Recommendation? O1 troubles

N

Nick2229

Joined
Oct 16, 2018
Messages
2
I recently started playing with some O1 tool steel. And was trying to make a small work knife for myself. When grinding I noticed the tang was bent and when I gently tapped it cracked right in half with very little force. I also was trying to drill holes in the tang for handle pins and it was like I was drilling hardened steel. This was all done before heat treat. Any suggestions on what I have done wrong?
 
You got it too hot while grinding and it hardened
That's assuming it was properly annealled when you got it
When grinding keep dipping in water
Get more and start again
 
Sorry John, but that is wrong. Unless you got the steel to above 1400°F and then cooled it rapidly it isn't hardened by heating and cooling in grinding.

You can work harden steel by grinding it too long and hard. It does not matter if it gets hot or not during the grinding. You can make an edge turn red in rough grinding with no harm.

If you are going to drill holes or straighten a bend, the best method is to stress relieve the blade first. Heat to well above magnetic ( 1600°+) and let cool to black. Repeat at a little less red (1400-1500F). Then repeat by just getting the blade BARELY red (1200-1300F) but still magnetic. If you can hold it at this temperature for a while that is even better. This will relieve the internal stress and soften the blade.
 
Sorry Stacy my wrong
I've always avoided getting my pre ht blade too hot when grinding then quenching it because I thought it would harden even just a bit.esp the tip
But I've never read that
1 less thing to worry about when grinding so that's good
 
Also when drilling go slow. Most people run a drill bit WAY to fast in RPM. If you don’t have flood coolent then slower is better. We are talking under 500rpm. 300rpm is a good catch all but the smaller the drill the faster it needs to go. And keep it lubed up.
 
I bore 1/4" holes in unhardened blades at 600 RPM (40SFM) and use cutting oil. On many lower priced drill presses, the lowest speed is more than that. If you have the drill press running in the mid range, it is running three times the proper speed. You will burn up a 1/4" drill bit in seconds at 1500RPM.

In a metal working shop, the best practice is to set the drill press and the metal cutting band saw on their lowest speeds.

You will find some speed charts that list speed in RPM are a good bit high in what they list for drilling steel. It is because the steel they are talking about is mild steel used in welding. Tool steel, stainless, and knife steel need slower speeds by nearly half what the chars show, IMHO.

Here is a good chart for picking bit speed in SFM.
drill-speeds-and-feeds-chart_465159.png


Here is a good conversion chart for RPM/SFM:
http://www.tapdie.com/html/sfm_to_rpm-_surface_feet_per_minute_to_revolutions_per_minute.html
 
Last edited:
Nick2229 said:
I recently started playing with some O1 tool steel. And was trying to make a small work knife for myself. When grinding I noticed the tang was bent and when I gently tapped it cracked right in half with very little force. I also was trying to drill holes in the tang for handle pins and it was like I was drilling hardened steel. This was all done before heat treat. Any suggestions on what I have done wrong?
Click to expand...

Check the hardness with a file or rockwell tester.

Hoss
 
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