Edge thickness before heat treating?

G

GD1911

Joined
Jun 21, 2012
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14
Hey guys,

Just a quick question about edge thickness before heat treat. I know it varies on steel and thickness etc, so what would be the ideal pre-heat thickness for O1 tool Steel at 3/16" thick and 2" wide?

On a side note, being terrible at math what size bit could i use to do a double line marking on the blank?

Thanks for any and all help on this.

Cheers.
 
I just spoke with Brad at Peter's Heat Treat the other day about some blades I plan on shipping to them. He recommended I keep the edge about .020 even with stainless to help avoid any warp at the edge. For your scribe lines you could use an 11/64" bit and it should leave you about .020 between the lines.

Chris
 
On their website they have .015 as the minimum for stainless. I just did some business with them. AEBL and cpm m4. All edges were below .010 and there were no issues at all.
 
I agree with Stuart, take them thin!

If you're heat-treating yourself make sure to use anti-scale compound as it will reduce decarb of the thin edge. I generally take O1 to about 0.020" or so when heat-treating it in a forge.

-A
 
aarongough said:
I agree with Stuart, take them thin!

If you're heat-treating yourself make sure to use anti-scale compound as it will reduce decarb of the thin edge. I generally take O1 to about 0.020" or so when heat-treating it in a forge.

-A
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Cheers Aaron,

Big fan BTW. I know you're in Canada, any advice on where to source the anti-scale? I saw it on Brownells but couldn't find anything local.
 
GD1911 said:
Cheers Aaron,

Big fan BTW. I know you're in Canada, any advice on where to source the anti-scale? I saw it on Brownells but couldn't find anything local.
Click to expand...

Thanks mate!

I bought my anti-scale from Brownells, price was reasonable, shipping was reasonable and I'm still using that single container that I bought 2-3 years ago! It lasts a long time!
 
aarongough said:
Thanks mate!

I bought my anti-scale from Brownells, price was reasonable, shipping was reasonable and I'm still using that single container that I bought 2-3 years ago! It lasts a long time!
Click to expand...

Hey Aaron, So i popped onto Brownell's site the other day and noticed they have 2 anti-scale compounds...are you referring to the ATP stuff or the 'Brownells Non-Scale'? seems like the ATP is more of a brush on
 
GD1911 said:
Hey Aaron, So i popped onto Brownell's site the other day and noticed they have 2 anti-scale compounds...are you referring to the ATP stuff or the 'Brownells Non-Scale'? seems like the ATP is more of a brush on
Click to expand...

I've only used the ATP-641, works very well though!

Biggest trick with it is to make sure your blades are degreased *exceptionally* well. If at any point the compounds beads up rather than staying in place then that's because of oil on the surface. I've found it's best to put on nitrile gloves, wash the gloves with soapy water, then wash the blades down with simple green, hot water and a toothbrush. Doesn't take very long, but makes a huge difference in how easy it is to apply!

-A
 
Ok so forgive the teacher in me.
Being bad at math doesn't mean you can't do it.
To convert any fraction to a decimal divide the top number by the bottom number.
So... if you have 3/16" steel and you want .020 edge for heat treat.
3 divided by 16= .1875"
divide that by 2 to get the center mark.
=.093
subtract half of the edge you want for heat treat.
.093- .010= .084
Now to figure out what size drill bit that would be, either look at your drill index if it has fractions and decimals, or take the decimal and multiply it by 64 as most drill indexes are in 64ths of an inch.
.084 x 64= 5.36
Round that to 5 and put it over 64 since we used it to multiply. That makes the fraction 5/64"
Using the 5/64" bit to scribe your lines will ultimately give you a thickness of .031" for the edge. That's awful close to .020" when you figure your scribe line is gonna be fairly wide. It all depends how accurate you want to be. Sometimes I'll just grab a bit out of the pile that's a little smaller than my thickness and scribe away. I typically use my transfer punch set to scribe my edges as they give a crisper, skinnier mark.
Also just for the drill bit guys out there, 1/64" is .015". So go to your drill index, find the size that is one bit smaller than your material thickness and you'll have 2 scribe lines .030" apart
 
Thanks guys, super helpful responses, I'll grab some anti-scale and my drill bits and I'm off to the races.

Cheers
 
I've pushed my luck big time with edge thickness sending to them to Brad. Hopefully he doesn't hate me for it, but some have been 0.007 and have come back perfect. There does seem to be some variance with steels. I saw a little wiggle here and there with AEB, but S30V seems to be impervious to just about everything... bending, warping... grinding, finishing...
 
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