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View Full Version : Why won't this endmill sharpening idea work?



DICKEYBIRD
05-11-2008, 12:43 PM
I was setting up to drill the 5C fixture mounting plate for the endmill grinding device I'm building in another thread and I dope slapped myself and said: "Why dont'cha just mount a diamond wheel on an arbor in the mill and use the mill table to precisely move the endmill?" Sitting in my comfortable milling machine chair with my magnifying visor on, looking at the endmill under a strong light made it look dead easy to crank the y axis over and dress the
end accurately. The 5C collet fixture holds the tool at the proper angles and indexes for 2, 3, or 4 flutes. The wheel shown here is just a mockup to show the concept.

http://i57.photobucket.com/albums/g227/DBAviation/MillSharpener.jpg

The wheel speeds mentioned on the Glendo sharpener thread say a 6" wheel is spun at 308 rpm...I assume to control heat and diamond degradation. The surface speed of the Glendo wheel would be about 480 FPM (if my math is correct) so if you convert that to one of these 1" wheels http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=40551 you get roughly 1850 rpm, well within my X-3's capabilities. Yes, I know that's a cheap, crappy wheel but I'm just doing a "what-if" mental exercise. Other, larger wheels could be used to do the same thing with a corresponding drop in rpm to control surface speed.

Anyhoo, let's say we mount the whole rig up in a big plastic storage tub and rig a pump to flow coolant onto the grinding process to wash all the dust safely into tub. To make it really slick, we could mount one of the webcam viewers mentioned in another thread for a closeup view of the process.

Seems like it'd work well to me. Makes me want to sh!t can my original project and do this one.:) The only advantage in finishing the original project is I could sharpen a tool without having to stop and teardown an existing setup in the mill.

Paul Alciatore
05-11-2008, 12:58 PM
I can't think of any reason why it won't work. But I do have a couple of considerations after looking at your pictures.

First, the wheel you have mounted looks very coarse. Perhaps an artifact of the photo, but wouldn't you want an extra fine wheel to produce a nice edge on the mill? You did say it was just for the photo, but I still want to know what kind of wheel you should use.

Second, I assume that either the wheel or the tool is tilted to an angle to grind the proper relief on the edge. I would want to insure that the wheel's rotation would not be in a direction that would tend to wedge the tool under the wheel. It looks like you have it right in the photo, but I think it is worth mentioning for all who read this. With the HP available on a mill spindle, rotation the other way could result in a ruined mill and wheel.

DICKEYBIRD
05-11-2008, 01:01 PM
You're right Paul, that is a coarse wheel; I just stuck it in to show the idea.

Good point about the wedging effect. Didn't think of that. So in the pic, the tool is leaning to the right 5 degrees and I was thinking the wheel should spin in reverse, counter-clockwise. Is that correct?

IOWOLF
05-11-2008, 01:08 PM
Like he said,"The wheel shown here is just a mockup to show the concept."

Mike Burdick
05-11-2008, 01:11 PM
My endmills always get dull on the side edges too!

But... your idea is a good one if one only uses the endmill for maybe a 0.100 depth cut and then cuts that eitire amount off when sharpening. I know many hobbyist that do just that - but they mostly use a surface grinder and a fixture that can be bought to hold it very economically.

DICKEYBIRD
05-11-2008, 01:35 PM
Hi Mike, for whatever reason, I don't seem to be doing much side milling to dull the sides. The ends and corners, though, that's another story!

The fixture shown in the pic is in fact designed to be used in a mag chuck on a surface grinder. I have the fixture; now if I could just find a cheap bench-top surface grinder to go with it. Talk about getting the cart before a horse!;)

Allan Waterfall
05-11-2008, 01:36 PM
I posted something similar about three years ago,but used a Dremel clamped in an adjustable fixture for angle and the fixture clamped to the quill.

The endmill was clamped upright in a simple jig in the vice and the jig was made so that it inclined the endmill about a degree if memory serves me,this was so the end was ground concave.

It was in the first tips book,so it's a while ago.

Allan

Tinkerer
05-11-2008, 01:58 PM
Should... here's a site I found awhile ago showing it being done.
http://pico-systems.com/sharpen.html

The only concern would be the grinding dust on the ways but some rags would minimize that.

Mcgyver
05-12-2008, 07:17 AM
Dickey, a couple of things - hey power to you for trying, but you asked :D.

That that relief angle that you are getting by tilting the head also needs to slant in toward the centre a degree or two. Picture the end mill in a collet; the outside of the mill is slightly lower than the inside to prevent rubbing. you may have that angle built into your set up, i can't tell.

I agree with Mike, unless you are plunging, going straight down, it is the sides you are dulling not the end. Because the corners are weakest and the poorest at dissipating heat, the wear shows up there quicker....but basically you're wearing sides by how much you DOC is. if you're taking off .200 DOC, you'd have to grand back 200 thou of cutter - kind of grinding away the dull section rather than sharpening it.

you've thought about how to use the diamond with ferrous which is good, but I'm not sure what advantage in provides, seems like at those speeds the removal rate would be very slow??

dewat
05-12-2008, 07:46 AM
I have been sharpening my end mills this way for 3 yrs, down to 3/16, 4 flute. I usually use AO wheels. To minimize dust I made a fixture to hold a shop vac nozzle close to the wheel and cover the table with plastic. For those who aren't familiar with this 5C fixture all three angles needed are built into the base.

see this link, half way down on the left.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=473&PMITEM=287-6840

tdmidget
05-12-2008, 02:17 PM
[QUOTE=DICKEYBIRD]I was setting up to drill the 5C fixture mounting plate for the endmill grinding device I'm building in another thread and I dope slapped myself and said: "Why dont'cha just mount a diamond wheel on an arbor in the mill and use the mill table to precisely move the endmill?"
Well for starters that looks like a high speed end mill and you don't grind steel with diamond. The proper wheel would be Norton 38A. BUT with a vitrified wheel on a vertical spindle and no guard you would right in the path of fragments if a wheel explodes. And they do from time to time.

chrsbrbnk
05-12-2008, 11:58 PM
It should work but a couple down sides are fairly slow wheel movement across the tool lighter cuts will help prevent burning the seconds a bit more of a problem in that you have to be really aggresive about wiping down any surface that gets grit on it get covers for the ways and don't retract the quill until its wiped clean. We used a bridgeport mill to grind high speed punchs the grit problem was really hard on it most because of lack of attention

Paul Alciatore
05-13-2008, 02:37 AM
You're right Paul, that is a coarse wheel; I just stuck it in to show the idea.

Good point about the wedging effect. Didn't think of that. So in the pic, the tool is leaning to the right 5 degrees and I was thinking the wheel should spin in reverse, counter-clockwise. Is that correct?

I would think that would be the correct way. But I was thinking the exact opposite after looking at your picture: left tilt and CW rotation as viewed from above.

Paul Alciatore
05-13-2008, 02:39 AM
I have been sharpening my end mills this way for 3 yrs, down to 3/16, 4 flute. I usually use AO wheels. To minimize dust I made a fixture to hold a shop vac nozzle close to the wheel and cover the table with plastic. For those who aren't familiar with this 5C fixture all three angles needed are built into the base.

see this link, half way down on the left.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=473&PMITEM=287-6840


I have seen these advertised before and wondered how good they were. What means are used to hold them to the table? Hand held? Clamps? But how would you clamp it in the 30 degree position? Or magnetic? Or what?

tdmidget
05-13-2008, 05:25 AM
I have seen these advertised before and wondered how good they were. What means are used to hold them to the table? Hand held? Clamps? But how would you clamp it in the 30 degree position? Or magnetic? Or what?
They are for use on a surface grinder with a magnetic chuck. I must point out here that a Bridgeport is not a grinding machine. Think SAFETY

DICKEYBIRD
05-13-2008, 09:14 AM
Paul, I drilled & tapped my fixture so it could be bolted to a vertical plate in the grinding gizmo I'm working on shown below. The fixture is a fairly hard metal and it was tough going with HSS tools but I got 'er done.

http://i57.photobucket.com/albums/g227/DBAviation/EndmillFixtureMockup.jpg

The pic shown at the beginning of this thread was made while the vertical plate was being drilled for the fixture and that's where the thought about using the mill for a grinder came from.

Thanks Mike, Mcgyver & all for reminding me about the sides at the end getting worn as well as the ends. On most of the endmills I'm wanting to sharpen, the corners are chipped a little past the wear showing on the sides so they should be OK once I've ground down past the chipping. Then I'll have to worry about gashing the ends.:(

tiptop
05-15-2008, 06:56 PM
Milton and everyone,
I have posted some pictures at my imagevent site, showing the Air Bearing fixtures made by Cuttermaster and Harig that I have. These are just for the proverbial "food for thought" crowd. Not trying to steal the thread Milton, I just figurered some of these folks may be interested, since you have them walking down the road, so to say.

Here is a link to them.
http://imageevent.com/aatiptop/toolspage/airbearingsharigandcuttermaster

DICKEYBIRD
05-15-2008, 08:21 PM
Thanks Jay, I've often wondered what type of magic lies within an air bearing...now I know! It'll prolly be a while before I get my hands on one though.:)

dewat
05-16-2008, 05:47 AM
I have seen these advertised before and wondered how good they were. What means are used to hold them to the table? Hand held? Clamps? But how would you clamp it in the 30 degree position? Or magnetic? Or what?

I just clamp it in the vise, first the 30deg and if needed rotate it to cut in front of the leading edge, then re-clamp the fixture so its sitting flat, in this position the other 2 angles are already built into the design. I bought mine from ENCO, I don't know if they have changed their supplier, but the one I have is crude, the indexing is with 3 ball detents, the springs are weak, the CDCO "looks" like its a better product.

dewat
05-16-2008, 06:28 AM
I took these pics just to give a general idea of how I use it.
At the bottom left of the fixture you can see the 30 deg angle, also notice the collet barrel is at a forward angle. I added the clamp due to the sloppy detents.

http://i81.photobucket.com/albums/j218/dewat/Gordy307.jpg



http://i81.photobucket.com/albums/j218/dewat/Gordy304.jpg

http://i81.photobucket.com/albums/j218/dewat/Gordy303.jpg

DICKEYBIRD
05-16-2008, 08:12 AM
Thanks for the pics dewat.

Yup, the CDCO jig looks better than the one from ENCO...and only $32.00. Go figure. It has a one ball detent locked by a thumbscrew and locks down solid with just a twist. I'm still amazed at what $32.00 can buy.

What kind of wheel is that and where did you get it? Looks great (and expensive.)

dewat
05-16-2008, 07:02 PM
I bought that wheel off of ebay, if you go to the CDCO web site and do a search for "diamond wheel" the first one that comes up looks exactly like mine, probably made in the same place, $43.00

DICKEYBIRD
05-16-2008, 08:51 PM
Holy Cow dewat! You're sharpening HSS endmills with a DIAMOND wheel? Surely the gods of machinery will smite thee down for such blatant blasphemy.;)

Seriously though, what dia. is the wheel and roughly what rpm are you turning it? Have you sharpened many HSS cutters and does it hold up OK? I've read that diamond wheels "go away" pretty quickly when used on steel but the Glendo sharpener uses a diamond wheel on steel at slow speeds. I've never seen a Glendo wheel close-up so I don't know if they are the "resinoid" type or something different.

dewat
05-17-2008, 02:22 PM
Sorry for the confusion, I only use a diamond wheel for carbide, that wheel was handy for the mock-up just to take the pics. When I do use it I run it at about 500 rpm, its just under 4" dia., the one on CDCO lists it at 3 3/4" so it probanly the same MFG. I guess a CBN wheel would be best for HSS, for now I just use AO.

tdmidget
05-18-2008, 12:19 PM
Dry grinding of tungsten carbide should be done at about 3500 sfm. turning a 4 inch wheel at 3600 gives you 3769. This is for a resinoid wheel. The electroplated wheel can't be turned the proper speed without damaging the bond.
Also many people call all super abrasives "diamond" . The wheel might actually be CBN.