difficult.

I'm sure not saying this is a bad idea if you want one, I love gadgets. I often grind my HSS lathe bits on a T&C grinder, but I do that mostly just because I have one and simply like using it. I have nothing that makes me think that it makes my bits way better due to the angles being exactly X degrees, rather than X.5 degrees.

metalmagpie
10-24-2015, 11:31 AM
If you have a mill it's pretty easy to make one (or several) :-)
...lew... http://home.earthlink.net/~lhartswick/Diamond-turning-facing/

How did you machine that sharp inside square corner?

In general, once you get an angle started, on a belt grinder with a decent platen it's very easy to hold that angle flat against the belt. That's how I rough out HSS bits. Then I touch them up on the grinding wheel and hone to razor sharp with diamond.

metalmagpie

Mcgyver
10-24-2015, 11:33 AM
I'd pass.... tools bits, what Alan said. stand there and do it free hand with a protractor until you get onto it (10 minutes)

For endmills.....I never bought into sharpening the ends. Few of us spend anytime plunging, its the sides that need sharpening. You want an air bearing for this and ideally a tool and cutter grinder (a GREAT addition to the home shop)

for drills....hmmm....it says you have to make an insert or bushing for each size. Ugh. Limited size range. Ugh.

Learn to do drills by hand, its good enough most of the time. But if you want to make one, the challenges for mechanized drill sharpening are holding a wide range of sizes (collets can be trouble because of the geometry of the lands) and being able to index them dead on 180 degrees. Here's what I came up with. the oldtimers are probably sick of seeing it but it is very functional - holds a huge range of sizes. Its mounted on a universal swivel I made, although nowadays its hardly worth it as cheap imports are available. One day I'll submit as an article, in the meantime, the photos should be enough if you wanted to have a go. The V block is case hardened and has stood up perfectly.

http://i20.photobucket.com/albums/b201/michael0100/universal%20swivel/pt2trvbloc.jpg (http://s20.photobucket.com/user/michael0100/media/universal%20swivel/pt2trvbloc.jpg.html)

http://i20.photobucket.com/albums/b201/michael0100/universal%20swivel/pt2trassembly.jpg (http://s20.photobucket.com/user/michael0100/media/universal%20swivel/pt2trassembly.jpg.html)

http://i20.photobucket.com/albums/b201/michael0100/universal%20swivel/pt2withlargerdrill.jpg (http://s20.photobucket.com/user/michael0100/media/universal%20swivel/pt2withlargerdrill.jpg.html)

http://i20.photobucket.com/albums/b201/michael0100/universal%20swivel/pt2toothrest.jpg (http://s20.photobucket.com/user/michael0100/media/universal%20swivel/pt2toothrest.jpg.html)

John Stevenson
10-24-2015, 01:16 PM
For endmills.....I never bought into sharpening the ends. Few of us spend anytime plunging, its the sides that need sharpening. You want an air bearing for this and ideally a tool and cutter grinder (a GREAT addition to the home shop)



Unless you are solely squaring up the outside of blocks, then any pocket operation or keyway requires you to plunge.
As as we are talking hobby machines here instead of full blown INT 50 tooling production machines you will have a limited depth of cut so it only this depth that you are using the sides on.
It when badly work this short end piece was cut off then an end grind would result in a like new cutter and still keep the diameter so you are not using spurious diameter cutters.

I can take a slightly worn or even a cut down 10mm - 12mm [ 3/8" - 1/2" ] cutter, 2 flute, 3 flute or even 4 flute and sharpen the end to like new in one minute.

I couldn't even clear the crap off my tool and cutter grinder in that time and setting up for any cutter would take 10 minutes at least.

alanganes
10-24-2015, 01:46 PM
I can take a slightly worn or even a cut down 10mm - 12mm [ 3/8" - 1/2" ] cutter, 2 flute, 3 flute or even 4 flute and sharpen the end to like new in one minute.

I couldn't even clear the crap off my tool and cutter grinder in that time and setting up for any cutter would take 10 minutes at least.

But Sir John, not all of us have a lunar lander to sharpen our end mills with. :)

Mcgyver
10-24-2015, 01:59 PM
Unless you are solely squaring up the outside of blocks, then any pocket operation or keyway requires you to plunge.
As as we are talking hobby machines here instead of full blown INT 50 tooling production machines you will have a limited depth of cut so it only this depth that you are using the sides on.
.

I suppose its individual to the man/shop. I don't usually make keyways with endmills, and rarely do 'pockets' on manual machines. Most work (I do) uses the sides, and I will generally us as much of the side as I can, ie reduce feed/speed increase doc can equal the same removal rate but longer cutter life.

a rig than grinds the end of end mills isn't much use to me, half the time after sharpening the flutes is don't bother the ends:p

John Stevenson
10-24-2015, 02:35 PM
Must agree it is individual to the man/shop.

When we were developing the lunar lander end mill grinder it didn't take long for me to use up all my stock of blunt end mills, although I do still continue to discover pockets of them in other places.
To this end I went to the local scrap yard and asked them to save me any HSS or carbide cutters that came in and finished up with 1/2 a washing machine tub of worn cutters. Small tub I hasten to add, probably 30 to 40 pounds max weight.

The vast majority of these from industrial users were worn or chipped on the very ends only, some were totalled with broken flutes running up a fair way but these were mainly carbide. Very few showed signs of being used predominantly on the sides.

So this has now caused me to examine the last 3 jobs I have milled.
Cutters from 4mm to 10mm and total depths from 1mm to 10mm. The deepest depth the 10mm was done with the 4mm cutter as that is as big a cutter as I could use and I had to do this in 2mm passes as there is no way that I would trust a 4mm cutter not to snap trying to do 10mm in one pass.

After travelling round a far bit of the UK doing CNC training I think this is a very close view of how others cut as well. Taking full side cuts of possibly 20mm depth is OK IF you need to go 20mm deep.

Mcgyver
10-24-2015, 03:22 PM
whats your sop for cutting ends off?

likewise, one ends up with washtubs full of dull cutters - not from buying and using so much, but they seem to make their way into the shop. So with bins of them, its easy to batch sharpen. grab a dozen or two with 5/8 shanks and do them all at once. that way each one takes very little time; its the set and remember how to do it that taxes me. To do one, bahh, can't be bothered unless its something special that is needed.

John Stevenson
10-24-2015, 03:39 PM
I have one of these el cheapo angle grinder cut off stands, possibly Harbor Freight ?

https://www.machinemart.co.uk/images/library/product/large/06/060521040.jpg?2

Not mine but close enough.
For HSS I use one of the thin 0.8mm wide cutting wheels and for carbide I use one of these.

http://www.arceurotrade.co.uk/imagecache/fe6160d8-080a-4c80-854c-a23e00bf02a0_400x297.jpg

4" diamond cutting disk, costs about $10 and works well. I also use the same disk for grinding brazed carbide lathe tool to rough out. Never use green grit wheels any more.

Where that lunar lander comes in is speed. All the skill is in the machine and the wheels. You can train a 12 year old to use on in 10 minutes, there are only two setting, length of cutter in the holder and orientation of the cutting edge, both done with a simple inbuilt jig.

After that it's pick a holder and that matches shank size then pick a cam, that matches cutter size and if 2,3 or 4 flute.
Unlike a T&C grinder where it pays to do batches of the same size and type you can swap and change as much as you like.
If you get a 4 flute cutter what you call end mills with the centre pip in, they can't plunge but if you find the hole is wearing down short then just chop it off and on a regrind it comes out as a 4 flute centre cutting cutter with two flutes going over centre.

Mcgyver
10-24-2015, 03:41 PM
you lost me on the lunar lander......??

John Stevenson
10-24-2015, 04:07 PM
Sorry, not intentional.

http://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/End-Mill-Re-Sharpening-Module

Worked closely with the Chinese over this over an 8 month period.

Write up in MEW on it.

http://www.stevenson-engineers.co.uk/files/MEW%20article.pdf

Kiwi
10-24-2015, 06:13 PM
[QUOTE=alangane Turned out most were off by a significant amount, but it generally made no significant performance difference.

.[/QUOTE]

Alan I think that sums it up very nicely I was thinking that the time fiddle factor in setting it up for each job might just keep it in the draw
Thanks Guys
Kiwi

EddyCurr
10-24-2015, 06:57 PM
you lost me on the lunar lander......??Only in Britain you say?

Pity ...

.

EddyCurr
10-24-2015, 07:04 PM
whats your sop for cutting ends off?.See whether one of these might serve your needs: 6" Abrasive Chop Saw (http://bbs.homeshopmachinist.net/threads/53777-6-quot-Abrasive-Chop-Saw?p=760962) (2012.04.13).

.

Spin Doctor
10-24-2015, 07:07 PM
For HSS tool bits I've got an adjustable fixture for use on a surface grinder. IMO a surface grinder as long as it can be used to do tool& cutter grinding is far useful than a straight t&c

Mcgyver
10-25-2015, 11:21 AM
Sorry, not intentional.]

man, that is lunar module, lol!


See whether one of these might serve your needs: 6" Abrasive Chop Saw (2012.04.13).

I've got a larger version of that, and imo its an outdoor tool....sends a spray of abrasive everywhere.....unless you are using a diamond wheel or something. That would be handy

To the notion of sharpening ends, I see the value if you've got a cutter which a chunk out of the bottom, or as a quick second op to grinding the flutes to finish the job, but overall I still don't see value in sharpening the end without doing the flutes. The thread has caused me top reflect how I use them, surfacing, profiling, dimensionless, cleaning up the ends of cut barstock....its all cutting on the sides. keys are done with key cutters. Not like I never plunge, but it'd be rare compared to the sides.

for me there'd be a spot for it as a second op, doing the ends with a T&CG is pita and requires a change of set up (I have a machine that mostly sits there with an air bearing on it). Also for reworking quantities of chunk-missing ends, especially for larger sizes ($$$), it would be a good thing. Lastly, if you a doing small endmil;s, say under 3/8, my objections are probably less relevant.....ie you're not using the first 1/2" of a 1/8" end mill, so chopping and grinding the end might make more sense