Round edges flat platen

Stromberg Knives

strombergknives.com
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Hi!

I feel that my plunges are getting to sharp so I'm making a new flat platen with rounded edges.

Unfortunately I don't own a milling machine. What would be the best way to round the edges and get them matched and consistent?
 
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if you want a 2 for one benefit, get yourself a ceramic glass platen that has the edges rounded already. Otherwise, you can use another grinder/ sander with a platen as long as the one you want to radius to do it. Or do what i did before i added glass and draw file it.
 

kuraki

Fimbulvetr Knifeworks
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Where do you get glass with round edges? I've been thinking about this myself, but I didn't want to go back to a steel platen.
 
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i don't actually know where i got it. it is not very rounded, but moreso than the steel platen. I can roll my j flex belt over it and get nice rounded plunges. If i really booger one up. I have a steel plate with a radiused edge i can clamp to my bench. I will glue a sheet of abrasive on it with the edge of the paper run over the radiused corner of the plate. then I will hand sand it. I think I saw a video of Nick Wheeler demonstrating this and that is where i got the idea.
 

Willie71

Warren J. Krywko. Part Time Knifemaker
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I used O1 tempered at only 300 for my radiused platen.
 

Stromberg Knives

strombergknives.com
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Any ideas of how to perform the actual radiusing?
 

kuraki

Fimbulvetr Knifeworks
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i don't actually know where i got it. it is not very rounded, but moreso than the steel platen. I can roll my j flex belt over it and get nice rounded plunges. If i really booger one up. I have a steel plate with a radiused edge i can clamp to my bench. I will glue a sheet of abrasive on it with the edge of the paper run over the radiused corner of the plate. then I will hand sand it. I think I saw a video of Nick Wheeler demonstrating this and that is where i got the idea.

Yeah I made a plate like that too. Still, would like radiused edges on my platen. For some reason right now I'm having a hell of a time getting even top radii on my plunges. The right one will be about a .25 radius, which is what I'm shooting for, the left side will end up only .125 no matter how much belt I hang off. Takes a lot of work on the bench plate to get them even again.
 

kuraki

Fimbulvetr Knifeworks
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Like this.

120i5hw.jpg
 
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I have had that happen as well. I think it was my technique. Usually you are more accurate/ confident with one side over the other. I think i was just not committing to the grind since i was less confident in my ability with my weak side. Have you tried starting your grind an inch or so from the plunge, grinding to the plunge, then back out? I have found this change in my technique helpful for this problem as well as "2 inchitus". if you are having problems with the belt not wrapping around one side of your platen as it does on the other. I would check out the alignment of your platen, the platen wheels and the tracking wheel. in that order.
 

kuraki

Fimbulvetr Knifeworks
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I've been able to do it. In fact it just recently became a problem. It seems like the J flex belts wrap tighter around the left side than the right.

ETA: Now that I just said that, I had a thought. What did I change recently? The amount of tension on my belts. I'll kick it back up to the higher setting and see if that changes anything.

Still, if anyone knows how to radius a ceramic glass platen, or where to obtain one with radius edges, I'm all ears. Otherwise I'll make a tool steel one I guess.
 
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How is the condition of the platen? Is it dirty or have any deep scratches/gouges in it? I ask this because I recently had an issue with one of my steel platen. Grind lines near the top of the plunge were uneven. I inspected the platen and found that it had a couple deep scratches and some build up on it. It was weird because it hadn't been they long since I had resurfaced it. I surfaced it again and it was gtg.

Now as far as not having suck an acute angle at the top of the plunge, I've found if I don't really press that part of the blade into the edge/corner of the platen, then it will give it that swept plunge line that leads up to the spine. I seem to have to TRY to get a real sharp angle there otherwise.

If you always puts the plunge into the corner edge of the platen hard, then you might want to radius the edge. If I was tondo that I'd just buzz the very corner off and then go back by hand and round it over smooth with stripsnor sandpaper(with shoeshine method).

All this being said, I really like to take it super easy on the plunge area so, at the end, I have excess material to work with and can blend it in exactly how I want it(slowly and carefully).

Good luck, hope my babbling helped you to some degree. Lol
 

KnuckleDownKnives

Time to make the doughnuts..
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I've been able to do it. In fact it just recently became a problem. It seems like the J flex belts wrap tighter around the left side than the right.

ETA: Now that I just said that, I had a thought. What did I change recently? The amount of tension on my belts. I'll kick it back up to the higher setting and see if that changes anything.

Still, if anyone knows how to radius a ceramic glass platen, or where to obtain one with radius edges, I'm all ears. Otherwise I'll make a tool steel one I guess.

This may work.

[video=youtube;VJBZsAewU-A]https://www.youtube.com/watch?v=VJBZsAewU-A[/video]
 
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I like my platen edges square because I feel it gives me the most control. This is the current shop project, and it was ground with a square edge platen.

medium800.jpg


If you're really set on a radiused edge... a file and a radius guage will get you there pretty easily. I showed it in the youtube video I did about hand tweaking plunges. :)
 

JTknives

Blade Heat Treating www.jarodtodd.com
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I use a square edge platten, I just brake the edge of the platten so it's not sharp and does not cut the belt. When I upgraded to a glass platten I just used the belt grinder to grind a very tiny radis onto the edge of the glass so it's not sharp. Let me say this up front, I suck at sweeping plunges but I give it my best try and this was done with a square edge platten. The problem I think with a large radius on a platten is that your stuck with it unless you change it out.

Photo%20Feb%2006%2C%2011%2001%2031%20AM.jpg


This was my most recent attempt at a sweeping plunge. This is a Damascus cutlass I'm working on for the WIP.

Photo%20Oct%2005%2C%2017%2003%2014.jpg


Photo%20Oct%2005%2C%2017%2003%2047.jpg
 
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