The Shop > Tools

Using the endmill sharpening fixture

(1/4) > >>

bogstandard:
Because there were no instructions with this unit, I had to work out how to do the job myself, so if it is wrong to the way the manufacturers want you to do it, then I apologise.
I know my way works, and I will be sticking to it. As long as the cutter does the job afterwards, then I will be happy.

First off, find a blunt cutter.




This is the unit stripped down into its component parts.
I scribed a line on the top of the block, to help me align the markings around collet holder. It runs in line with the centre line of the locking screw. The PITA ball goes into the end of the hole that the screw fits thru. It is that which sits into the detents and locks everything in the correct position for grinding.




The collet goes thru the rotating sleeve and is tightened up by the lock ring on the bottom, after the cutter is put into the collet.




I aligned the zero mark with my scribed line and made sure one of the cutting faces was roughly at 90 degrees to it. Then the lock screw was tightened.




This is the bottom of the main plate. As you can see, it isn't just a straight across split. I got it wrong last time when I said about the two angles. It is the main cutter face that has the forward face and drop to one side angle on it. The relief angle is the same all the way across. I have no idea at the moment why the angles are like that, YET.




On this shot I have removed the guard so I can show what is going on. The wheel has been fine dressed and the back fence has been raised on the mag chuck.




The main block face was popped onto the mag chuck and pushed back until it rested along the back fence stop. Mag chuck turned on.




This bit is now experimental.

I raised the cutter up until it was at the side of the wheel, and checked to see if the cutting edge of the cutter was square to the wheel. It wasn't, so the collet holder was removed from the block, the cutter turned and then retried for squareness.




It was difficult to see if it was accurately in line because of the shadows and even my smallest square was too big. Note to myself, MAKE A SMALL SQUARE SETTING JIG, so that I can get it really spot on.




You will notice a few pictures larger than others. This is so that you can see the highlights better.
This is where you start your first grind. You need to remove only just enough to clean the damaged faces up. This is normally on the very outside edge, so here you see the cut brought to where the damage has been removed, about 0.003" (0.015mm). Maybe a bit too much of a cut, but because this is experimental, I will see how it goes




It was gently fed across in the Y axis whilst grinding until the whole face had been 'sparked out'




The tool was wound out in the Y axis, and without touching any feeds on the grinder, the next face was turned into play using the indexer. The second face was ground at exactly the same settings and method as the first.
Both cutting faces done. This grinding took no more than a few minutes.




Now for the relief cut. Mag switched off, push down on angle end and turn mag back on. Still hard against the back fence.




Because this cutter had a forged relief angle on it, I took it down in about four separate grinds (using the same method as the cutting face grinding).




Without touching anything, I zeroed the Z axis lift handle. Then wound the cut off.
The second side was indexed round, and ground down like the first, in stages, until I reached the zero mark on the Z handle.




The finished grind.
I still had things a little out of square. Also I noticed a few 'burn' marks, despite taking things steady. I think I need a different grade of wheel for doing HSS cutters. I have a few 'specials', so I will try one of those next time.




I noticed that the gash had become a tad shallow, so using my dremel clone and a bonded cutting disc, I gashed it a little deeper.




For my second attempt, I am well pleased with this one. I did another one after this, and despite spending more time trying to get it square to the wheel, it still came out with a slight taper along the cutting edge. Maybe this is how this grinder does them all, not having anything to go by, it is difficult to assume otherwise. Maybe Bob Deere could shed a bit of light on it.




The second one took only ten minutes from start to finish, despite piddling about trying to get it more square. So really it does look like a good cost saver.

Time for that coffee in the background, before it goes too cold.


Bogs.


BTW, There is a little crisis on the personal front at the moment, so if there are any questions, I will get to them when I can.

sbwhart:
Quote

 I have no idea at the moment why the angles are like that, YET.
 
:scratch:


John its so you've got side clearance across the face of the cutter.

To stop the burning you need a softer wheel a I or J bond, You probably know this anyway.

Cheers

Stew

Darren:

--- Quote from: sbwhart on July 10, 2009, 04:21:18 AM ---


John its so you've got side clearance across the face of the cutter.



--- End quote ---

Are you referring to the depressed center..............that sounds odd, but I'm sure you know what I mean... :ddb:

Nice post again John, I thought these things looked a bit a gimmick but you seem to be doing fine with one.

John Stevenson:
The reason there is a slight side angle is that an end mill or slot drill isn't flat across the bottom.

There is a slight, about 1 degree tilt to the cutter so the outer edges are higher than the inner  to stop it rubbing hence the widening of the lands in Johns pic.

It maybe that the angle on these blocks is greater than 1 degree, hard to tell from a picture, it only needs to be very slight to stop rubbing, that slight most people don't know it's there in the first place.

John S.

bogstandard:
Thanks lads.

I have a load of softer bonds for use with mnemonic steels, one of those will be perfect.

I know about the depressed centre to the cutting edges, it is just that it looks slightly excessive, but if they cut, then no problems.

Although it looks a bit gimmicky, as Darren has said, for cutting up to four end faces, it cannot be faulted in the way it operates and how quickly it gets the job done using just a standard wheel. Any more facets than that is a bonus, as and when I can work it out, as most of the standard cutters we use fall into the 2 to 4 category anyway.

So, would I recommend it. Well from what I have seen already, for the cost of half a dozen cutters, then a definite yes.

All you need to go with it are a surface grinder, a mag chuck and a set of 5c collets. If you already have those, then it is just what you want, if you haven't, and you had to buy them, it would be a rather expensive way of sharpening your cutters.

John

Navigation

[0] Message Index

[#] Next page