Temper steel dowel pins

[doubleboost]

Hi
Lads
I have some parallel steel dowel pins
They are that hard if you put one in a vice and hit it with a hammer it will snap
I put a few in the log burner last nite , (also great for drying welding electrodes)  this morning they can be filed and machined 
Would I just re temper it with water like silver steel (drill Rod)
Or do I need Sperm oil  (10 40)
I am wanting to make a centre punch for a video project
Regards
John

[philf]

Hi
Lads
I have some parallel steel dowel pins
They are that hard if you put one in a vice and hit it with a hammer it will snap
I put a few in the log burner last nite , (also great for drying welding electrodes)  this morning they can be filed and machined
Would I just re temper it with water like silver steel (drill Rod)
Or do I need Sperm oil  10 40
I am wanting to make a centre punch for a video project
Regards
John

John,

I think oil hardening would be safer. I use old vegetable oil with silver steel and similar steels and it gets plenty hard enough for making cutting tools. (I usually temper them in the deep fat fryer! but I think you would need to temper at a higher temp for a centre punch or else it would be too brittle.)

I have found some hardened dowel pins which are in 100CR6 steel. This needs heating to 840C before quenching in oil.

Hope this helps.

Cheers.

Phil.

[mattinker]

John,

you have several, why not experiment, test in water and oil?

Regards, Matthew

[krv3000]

hi john if its the ones from me witch i think they are you need oil to put them in we just reharden them the same as silver steel 

[doubleboost]

Thanks Bob
I have put a few more in the fire
Like Mathew suggests I will have a bit experiment
John

[Lew_Merrick_PE]

John,

Here in the U.S., plain steel cylindrical dowel pins are most commonly LC steel that has been case hardened.  You may be able to reconstitute the case by heating & quenching, but that would be drawing to an inside straight.  Stainless steel cylindrical dowel pins are either (Austenitic) hard drawn, (Martensitic) hardened & tempered, or precipitation hardened -- making home retreating a crap's shoot at best.

The problem with a reconstituting a case hardened part is that the heating for hardening often (usually) dissipates the carbon (decarburizing) to surrounding areas reducing the ability to get a hard surface.

[chipenter]

Hi John I bought some H S S drill blanks ages ago have soffend some bent and retempard them , coat them with likuid soap berore heating stops them going black , I quench in used engine oil that I use for oil blacking (the price is right) , looking forward to the video .