Hollow grinding Jig ???

H

hellgap

Joined
Dec 17, 2008
Messages
1,189
Is there a jig to help even out the hollow grinds ive been doing it by eye and feel and sometimes Im off.I know about the scribe and have tried jiffy marker to and it helps but if thereis a jig for hollow grinds Ide like to see one. I have a kmg clone with a big rest. I also have noticed sometimes not always my grinding lines have a bit of a wow on the top and the other side of my blade is near perfect. Any tips are more than welcome
 
You just need to practice. It's nothing that is uncommon for a new maker. Jigs won't make "You" better. Don't waste you money, just buy more steel and make more knives.
-John
 
The best tip I've been given is, "Get rid of the tool rest when grinding the blade". The tool rest works great when profiling the blade, but I have found that I try to depend on the tool rest when grinding the bevels and end up screwing up. I keep practicing and find I'm doing much better without it. Of course, I'm a newbie that is trying to learn. The real makers will have better advice to offer.

Murph
 
Barker said:
just buy more steel and make more knives.
-John
Click to expand...

:thumbup: Now that's the kind of advice that a steel supplier likes to hear! :D

However, I'd have to modify it a bit in fairness. Maybe buy more steel and slow down. The old speedy muffler commercial used to say "First you get good. Then you get fast."

Many makers take a month (or many months) or more to make a single blade. Practice doesn't make perfect. Practice makes permanent.

Rob!
 
You may want to read this thread I started on KD, as it has some really good tips from Josh Dabney and Nathan.

I totally screwed up my first attempt, and then I slowed down my grinder, and it worked sooo much better. As Rob said, you need the technique down before you can get faster. And as Nathan said in my thread, steel is cheap, and the hollow grind is early in the knife making stages, so just scrap a few pieces of steel.

By the way, I'm still learning to just freehand, because I feel it will make everything easier later.

Hope this helps.
 
Rob lmao I must be your best customer then cuzz i had you heat treat over 10 knives last month alone. I hear eveyone of you did say slow down . So ill try one tonight, im going to try counting passes and see if that helps on evening it out more and stoping to use my calipers . Probably like counting sheep , hope I dont fall asleep. I do believe you about free hand. Here is a serious question though. How wide of steel is the best all around width to hollow grind. 1 1/4 to me seems like the best is there a better width. When I attempted 1.5 inches I destroyed one blank by burning a hole right through.
 
hellgap, the width and depth of the hollow grind is relative to the diameter of your contact wheel.
I saw a grinding table here once that is an excellent guide but I don't know where it is now. Maybe someone can post it again?

Mike
 
sam
Lock your hands in tight, once you get the bevel established it almost grinds itself.
 
The chart below assumes you leave .020-.025 prior to HT. After HT the cut height can change slightly. Hope this helps. When I space it all the data runs together, If anyone needs a better copy email me and I will send you a copy!



wheel dia metal thickness cut height
14" 0.125" 0.86"
14 .156=5/32" 0.974
14 .1875= 3/16" 1.08"
14 7/32" 1.18"
14 0.25 1.26"
10 0.125 0.72
10 0.156 .823"
10 0.1875 .911"
10 0.21875 0.992
10 0.25 1.07"
8" 0.125 0.646
8 0.156 0.735
8 0.1875 0.814
8 0.21875 0.887
8 0.25 0.952
5" 0.125 0.50965
5 0.156 0.579
5 0.1875 0.642
5 0.21875 0.698
5 0.25 0.7495
3" 0.125 0.393
3 0.156 0.4469
3 0.1875 0.4942
3 0.21875 0.5369
3 0.25 0.576
 
Last edited:
i am by no stretch an expert but...an effective and cheap way to practice is by grinding wood. (paint stir sticks, scraps etc.) slow the grinder down and practice your hollow grinds with thin pcs of wood. i found it especially great for learning how to grind the trouble areas like the tip.
when you screw one up it doesn't hurt to toss it in the trash. also, wood obviously disappears quicker so you can get instant feed back on your technique. (what results come from using different angles etc)
 
Thanks everyone I went at it starting last night profiled one then started my hollow grinds by using a jiffy marker outline . I was going to start off with a 36 grit but decided 60 orange blaze is good enoiugh. I am grinding cpm154 so its a little tuffer than most steel . From start to finish was around 2 hours. I stopped at 320 grit stuctured abbrasive belt and will send off for heat treat. I think just trying to be more self concience about keeping it even and taking my time really helped . Thanks for posting the chart but I think ill email you for a copy. thanks ya all , kellyw
 
Rob the link worked but I couldnt get the chart to operate could be on my end . Thanks anyway. kellyw
 
DONT DO THIS SERIOUSLY DONT DO THIS........ you can get 2 hand held disc grinders and mount them side by side at desired space and angle then slowly move the griders in. DO NOT DO THIS . ITS A STUPID JOKE----(it may work but) DONT DO IT-marekz
 
Just relax. I built and tried tool rests. But I find it much easier to just grind them off handed. It is so easy once you get the hang of it. I fought it for over a year. Now n I wont do it any other way.
 
Jim thanks for the comments I appreciate all the help. Would it be safe to say if a person started to grind a fresh blade on a10 inch contact wheel with 36 grit blaze orange ,should the bottom of the steel beheld approximately dead to centre on the bottom edge . On the chart it is normally about 3/4 the distance up from the bottom edge. kellyw
 
You must log in or register to reply here.
Back
Top