Please help me fix this newbie sharpening issue

R

Randall_FA

Joined
Mar 27, 2015
Messages
9
Hi,
I am trying to use a HF 1x30 belt sander to sharpen a set of knives that have a straight edge from choil to tip, something of a wharncliffe design.
I always used stones or a lansky system with no problem, but with the belt sander I am creating a "recurve" edge around one inch from the fingerguard and thus breaking the straight line of the edge.
A cursory search here and watching some videos have not clarified for me what I am doing wrong though it is clear it has to do with the speed at which I move the knife.
specific pointers will be much appreciated.
Thanks in advance!
 
Steady smooth movement of the edge across the belt from handle to tip. On Wharncliffe blades do not pull the tip across the belt.

I suspect that you are not applying consistent pressure against the belt and/or speed across the belt.

Mike
 
If you're like me, you'll never get get a true/straight/flat grind by free handing with powered equipment, even on a 6 inch wide belt! - One inch wide? forget it - and... I've been grinding out blades for 30+ years.
I only power grind to rough it out, then finish by hand on flat stone/sandpaper or guided system.
 
Thanks, it seems there is no easy fix and I better stay with stone sharpening.
Thanks to all for the comments.
 
jpm2 said:
I only power grind to rough it out, then finish by hand on flat stone/sandpaper or guided system.
Click to expand...

I couldn't have said it better...should have said it. A belt is fine for profiling and setting an edge but not for finish work.

Mike
 
I have no problem finishing on a belt, it took a while for me to get the technique right, but the three best pointers I can give you are:
1. Keep your elbows in and wrists stationary. Let your torso move the knife.
2. Let the machine do the work, the belt should barely be flexing. If it isn't cutting, your belt is clogged.
3. Stop with the tip in the center of the belt and pull directly towards you, this way you don't round the tip either.
 
Randall_FA said:
...but with the belt sander I am creating a "recurve" edge around one inch from the fingerguard and thus breaking the straight line of the edge.
Click to expand...

If you're getting a dip or recurve near the heel of the blade, it means you are spending more time in that section on the belt. It *might* mean that you are dropping the handle near that section also. But it's more likely that you are letting the blade "sit" in that spot for some small amount of time longer than the rest of the blade.

The HF 1x30 sander is a very fast powerful machine from what I can tell. It would seem to require a very light touch and rather rapid motion of the blade (like 3 inches per second of linear motion or so). It's fairly common for people to damage the heel of the blade on a belt sander, as this is the starting point for most people and you may be trying to align your blade to the belt at that point, thus keeping it in place longer and grinding it away.

I have a much slower, less powerful sander: The Work Sharp Ken Onion edition. It's variable speed and I always use it at 75% or less; usually closer to 50%. I made up a technique that seems to work for me: I start with the belt touching the blade about an inch back from the heel. Then I move the blade towards the heel and stop when the edge of the belt is at the lowest part of the heel that I want to grind. Then I move the blade the other direction all the way to the tip. Finally I stop with the tip on the belt and lift off.

This way of "starting near the middle" seems more stable to me and I've never ground away the heel of the blade. But again, my sander is something like 5 or 6 times less powerful than the HF 1x30, so it's easier.

Good luck.

Brian.
 
Thanks, I think in fact this machine is too much for what I need, I will just use it for stropping I guess.
I was trying to sharpen faster than with stones and I am not sure I want to shell out the $ for a WSKO.
Thanks again
 
Most of the 1x30 units really run to fast IHMO for sharpening. Many have good luck with them. I sharpen hundreds of knives a year on belts so its really not the media or unit used. Its all about technique for the job at hand. Practice and more practice. Then more practice.
 
With the HF sander it is easy to take more material off quick, because of the speed.

You are likely touching the edge to the belt longer, not moving as quickly in that spot.

You can start the stroke at the tip and not go all the way to the back to try and fix.



Randall_FA said:
Thanks, I think in fact this machine is too much for what I need, I will just use it for stropping I guess.
I was trying to sharpen faster than with stones and I am not sure I want to shell out the $ for a WSKO.
Thanks again
Click to expand...

I've sharpened, and reprofiled quite a few knives, including some pretty expensive Busse knives with mine.

You can ruin a knife quick with them, for sure. They are running fast, and there is no speed control.



I have a lot of knives that will NEVER see that belt sander, but it is handy when I need it! (re-profiling a 12 inch Busse or an 18 inch Thick Cold Steel Machete is a snap).
 
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