Contact wheel

M

M1911a

Active Member
I have just started to hollow grind and am having trouble with my plunge lines. I see on some of the instagram pages that I visit it looks like the contact wheels have a radius on the outer edge. If I am seeing this right, what size of radius do they put on their contact wheel?
Brent
 
I wouldn't put a radius on my wheel. Just let the belt hang over 5/16 or so and push your plunges up against that. Maybe you've already tried that, but I would do that first.
 
Yes I have tried hanging the belt over the edge of the wheel and didn't end up with a good result. I even tried that with a file guide attached to the blade still not the result I was hoping for. I am hesitant about a radius I don't want to ruin an expensive contact wheel. Thank you for your reply.
Brent
 
Depending on what type of belt you tried to hang over the side. it seems the J-Flex belts work better for this.
 
I agree the J- Flex belts are what work the best for hanging over the edge of the contact wheel.
Thank you.
Brent
 
I'm guessing that you want that swoopy curve at the top of your plunge lines? Hanging the belt off is the way to go but it takes a steady hand to get both sides the same. And as Ken mentioned, it's the j-flex belts that really give you want you want, but you still want to hang your lower grit belts off too so that you don't get a hard, deep plunge cut with those deep scratches that nobody can ever get out. You mentioned that you're using a file guide to grind. That's a great method. A good trick to use with that is to do all of your bevel grinding up through 120, then sneak your file guide back 1/16 or so. Your 220 j-weight belt will then remove all of the previous scratches in the plunges and make a really pretty plunge line with that swoop at the top you're looking for.

You can angle your blade to increase the arc length of the swoop. A tiny bit of angle goes a long way.
 
John thank you for your advise I will try that and see what happens. When I started flat grinding I used a jig and angled my blade as you suggested so I think I understand what you are telling me. I am probably rushing to get a good result to soon, more practice is what I need. Thanks to all you guys for the advice, that's what I like about Knife Dogs forum people are always willing to help.
Brent
 
Brent, these guys here will never steer you wrong. Grinding is 80% finesse.

If you have a picture of a specific problem / result you're getting then I promise you that somebody here has already climbed that mountain and can save you a whole lot of suffering.
 
M1911a said:
I would like to thank everyone for their suggestions on my question. I ground a new blade tonight and with your help I got a result that I was trying to achieve. Thank you very much. Brent
Click to expand...
That's good to hear. Any chance we can get a photo of the finished knife? :)
 
Let me finish it and then I can decide if it is good enough. This will be my first hollow grind I could mess it up, I have ruined a few on my knife making journey. Then I would need to figure out how to post a picture.
Brent
 
If you're talking about a plunge like below I don't like to hang my belt off of the edge at all (maybe 1/32"). When you hang it over the edge of the wheel you get some rounding in the plunge and it's not as crisp... If you're hand Sanding it's not really an issue I suppose but if you want a good machine finish then you need to practice your pressure and even slightly twisting as you approach a the choil/plunge. Try it on some mild steel just to get the hang of it!

i-WqJK7Kk-X2.jpg
 
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