Learning to use a Bevel Grinding Jig

Ron Raducanu

Ron Raducanu

Joined
Feb 10, 2021
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I'm slowly practicing with the jig I made, on my 1x30, but can't seem to find any real guidelines through the many YT videos I've watched.

I'm using 1/8" stock and spine to blade is about 1.25". Is there a chart somewhere where I can guesstimate the angle I need to use on the jig for a certain bevel geometry? I did a search here, and thought I found something, but then when I searched again, I couldn't find it. Do people mostly do this by feel and experience with time?

The other question is whether you slowly get to your bevel line or just get there leaving the jig at one angle. With the hand jig, I start at a very steep angle and then slowly work my way back. Is that the same technique to employ with the Bevel Grinding Jig? I've also noticed that things can get hot. For now, I grind the bevel before HT, so I assume as long as I don't burn the metal, I should be okay. Yes?

Thanks for any help!
 
You can use math to calculate the angle. Let's say your stock thickness is T, the height of the grind is H, and the thickness at the edge is E. You can get the angle alpha=atan((T-E)/(2H)). A digital angle gauge (Wixey gauge) might be helpful. I don't know how to best use the jig, hopefully somebody else can answer that question.
 
I just use a "bevel board" or a simple piece of plywood, with lines drawn to give the correct angle (use a bevel gauge) for a given blade. You can do a scale layout of the blade dimensions (maybe 3 times the actual size of the blade to make it easier) and use the angle you have drawn to transfer to the jig.

My bevel guide is at a fixed 90 degrees, but on my grinder I can swing the head to adjust the angle, still the same thing. The largest bade I've done was a chopper I did on the 1x30 HF grinder, before making the 2x72 which is much better. It took forever to grind, but it worked...

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This is one of those things you shouldn’t overthink. I got lost in the math when I started out. My approach to bevel jig grinding is similar to freehand in the way you increase bevel width. Start at a steep (say 45) degree angle and grind to your center scribe lines. If it’s pre-HT, you don’t really need to worry about overheating the steel as long as you don’t really get it cranking.

Once you’ve got your 45s in to your scribe lines, slowly start making the angle of your jig shallower (tighten or loosen the screws depending on the jig). As you do this and make passes on your grinder, you’ll notice where the steel is being removed and where your bevel height is increasing. Get your new angle ground all the way down to the edge before you continue to make it shallower. Do this process slowly, and you’ll be able to raise your bevels to exactly where you want them without trying to establish a perfect angle to bevel height ratio right from the get-go.

If you have any other questions I’d be happy to help. Hope some of that made sense haha.
 
Cliff Carter Knives said:
This is one of those things you shouldn’t overthink. I got lost in the math when I started out. My approach to bevel jig grinding is similar to freehand in the way you increase bevel width. Start at a steep (say 45) degree angle and grind to your center scribe lines. If it’s pre-HT, you don’t really need to worry about overheating the steel as long as you don’t really get it cranking.

Once you’ve got your 45s in to your scribe lines, slowly start making the angle of your jig shallower (tighten or loosen the screws depending on the jig). As you do this and make passes on your grinder, you’ll notice where the steel is being removed and where your bevel height is increasing. Get your new angle ground all the way down to the edge before you continue to make it shallower. Do this process slowly, and you’ll be able to raise your bevels to exactly where you want them without trying to establish a perfect angle to bevel height ratio right from the get-go.

If you have any other questions I’d be happy to help. Hope some of that made sense haha.
Click to expand...

This. I also used a digital angle finder and noted my adjustments made so I could duplicate the same process with the exact same angles on the other side of the blade.
 
Cliff Carter Knives said:
This is one of those things you shouldn’t overthink. I got lost in the math when I started out. My approach to bevel jig grinding is similar to freehand in the way you increase bevel width. Start at a steep (say 45) degree angle and grind to your center scribe lines. If it’s pre-HT, you don’t really need to worry about overheating the steel as long as you don’t really get it cranking.

Once you’ve got your 45s in to your scribe lines, slowly start making the angle of your jig shallower (tighten or loosen the screws depending on the jig). As you do this and make passes on your grinder, you’ll notice where the steel is being removed and where your bevel height is increasing. Get your new angle ground all the way down to the edge before you continue to make it shallower. Do this process slowly, and you’ll be able to raise your bevels to exactly where you want them without trying to establish a perfect angle to bevel height ratio right from the get-go.

If you have any other questions I’d be happy to help. Hope some of that made sense haha.
Click to expand...

Thank you, sir! This is exactly what I needed. Appreciate the feedback very much.
 
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