Jig grinding bevel issue

[gwallace]

Hello everyone!
I've been grinding on a 1x30 and only have good results using a jig.

My issue is the tip on the blade grind doesn't go as deep into the spine.
In other words, the grind line is not parallel to the blade edge. It gets narrow towards the tip.

I can angle the blade towards me as it comes to the tip, bit then it gets too thin, too fast.

I've thought really hard, but just can't figure it out.

I've seen people make perfect bevels with a jig so I know I'm missing something.

Any tips would be appreciated!

 

[Diego_B]

I had the same problem when I was on the 1x30 and using a jig. The problem was my crappy jig. Most people I see with a jig have a shelf that the knife spine rests on so that it doesn't get "pulled down" when you get close to the tip otherwise the belt seems to pull the knife down somewhat and the result is the problem you seem to be having.
What kind of jig did you make or are using? Also make sure to use sharp belts that makes the WORLD of a difference and it saves you LOTS of time and effort.

 

[gwallace]

I had the same problem when I was on the 1x30 and using a jig. The problem was my crappy jig. Most people I see with a jig have a shelf that the knife spine rests on so that it doesn't get "pulled down" when you get close to the tip otherwise the belt seems to pull the knife down somewhat and the result is the problem you seem to be having.
What kind of jig did you make or are using? Also make sure to use sharp belts that makes the WORLD of a difference and it saves you LOTS of time and effort.

I really try to watch the level of the knife. I mount the blade level using the opposite sides Dykem grind line. You may be correct, though. I have caught the knife tilted down a few times.
Tonight I used a belt as old as the hills. I got impatient waiting for a delivery. The grind is great, just not even to the tip.

Thanks for your help.

 

[Diego_B]

I understand that frustration. If I had to do it all over again only using the 1x30 I would try and reinforce the crappy platen on it and get a glass platen for it. Then I would get my hands on some ceramic belts. Combat Abrasives sells 1x30 ceramics. Although I am not sure how well it would work on a 1x30, but I use a 2x42 with ceramics and I seem to get what is expected of the a belt.

This would probably do fine if your just periodically making a couple blades but if your doing more I would definitely get at least a 2x42 or a grizzly 2x72.

 

[gwallace]

I understand that frustration. If I had to do it all over again only using the 1x30 I would try and reinforce the crappy platen on it and get a glass platen for it. Then I would get my hands on some ceramic belts. Combat Abrasives sells 1x30 ceramics. Although I am not sure how well it would work on a 1x30, but I use a 2x42 with ceramics and I seem to get what is expected of the a belt.

This would probably do fine if your just periodically making a couple blades but if your doing more I would definitely get at least a 2x42 or a grizzly 2x72.

Totally agree. I do use Combat ceramic belts.
After sleeping on it I think I figured it out. The crappy platen has a nice crater from profiling. no big deal because it's down low. What I didn't think about is I ground off the bottom of the work rest so I can tilt it backwards and use a 90 degree jig.
That puts the divot right at the spine if the tip of the blade. That and a very worn belt is probably the issue.

Thanks for helping!

 

[Diego_B]

Totally agree. I do use Combat ceramic belts.
After sleeping on it I think I figured it out. The crappy platen has a nice crater from profiling. no big deal because it's down low. What I didn't think about is I ground off the bottom of the work rest so I can tilt it backwards and use a 90 degree jig.
That puts the divot right at the spine if the tip of the blade. That and a very worn belt is probably the issue.

Thanks for helping!

Well you sound like your on the right track to solving your problem. Those ceramics are 100% the way to go but you know that already. Most new people here are using a year old aluminum oxide belt and wonder why grinding bevels is so difficult.

Use belts like they are free is the best advice I have been given but it also crushes my soul cause I feel like I am wasting belts. But in the end you are saving time, effort, and your grind lines will be more "crisp" and to me that is worth the cost as I have learned over and over. It's just kind of hard to accept at first.

 

[gwallace]

Well you sound like your on the right track to solving your problem. Those ceramics are 100% the way to go but you know that already. Most new people here are using a year old aluminum oxide belt and wonder why grinding bevels is so difficult.

Use belts like they are free is the best advice I have been given but it also crushes my soul cause I feel like I am wasting belts. But in the end you are saving time, effort, and your grind lines will be more "crisp" and to me that is worth the cost as I have learned over and over. It's just kind of hard to accept at first.

Agreed. Those ceramic belts are only $3. Even if you used a new one every knife you'd be ok.
I'm like you. I save old sheet sand paper. I have a pile of old 4x36 belts, just in case. And it's not a money thing, it's a sickness.

 

[P.Brewster]

What you describe is how the jigs work; they don't maintain a steady angle at the belly or curves of the blade. Imagine you are beveling a giant 12-inch diameter pizza cutting wheel on your jig and you'll understand the problem.

 

[N.W. Gean]

The issue you're describing has plagued me from the 1x30 to a DIY 2x72 grinder. For whatever reason, I cannot grind on a sled style jig without creating a wide edge at the tip of the knife with a thinned out belly. The grind line always reflects this, too. For a while I used a tilt table jig for the 2x72 (it would take fabrication of a whole new frame to make that work on a 1x30), which solves that problem, but scratches the flats, meaning you can't do the bevels last (more likely to mess up the bevels this way).

The solution was to switch to freehand, in which I am still experiencing growing pains, but I am getting better at it. Once you really learn exactly how to use pressure on a specific area to manipulate the grind line, you won't really wanna go back to a jig. You instantly feel every limitation it imposes.

 

[gwallace]

The issue you're describing has plagued me from the 1x30 to a DIY 2x72 grinder. For whatever reason, I cannot grind on a sled style jig without creating a wide edge at the tip of the knife with a thinned out belly. The grind line always reflects this, too. For a while I used a tilt table jig for the 2x72 (it would take fabrication of a whole new frame to make that work on a 1x30), which solves that problem, but scratches the flats, meaning you can't do the bevels last (more likely to mess up the bevels this way).

The solution was to switch to freehand, in which I am still experiencing growing pains, but I am getting better at it. Once you really learn exactly how to use pressure on a specific area to manipulate the grind line, you won't really wanna go back to a jig. You instantly feel every limitation it imposes.

I have made quite a few big knives freehand on my 4x36. They come out pretty good, but not perfect. I just need to break down and buy a better grinder. It's hard for me to justify a $1200+ grinder, but I think a $260 2x42 will be a step in the right direction.

 

[N.W. Gean]

I have made quite a few big knives freehand on my 4x36. They come out pretty good, but not perfect. I just need to break down and buy a better grinder. It's hard for me to justify a $1200+ grinder, but I think a $260 2x42 will be a step in the right direction.

It's harder without a VFD but not impossible. Keep going freehand and you'll be pleasantly surprised at where you end up.

 

[AVigil]

With this problem, start the grind at the tip and work back.
Then move to the flat and do not go to the tip.

When you get to the point you have a grind on the flat and a grind at the tip, take it off the jig and free hand grind and blend both the flat and tip together. All you need to do is ride the already established grind.

 

[gwallace]

With this problem, start the grind at the tip and work back.
Then move to the flat and do not go to the tip.

When you get to the point you have a grind on the flat and a grind at the tip, take it off the jig and free hand grind and blend both the flat and tip together. All you need to do is ride the already established grind.

Totally makes sense.
Thanks!

 

[Diego_B]

Like most I have to agree that freehand grinding is the best and way better than using a jig. Now if I try and use a jig I have to "work harder" than if I wasn't using one. All they do is really just limit your ability. Although a 1x30 has a very small platen and it may be hard for someone to free hand grind a bevel on one because it defiantly was hard for me. I was better off grinding what I could with a angle grinder and then file the rest of the bevel.

 

[gwallace]

Like most I have to agree that freehand grinding is the best and way better than using a jig. Now if I try and use a jig I have to "work harder" than if I wasn't using one. All they do is really just limit your ability. Although a 1x30 has a very small platen and it may be hard for someone to free hand grind a bevel on one because it defiantly was hard for me. I was better off grinding what I could with a angle grinder and then file the rest of the bevel.

Yes, I have done the file/grinder thing. I can do my bevels relatively fast and very clean on the 1x30, but I can't get the exact bevel I want the entire curve of the blade.

 

[noseoil]

When I just had the 1x30 grinder for blades, I used a small piece of glazed bathroom tile for a platten, which was better than the original one. I just glued it in place with some JB Weld on the steel & it's much better than the plain metal for a backer. The 1x30 is a bit more time-consuming & difficult to use, due to the motor being relatively weak & work areas being really too small for comfort. That being said, the largest blade I've done was this chopper, it was a PITA, but it worked well enough. I like the 2x72 I'm running now, but if resources are limited, a small grinder will still do the job with patience & practice...

 

[gwallace]

When I just had the 1x30 grinder for blades, I used a small piece of glazed bathroom tile for a platten, which was better than the original one. I just glued it in place with some JB Weld on the steel & it's much better than the plain metal for a backer. The 1x30 is a bit more time-consuming & difficult to use, due to the motor being relatively weak & work areas being really too small for comfort. That being said, the largest blade I've done was this chopper, it was a PITA, but it worked well enough. I like the 2x72 I'm running now, but if resources are limited, a small grinder will still do the job with patience & practice...

I ground down the work table to be really smooth, but being aluminum it still binds (galls) when you slide across it. My platen is really jacked up too. I just ordered some 3/32 O1 to make a temporary plate for the table and platen. With the O1 hardened, it should last a little while. I never thought about using tile. That's pretty genius.