V-Grind Plunge Fun

Burchtree

Burchtree

KnifeMaker & Moderator
Moderator
Joined
Mar 15, 2002
Messages
5,368
Well folks, I'm working on a full v-flat ground bowie. I've never done one before, but have been practicing on some scrap metal. My problem is that I'm not happy with my plunges. They are just 90-degree cuts. I'd like to get some rounded radius action going (I hope that explains it) but I can't get it. I tried letting some of the belt overhand the platen, but all it does is cut into the plunge instead of rounding it. Any suggestions? (besides practice, practice, etc. ;) )
 
I'd feather it
but some guys use a flattened round file to get the rounded part..
flatened about 20% I'd say
anyone else??
 
Kill the edge of the belt (knock off/wear out) to approximately 3/16"-1/4" from the edge. Use some old steel or a crock stick, or whatever to do this. Make it gradually blend into the new part of the belt, and then adjust your rollover on the radiused platten edge to your satisfaction.
 
DO what RARAnney said, learned this by accident doing something else with belt hanging off edge(can't reember what).

Just don't(at least in my experience) expect this belt to again track naturally(ie over wheels and platen without overhanging) as once you break the edge liek that, it wants to stay off the edge of the platen.

But it makes for a nice rounder cut.

Course, i still ahven't mastered the plunge. :)
 
it's not tracking, I adjusted tracking on it, jsut with the cheap belt it wanted to saty folded over. Whether that was symptom of cheap belt, or not being completely broken in, dont' know. belt was too clogged/dull even for polishing a convex edge anymore, I ditched it last time I was working on grinder.
 
do what RANNY said. also you can round the palten or piece of pryocerm too the desired raduis. and of course theres that practice thing again:D all joking aside, it takes time to figure out what will work for you. happy plunging!
 
BruchTree
This may go against the grain but running the belt of the side of the wheel,really does not get real rounded plungs like you are speaking off,nor braking the belt,getting the shoulder you are looking for are made by the way you move the blade.
As you are moveing in as soon as you blade is were you want it
move in as soon as the blade touches move the blade to the side
keep the blade moving from the side that will give you what you are
prototyperecurve.jpg
looking for. Here is a quick shoot of a prototype knife I am working on
are these the shoulders your are looing for.
;)
 
Wow !
Cool blade Nathan !
You really found the grinding trick!
It is exactly what I would like to be able to make ; -)

Alain M-D
 
Yeah Nathan that's some serious grinding!!! Wow! :eek:

Michael, I do it like RA does, you will have to change the angle a bit at the edge end of the plunge; the plunge will angle toward the handle more than presently - you'll see. This is a hard one and I didn't try to learn it for many many knives. Hat's off to you!

Dave
 
I did say feather it didn't I :D :D
nice job Nathan
dulling the edge of the belt will help slow
cutting a hard tight radius
if you start away from where you want to end up
you'll have more control of it
as to say start at about 1/2" or so
from the plunge and feather in
like Nathan said keep moving :)
 
Sweet grinds Nathan! That's not exactly what I was talking about though -- I should have worded it better.

I think I will try to "kill" the edge of a 220 and see if it works.

Thanks everyone for their help!
 
Indian George -- Thanks for the info on the Klingspor belts. I've got to get a new supply of belts anyway, so how are their other belts? Are they smooth running? They are extremely cheap from Pops, so I was just wondering. Besides the flex ones, which ones are good for regular ol' grinding?
 
I agree with I.G. when doing plunge cut dress up and clean up, I use 280 j-flexs at a slow speed. you can roll the plunge anyway you want then, and the hand work later is very minimal.

Good Luck

Bill
 
Dan
Brought a up a good point in by starting the plung and working back,that way the plung will not get away from you and you can slowly walk it back.I do the same when I grind,I make my plung cut
with some extra meat on the blade and then slowly walk it back.
;)
 
I too make my initial plunge forward of where I want the final. Then I have plenty of meat to work with.

However, one knife I started way forward and got the plunge perfect in one try. That left a large ricasso. I'm more prepared to tell the customer it's to his advantage, rather than re-do the plunge.

FWIW, here's what I'm doing now.

I leave 1/4" plus extra ricasso area and rough the grind out with 80 grit. Then I smooth it out with 120.

Next I mark the edge where the plunge goes. Now with the work rest on and the belt perfectly on the edge of the platen, I carefully, slowly angle the blade against the belt. I'm cutting ONLY the ricasso area. The angle of the blade is such that I only cut about 1/4 the distance of the full grind and match up the edge thickness (Did that make sense?) Then work the grind line up to match the previous one. Then do the other side.

This creates a very sharp plunge cut.

Once two plunge lines are even and the grind lines are matched, I move on to the 220 belt and smooth bevel and shape the plunge.

Steve
 
That really is a nice looking grind Nathan. Not knowing better I would have thought it a hollow grind; no matter - still nice indeed.

RL
 
Roger
The knife is hollow ground that is the only grind I do.
But I think the same would hold true with a V grind.:)
 
You must log in or register to reply here.
Back
Top