Recommendation? Knife Bevel help

B

Brenden Robinson

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Mar 24, 2018
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I have recently started making knives on my homemade 2x72 grinder. Everything has been going really well except my knife bevels. My Bevels lines are coming out really wavy even though I use a jig (2x4 ripped down to the angle I want). I am ordering a glass platen that I hope will help. Are there any suggestions beyond what I have already done. Thanks in advance for the help
 
Any picture ? Jig only help to keep constant angle while grinding . It is up to you to hold jig/blade in properly position to belt while grinding ....
 
how many blades have you ground?
there is almost no answer/suggestions except it takes practice and understanding of pressure.
you have to stop and review and evaluate the grinding result on each pass
 
A jig doesn't eliminate the factor of pressure, +1 to what Harbeer said to always check your work. Also, your steel needs to be dead flat for a clean grind line. A high spot "pushes" the line up towards the spine, a low spot pushes it down towards the edge. Practice makes better :)
 
Faces aren't flat. Stock isn't straight. Work rest isn't consistent. Jig has flex. Pressure isn't consistent. Area of contact with the belt isn't consistent. Travel speed isn't consistent. Belt is worn unevenly. Belt is too worn period.

One or more of them things.
 
I think almost everyone will agree that grinding bevels is one of the most challenging parts of knifemaking. I found that designing knives that can be either saber of ffg was helpful. I personally find that if a saber grind goes south it can slill be made into an ffg. Also grinding ffg alows for the most practice. It gets harder the higher up your bevels go. Your mistakes are magnified as are your corrections. Unfortunatley there are no fast and easy answers. I wouldnt hesitate to practice on mild steel or really anything to improve your skills. I would also try freehand, i think it may help you make mistakes quicker wich will help you learn quicker.
Ps. If you do find an easy answer please let me know, it would sure save me some headaches.

Good luck.
 
Brenden Robinson said:
I have recently started making knives on my homemade 2x72 grinder. Everything has been going really well except my knife bevels. My Bevels lines are coming out really wavy even though I use a jig (2x4 ripped down to the angle I want). I am ordering a glass platen that I hope will help. Are there any suggestions beyond what I have already done. Thanks in advance for the help
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Brenden, Yes pics would help but I suggest starting at the tip of the blade with a light touch and working back to the plunge/Recassio area. You will work in a nice distal taper and slowly build the plunge line and heel if the blade to match..Also if your right handed, do your left hand side first and then match it in with your dominant hand.....Stay safe & have fun!
 
Yep, it's sure hard to keep that grind line really straight. That's why a disk grinder is so handy. I asked the question other day about how important is a disk grinder, got many good answers. Hooked up my disk grinder attachment using a rubber pad on disk. I was amazed how well it cleaned up grind lines and flatten bevels.
 
There are three rotational axes of motion; pitch, yaw, and roll - look them up if you don't know what I'm talking about. All three must be correct for the bevel grind to be correct.

A standard grinding jig only restricts two axes of rotation (pitch and roll). Controlling the yaw is dependent on your hand/eye skill/coordination. If your grinds are wavy, it's because you aren't controlling the yaw accurately.
 
Brenden Robinson said:
I would pictures but as far as I'm aware I have to be a paid member on the site to do that.
Click to expand...

You can create an account with flickr. Then upload your pictures there. Under each picture in your photo stream there will be a "share photo" icon. Select the BBCode option. You can then copy and paste this BBCode into your form post and show your pictures.

https://www.flickr.com/
 
Brenden Robinson said:
I would pictures but as far as I'm aware I have to be a paid member on the site to do that.
Click to expand...
You don't have to be a paid member. Upload them to a hosting site like Flickr or Imgur and then you can link or embed them here.

As for the solution to your grind lines, the short and long answer is a three step process:

1. Practice
2. Practice
3. PRACTICE

Start simple. Just take a piece of scrap flat stock, and grind a short bevel. Watch your pressure and try to keep it even. If you push more on one side or the other of your platen, the grind will go deeper on the side, and your bevel will start waving at you. Make sure everything is in fact flat and square, as that will simplify things in the long run

Use fresh, sharp belts. A dull belt will cause uneven grinding and waves, and just end up frustrating you.

You might want to use a sharpie, or a scribe and some dykem to mark where your grind lines will end. Practice grinding to the lines. Be purposeful with your movements. You want sparks going down the middle of the platen, not just one side or the other.

You'll get there.
 
I like Fred's Bubble jig to get started (and it is always useful). I would say that as grinding aids go, it trains you and gives you a reference without taking any of the process out of your hands (which is a good thing). Once you use it, the bevel angle is sorted, so you just kind of need to control depth. Do a couple scandi or sabre grinds with it to get used to it.

I started using it pretty early in my process. I still use it semi-regularly. It wont do the work for you but it is a great reference. I mostly find myself doing more complex grinds lately (a lot of kitchen knives, bowies, etc.). With something like a chef's knife (thin, FFG or blended sabre, tapered, etc.) you find that there is a lot of eyeballing, but even then, the BJ (heh heh) gives you a great point to deviate from.
 
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