Bevel battle - help please

[BradGE]

Hi All,

I'm going in circles this morning and hoping that the forum can spare me from an afternoon of frustration.  I've been working on a Global, and for some reason I can't figure out I can't seem to get to the apex of one bevel about an inch from the heel and two inches from the tip.  See photos attached showing the problem area, plus the opposite side of that same part of the knife (with a clean edge)... I've also attached a shot of my jig set-up.  I've tried flipping the knife around 180 degrees, moving the jig forward and backwards along the knife and even deeper and shallower within the jig. 

I'm currently on the SG-250, coarse graded, but have also tried my DC-250 without success...

Does anyone have ideas or experience this where one part (and one side) of a blade just won't take an edge?... 

Thank you in advance for any help or advice. 

[micha]

Hi Brad,

cheer up, you're not alone 

I think it's quite easy to create an uneven bevel without noticing it, especially with tapered or very thick knives. Once the bevel has different angles on each side, you may get exactly that awkward behaviour. Are the bevels same length and angles now?

Make sure the knife is clamped really straight (following the axis of the jig's shaft).

I'd also suggest clamping it so that the knife edge and not the spine is parallel to the jig's edge (or the USB), otherwise the angle will inevitably change over the length of the blade. Then you won't be able to replicate the grind exactly. That might also explain why it doesn't match at heel and towards the tip.
Clamping it exactly rectangularly every time will make it repeatable.

Correcting that sometimes took me a bit of time.

Mike

[Al]

I noticed that you have your knife jig quite close to the heel.I would move the jig so it's more central

[BradGE]

Thank you both.  Nothing like a Tormek to keep one humble, eh?

In the end I ran out of time for trouble shooting so went to 20dps and it cleared the problem (previously I was working at 15dps).  I think I'm pretty good at keeping the blade edge aligned with the jig, but perhaps the knife was slightly tilted within the clamp? Nothing I could see with my eye, but the answer must have been there somewhere...    This is my fifth Global this week - first four <60BESS, and then 3+ hours on this quagmire...  I originally thought maybe my DC250 was worn out, but then switching to the SG250 had no effect.

Al - I did try moving the jig along the blade too - but you're right that in the photo I'm a bit close to the heel...

[chefknifeworks]

I have been there and done all of that Brad.
Another issue I corrected though was to be conscious of pressure, placement, and alignment of my fingers when switching hands as the less dominant took over the second half of the sharpening.
With less pressure, exactly replicated finger placement on the blade and making sure the black stop of the jig is square on the USB, my bevels started matching up and looked a lot more uniform.
Cheers!