An unfortunate learnt something new lesson

Somewhere in one of my safe places I have that formulae for knurling. Had a quick look through some old stuff and found an old article about knurling that might help someone. I'll see if I can find that formulae.

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Thanks for the warning, Savarin. I woulda never guessed it. Havent seen this problem with all the aluminum and brass that I've knurled.
 
Bruce, the lathe was stopped so I just ran the rag along the length as it was a straight knurl, I dont do that to cross hatch knurls. as you said, the thought of a rag caught up and spinning is a tad scary.
Shootymacshootface, they've turned black today, cant feel them but there they are just laying under the skin. 2 left.
I used to use the formula to turn the piece to the "correct" size but now if I see double tracking I just crank down harder till it looks correct. I dont think I could have knurled this stainless with a conventional (push) knurler.
 
savarin said:
As some will know I have been doing a lot of straight knurling in stainless steel of late.
I use a cam jack knurler to really apply the pressure required to get full depth knurls with no double tracking.
I'm very happy with the results but learnt a valuable lesson unfortunately the hard way the other day.
I wiped the finished knurl along its length with a rag to get a good look at it and all was well untill I picked up another tool whereupon I felt the splinters in my thumb that had gone clean through the rag.
BUT, I couldnt see them or even feel them lightly passing a finger over where I thought they were.
Nope, they hadnt gone, just so fine they couldnt be seen.
Even with a 10x loup I could barely see them, I swear they were finer than prickly pear hairs and even more irritating.
I checked a couple of the finished knurls that still had oil on them and there they were, long but ultra fine hair like swarf sitting in the grooves.
I usually use a very thin oil for lubricating the knurling and I think this flushes the fine swarf out but this time had run out and used a thicker oil.
A good wash got rid of them and the ones in my thumb appear to have eventually worn away.
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I spend at least half an hour every week under a microscope with a scalpel blade and tweezers digging splinters out of my hands.
 
When I was much younger I had a job at a Borg-Warner plant taking apart pieces of transmissions. we did this for about 3 weeks. About 4 days after we were done I woke up with one hand that was about 2.5 times the size of the other. It did not hurt but it was so swollen that I could not shut it. Doc poked around and pulled out a tiny metal splinter I did not even know was there.
 
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