Some beginner questions

[Drake Donovan]

Hi all, I'm Drake and I've decided to have a go at knife making. I've had a great time reading through all of the resources that have been compiled here, so thanks for getting me off to a good start!

I have a few questions that I'd be interested to hear y'all weigh in on! I hope they aren't too redundant.

First, I built a filing jig because the only power equipment I have is an angle grinder and a drill press and I figured I'd rather make the bevels with a file than an angle grinder. One of the methods I've seen to use the jig involves starting at a relatively obtuse angle and grinding up the blade toward the spine (lowering the eyebolt) as you go in order to avoid overgrinding at the spine. I definitely plan to try this method, however it seems more controlled to me to use the chart here: (https://www.bladeforums.com/threads/knife-bevel-rule-of-thumb.659580/) to calculate the desired angle for your desired materials.

For example: Say I'm using 1/8th inch thick steel that is 1 inch wide and I want a full flat bevel. The chart suggests I should grind each bevel at 3.6 degrees to achieve this, which I should be able to establish on my jig trigonometrically (for the 12 inch hole I would need the eyebolt to be 3/4 inch tall to get ~3.6 degrees). Am I thinking about this incorrectly in some way? Also, how can I think about reproducibly making a distal taper? This doesn't seem as simple to calculate.



Second, I am pretty quantitative and not very "artistic" or design oriented. I thought about using CAD software to design my knives, but became overwhelmed and just did the old paper/cardboard trick instead. What is the general consensus around here on CAD vs cardboard? I tried some of the more highly recommended programs from the forums (Fusion 360, Sketchup, etc).

On a follow up-- do y'all have any comments on those two designs? I wanted to make kitchen knives, but have now decided that 1/8th inch is too thick for the kitchen so I'll be ordering some more steel soon. So, these will be more outdoor oriented... One is intended to be more of a EDC/defense type knife, and one is intended to be more of an all around outdoors/camp cooking/etc type of blade. I tried to keep things simple and relatively easy for a beginner, so please point out anything that you think will be trouble!

I also have designed two plunge lines for each-- in the thin one, I can envision it either going straight up to the spine or doing more of a scandi grind and bringing it out to where the clip meets the spine. I prefer the latter but am unsure of the difficulty. On the other, I'm just not sure if I should square the plunge with the blade or the handle given that they are not parallel. I think square with the handle looks much better.



Third, I have decided to go with 1084 for now as it seems pretty conclusive that it is the best for home HT. I have read about both using a propane torch as well as using a coal fire to HT 1084. I could do either, but I have a large outdoor propane burner for homebrewing (often called a turkey fryer as well). I haven't seen anyone else using this for HT, but it seems like it would work very well for temperature control as well as even heating of the whole blade. Any comments on this?

Fourth, I am curious about the temperature control necessary in tempering. From what I understand, you basically want the carbon in the martensite to be labile enough to relieve stress but not so much so that it crashes out as big cementite crystals. It seems like around 400F is ideal for this, but specific control is not important like it is when near the critical point-- so a home oven works fine? Does anyone have some specific further reading to suggest on this?

Finally, what exactly is a positive included angle? That just simply means that the edge of the knife blade is lower than the bottom of the handle steel? Whereas a non-positive included angle blade would just be in line with the handle? So one of my designs has the positive included angle, and one doesn't?

Sorry for the wall of text, and thanks so much for any help! Cheers.

 

[Richard338]

I like to design using a combination of software (mostly just shapes in ppt), and pencil and cardboard.
I'm terrible at drawing, so I either use "french curves" (plastic shapes with curves of varying radii), or ask my daughter to sketch it.
PPT shapes are good for meeting certain dimensions or keeping symmetry.

 

[Willie71]

I’m odd. I just draw on the steel with a sharpie and cut the knife out. Not recommended to start with though.

 

[FunkCoaster]

For me, the pattern will end up on cardboard or some other template eventually in order to get a feel for it, so you might as well skip to that as a beginner. That said, you can use some templates as long as you adhere to the publisher's wishes. Example: http://dcknives.blogspot.com/p/knife-profiles.html
CAD will be almost necessary for precise items like high-end folding knives. Not always necessary for even tight tolerance fixed blades.
To split the difference, a vector graphics tool like inkscape can be good. There are youtube videos specific to knife design in inkscape.

I started with a file jig like yours. I don't think either method is a problem, since you can easily identify and correct an overshoot.
The trigonometry seems valid, but if anything shifts or bends, or your parts measurements aren't perfect, you'll have to adjust for them anyway, so I'd use that as a start, but don't blindly trust it.
Distal taper - I would simply prop the tip of the knife up the amount that you need by shoving a wedge underneath. Make sure it supports the length of the blade.

Regarding designs:
Left: I'm unsure if the marking is where the handle ends. If so, consider how thin the handle material is at the heel. If using a natural wood, you will have a very small amount of material at a region expected to see some impact, and therefore may get damaged. Especially if the grain of the wood is running in the direction of the knife. If using metal bolsters, not as much of a problem. I would consider the plunge line a matter of personal preference, so no wrong answers there (well, there are some).

Right: Same note as the left design on the thin handle material near the heel. As long as your design is strong for it, you're good. I personally like the flat along the spine. I'd suggest trying for that, and if you struggle with getting it symmetric on both sides, you can fall back to pushing the bevel to the spine.
If it is intended as a 'defense type' knife, think on that purpose as you hold it. Many knives of this design have deeper finger wells, guards, or subhilt guards to make sure your fingers stay where they are supposed to in high stress situations. Your design might allow fingers to slide in either direction.

1084 heat treat:
If using the turkey fryer, the biggest challenge is keeping a consistent heat. Without a chamber to keep the heat in, it is difficult to apply heat evenly throughout the blade. If you were to build a chamber to insulate (essentially building a forge), that helps.
If a coal fire is available to you, I'd suggest that. However, do some test pieces first to make sure you can get it right, and check the grain to see if you overheated.

Tempering:
A home oven can work well - but two things can help a great deal.
1) Don't trust the oven setting. Oven temperatures have been known to vary by 50 degrees off target. Use some other means to verify temperature, such as another thermometer or thermocouple.
2) Use a muffle to shield the blade. This will avoid overheating the blade when the an oven heating cycle occurs, and help with consistent heat throughout. The muffle could be a steel pipe, or similar.

Might help to include context on where you hear the positive included angle.
As I know it, 'included angle' is the full angle from one bevel to the other, which would be double your edge/sharpening angle.
I've seen positive and negative in reference to tool design (such as lathe tooling), but not sure in the context of knives.

Hope it might help, and good luck!

 

[Mikko Pitkanen]

I just do a rough idea in my head or a 3 minute drawing with a pencil. After that I just look at the mental image or drawing for reference when making the knife.

 

[J-T-K]

I just do a rough idea in my head or a 3 minute drawing with a pencil. After that I just look at the mental image or drawing for reference when making the knife.

I'm with Mikko: I can't draw as accurately as I can carve and sand an object. I do check on other knives and pictures as reference.

 

[weo]

so a home oven works fine? Does anyone have some specific further reading to suggest on this?

reading through all of the resources that have been compiled here, so thanks

Have you tried the search function in the stickes?https://bladeforums.com/threads/bladeforums-custom-search-engine.1313722/

 

[wrankin]

I started out using a file jig much like yours. Still using it, in fact.

I would recommend forgetting about trying to get the angle math right. Theoretically it should be possible to set the support eye at exactly the right height and grind the flats as a single operation. In reality this just does not end up working out well. If for no other reason than you have to take into account the offset thickness of the file, half the thickness of the blade stock and other items.

The important thing is the final edge thickness (prior to heat treat) and you grind to that iteratively in a series of passes. Aaron Gough has a nice video on YouTube explaining the process. To summarize:

1. Make sure the side of your stock where your edge is going to be is smooth and represents the final curve of the blade.
2. Lay the blank on a hard flat surface and using a marking tool, scribe where the blade edge will be. If you don't have a marking tool, use the tip of a drill bit that is the same thickness as your stock.
3. Since no marking tool is 100% accurate, flip the blade over and repeat from the other side. You should end up with two lines very close together that represent the final position of your edge.
4. Set your initial file/grind angle much steeper than your final one - about 30-40 degrees. Grind along the full length of the edge until you get down to just above where you want your finished edge.
5. Remove the file and lower the pivot by a few screw twists (reducing the overall angle).
6. Use a sharpie or marking fluid to color the area where you just filed away steel. You don't need to cover the whole bevel, but at least get the area near the edge.
7. Start filing with the new angle. You will notice that your are initially removing steel from above where you last finished filing (away from the edge) and as you grind deeper the it progresses towards the edge. Keep filing until you reach the edge across the entire length of the bevel - this is where the marking fluid/sharpie comes in handy in letting you know when you've reached this point.
8. Repeat steps 5-7, slowly reducing your angle until the top line of your bevel reaches where it needs to be. If you are filing all the way to the spine then note that you will start cutting into the spine resulting in a natural distal taper as you approach the tip.
9. Flip the knife over and repeat steps 4-8. Sometimes I will actually flip the knife over between every cycle where I am reducing the file angle, especially when I am trying to file back to the spine.

These are the basics. Again, I found Aaron Gough's videos to be extremely helpful in describing the process and identifying things you need to watch out for.

Hope this helps.

-bill

 

[Drake Donovan]

I like to design...
PPT shapes are good for meeting certain dimensions or keeping symmetry.

Shapes in PPT are definitely more my speed... That's a fantastic idea, it sounds so much better than trying to figure out the CAD programs AND figure out how to make a knife. Thanks a lot, I look forward to trying this out.

I’m odd. I just draw on the steel with a sharpie and cut the knife out. Not recommended to start with though.

Thanks Warren! It definitely seems like the knives sort of come-to-be as they are crafted, at least for the skilled makers. I am noticing a trend of people saying essentially "I can't draw well, but I can make the steel look good." Well-- I've got the first half of that process down, so fingers crossed for the latter half!

For me, the pattern will end up on cardboard or some other template eventually...

Hope it might help, and good luck!

Cheers Funk (boy, I'm sure glad I got to catch George Clinton's final tour last summer), I really appreciate your time and energy in writing this complete and well thought out reply!

The links to designs is awesome-- I definitely tried to base my knives off of some that I own and love (with some twists of my own of course). Good to know that I can get along fine without CAD and I'm decent at illustrator, so vector-based stuff will be my next step after PPT!

I will definitely be using the calculated angles as a starting point for my own empirical angle determinations rather than assuming they are correct. Wow, super cool idea for making a wedge and sliding it under the blade to ensure that I get an even and pre-determined distal taper, and good point about making sure the entire length of the blade is supported! Hmm I'll have to see about constructing something for this purpose (and I'm open to ideas both about distal taper angles and lengths relative to blade lengths, as well as actually creating the device).

Thanks for digging into my basic, beginner designs with such a critical eye. You brought up a lot of things I didn't address specifically so here goes for the left:

I see what you mean about that being a vulnerable place for wood... I intended to make the wooden handle end about where the tang starts to sweep down to the edge, leaving a quarter inch or so wide ricasso (which includes the very heel of the blade). My design process was to get the steel shaped and then think in more detail about the handle with the blade in hand-- it is really hard for me to visualize the "final handle" now. I guess what I envision right in this moment is the plunge being the "closer-to-the-handle" line in the picture, and the front edge of the handle ending about 1/4 inch behind that plunge where the tang begins to widen into the blade.

For the right, the heel issue is similar. I intended to have the handle material end at the blade-proximal end of the finger choil, leaving the ricasso to include that bit of protruding steel between the finger choil and the choil on the blade (which I'm not sure of the most proper name of... Kick? Finger guard? Quillon?) I also can see creating a more full-length handle with G-10 to overcome the durability issue, which I think could look good and function well to boot. Thanks for the encouragement on extending the plunge down the spine and for the good idea to switch to a plan B if shit hits the fan when I'm filing! I'm glad to have options on all of these things. Also, your points are well taken regarding design elements of a defense-type knife.

Regarding the propane burner consistent heat issue, my thoughts were that if I kept the entire knife in the flame it would heat relatively evenly at a consistent temperature, but I suppose I'm not really sure how much these "Bayou Classic" backyard burners fluctuate in terms of output... I could try to make a small chamber out of fire bricks that the burner could blast directly into, which is still pretty crude. I know the regulator on it is only 5 PSI which might be too weak based on some of the DIY forge threads I've skimmed. I wish the IR thermometer that I use in the kitchen would be helpful here, but apparently it was made under the assumption that if the soup I am measuring is over 1000F, "+++" is an accurate enough reading as I must have bigger problems to worry about than a specific temperature! Using test pieces is a good idea-- and hopefully I can train myself to spot decalescence early on.

I know what you mean about included angle of a bevel-- but this isn't what I'm referring to. See the definition here: https://web.archive.org/web/2012050.../info/blade-geometry-by-joe-talamadge-25.html
I'm especially confused by his use of the ATAK as a "positive included angle" blade rather than something more obvious (like any chef's knife ever), if my original interpretation is correct.

I just do a rough idea in my head or a 3 minute drawing with a pencil. After that I just look at the mental image or drawing for reference when making the knife.

I'm with Mikko: I can't draw as accurately as I can carve and sand an object. I do check on other knives and pictures as reference.

Thank you for sharing both of your experiences. As I said to Warren, it is clear to me that for many makers the design is ongoing until the blade is complete. The drawing/conceptualizing stage is just a brief stepping stone in the design process for most of you! I tend to overthink before I act, and this is further enabled here by my lack of experience. I spent a long time (too long) drawing and redrawing and making those cutouts... But my steel comes today and I'm ready to get into it!

I started out using a file jig much like yours. Still using it, in fact.
...

Hope this helps.

-bill

Hey Bill, I appreciate it. Yes, Aaron Gough's videos are where I got the inspiration for the jig, and I do like that idea of grinding the bevel stepwise and will absolutely be trying it that way as well. Thanks a bunch to everyone so far!

 

[Drake Donovan]

Tempering:
A home oven can work well - but two things can help a great deal.
1) Don't trust the oven setting. Oven temperatures have been known to vary by 50 degrees off target. Use some other means to verify temperature, such as another thermometer or thermocouple.
2) Use a muffle to shield the blade. This will avoid overheating the blade when the an oven heating cycle occurs, and help with consistent heat throughout. The muffle could be a steel pipe, or similar.

I had to write another post on this subject because it was too much to put all in one-- thanks verbosity!

Regarding the tempering, I definitely would not trust my home oven temperature setting. I have some high quality thermocouples in there that I use for cooking things properly and I would use for proper tempering too. Protecting from radiant heat is also something I have been thinking about.. I was thinking two cookie sheets with a rack in between holding the blades, but I think my lady will be much happier if I just pick up a large diameter chunk of pipe, haha!

I am more curious about the metallurgy behind the process. I think a lot about the physical orientation of molecules at my day job and I've unsurprisingly become fascinated with the heat treatment of steel. Before this, I didn't realize the depth of knowledge and complexity of processes involved in steel, so it has been easy to immerse myself due to coming from a place of total ignorance. I know this is rather obscure, but this community seems great to me for having helpful and insightful discussions about niche topics.... While Googling things and reading is undoubtedly great and the basis for the majority of my knowledge on the topic, it is evident to me that this forum is more valuable than that. That being said, here are a couple of great resources I have been diving into that I hope will provide someone else with help or information too!

https://www.engineeringenotes.com/m...lassification-heat-treatment-metallurgy/26205
http://www.eurospares.com/graphics/metalwork/heat treating/ASM Metals HandBook Volume 4 - Heat Treating.pdf

Both of these resources go way beyond tempering and way beyond knife making, but damn they are awesome bits of chemical literature!

To expand on my original interests (stop reading here if you don't want to go down the rabbit hole that is my brain): I see that with 1084, for example, there is not a huge different in hardness tempering at 400F vs 500F (a hardness of 57 vs 55). Okay, so what is the molecular explanation for this relatively low change in hardness over a relatively huge temperature range?
We start with the quenched steel containing hardened martensite and a bit (say <10%) of austenite. The problem is that these are now unstable solutions of too-much carbon in iron in vulnerable lattices and, while hard, we don't want unstable and vulnerable material composing our knives (as vulnerable, unstable things lack toughness and, well, stability). So, we temper the knives to drive the most unstable carbon in the solution out in order to generate more stable configurations. To do this, we "grease" the carbon by putting energy back into the system via added heat, allowing the carbon to move from an superficially "locked" state (ie in metastable hardened martensite or retained austenite) to a new configuration that results in a lower energy state of the molecule (which also disrupts the well-aligned lattice, which is fragile). The problem is that the "most" stable option is cementite. Cementite is allowed to crash out of solution and grow as the carbon become more and more labile with increasing heat.
Okay, so, what are we to do to have the most amount of crystalline martensite in our steel with the least amount of stress-inducing trapped carbon and vulnerable latticing without turning everything into cementite? Well, it seems simple given some of what we know. First, we know that up to about 400F is the temperature range at which carbon is labile enough to move around in the martensite and just start to crash out as epsilon carbide. Second, we know that at about 400F the retained austenite begins to decompose. Third, we know that at about 500F, cementite really starts to crash out of solution and continues to grow from there.
Putting this all together, we know that we need to heat to 400F to liberate trapped carbon, reduce retained austenite, and disrupt the overall lattice of the structure. We also know that we don't want to go over about 500F as we being to lose the benefits of the carbon liberation (for our applications) and start to encounter the drawbacks (cementite formation, softer steel, etc).

Okay, that all makes perfect sense to me... But what I'm curious about are temperature fluctuations in the range of, say, 350F to 450F? I can't find any literature on this, though I think of myself as decent at operating a search engine. While I don't imagine there is an immense difference, I can imagine this potentially being beneficial for allowing carbides to crash out while minimizing growth of cementite. If you get a brief swing up to 450 that is then dropped back to 375, you are allowing those carbon atoms to wiggle quite a lot relative to allowing the cementite crystals to grow significantly (the time-dependence difference for these processes is important here).

This is what I was trying to get at when I was contrasting it to the relative importance of temperature control near the critical point, where a 50F difference can be a very important factor for what the structure of your steel ends up being. If anyone has thoughts or data on this I would love to learn! Please note-- I'm trying to understand all of this stuff myself, not trying to preach or teach anything to those that are more knowledgeable than me on the matter.

Cheers, -Drake.

 

[Richard338]

I'll add one comment about ppt.
Make sure that your page is setup as the size of your printer paper. A couple times I forgot and my shapes got resized when printing.
Also, even if I'm just printing an oval, I'll add crosshairs extending outwards. This helps alignment on the steel while tracing.

 

[J-T-K]

Drake: I just think I'm particularly bad at drawing, and I wouldn't like my lack of drawing ability to hold me back. I can make on wood the shapes I picture in my head even if I'm unable to draw them. I would rather do the thing than hold back.

 

[weo]

I'm trying to understand all of this stuff myself,

Good morning, Drake. I'll again suggest the custom search engine. This rabbit hole has been discussed many times.
Another resource would be @Larrin's website: https://knifesteelnerds.com/

 

[Ruukuu]

Could i hijack this thread for a quick question please. Dont want to start a new one for one question.

I'm watching forged in fire right now and they have made the blades and tempered them.....but then they are going hell for leather grinding material off. Surely that much grinding will remove the temper from the blades. Am i right or am i missing something?

Sorry for the hijack.

 

[Rhinoknives1]

Could i hijack this thread for a quick question please. Dont want to start a new one for one question.

I'm watching forged in fire right now and they have made the blades and tempered them.....but then they are going hell for leather grinding material off. Surely that much grinding will remove the temper from the blades. Am i right or am i missing something?

Sorry for the hijack.

Your missing a lot. Not your fault. They harden on camera , they don’t Temper on the show. Done by someone off camera. Don’t rely on that show for a factual way to make knives. Also I grind after Heat treat/ Temper. You can do this if you keep the temp down to 200-225 degrees. Use a dunk bucket etc.

 

[Ruukuu]

Your missing a lot. Not your fault. They harden on camera , they don’t Temper on the show. Done by someone off camera. Don’t rely on that show for a factual way to make knives. Also I grind after Heat treat/ Temper. You can do this if you keep the temp down to 200-225 degrees. Use a dunk bucket etc.

Ah thank you. Appreciate the info mate.

 

[A.McPherson]

Ruukuu,
As long as you keep the blade below the temper temperature you keep the temper. This means dipping the blade in water to cool it often.

Also forged in fire is a tv show for entertainment. While the competitors are actually knife makers, and they do make legit knives, swords etc, the show doesn't necessarily show all the steps/actions that the makers do.

 

[Drake Donovan]

I'll add one comment about ppt.
Make sure that your page is setup as the size of your printer paper. A couple times I forgot and my shapes got resized when printing.
Also, even if I'm just printing an oval, I'll add crosshairs extending outwards. This helps alignment on the steel while tracing.

Good points! It will be fun to design some things more accurately than I can scribble. Looking forward to this on the next blades.

Drake: I just think I'm particularly bad at drawing, and I wouldn't like my lack of drawing ability to hold me back. I can make on wood the shapes I picture in my head even if I'm unable to draw them. I would rather do the thing than hold back.

Fair enough. After playing with some steel yesterday, I can understand totally understand this!

Good morning, Drake. I'll again suggest the custom search engine. This rabbit hole has been discussed many times.
Another resource would be @Larrin's website: https://knifesteelnerds.com/

Everyone's got their own motivations, I suppose. I am in awe of your superior searching skills and certainly wish I had your level of experience with the many discussions of rabbit holes.

Quite seriously-- that is an awesome resource and I have really thoroughly enjoyed reading every single article on tempering (silicon alloying and cryogenic treatment of steel will be what I think about as I grind some bevels this morning).

Unfortunately, I didn't see the theory behind, or practical application of, what I am pondering regarding temperature fluctuations within a defined range mentioned even once... Although we have already established that I am not quite capable of finding widely available and commonly known information, so I likely missed it!

I'm sure Larrin would have some fascinating information on the matter though-- the data compiled on that site is impressive!

Could i hijack this thread for a quick question please. Dont want to start a new one for one question.

I'm watching forged in fire right now and they have made the blades and tempered them.....but then they are going hell for leather grinding material off. Surely that much grinding will remove the temper from the blades. Am i right or am i missing something?

Sorry for the hijack.

No worries, the more knowledge the better. I haven't watched that show-- maybe I'll check it out!

Hope to put some progress pictures up of the blades today. Bled my first blood, burned my first burn, and had a hell of a time doing it. Thank you all for the help in these first steps.

 

[Ruukuu]

Thanks for the replies guys. If i don't know something i ask......so i ask a lot

Thx Drake, now back to your thread mate. By the way, i like the design on the right hand side, but without the finger choil and if it was full flat grind. I'd save my pennies and buy that.. Without the choil so i can hold different ways, and the flat grind because they slice so freely. in my laymans opinion.

 

[Richard Coyle]

...burned my first burn...

If your anything like me, you’ll keep burning, and burning, and burning your poor fingers...
Maybe someday I will find relief when all feeling is lost... or maybe I’m doing it wrong


Can’t wait to see some progress!