Blade Mounting Help, Please…
- This topic has 5 replies, 4 voices, and was last updated 05/18/2020 at 7:55 pm by
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Great question. I find that the majority of knives I do allow for basic adjustments to find the sweet spot. Every now and then I do find a blade that won’t work with only back and forth adjustments. In those cases, I definitely break out my Advanced Alignment Guide and adjust the tilt of the blade as well. If you are trying to mount a knife and are not able to find a sweet spot by adjusting it back and forth (using the marker to guide you) and you don’t adjust the tilt, then it’s possible that you’ll end up with a bevel width that is inconsistent down the length of the blade. On some knives, you may not care if that’s the case. On other knives, if the aesthetics are more important, then you should probably try tilting the blade to get the best match you can.
-Clay
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Have you checked the “knowledge database” to see if your knife is in there? Maybe another WE customer has already found the “sweet spot” for you.
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Geometry-and-Kinematics-of-Guided-Rod-Sharpening-Systems-Example
So, I went away from the sharpie approach because for a knife in the WEPS for the 1st time it seemed like an inefficient way to do it. Especially if you have to move the knife multiple times, resharpie it, do another stone pass and eyeball your result. This and the below only needs to be done one time as long as you record the settings of top/bottom key and AAG center square. If you read up on the geometry aspects of the WEPS you will find that the WEPS will put a consistent bevel on a clamped straight edge even if the edge is not horizontal (of course approx horizontal is how we typically mount a blade so we can see what we are doing). There is not much that you can do for a straight knife edge that is not “exactly” straight like where it “approaches” the curve but there is enough “play” in the WEPS tolerances such that the stones will absolutely find the apex and create your initial burr without messing up the approach to the curve.
The curve to the tip is the important part. The geometry says that if you locate a fixed spot on the rod (no stone yet) and put the rod against a mounted knife at the start of the curve then move the fixed spot just below or at the bevel (some of us use an o-ring or just my thumb). You then move the rod like you are sharpening and watch the fixed spot o-ring vs. the bevel curve. The fixed spot will follow a precise, repeatable arc. You adjust the knife location in the clamp to match the arc traversed by the fixed spot. Once I got the hang of it I just used my thumb. Keep in mind that if the steel is thicker/thinner near the bevel in sections like many folders are then you will have a very slightly wider bevel no matter what you do. A slightly more detailed process is described below from my other post. Also, the start of the curve typically ends up near the clamp (depending upon the radius of the arc that you are trying to replicate with the fixed spot).
This all seemed a bit counter intuitive to me until I read thru Anthony Yan’s mathematical proof and simulations (great stuff to read if your are inclined).
More detailed process: Fine tune your blade placement in the clamp by focusing on the curve and putting your thumb/o-ring on the rod (without a stone and without the AAG as it is in the way), and gently putting your thumb/o-ring against the blade, rotate the rod to watch how close your thumb/o-ring (fixed point) follows the knife curve. Its a little 2 hand tricky (the knife needs to be moved iteratively to find the sweet spot) but it does a good job honoring the geometry prospects of the WEPS vs. a factory bevel. Once the sweet spot is found I clamp the knife and the put on the AAG & key. I then document the location (I may slightly reorientate the blade to rest on the key and be centered in an AAG square). I double check the thumb/o-ring curve thing and move on. I no longer use the sharpie. It sounds like alot of back and forth but it really isn’t. If I confused the heck out of you, I can make a video if someone wants.
Here is the link to the Anthony Yan’s work (it should be put in the WEPS Knowledge Base):
https://knife.wickededgeusa.com/forums/topic/geometry-and-kinematics-of-guided-rod-sharpeners/
I attached a a small file size sample of what Anthony Yan was talking about. The actual full pdf is available thru the previous link. It is like 195 MB with animations (really great stuff) and needs to be accessed separately (hopefully the links still work). Again …. someone at WEPS should put this on the Knowledge Base but we don’t often get one of them to chime in (except Clay occassionally).
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Thanks so much for posting this. It’s way over my head, but I think I grasp your practical explanation of how you apply it all to your mounting methodology. I’m going to reread your post and see if I can get it all to work for me. Thanks again.
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