Grind Line Issues

TCurry

TCurry

Joined
Dec 29, 2010
Messages
271
Anyone around the Ft Worth, TX area that could give me some insight on proper grind lines and how to achieve them. I've read and read and practiced and practiced and just cant seem to get it right.

Thanks, TC
 
Until you get used to grinding you may want to mark where you want your plunge lines to be. You may even want to put 3 or 4 layers of tape where you want them to be. Another thing you could try is start them about 1/4" ahead of where you actually want them. Then once you have the blade rough ground you can CAREFULLY move them back to where you want them. Try as many things as you can think of or read about and see what works best for YOU. Hope this helps.
 
What are the platen edges like on that grinder? Can you use them to fold a -flex belt around? Is the screaming speed of the grinder not conducive to such a technique? By grind lines, do you mean the plunges or the grind line along the top of a partial height flat grind, or both? Like Darrin says, I always rough grind at least 1/16" short of where I want my finished plunge cut to be, it gives room to even them up with each other, etc.

You've probably read about it, but if your partial height grinds are not even, try the technique of locking your elbows and grinding evenly by sliding to the left or right with your hips, not your arms. It really helps. Try to act like the carriage in a grinding machine- a perfectly even slide to left and right. It may help when rough grinding to be aware of the spark pattern- if the entire width of the belt is not throwing sparks, you may have the blade unevenly applied to the belt.

Do you grind with a push-stick? I use one almost all the time, unless I'm at a finish/polish stage. I use the belt grinder to cut a notch almost all the way to the bottom of the push-stick face, so that there is a ledge on it to hold the spine of the blade. I find it gives some solidity to my grinding and is surprisingly sensitive.
 
Salem,

Sorry, yes I mean Plunge line and grind lines. Im Starting at about a 1/4" and moving back so I dont take too much off each pass. For instance, when im doing a flat grind on some 1/8 O1, my plunge lines are very inconsistant and uneven. I never thought of using my hips, Ive always gone from left to right with my arms, maybe that the problem. Its probably just that I need to practice and perfect. As far as your first questions, I have no idea what any of that means, sorry Ive only been doing this for about 4 months now so Im still learning a lot.

I dont use a push-stick and dont have any idea how to. Im in the process of trying to build a flat grind jig.

Thanks for the info.

TC
 
My grinding improved a lot when I started making my movements a lot more deliberate, and started using a bit more pressure. If you are to gentle once your grind goes a bit wobbly all you will do is follow the wobble!

The other thing I sussed is to watch the sparks, they should come off the blade evenly where the belt is in contact with the blade to tell you your square to the platten!
 
Thanks john, I ll try it out this weekend. I guess if i think about it, I have been sorta gentle on pressure because Ive taken the tip off a few of my practice blades.
 
So, the platen would be the flat surface that the belt rides over. The edge of the platen would be, well, the edge. Where you do your plunge cuts. I ask what the edges are like because you want to use them as a grinding surface. It's nice if the platen is flat all the way to the edge, with a good 90 degree corner radiused very slightly (if it's kind of a sharp edge, just round it lightly with some 220 grit paper.) Why is this important?

A common technique for refining your plunge cuts is as follows: take a flexible belt, a common choice would be a J-flex (J weight cloth backing, flexible belt) aluminum oxide at 220 grit, Tru Grit probably has some in 2x48. Track the belt over so that approximately 1/8 - 3/16" is riding past the edge of the platen, on whichever side you are cutting the plunge with, take a piece of scrap metal, and bend the belt around the edge of the platen where it overlaps. This is to make sure the edge of the belt is used to curling around the platen edge at speed, and can help break the belt edge down a bit softer if you don't have a real flexible belt.
You take your blade, apply it nice and flat to the belt, edge up, and grind toward your plunge cut, so that when you get there the belt rides over the platen edge and is actually grinding lightly on the flat and lightly on the inside of the plunge cut. You're then grinding the plunge face sideways toward the ricasso. It will take some practice and feel to be able to do this evenly and to your satisfaction.
Your grinder may prove to be a limiting factor. Go to the late Bob Engnath's website, it's still there and has some great grinding tips. He'll tell you the same thing about moving from the waist.
 
Last edited:
Ok, that makes sense. Yea the platen is about 9 inches and is completely flat. Ill try what you suggested and see if it helps. Thanks.

TC
 
Also

use GOOD quality SHARP belts.

I can't tell you how many issues that cleared up for me when I finally started throwing belts away when they got dull.

you grinds will be sharper / cleaner
your blade won't get as hot
you will save a LOT of time.
 
sharp belts was a biggy for me too. I was trying to make them stretch a lot further than I should have. You might save a couple dollars per knife, MAYBE, but the added frustration and chance for significant problems is a lot higher. A fresh belt makes everything work more effectively.
 
You must log in or register to reply here.
Back
Top