Help with Flat Grinding

It's called distal taper, Mitch. When you look down on the spine, it tapers from ricasso to tip smoothly, when done right.
 
fitzo said:
It's called distal taper, Mitch. When you look down on the spine, it tapers from ricasso to tip smoothly, when done right.
Click to expand...

I didn't know that "distal taper" was a part of flat grinding.:o The light bulb between my ears just came on.
- Mitch
 
Fitzo got your answer...pretty much starting at the ricasso....but it is very very slight a taper and, on the smaller blades I grind, may not be completely flat ricasso to tip....but ought to be very very close.
Mike, how come you answered in one word that can be googled on when I took several paragraphs to try to explain it? (smile)
I always grind edge up, but most of my blades are not large, at least 1/2 of the length of the blade is in contact with the belt during most of the pass. and its what you get used to. I also usually use a work rest a good part of the time
 
The other part to understanding flat grinds is to realize that the "V" at the ricasso has to be slightly wider than the "V" at the tip, since the spine has that distal taper. This means that the "flat" grind is actually a subtly twisted plane and necessitates some tiny repositioning as we draw the grind across the blade. Practice, practice, practice. If it remains mysterious, see someone who can watch and correct your movements.

Keep practicing. Personally, I would have a helluva time grinding edge down. Then, of course, there's Harvey Dean who grinds one side edge up, one edge down. <shakes head in wonder>
 
Thanks, Guys, and especially JT for that great video clip. The missing piece of the puzzle was that, with flat grinding, the taper starts all the way from the ricasso. Now I see that there really is no transition from the straight part of the blade to the taper of the belly, because the whole blade is one big taper! Now I understand.
Thanks again everybody; you guys are the best.:thumbup:
- Mitch
 
I don't know if I can describe this the way I want to or not.
A correctly done flat grind IS completely flat from spine to edge, and ricasso to point.
It had better be.
Stand up with your hands to your sides and your fingers out-stretched to the ground. Now raise your arms stright out in front of you, keeping them at shoulder width and palms facing each other.
Now, raise your thumbs to the ceiling.
Slowly tilt your thumbs toward each other about 20 degrees.
That represents the plane from the cutting edge to the spine, in the edge-up position.
Now, bring your hands closer together until the thumbs touch.
The plane from your shoulders (ricasso) to your hands (point) represents the distal taper. (this is in the edge up position)
All straight lines - only two flat planes.
There is no rolling, or tweaking, or feathering, etc.
Two flat planes.
Imagine them going off to infinity in all directions.
 
Keep feeding me different vantage points to make me understand better, guys. I most certainly appreciate it big time. Now I have to leave for work.(night shift...Eeeeek!) I'll meditate on all this at work tonight.
Thanks again.
- Mitch
 
Nice job on the video J-Rod... do you wear that many rings grinding? :eek:

Sounds like you've got a cold, hope ya feel better :barf:
 
Troop,

After reading these today, I went down and really paid attention to what I do. The one thing that may help (newbie here also) is to make sure and watch your spark line. As you move across the platen, the sparks will fly out from where your steel is meeting the belt. If you're only getting sparks on one side or the other, try to flex your pressure until you get a nice even spray the width of the belt. It really does help.
 
when i was grinding the collaboration-auction knife for vg, i took some picks from start to finish on grinding the single bevel. i use a disc sander and i do the same thing that eric mentioned, i watch my sparks but as i move up to the tip, i'm pulling the handle away from the disc and concentrating on where the sparks are coming off at. i have some picks from another smaller knife that shows how the grind progresses. here is a link to the other links at my website. there are 6 links 3/4 down the page.
http://mysite.verizon.net/ress6fq6/id21.html i hope these help.
 
Thanks for the vid JT, I can only get halfway through it though...... I have cable internet but every time I try to watch streaming video like You tube I get part way through and she stops..

Half is better than nothing I suppose. Thanks man!
 
TekSec said:
Troop,

After reading these today, I went down and really paid attention to what I do. The one thing that may help (newbie here also) is to make sure and watch your spark line. As you move across the platen, the sparks will fly out from where your steel is meeting the belt. If you're only getting sparks on one side or the other, try to flex your pressure until you get a nice even spray the width of the belt. It really does help.
Click to expand...

When I read that on Bob Engnath's site I was like "EUREKA!!!!!!!!!" LOL.
 
There are two ways to do it. Some guys hold the knife perpendicular to the ground and pull the handle away from the belt as they get towards the tip. I like to go the other way and keep the handle the same distance from the belt but move it down as I get towards the tip. in other words I try to keep the portion of the blade that is in contact with the belt perpendicular to the belt.

Here's a super cheeseball drawing I did in paint to hopefully help show how I do it. I suck at paint :P

http://i267.photobucket.com/albums/ii316/Belstain/1supercornydrawing.jpg

Blue lines are the edges of the belt red is point of contact and yellow is what the spark pattern should look like.
 
Keithcellini said:
Thanks for the vid JT, I can only get halfway through it though...... I have cable internet but every time I try to watch streaming video like You tube I get part way through and she stops..

Half is better than nothing I suppose. Thanks man!
Click to expand...

just save it to your computer. right click and save link target or somthing like that.
 
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