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A question and a discovery.

Started by ozhunter, July 12, 2022, 10:38:23 AM

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ozhunter

Greetings

I have gone completely down the sharpening rabbit hole. I can get a knife sharper than I have ever been able to, but.....

I discovered the over-grinding a portion of the edge problem. After reading a lot of posts, it seems to me that the best remedy is practice, although there are techniques to help. It's better than it was a week ago, but still there.

It seemed as I tried to correct the over-grinding, other issues appeared. Nothing specific, things just didn't seem to be going right, frustrations with the process I suppose. I was sitting at the computer trying to work out the over-grinding problem, looking at many posts, and I came across a post from some years ago that spoke about the jaws of the SVM-45 being parallel once the knife is clamped.

I said to myself, "Self, you have never checked that. Stupid boy!" So out to the shop and sure enough the jaws were not parallel. I corrected that and had a grind, and the other frustrations seemed to disappear, and even the over-grinding appears less.

My question is, if the jaws are not parallel, would that exacerbate the over-grinding and cause things to not go well, a general difficulty in sharpening?

My discovery came about in the same moment. The jig felt like it wanted to drag as I moved across the USB, and I thought about what I do on my wood lathe when the gouges seemed to drag on the tool rest. A thin coat of turning wax! The jig slides across the USB with ease now.

Combining the apparent improvement in the process with having the jaws parallel and no drag on the USB, the sharpening improved immediately.

Thanks for the knowledge, and occasional giggle in this forum. Much to absorb.

RickKrung

What do you mean by "overgrinding"?  Photos would help. 

If you mean wider bevel/different angles around the curve to the tip, lifting a lot more would help a lot.  There is also the pivoting camp.  I had trouble with this and I totally missed the lifting part.  I was amazed at how much it takes and how far "up" on the wheel I have to go. 

Or do you mean grinding a concavity in the middle of the edge, between the heel and tip?  That I think is caused by dwelling too much time in that area, particularly if grinding back and forth rather than only grinding from heel to tip. 

Elaboration of what you mean would help. 

Rick
Quality is like buying oats.  If you want nice, clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

ozhunter

Rick

I meant grinding a concavity in one part of the edge. Typically in the third closest to the heel.

I don't grind back and forth, only in one direction, from heel to tip.

I make an effort not to dwell in one area. I fell in that hole early on sharpening chisels, plane irons and turning tools. That's not to say it isn't a contributing factor, but in my mind, I'm aware of it.

After I became aware that I was leaving the concavity, I observed my finger placement and where I was putting pressure as the edge traverses the wheel and I may have been putting pressure on the blade more in that area.

Seems to be lessening now I am aware of it. I was just wondered if the jaws of the jig not being parallel may have been a factor, and since there is no-one within a bulls roar of where I am that would have any clue, I turned to the brains trust here.

cbwx34

I don't see how the clamp issue would make any difference in this instance.  It's usually relate more to uneven bevels.  Just my thought.

You're probably seeing better results simply because you're paying more attention to what's going on?  Or as the saying goes...



;D
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ozhunter

Thanks for the replies fellas.

cbwx34 and there are quite a few details to get right. I am enjoying the journey though.