How can a burr form on both sides?

J

jamiesaun

Joined
Jan 1, 2016
Messages
44
So in visualizing a burr formation, it makes sense. Ya grind away material until you reach the tip or apex. At which time the remaining material folds over because there is no more support from underneath, (because it's been ground away.) Or there's simply just a tiny bit left sticking out in front of the apex...either way, If I have that right it makes sense to me.

What has me puzzled is how there can be a burr on both sides at the same time? I've noticed this particularly when I stone thin blades. Almost like there's an X formed at the apex...but this can't be right if what I stated above is true.

What's going on here?
 
two ways
if you've fully apexed, so you have V edge with burr like you say X
a ragged burr, where its like fingers, half a bent one left and half right,
so anyway you check/feel for it, it feels like both both sides have a burr

not apexed yet, you still have flat, but burr on both sides, like an H

whatever you have, procedure is the same, cut it off at increased angle,
either double angle, or straight at 40 degrees, or at least +10 degrees from existing angle,
then go back and raise burr again


there is a third possibility, you've raised a gigantic massive burr on one side
and it folded over
so when you went to raise a burr on other side,
you raised a burr on the existing burr
so you have one burr on top of another both going in opposite directions


I believe I've experienced all three versions, but I dont have magnification :)
 
jamiesaun said:
Cool stuff! So I guess just push it all to one side, then raise the angle to grind it away?
Click to expand...
yes, that will work
if you raised too much of a burr thats folded up tight,
its hard to move it to the other side,
so you have press a little harder, 100grams or more

but if the burr you're raised is really tiny,
then you should use alternating strokes and light force to stand up the burr,
so its standing straight up, you won't be able to detect it with your nail
then remove it at increased angle with under 100 grams of force

either method should get you shaving sharp, but going lighter means more hair whittling ability
 
As an additional possibility you could have the true wire edge. It appears as a burr from both sides because there's a fin of steel that runs down the center and doesn't line up with either bevel side.

These tend to be largish and may even begin as a big burr that gets finessed too well. Or could be on very thin stock the edge deflected away from the abrasive a bit and when flipped more of the same - essentially grinding away the support steel faster than the extremity as it sways back and forth. I have only seen this a few times, and the easiest solution is generally to grind it off 90° and start over.
 
It definitely feels like a burr from both sides. It scrapes off a bit of my fingernail all down the blade from both sides.. and it's way thin, and seems impossible to get rid of. It doesn't really get worse or better, just kinda hangs around.
 
Use bright light to examine the edge bevels. Make sure to look directly DOWN at the edge also; edge on. See if it reflects light. A squared off edge will have corners on both sides. Both corners will feel sharp to the touch. I might be totally off base, but it's a possibility.

If it's really burr on both sides, I would think that drawing it through end grain wood, should strip most of it off and leave behind metal residue.

Magnification might be a good idea to examine the edge more closely.

Brian.
 
What you feel could be serrated edge bevel shoulders - most likely formed by sharp coarse grit. Do a 5-10 strokes at 5dps below sharpening angle against 1K stone. If suddenly burr seem much smaller, voila`
 
bluntcut said:
What you feel could be serrated edge bevel shoulders - most likely formed by sharp coarse grit. Do a 5-10 strokes at 5dps below sharpening angle against 1K stone. If suddenly burr seem much smaller, voila`
Click to expand...

This! On coarse stones I have had trouble at times differentiating between the coarse bevel and a possible burr.
 
You must log in or register to reply here.
Back
Top