Author Topic: Hot Stuff!  (Read 367 times)

Offline Allen Smithee

  • Full Member
  • ****
  • Posts: 1037
  • Mordor, Middle Earth
Hot Stuff!
« on: May 12, 2021, 12:26:18 AM »
So there I was, parting about 20mm off the front of an 2MT blank arbor to make a spindle backstop so that I could part some lengths of bar to a standard length (to make four motor mount pillars). I was enjoying the brute grunt of my recent 1hp 3-phase conversion which, when coupled to a carbide insert parting tool, allowed me to run the job at 2,000rpm. The motor had the torque, the tool could take the heat and provided I kept a steady pressure on the cross slide it cut cleanly with no chattering. I'd drilled a small hole in the waste metal and had a 4mm pin in the tailstock to catch the end when it parted through.

The swarf was coming off in a steady stream of blued steel, and as the cut progressed I watched the waste metal go through straw, yellow and purple before settling on a nice deep blue colour. It was remarkably even, but I knew it was telling me the metal was a tad on the warm side.

The parting completed and the waste slug slowed to a stop on the 4mm pin, so I backed out the tailstock and used a pair of pliers to transfer the hot lump to the boring table while I tidied up the edges of my new backstop with an artistic-looking chamfer. 4 or 5 minutes later I'd finished, and was tidying up, I picked up the slug with an ungloved hand and immediately learned that a piece of steel about 30mm in diameter and 20mm long takes longer than 4-5 minutes to cool from >500degC to a handlable temperature even when sat of a big chunk of cast-iron heat sink. Fortunately I had been soldering on the other bench and so there was a wet soldering iron sponge to quench my thumb and forefinger. That was two weeks ago, and the skin has healed but is still smooth - I still have to use the other hand to operate the fingerprint ID that unlocks my phone.

Every day is a school day...

AS
Quidquid latine dictum sit altum sonatur

Offline RReid

  • Full Member
  • ****
  • Posts: 121
  • Northern California
Re: Hot Stuff!
« Reply #1 on: May 12, 2021, 01:18:24 AM »
Oww! Burns are worse than cuts. As a young man I ran a lathe in an oil patch type shop. One day I pushed in the carriage feed clutch lever with my thumb, not seeing the 1/2 inch, very blue, semi-curled chip resting there. Went to the bone, never bled a drop so cauterized was it, but 40 years on I still have the scar on my thumb. Always used my foot on that clutch lever after that.
Ronald

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 14067
  • Hampshire, england.
Re: Hot Stuff!
« Reply #2 on: May 12, 2021, 08:46:59 AM »
So easily done  :toilet_claw:

Jo
Enjoyment is more important than achievement.

Offline john mills

  • Full Member
  • ****
  • Posts: 255
Re: Hot Stuff!
« Reply #3 on: May 12, 2021, 09:31:57 AM »
in more reciente times sent to a job labor hirer to a turning job  turning a 30 mm chamfer  on discs 750mm dia  65mm thick  the swaf came off hot and large ,while safety people might say don't wear gloves  you would only take 5minutes to work out you needed leather gloves or you would end up with burnt hands it was a case of
look after me and wear gloves the chips might only hit you and fall on the floor but that was enough to burn.  the people who wear full time turners would tell you gloves wear required  .
       John