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The Newbies Arena Are you new to knife making? Here is all the help you will need. |
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#16
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On small knives you need the back door. I used to do small knives with an oxy-acetylene torch with a rosebud tip. It works great for small knives if you are experienced with gas welding as I am. Matter of fact for some of the smaller knives I've been making I've thought about the oxy-acetylene route. It makes not overheating your tips easier, but like most things it takes practice. That little forge is the coolest thing I've seen.
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#17
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Kind of figured with the table "arrangement", just a lot of new guys don't think things through until they are wondering "how'd that happen?"
Another thing with the kirideshi geometry of the one-side chisel grind, makes it harder to get the heavier mass part of the blade up to heat while keeping the edge safe. Usually better to leave over thick and grind to finish after HT on these. Just a lot of differential in mass in a small area. Sounds like you are getting right with the other blade. Grand Muddy used to say "If'n you ain't larnin nuttin, may otta take up tadpole huntin!" __________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#18
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"Curiouser and curiouser!" cried Alice. Interesting development - after an hour in the oven @400F I mounted the blades into the file jig to put the final bevel on them. I found that there was a significant variation in hardness along the length of the edge. Around the base of the blade the file was cutting in reasonably well but up at the tip it was just skating on the surface. This was for both the kiridashi and the drop point using a good Nicholson file. So I have come up with a couple thoughts on the matter:
Your comments and advice are greatly appreciated. Thanks, -bill |
#19
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You're probably right about what happened. Another temper won't help but re-doing the HT can. You will need to add three normalizing cycles this time ...
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#20
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On a positive note this has been an object lesson in "this is what soft steel feels like and this is what really hard steel feels like".
-bill "bright side of life" rankin Last edited by Wrankin; 06-02-2016 at 01:28 AM. |
#21
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See.....right there! You picked a good simple blade steel to work with and you are learning a lot more than you realize working with it right out of the box. 1084 is probably the most "forgiving" blade steel out there and still makes an excellent blade.
Ray's advice is spot on for re-do (as usual). Thing with the magnet is that where things become non-mag is still a bit shy of quench temp for the steel. It just lets you know you are very close and need to stay focused on the subtle color changes in the steel at this point. It's obvious you are detail oriented so this is one of those times to be on point. I think it's all going to go really well for you as your skills improve. Just a quick question - what kind of oven are you drawing the temper in? If it's a kitchen oven, the T-stat is not all that accurate so use an additional oven t-meter next to your blades so you can be more on the nose. I'd also soak for 2 hours instead of one, as kitchen ovens bounce around on temps due to the larger area/volume to try to control. If using a smaller modified toaster oven, the issue still exist just not on the same scale and their T-stats are usually way off, so an extra T-meter is a must. I recommend two and work the "average". __________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#22
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Thanks, Carl. Yes - the temper was done in the big kitchen oven. The big oven was preferable b/c I know the thermostat on the smaller toaster oven is *way* off - at least 25F, probably closer to 50.. One side effect of running the big oven for oven an hour inside on a hot day was my wife giving me a look and telling me to go buy a toaster oven for the garage if I was planning on doing this again.
I've ordered an oven thermometer off of Amazon. I went with a liquid-based design b/c in the past I've had cheap bi-metal ones that are also way off. I'm hoping that this one is a little better, and at least I can calibrate it with a pot of boiling water: Hopefully things will go better this time. Last edited by Wrankin; 06-14-2016 at 03:00 AM. |
#23
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If you take the shell off the TO, remove the nonessential parts of the controls and line the inner shell with a 1" blanket of K-wool, you will be able to get reasonably good stabilization of the heat control. This will greatly reduce the cycling and fluxuation of temps in the TO. I left the "toaster" lever option intact to turbo the temp up prior to tempering but not really necessary. Get an appliance grade timer to run the on/off cycle and you don't have to watch your watch....2 hr-on, 1 hr-off, 2 hr on .....simple as it gets and uses way less power or gas to op.
__________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#24
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One more time
Update - well it's Heat-Treat Monday here at Uncle Bill's Home For Wayward Steel. Time to see if things go a little better the second time around.
Per your suggestions, I ran the two earlier blades through three rounds of normalization, heating them well above the quench point and letting them air cool to black. Then lather, rinse, repeat. This also gave me a lot more practice in trying to get a good even heat across the blade. One thing I changed involved doing all the work after the sun went down with minimal lighting in the garage. It really helped to be able to see how the colors in the steel changed as it got hotter. There appeared to be a definite color transition "zone" between the hot non-magnetic region on the blade versus the cooler steel in the handle. I did my best to make sure that transition had progressed well into the handle region before quench while trying to keep a consistent color across the blade and avoid overheating. I also added another un-beveled kiridashi blank to the HT mix, so I can have something to check my normalization efforts against. Tomorrow is Tempering Tuesday, so we'll know more after that. Thanks, -bill Last edited by Wrankin; 06-14-2016 at 03:01 AM. |
#25
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I would not leave the hardened blades overnight without being put through at least one tempering cycle. You could even do that cycle at something like 350? just to relieve the stress but I see no reason not to do it at the target tempering heat. Leaving to sit overnight untempered might run the risk of you finking broken or cracked blades the next day.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#26
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Quote:
Using the appliance grade timer (20amp) allows me to set it for 2 or 3 on/off cycles while I do other things in the shop, work the dog or eat dinner. I just check on it and make sure it's off before I go to bed. Planning a little ahead pays off. __________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#27
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Go back and read the thread? Specifically posts 1,3&7.
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#28
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Well, it looks like I got lucky - no cracks, no "tinks". At lunchtime I picked up a toaster-oven that was on sale and set it up when I got home this evening. I had time for a 1-hour bake at 400F. Temps were pretty steady overall. I had to adjust the thermostat once about 30 minutes in, but other than that it went okay. Now that I have the oven in the garage, it will a simple matter of running a temper cycle right after the quench completes.
All three blades developed areas with a bronze-ish colouration, which I understand is expected behavior. I'll know more tomorrow night once I start working on getting the final bevels done. Thanks for all the help - it has been greatly appreciated. -bill __________________ -bill rankin Last edited by Wrankin; 06-14-2016 at 11:24 PM. |
#29
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Get a good thermometer to use with the toaster oven. Their temperature control is notoriously bad ....
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#30
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Quote:
The final setting on the knob was ~425F. In another thread someone mentioned using a bed of sand in the tray to provide some thermal mass and help stabilize temps a bit. I was thinking of giving this a try on my next run. -b __________________ -bill rankin |
Tags |
1084, art, back, bevel, charcoal forge, cleaning, design, files, forge, grinder, handle, heat, heat treat, hot, knife, knife making, lanyard, made, making, metal, profile, sander, simple, steel, tools |
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