Thread: What did you learn today?

Drilling a 1/4" hole yesterday in a piece of offcut steel. Set up in the x3 mill at desired angle, little thought about speed....... 2000 rpm should do it.

Drilling went well for 9/10ths of the hole ( about 3/8" deep).
Drill jambs. Tighten chuck, extract drill manually and restart drilling gently to prevent a re-catch on breaking through.
Some resistance so lean on feed a little. Drill feels like it breaks through, but not cleanly. feed a little more. something funny.

Withdraw drill to discover bright red hot drill with 1/4" of tip now 3/16" diameter. My own countersink creation!!!

Spark test on grinder hints my scrap was a higher carbon piece of something. I think.
Drill was an old P&N HSS sample that had done lots of work and is now resharpended to do more.

I learnt HSS is no match for recently hardened carbon steel. I also learnt more haste, less speed.... or in this case, speed and feed matter!

After the drill was removed from the job after jamming, did you remove the drill and check the end of it to see if it had been damaged or had metal build up on the point.

Some times the edges can chip or a small amount of material will build up on the point causing problems as described, if its the metal build up a flick with a scriber or similar will remove, if its the edges a touch up on the grinder.

Originally Posted by HavinaGo

I learnt HSS is no match for recently hardened carbon steel. I also learnt more haste, less speed.... or in this case, speed and feed matter!

Carbon steel can be made harder then HSS... It is carbon alone that determines the final hardness of steel...

HSS only means the steel alloy has a higher tempering range.. ie it tempers at higher temperatures...

Originally Posted by RayG

Nothing wrong with Fastenal's description... and it's not incompatible with the description given in Machinery's Handbook.. it's just called the M profile, and there's an ISO standard if you google for "M thread profile" you should find it. There are lots of other metric profiles, MJ, S, etc..

Regards
Ray

Ray, the machinery's handbook is a great resource. Just not for anything metric. Our American friends are still at the very beginning of making the transition to metric. Not yet past the stage of desiring to "reinvent the wheel". It makes me remember my first holiday in Australia, it was 1979, and Aussies were about at the same stage with their metric conversion as the Americans are now. Height limits under bridges where signalled something like "2.743m (9ft)". Same with speed limits, or with the volumetric contents of a beer can. It takes well and truly one full generation for common sense to prevail. Chris

Originally Posted by HavinaGo

Drilling a 1/4" hole yesterday in a piece of offcut steel. Set up in the x3 mill at desired angle, little thought about speed....... 2000 rpm should do it.

Drilling went well for 9/10ths of the hole ( about 3/8" deep).
Drill jambs. Tighten chuck, extract drill manually and restart drilling gently to prevent a re-catch on breaking through.
Some resistance so lean on feed a little. Drill feels like it breaks through, but not cleanly. feed a little more. something funny.

Withdraw drill to discover bright red hot drill with 1/4" of tip now 3/16" diameter. My own countersink creation!!!

Spark test on grinder hints my scrap was a higher carbon piece of something. I think.
Drill was an old P&N HSS sample that had done lots of work and is now resharpended to do more.

I learnt HSS is no match for recently hardened carbon steel. I also learnt more haste, less speed.... or in this case, speed and feed matter!

I had a problem with some case hardened pins that needed holes drilled for split pins. An ordinary twist drill wouldn't look at it, so I had a go with a tipped (new unused masonry) this drilled in but as soon as it got into the softer metal it dug in and jammed. I had to drill through the case with the tipped drill then change to the twist drill till it stopped drilling then use the tipped one to drill through the case on the other side.
I don't know if this was your problem but the symptoms when getting near the end of the hole sound the same.
Regards

Originally Posted by pipeclay

After the drill was removed from the job after jamming, did you remove the drill and check the end of it to see if it had been damaged or had metal build up on the point.

.....

Hi pipeclay, A Duke and .RC.

I confess to not checking the tip, so it is an option .. or maybe case hardening as A Duke suggested. Having made a small form cutting tool from drill rod earlier in the day, my mind lept to the "carbon steel" cause. The scrap had been cut by hack saw in the past based on the marks on its side so I also thought something during the drilling process had caused the problem ... pipeclay might be onto it ..

thanks for the thoughts

I had the same problem the other day with a bit of good quality mystery metal (frame from an old finger mower and possibly a type of spring steel).

I Was able to drill it with Sutton drills, but when opening up the hole with a reduced shank 25mm HSS? chinese drill; the drill promptly just softened and wore away and work hardened the metal. A good quality freshly sharpened drill with "Rocol" lube did the job. I could feel the drill break through the hardened skin into the softer metal. Lowest speed on the MH50 was used also.

Sad state of affairs when 50 year old steel is better than modern 'state of the art' chinese drills.

Ken

I learnt reversing a single phase lathe before it has slowed(or slown if you like?) enough of the centrifugal switch to close doesnt work.

Did I know this already and have just forgotten? I'm not sure anymore.

Stuart

Originally Posted by Stustoys

I learnt reversing a single phase lathe before it has slowed(or slown if you like?) enough of the centrifugal switch to close doesnt work.

Did I know this already and have just forgotten? I'm not sure anymore.

Stuart

I learned that once, and sometime between then and now forgot, until you just reminded me. Thanks for the technical reason too - at the time I just created some nuggets, and observed 'that's not gone well, wait for it to stop next time!' No consideration was given as to why it happened. Although now I don't remember if I was actually trying to go from forward to stop, and somehow managed to get right through to reverse... I think I've done both

I learnt that when you buy a second hand set of gauge pins "with a few missing", it is wise to check the sizes that you do have before buying replacement pins. (Anyone need an 85 thou pin?)

Michael

Originally Posted by Toggy

Sad state of affairs when 50 year old steel is better than modern 'state of the art' chinese drills.

Ken

HSS "Highly Soft S#@t"

Very nice Chris....which way do you spin it?

Originally Posted by Ueee

HSS "Highly Soft S#@t"

Very nice Chris....which way do you spin it?

The opposite direction to when you last used it?

Hi,

I learnt tonight not to wear pluggers in the garage when your using your shaper. Your missus doesn't like it when you walk "sharpies" through out the house that where previously lodged in the bottom of your thongs (I know its not WHS compliant but I was wearing my safeties at all times).

Cheers Ben.

Originally Posted by cba_melbourne

Sutton's drill's do the same some times. Strange isn't it that these should try straighten out when some tailshafts do the opposite I have seen 3 in years gone by.