Hand Tools

Response To:
Request ()

David Weaver
* cut blank from bar stock (like rectangle width of the chisel at the shoulder)
* hammer business end flat in three heats (to approximately half of the original thickness). The heats are descending and the third is just flattening on the anvil to lessen grinding. The heats start at orange and then the next is lower heat and the third is subcritical heat (thermal cycling of steel to keep grain size small is always in descending heats like this with later heats subcritical - it's possible to do quenches multiple times but when steel gets too full of carbon, then you can end up with increasing carbide sizes, so I don't do this).
* grind chisel to rough shape, including initial tang
* hammer tang (heat, on anvil, but not heating business end at this point) to basic tip, but not totally sharp - finishing grinding can be done later
* file tang to shape, finish filing and grinding blank and flatten back on hard platen sander (my objective here is to have a curved top and a flat back)
* make 1x1 bolster blank (inches), drilled with hole slightly smaller than the tang wherever you've marked that the bolster should stop
* heat the bolster blank, drive the tang through it as far as reasonable, turn over, tap the chisel back out hitting the tang (after hammering the blank as square to the tang as possible), flatten, reheat (I have a hole on my anvil to drive the tang down through - this would be difficult without that).
* flux the bolster, heat to high heat again (the bolster is mild steel, like 1018 or something similar), drive it onto the chisel (repeat a third time if needed to flatten the bolster - needs to be flat before forge weld.
* once the bolster is on well, heat the junction with a cutting torch (as fast as possible) and then several light taps to set forge weld and then a few heavy hammers to ensure a good weld and hide any gaps where the weld wasn't perfect
* grind bolster on the belt grinder to rough shape
* finish file
* clean up the chisel blank for any damage, etc, reflatten back
* heat the chisel up to the tang to a full color shade above nonmagnetic for most (52100 goes a little higher, no chromium and this can be a little lower). This is where people screw up as well as at the beginning trying to do too much with the steel and leaving it at high temperature and causing cracking issues. the contest here is that good even heat and the chisel won't warp that much in the quench and it will be converted fully to austenite. If you intentionally make it way too hot, you can end up wtih retained austenite and low hardness, but I haven't had that much of an issue with this (I think it's more of an issue if you use a furnace and leave heat really high temp for a while).

Important - I heat as fast as possible and then quench. There is no great need to normalize here, it's open atmosphere and we don't want decarb and I'm not using steels that have complex carbs (hah) ...carbides that need a soak.

The quench is in parks 50, then finish in cold water and then throw into the freezer. This converts as much austenite as possible (harder before temper, and lower toughness, but I don't think we challenge toughness). A commercial service quenches and then goes to liquid nitrogen for a long time to convert as much austenite as possible.

After half an hour, chisel comes out of the freezer and goes into a plane iron sandwich in a toaster oven that also has two trays (one above and one below) and an oven thermometer. I will do anything from one half hour temper to two one hour tempers. I can't really tell that much of a difference as long as the chisels get to temp - with more complex steels, there would be a big difference. I think two tempers leads to better toughness, but it's a marginal thing. The plane iron sandwich and the trays limit temp variation (the chisel is between the irons, which are sitting on a wire rack between the shielding trays). a toaster oven itself set at 400F will radiate over 500 according to the noncontact thermometer. The oven thermometer between the trays gets to temp smoothly and wavers less than 5 degrees.

* after temper, reflatten back on belt sander, and on coarse ceramic belt, cut bevels, then one grit finer and then hand finish. Flatten back by hand, grind bevel and sharpen.

I believe what I think is good hardness and what's off the mark is less than 2 on the C scale based on chisels I've had that I had tested on a versitron. With an india and washita stone, the range of ideal is really narrow. Some steels (like files) are so low in toughness that they work well even at lower hardness - the edge doesn't deflect and then propagate. 52100 has taught me a lesson - it's fine at really high hardness.

I have a 26c3 chisel in the toaster oven now (relatively plain 1.25% carbon steel with very low toughness - it'll help me test my theory).

I was so smitten with 52100 before pushing it hard enough to create some edge damage.

Messages In This Thread

52100 experimentation continues *PIC*
same chisels. *PIC*
Re: same chisels.
The reason for the choice...
Re: The reason for the choice...
Better than O1
relying on the charts...
caveat on my sharpening perceptions..
Re: caveat on my sharpening perceptions..
Re: caveat on my sharpening perceptions..
for the non-metal folks..
"through hardening"...
Re: same chisels.
Re: same chisels.
Re: 52100 experimentation continues
These get a trip to the freezer...
Re: These get a trip to the freezer...
if it's like the machine areas...
Maybe toughness *isn't* .....
Re: Maybe toughness *isn't* .....
A stake in the ground is needed
Re: A stake in the ground is needed
There's an absolute property..
optimizing hardness and toughness
Discussion and personal value
now I am confused more
Re: now I am confused more
Re: optimizing hardness and toughness
Thank you for the search results
Testing three chisels..
re-do with one of the (52100) chisels
Re: question
26c3 mule...
For those like me unfamiliar with 26c3
Re: For those like me unfamiliar with 26c3
Re: 26c3 mule...
Re: 26c3 mule...
pics... *PIC*
(looking back at those four pictures...
When work pressure lets up some,
It'll look the same...
Re: pics...
Re: pics...
Deflecting vs. letting go
I think that's pretty much it...
Re: Deflecting vs. letting go
Re: Deflecting vs. letting go
I didn't check with a metallurgist..
26c3 pictures vs. ward later...
not that much later...the 26c3 *PIC*
Tempered to 380F? *NM*
Re: Tempered to 380F?
and the ward *PIC*
Temper temperature...
too much?
Re: Sure... *PIC*
Re: Sure...
David's knife
Re: David's knife
short follow up thought....
Re: short follow up thought....
Re: short follow up thought....
Re: Sure...
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