Grinding tips

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Will Estes

Joined
Apr 25, 2022
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Does anyone have any tips for grinding a knife with a slanted plunge line? I tried one the other day and it turned out fairly well, but I was wondering if anyone has any tips for doing something like that. I’m thinking about maybe getting a file guide or something like that, but for now I’m just freehanding it. Thanks!
 
fitzo said:
Once you get the bulk of the height of the plunge, flare the belt off the side to get a rounder, softer transition at the top.
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How much? Does this technique work with plunge guides? Can you flare it off with the lower grit belts?
 
Thank you all for this info! I think the file guide is going to be a win, but do you have any more tips for doing it without the guide? Right now I can get the plunges pretty even, but I am having trouble keeping the rest of the grind even. Since I have to grind that’ll whole thing at a 30 degree angle or so, it is really messing with now much pressure I put on the belt so I get some deep spots, always in the same place. Does anyone know a good way to fix that? I am planning on making more, so maybe that will go away with practice, but if there’s anything I can change when I’m grinding, I’d love to know! Thank you!
 
There's only so much that can be said. Grinding is a skill that must be developed and maintained. If work prevents me from grinding for more than a week or two, I don't just jump back onto a project that is close to finished. I'll rough grind a couple new pieces to get the feel back.
In general if you are looking at a partially ground bevel, and you see where you want to remove material or straighten things, the trick is getting onto the bevel smoothly in an easy location, getting over to where you need to work without doing anything along the way, then grinding a little where you need to, and getting off. Then look closely at what was achieved and then make another pass. You will develop a sense of what caused small unintended things and slowly find that you can more directly get at what you want.
 
Signalprick said:
How much? Does this technique work with plunge guides? Can you flare it off with the lower grit belts?
Click to expand...

Most coarse belts aren't flexible enough. I do the bulk of my grinding with 60 and 80, don't use 36 for bevels. An 80 will start to flex but the pressure had better be right. I prefer to finish the top of the plunge in that situtation with a 120 or 150. Note, these are ANSI grits. You'd have to consult a conversion chart for P grades.

I have used the file guide at 120 and 150. It will work but it better be a really flexable belt and a carbide guide. Again, bear in mind this is for the top, not the whole plunge. Think blending in a curve. I have drifted the belt from a 1/4 to more than a 1/2" off the edge. And I have failed a lot. This is an acquired skill as Richard 338 mentioned.
 
Richard338 said:
There's only so much that can be said. Grinding is a skill that must be developed and maintained. If work prevents me from grinding for more than a week or two, I don't just jump back onto a project that is close to finished. I'll rough grind a couple new pieces to get the feel back.
In general if you are looking at a partially ground bevel, and you see where you want to remove material or straighten things, the trick is getting onto the bevel smoothly in an easy location, getting over to where you need to work without doing anything along the way, then grinding a little where you need to, and getting off. Then look closely at what was achieved and then make another pass. You will develop a sense of what caused small unintended things and slowly find that you can more directly get at what you want.
Click to expand...
That’s great! Thank you!
 
fitzo said:
Once you get the bulk of the height of the plunge, flare the belt off the side to get a rounder, softer transition at the top.
Click to expand...
I have different approach to that .I don t flare belt on side , I start grinding bevels about 5-7 mm from place where i want plunges to be .When i finish with grinding bevels i start to work on plunges .That give me room for small mistake and to get them perfectly symmetrical at end . How soft transition you get on top depends from radius on plunge on bottom / edge side , bigger radius down bigger radius you get on top .Of course all that i do with jig .
This is what I am talking about
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I grind small folder blades primarily. I also use a small piece of tungsten carbide as a plunge guide. I start at 60X, 120X, 220J, 400J. I was pretty sure about the answer to my question using the lower grits but wanted to ask thinking maybe if a person wasn't using a guide maybe it would work. Anyway, what I have noticed is that when I hang the belt over and run it up next to the guide it sometimes screws up my plunge and the top line. It make a weird squiggle? Maybe pressing too hard into the plunge guide? I can't figure it out. Luckily I am good enough to fix it but then I end up with a more squared off plunge at the top and not the big round curve I am trying to achieve. Does it help to radius the edges of your wheel?

20220807_155616.jpg

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If you run the belt out over the edge long enough it will radius the edge of a rubber wheel all on its own in time. Different radii on the two sides of the wheel become a problem.

As for your squiggle, I'd say you've diagnosed it yourself. Less pressure, creep up to the top.
You make nice knives. Your plunges are just right.
 
fitzo said:
If you run the belt out over the edge long enough it will radius the edge of a rubber wheel all on its own in time. Different radii on the two sides of the wheel become a problem.

As for your squiggle, I'd say you've diagnosed it yourself. Less pressure, creep up to the top.
You make nice knives. Your plunges are just right.
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I appreciate that. Always trying to get better and lean more. Grinding is my absolute favorite part of the process good or bad, I love it. Thank you for the help. :)
 
If it's always in the same spot, is it possible you're getting 2 inch bump? It would be caused by you being slightly off when you initially touch the blade to the grinder. Which I'm thinking could be more likely with you doing the angled plunge line, if you're not used to doing those.
 
Blankblank said:
If it's always in the same spot, is it possible you're getting 2 inch bump? It would be caused by you being slightly off when you initially touch the blade to the grinder. Which I'm thinking could be more likely with you doing the angled plunge line, if you're not used to doing those.
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That sounds like that’s it! Instead of starting to grind right at the plunge, when I saw those I changed to starting in some other places and it didn’t make the divot bigger. How would you avoid that? Would you just keep changing it up instead of starting at the plunge every time?
 
Walter sorrells has a great video on avoiding 2 inch divot on youtube. I recommend checking that out.

I think that starting in a different area could help. You should definitely stay very conscious about your movements when you are about to touch the blade to the belt to help avoid this.
 
I find it better making multiple blades. they can even be different types.
But just doing more grinding then, in groups helps.

Rather than making one knife form start to finish.
then starting another from start to finish.


My grinds always look better when I am doing batches.
 
Blankblank said:
Walter sorrells has a great video on avoiding 2 inch divot on youtube. I recommend checking that out.

I think that starting in a different area could help. You should definitely stay very conscious about your movements when you are about to touch the blade to the belt to help avoid this.
Click to expand...
Thank you! I’ll check out that video and practice grinding that way!
 
Crag the Brewer said:
I find it better making multiple blades. they can even be different types.
But just doing more grinding then, in groups helps.

Rather than making one knife form start to finish.
then starting another from start to finish.


My grinds always look better when I am doing batches.
Click to expand...
Oh, that’s a good idea. I’ve been starting to do some multiples, so that would be a really good opportunity to try that out. Thanks!
 
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