Folder making, when to surface grind?

C_Claycomb

C_Claycomb

Joined
Dec 11, 2000
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1,130
For folder blades, do you surface grind them before or after you get them heat treated?

I have four blades (CPM154 and RWL34) that I am starting and a couple of guys at work have offered to surface grind them when the time comes. The window isn't all that wide because we will be losing the machines in a few months. So I don't want to screw up since I won't get another chance.

After HT makes sense to me if you want maximum control of flatness and parallelism since you grind out any warpage, but I have read guys who do it first and then take their blades to almost final finish before HT. If you are experienced with plate quenching, or sending blades to someone like Paul Bos, how much of a real concern is warpage during HT? I have even read some stuff where there is no mention of surface grinding :confused:

So, what is your preferece? What do you reckon works best?

Thanks :)

Chris
 
Surface grind after heat treating – as a matter of fact, you cn do all of your grinding after heat treating for best results.
 
In a folder, I think its very important to have the pivot holes to be at right angles to the length of the blade.

I'd start with PG material before drilling and reaming the pivot holes.

But after HT I wouldn't be surprised if it needs another pass
 
I surface grind and grind bevels to 80% before heat treating. Partly because I stamp my mark on the tang and this has to be done after SGing, but before HTing. And like count said, drilling and reaming holes needs to be done on PG stock.
 
I surface grind to .005" over finished thickness, profile and bevel, heat treat, finish grind bevels, then surface grind to final thickness.
 
Thanks guys. So it is not or, but and. Doh!

The CPM154 is already pg, but is too thick as it is while the RWL34 is rolled stock, and only a little thick. All the blades are meant to be drop in replacement on two existing knives, so the thickness has to be spot on. I am doing an extra blade of each as insurance. I had a go at this last summer with O-1 to see if it was possible with my limited skills and got lucky; the lock bar engaged, the blade stayed centred and it didn't wobble, but even though O-1 grinds like butter compared to the stainless steels, working it down, hard, on a disk sander followed by hand lapping and stoning was no fun.

I like the idea of doing some rough grinding per HT. Not so sure the tool room boys will be so impressed!

Thanks for all the advice. I'll be sure to post the final results here, but it may take me a while!
 
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