3v before and after HT ?'s

K

kwakn

Joined
Oct 17, 2009
Messages
117
Hi all,
I have a few questions about how far to take 3v before HT and a couple about what to expect when you're expecting (to get your stuff back from the HT'er) queries. Insight appreciated.

1. If final grit is 600 hand rubbed, what grit do you go to before HT?
2. If 10 degrees per side is final edge bevel, what edge bevel (if any) or primary bevel thickness before HT?
4. Do you make thumb grooves before (with files) or after with something else?
5. How much scale (microns or yards) needs to be removed after HT?
6. What grit do you use to remove scale?
7. Are there any alternative's to just grinding away scale?

Rambling permitted...There's always a nugget or two in there.....

Eddie Yabs
amachore
 
  1. You'll probably go back to 400g after HT. This alloy gets triple tempered at 1000F. That doesn't leave scale, but it does leave oxides.
  2. Don't put final edge bevel on before HT. It's unsafe and ill advised to take a zero edge to high temps. Maybe 15 to 30 thou depending on intended use.
  3. Pork. The answer to all unasked questions is 'Pork'.
  4. Thumb grooves or filework before HT. They may get some clean up after.
  5. No Scale - some oxides -
  6. maybe go back to 400g
  7. Sure. Oxide removal could involve scotchbrite belts, tumbling, bead blasting....
Cleaner blades can be produced using a 400F temper, but some experts have suggested this may yeild a brittle blade. I'm not suggesting this is the case and I don't want to wade into the controversy again - just suggesting something you may want to try for yourself if clean up is difficult. There are some well respected makers that still use the 400F temper.

Rob!
 
Rob is spot-on.

I take 3V right up to finished polish, and right to finished edge thickness (but do not sharpen it) before sending off to HT. Pro shops like Rob, Peters' HT, and Bos HT will return your blade very clean. Step down a grit to clean off the oxide colors, come back up to your desired finish, etch it if you want and BOOM you're done :thumbup:

Many air-hardening steels can be treated this way to save time, but it's especially important for 3V and other super-wear-resistant steels because good gravy they're a PAIN to sand/polish after HT.
 
Thanks Rob,

Pork...Hmm...Fond of that substance too we are in the lower 48! It pairs exceptionally well with corn on the cob and a Pilsner.

Love Alberta. Spent my honeymoon touring Banff and Jasper National Parks. Still remember the roadside vietnamese restaurant, ate outside, sittin' on a log along the Athabasca watching salmon rise to the hatch. Rise they did about 2 ft out of the water! Need to get back....

....so about this 3v. I do not posess the skill or equipment to HT myself. I have a pro HT'er in Pittsburgh that I'll turn to. I don't believe they use the 400 degree temper method however but I'll ask and see what they say. In any event, thanks for clearing up some of my curiosity about what to expect after HT.

But that leads to more questions:
3. Since no scale but oxide after HT, I've seem some suggest Ferric Chloride to etch, patina, (aka oxidize) the blade as a mechanism to assist with rust prevention. Assuming I want to uniformly treat the entire blade and not seeking artistic effect, why bother to remove the oxidation from HT just to put it put it back on?
8. So with 3v, if I read between the lines a bit, all but final polishing and sharpening should be done in advance of HT?
9. At .003-.004 edge thickness before HT - do you ever expect warpage for say a 4-5" long edge, 1" wide, 9-10" long overall?

Appreciate the time.

Eddie Yabs
amachore
 
kwakn said:
3. ...why bother to remove the oxidation from HT just to put it put it back on?

The oxide colors from tempering are due to heat alone; oxidation from etching/passivating the HT'ed steel is a different, chemical mechanism which seems to mostly involve removing free iron from the surface. Here is a thread with links to what I and others found on the subject of etching 3V to reduce pitting/corrosion. Jerry Hossom has a lot to say on the subject and links to his thoughts are in that thread. I've etched my 3V blades in plain white vinegar but I can't yet say if it's as effective as ferric chloride, etc.

8. So with 3v, if I read between the lines a bit, all but final polishing and sharpening should be done in advance of HT? Yes.
9. At .003-.004 edge thickness before HT - do you ever expect warpage for say a 4-5" long edge, 1" wide, 9-10" long overall? .003"? I hope you mean .030", in which case no, I haven't seen edges that thin come back warped.
Click to expand...

Hope this helps... coming from a sparkmaker, not a heat-treater.
 
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James - much appreciated.

Yes - .030 vs .003. In another thread it was suggested that I take the primary bevel to .007 before putting on final edge bevel. I'll take this to mean after HT.

Heat oxidation vs acid oxidation. Chem was a shortcoming of mine so I'll read some more. FeCl vs vinegar: I would think a faster etch process out of the FeCl but with a bit more opportunity for errors to occur.

10. What kind of hold times do you use with vinegar?
11. Do you neutralize the vinegar with baking soda or just wash off with soap and water?

Eddie Yabs
amachore
 
10. I let the blades soak in the room temperature vinegar overnight, probably close to 12 hours. I can't really say if it needed that long. It might work faster if you heated up the vinegar but that gets pretty stinky. They ended up with a nice grey color. I don't know the safety specs on FeCl but I do know I can get vinegar on my skin and even take a sip and be fine. Plus it's dirt cheap and easy to find.

11. I just washed them off with Dawn dishsoap and hot water. Baking soda wouldn't hurt anything, though.
 
Thank you James.
12. After soaking overnight, do you ever remove the nice gray color? I read your thread on the other site and and others and from what I gather, the etching is done at the molecular level and rust/pitting is most likely to form in low spots. I would think removing the gray or adding some lustre would not affect the rust inhibiting effects of the etch.

Thoughts?
 
I did not remove the grey oxide color. I think it looks cool :)

I don't think it would hurt to remove the grey oxide layer; as I understand it, the purpose of the etch is to clean the surface of free iron and contaminants, which provide a handy spot for pitting. Hossom and others say they re-blast after etching/passivating to get the finish they want.

You mentioned low spots; I feel pretty strongly that any low spot in any steel is more likely to collect moisture or gunk and foster corrosion. Roughly-ground steel rusts quicker than polished steel. That's why I try to get surfaces clean and smooth even before HT, regardless of the alloy used.

Please bear in mind, I'm learning about this as we go along, I'm not an expert by any means!
 
Please bear in mind, I'm learning about this as we go along, I'm not an expert by any means![/QUOTE]

James,
In my "land-o-the-blind", he wit' da eye = king.

Are there not that many 'makers' using 3V? Maybe I'm missing some, but it seems like there are only a handful of posts on the subject. I went and did a quick search in the "Shop Talk" Forum. 145 threads since 2001. 15 threads in 2010. Hmm - niche to make the most of? or little demand?

Eddie Yabs
amachore
 
kwakn said:
Hmm - niche to make the most of? or little demand?
Click to expand...

That's a good question. Perhaps it's not more popular because it is hard to sharpen. I wouldn't restrict myself to only using 3V; I like plain carbon steels and stainless steels like CPM-154, too.

Personally, I think it's a great option to offer... I dislike sharpening more and more the older I get! And it's awfully tough to boot. Not much more difficult to grind than other popular steels, either. I'm sure it would make a difference to a big firm cranking out thousands of blades a year but I hardly notice it. It requires good HT and cryo, but so do a lot of other good steels.

I think it's a no-brainer to at least keep a bar or two on hand if you like to make heavy duty knives.
 
i love 3v and have my oen HT and grinding for it (its not secret or anything ) im 99% sure i have posted about it before

but i use FeCl to etch and soom i ll be parking my blades black if a buyer wants that
 
james terrio said:
Hossom and others say they re-blast after etching/passivating to get the finish they want.
Click to expand...

Not really. I never "blast" any steel as that creates a surface that will trap water. After etching, I brush finish the surface with 600 grit compound to remove most of the oxide. Comes out a light gray color.
 
If I misquote you can I get advice too?:)

Eddie Yabs
Hossom groupie
 
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Not a problem, James. And I'm always glad to offer advice or help out other makers. Do that all the time.
 
We appreciate it, too! A lot of what I know about 3V is from reading your experiences with it :thumbup: Any further thoughts or advice you have are certainly welcome.
 
Well, I have a headfull of experience but it sometimes takes a question or two to get it out. Feel free to ask. Bottom line in my opinion though is that if it's heat treated properly, it's simply the best knife steel there is. Ironically, it's not that expensive, less than many lesser steels, and there are several commercial heat treaters who can do that part of it properly. I get a lot of calls from other knifemakers who are pretty amazed at it's performance. I've never had one who said it didn't perform better than they expected. In other words, no 3V hate mail to date...! :D
 
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