Bonehead Move

[EdK]

I went to face a piece of brass that I had cut to rough length with a hack saw and it acted like it had work hardened from the sawing. I knew brass doesn't work harden but it was a bugger to cut. I tried three different types of cutting tools with no success. I scratched my head for a while and then it finally dawned on me that I had used the lathe to polish some steel rod with emery paper and I had run the lathe backwards for that.      

Ed

[EdK]

Bonehead move number two for today. I had used an MT3 collet to machine a part and needed to switch to the 3-jaw chuck. I could not find two of the three nuts for bolting the chuck to the flange so I took two from the 4-jaw chuck. I was machining away and thought the lathe sounded louder than normal, so much so that I had to install hearing protection. I reduced the RPMs to chamfer the edge and it sounded like something was loose inside the chuck. I removed the chuck to have a look at it and inside the spindle bore of the lathe sits the two missing screws.      

Ed

[rubes]

Well...I aint gonna throw any stones. We've all done stupid stuff (not anything I'm gonna share though ).

[Highpower]

Turned on the spindle switch of my mill 99.9% of the time with my right hand to the forward direction. The ONE time I reached up and turned the switch on with my left hand... my pea brain subconsciously told me to change the direction I turned the switch as well.     



The fact that it was a brand new end mill only made it sting that much more.  

[rleete]

The first one was funny. Hope you didn't ding up the spindle bore, Ed.

Highpower, I feel your pain. I know endmills are supposed to be consumables, but for me that's not usually an issue unless I mess them up.

[EdK]

(01-22-2024, 07:54 AM)rleete Wrote: Hope you didn't ding up the spindle bore, Ed.

That was my concern also but no damage. Good thing they were in there only for facing two ends.

Ed

[Highpower]

(01-22-2024, 07:54 AM)rleete Wrote: ...  I know endmills are supposed to be consumables, but for me that's not usually an issue unless I mess them up.

I agree. But when you get ZERO cuts out a brand new tool, that's taking "consumable" to a whole new level!  

What amazed me is the fact that a 1/2" HSS end mill snapped instantly the moment it contacted the part while running backwards. It's not like I was bearing down on the table crank handle trying to push through a cut. It just barely touched the side of an aluminum plate I wanted to cut a slot in. Didn't even leave a mark on the plate really. Just a thin vertical rub line where the end mill touched it.  

[EdK]

That is bizarre. I wonder if it had a crack in it?

What brand of end mill was it?

Ed

[Highpower]

(01-22-2024, 02:54 PM)EdK Wrote: That is bizarre. I wonder if it had a crack in it?

What brand of end mill was it?

Ed

Hard to say. It was one of a dozen or so random sizes of Enco end mills that I bought back when I bought my mill. They all sit in a drawer in one of my tool boxes reserved for machining tools only. Each end mill has it's own square plastic telescoping container as well so it's not like they are rolling around in the drawer banging into each other like my hand files do.  

Still, they were made in China. If it wasn't cracked before hand my only guess is that the force put on the flutes of the end mill running in reverse is much higher than running in the correct direction. Maybe something to do with the angles / corners of how the flutes are ground? Just a wild guess from a not-even-close to an engineer.  

I've never had any problem with any of the other Enco mills though - probably because I haven't tried running them backwards as well.

[rleete]

Well, this is your chance to test that theory on all your Enco end mills. Report to us when you stop crying.