Hardness tester

I just recently purchased a new hardness tester and I just wanted to throw out my two cents. These testers are like a grandfather clock made of cast iron. It comes shipped new with lots of solid wood blockings to keep everything from moving around damaging the unit. Instructions constantly warn about moving it after blocking has been removed. So I'd say if you do buy it take the time to block brace all moving parts inside before moving and hopefully it's been taken care of in that regard before you bought it.
 
That is 25 cents on the dollar ... good price. Don't wait long.

You can buy used test blocks on ebay, or make your own. Cut 4 ( or more) 2X2" squares by 1/4" thick 1095 and stamp A-B-C-D. HT then temper at 250F, 300F, 350F, and 400F. Have tested by someone with a good tester and mark the results on a card that you keep with the blocks.
 
If you do buy it Kevin I can make you a couple test blocks and verify them at work. If you don't buy it, I want to :)
 
Newbie Question: is it worth doing your own HT without a hardness tester to make sure you got it right?
 
Sure, with some degree of temperature control and a little metallurgical info, you can predict the approximate hardness. Even without that, you can do HT by the established programs and expect normal results. Testing the edges will tell you if you need to adjust anything.
 
PNWJimbo said:
Newbie Question: is it worth doing your own HT without a hardness tester to make sure you got it right?
Click to expand...

I would venture a guess that most knifemakers who do their own heat treat, do it without a hardness tester. The ones I would want to buy knives do it in a methodical proven fashion, either by testing as Stacy described, or by following developed procedures that they've had hardness tested by others in the past.

For an example, I do most of my own heat treating, and while I have a tester at work, and would like one at home, I do not test every knife I make, because I follow the procedures I established previously for a given alloy from a given supplier. Like this:

1095 from Aldo
1- Normalize 1600f
2- Thermal cycle 1550, 1475, 1425
3- Austenitize 1475 for 5-10 min soak depending on size of the knife
4- Quench in Parks 50
5- Test multiple blades and see 66 RC

Follow those steps for additional knives, I don't need to test, though I still run a file across them for piece of mind out of the quench.

Now if I were to get 1095 from another supplier, I might start over and test a few again.
 
Thank you for both for the quick and detailed responses! Do you really get your 1095 to 66 RC?! :eek:
 
Correct me if I'm wrong but that is still a bit higher than the 'industry standard' of somewhere in the 54-58 range, right? (Thanks for baring with me, I've been reading a ton about this stuff and just trying to make sure I'm remembering correctly)
 
Most knife manufacturers will run steels softer than they need/should be because it's cheaper to do so. And most consumers want a knife that is easier to sharpen, so it's a double plus for mass manufacturers to use the lower range. To get the most out of the different steels, they should usually be run harder than is common place. Hence why most custom knives are higher RC than mass produced knives of the same steel.
 
I'll often take blades over to a friend's die shop for Rockwell testing in working up a HT formula. The final test for me is always putting a knife to work for a while though. I'll differ from the commonly recommended hardness if it proves to work better in real world use.
I'd love my own Rockwell tester to do a bozo check on every single knife, but you can live without one. I wouldn't suggest going without real world testing though
 
Forgot the on topic part of my post

If that Rockwell tester was local to me I'd have already bought it
 
That is a GOOD Buy!!!

Remember this is a CALIBRATED INSTRUMENT and should be treated as such so the testing results you claim are verified when you post them to your records. You can easily keep a spread sheet so you can refer back to Steel purchases and Knives produced from each batch so that you would not have to test each individual blade just a batch sample of coupons.
 
PNWJimbo said:
Correct me if I'm wrong but that is still a bit higher than the 'industry standard' of somewhere in the 54-58 range, right? (Thanks for baring with me, I've been reading a ton about this stuff and just trying to make sure I'm remembering correctly)
Click to expand...

Just to be clear, 66 out of the quench is "full hardness." It needs to be tempered, and may even crack just sitting on the table as the martensite and retained austenite pull against each other. Tempering relieves this stress and reduces the hardness.

The industry standard you refer to is the tempered hardness many commercial knives are sold at. As Jrmysell stated it's cheaper to do so, not necessarily because it costs less to heat treat them to that standard, but because tempering them back to lower hardness increases toughness, gives them a larger window of hardness tolerance, and reduces the number of broken knives they need to replace.

Like Geoff said, most custom knives will by harder than any industry standard for any given alloy because we're generally producing one knife, for one person, for specific or general tasks. Our customers tend to use their knives the way they're intended, and we go to sometimes extreme lengths to demonstrate that the knife we made will hold up to the task without breaking or chipping.

Most people, who aren't custom knife customers, simply see custom knives as looking the way they want, or having a form factor that isn't available, when the real value isn't immediately apparent to the casual glance, it's having a knife tailor made to perform at the highest level that blade type and alloy is capable of performing.

I have a couple customers who were rather knowledgeable about knives prior to ordering a custom from me. They'd owned 1095 knives. They had rather low expectations in how the knife would perform, and while they appreciated the custom aspect of the appearance of the knives I made to their specifications, months later they email me about how impressed they are with the edge retention and toughness and how sharp they're able to keep the knife. It's not because I did anything secret, or exotic. I just left the knife as hard as I felt prudent based on my testing, and ground edge geometry that worked for that hardness and tasks.
 
kuraki said:
The industry standard you refer to is the tempered hardness many commercial knives are sold at. As Jrmysell stated it's cheaper to do so, not necessarily because it costs less to heat treat them to that standard, but because tempering them back to lower hardness increases toughness, gives them a larger window of hardness tolerance, and reduces the number of broken knives they need to replace.
Click to expand...
This is what I meant by cheaper. It is also easier on the equipment for the grinding/sanding they do after heat treat on the blades because they are softer.
 
PNWJimbo said:
Newbie Question: is it worth doing your own HT without a hardness tester to make sure you got it right?
Click to expand...
when i first got serious (or semi serious) about HT, I made a bunch of coupons of steels I use at different hardness targeted. I took them to a local shop and had them tested. none were more than 1 RC point off.
 
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