checking end mills for runout

[wmpy]

Wmpy

2 questions on your measuring method.
1) The picture looks like you are measuring on the relief and not at the cutting edge. Where on the end mill are you measuring. A close up photo would help.
2) The picture shows you are measuring pretty close to the tip, are you on the tip radius?

CarlBoyd

I am checking on the cutting edge. I slowly rotate the cutter in the V block to find the high spot. I am assuming that high spot is the cutting edge.

I was pretty close to the tip, but I was careful to not check on the radius as I was worried about that throwing off my measurements. I also checked further up the tool and found similar results.

I will see if I can get a close-up photo.

 

[DavidScott]

I will look for a corncob rougher. I ended up ordering some 4 flute corner radius end mills from MSC to try out because the 3 flute EMs seem to be hard to come by. I will see how well 4 flutes can slot.

I like Lakeshores Fireplugs??? I run them until they look totally trashed driving straight through narrow slots.

 

[CarbideBob]

Measuring method is fine for a runout check.
You may get somewhat different readings if using a 60 degree block rather than a 90.
Be careful not to let the coated section get int to the vee block.
The real question is what is a good number and what is bad.

Not so obvious is that ideally one should rotate the tool cutting edge first into the indicator tip.
Clockwise here.
This may seem backwards but puts the cutting edge in compression during measuring and lessens the risk of chipping the edge.
Bob

 

[Cole2534]

This may seem backwards but puts the cutting edge in compression during measuring and lessens the risk of chipping the edge.
Bob

Never would have guessed that.

 

[michiganbuck]

I have always rolled the heel/lower portion/area toward the indicator point so it would not catch, or shave the point. A sharp edge catching the indicator point often seemed to stress my height gauge or fixture holding the indicator point..agree using a carbide flat nose point with a dial indicator would have little chance to catch.

One interesting cutting tool test is to use a needle point contact to check right up to the very edge of an OD circular land, or to the very edge of a flat grind.
Depending on the machine's rigidity, condition of the spindle, and technique if the spark out the very edge of the grind may have a few tenths or more minus roll off. In making carbide cutting tools this factor can be seen in heat and tool life of certain types of cutters, The spin direction of spun cutter can reduce the occurrence.

One simple test to detect if this condition exists is to blue up a ground surface and reverse the spin direction to just spark out a tenth or a few to see if the grind changes.

Spiral flute tools have a less roll-off effect because wheel contact can be monitored by using a wide wheel so an interruption effect is reduced.

* The OD and end cutting edge of an end mill comes up to a sharp edge, with clearance just under that edge so this roll off condition would not be found on an end mill. or any up-to-sharp cutter edge.

 

[5 axis Fidia guy]

Your checking them properly, the problem is it says Garr on the package. That's an "economical" endmill at best.

 

[wmpy]

Your checking them properly, the problem is it says Garr on the package. That's an "economical" endmill at best.

Interesting. I always thought they were well regarded.

 

[Machinerer]

Interesting. I always thought they were well regarded.

They're not ultra high-end but I definitely wouldn't call them "economy at best". Their VX7 endmills beat lots of higher end tooling by a long shot in an apples to apples comparison in some Invar parts we make.

I agree, this seems like you're having a bad experience, but they're not "value" tooling.

 

[CarbideBob]

Never would have guessed that.

This does in fact seem counterintuitive.
Checking from the secondary or back side is a habit we have to "unteach" many.
Seems like the slower rise would be better for carbide, cbn, pcd until you get out the 500-750x microscope.
Gram weight on the DTI stylus also counts.
These are powder metals and like compression a whole lot more than tension at the sharp edge.
Optical the best but often one needs to use contact gauges.

Weird to see a Garr this far off. Perhaps a bit of dirt got in the collet at grind load.
Bob

 

[5 axis Fidia guy]

They're not ultra high-end but I definitely wouldn't call them "economy at best". Their VX7 endmills beat lots of higher end tooling by a long shot in an apples to apples comparison in some Invar parts we make.

I agree, this seems like you're having a bad experience, but they're not "value" tooling.

You could purchase much better more accurate tooling for the same or better cost. YG, JJ Tool, Han Song.

 

[Mechanola]

If you want to minimize your measuring errors, use a short V body, merely a blade, and put the cutter on a center (provided it has an astern center bore). The setup would ideally be inclined so that you can support the tool at varying heights.

 

[Mtndew]

You could purchase much better more accurate tooling for the same or better cost. YG, JJ Tool, Han Song.

I'd put Garr end mills above YG-1 any day of the week.
Never heard of the other 2 mfg's.

 

[CAMasochism]

I'd put Garr end mills above YG-1 any day of the week.
Never heard of the other 2 mfg's.

My shop mostly uses YG mills. I've been trying to get us to switch away for years. Did some tests on our standard parts and MA Ford and Niagara blew them out of the water while still being cheaper than Kennametal.