As one apprentice to another - I have to ask: "best" in what sense? I believe the ABS journeyman stamp judges are looking for a rectangular ricasso with the plunge line just curving a little as it comes up to the spine like this:

http://www.americanbladesmith.com/ipboard/index.php?/gallery/image/414-fighter-in-1095-and-walnut/

And I *believe* it's ABS kosher to use a round file (with one side ground flat so you don't dig into the blade itself) to true up the plunge lines after grinding - I've heard ABS master smiths recommend this. I follow that up with finer sandpaper wrapped around a thin wooden dowel or steel rod.

Personally I love variety - especially if you are in control of it. Like this guy's plunge lines:

http://www.tomasrucker.com/knives/Custom_Handmade_Knives_-_Tomas_Rucker.htm

Or no ricasso at all - just don't submit one of these for the journeyman stamp - think: chef's knife; cinquedea dagger; Kukri; or a scramasax like these awesome blades:

http://www.seekyee.com/Bladesmithing/past%20work/past%20work.htm

That's my 2 cents - but as I say - I'm at the ABS apprentice level - loving it, but BOY do I have a lot to learn - warped my latest blade in the quench yesterday - got it mostly straightened - need to straighten some more and re-harden. Ugh!

Michael

Kyle,

Thanks for the great question.

Michael,

Thanks for the great answer and links. The links provide great inspiration.

Ed C.

Hello All,

I was wondering if it matters how the plunge line transition from the ricasso to the blade is shaped. Does it need to be a smooth rounded transition, or can it be 90 degrees? I have filed the blade tapers and I used a file guide, so I ended up with a very straight plunge line that has a 90 degree transition to the blade. Please see the attached photo (sorry for the poor quality). Do I "need" to sand the transition into a smooth one or is the 90 degree transition acceptable?

Thanks for any help.

Ed C.

I will share a thought or two about your subject. This applies if you are grinding on a KMG type grinder. Whether the plunge is a sharp 90 degree step or a flowing curve depends on your platten. If the edge of your platten is sharp and square, it will impart that same shape to you plunge. If it has a radius, the plunge will have the curved feathering into the spine.

The main thing is to know what you want it to look like and to be able to achieve that and it look intentional, like you are in control. I personally like to use the curves of the plunge to compliment the choil's curve. I think this is a very often overlooked detail that can really improve the looks of a knife.

If it takes filing to achieve the intended look, then that is what I will do.

I have to go with Lin on this one. I use a Bader and my platen has slightly radiused edges. I like the curved transition at the plunge. Some people like the 90 degree plunge. It depends on what you like, but, once you have decided on a type of plunge make sure it looks good. If a radiused plunge, make sure the radii match. Radii??? dang there is my five dollar word for the week. If 90 degrees make sure they are even and a true 90. As Lin said if I have to use a file I will or my trusty Foredom with cratex. While we are talking about plunges, if you have a bowie type blade with a clip, false edge, etc. Make sure the plunges are even and match on it also.

Basically it comes down to personal preference and which method gets the best results for you, be it grinder or file.

Brion

Thanks Lin and Brion!

If there's no "hard and fast" rule, then I'll stick with the sharp 90 on this one, and try a radiused plunge on the next, until I decide what I like. However, just for information's sake, do you think the 90 degree plunge could increase the chance of a stress riser developing during the quench (I'm edge quenching this one, but...), or will it have no adverse effect?

Thanks again for the help,

Ed C.

Good question Ed and one I have wondered about myself. Theoretically there should not be a sharp 90 degree angle when quenching, because of the stress riser issue. I have not seen an adequate answer on that. Maybe something to ask our resident metallurgy guru. I will e-mail Kevin and see what he thinks.

Brion

I’ve been paged. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//biggrin.gi f' class='bbc_emoticon' alt=':D' /> This is one of those “depends” type of questions. I often see a lot of disagreement between makers about things like stress risers and the amount of stress issues in heat treating, as well as how to deal with them. Now one would think that since the same laws of physics govern how steel reacts to these things that it would be pretty cut and dried… but while the same laws of physics do apply they come into play in very different ways due to the fact that none of use the exact same steels or treat them exactly the same. I often see guys who only practice edge quenching laying down universal set in stone statements about minimal heat treating stresses, when they only have to deal with ¼ of the stresses that guys who fully harden would cope with. And most of your industrial, tooling or machinist guys will be very skiddish about stress risers as they deal with very precise parts with complex shapes that are fully quenched.

I can say that in my shop I don’t do sharp 90 degree anything before the heat treat since I am fully hardening steels like L6 and O-1, and they will come apart at those areas if given the opportunity. However if you are working with 5160, 1084, 1095, W2 etc… the 90 degree thing will become less critical due to either lower carbon contents or more shallow hardening, and if you are edge quenching (either clay or tray) the threat becomes even less.

In use of the finished blade, if the blade survived fine, it is splitting hairs to see the difference and most blades will never be pushed to the point that it would become evident. If one was destroying blades by applying force great enough to that specific area I can say that there would be a noticeable difference in the numbers if one was measuring it. A sharp 90 degree corner is a huge thing in impact testing and it doesn’t take a very big one to halve the impact strength of a piece of steel. But how often are we applying a given number of Joules directly perpendicular to the ricasso to bevel interface?

Since the physics of each knife is not so cut and dried I would offer this point that would actually affect us in a much more noticeable way- cleaning out an finishing a 90 degree corner is a serious pain in the butt compared to blending in a nice rounded shoulder. And I personally find the nice round shoulder much more aesthetically pleasing than the 90 degree cut, for what that is worth.

Thanks Kevin,

Can't ask for better info. than that <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//wink.gi f' class='bbc_emoticon' alt=';)' />

Ed C.

Thank you Kevin for responding to the page <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//biggrin.gi f' class='bbc_emoticon' alt=':D' /> . Very good information and I agree with you on the finishing. I much prefer a nice rounded contour, plus like you that is what I prefer in the looks department. It comes down to personal choice.

Thanks again.

Brion

This question was asked of Mike Williams and JR Cook during an ABS Judging Standards class at the recent Pineywoods hammer in. They answered that either style is ok for ABS judged knives. I was surprised to find that JR Cook cuts his plunge lines in with a file and jig. The teaching duo explained that consistency is more of a factor and that your plunge lines, ricasso, choil, etc should not have any signs of you covering up a mistake. They stressed, clean and consistent plunges, square and sharp corners and clean finish as being very important.

I posted the whole post you put up micheal, but I was wondering do you grind half the file off or just put a flat side on it. I know thats a stupid question, but I use a round file from time to time and kinda wondering about this. I'm new the ABS and this forum so forgive me if I don't do this right.

Jason Russell