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JPH

I am just wondering..Am I the only one hollow grinding forged blades??

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Hello;

 

I am sitting here in a pain pill enduced stupor (the VA gives us vets great drugs to kill pain) wondering..after seeing all these Show and Tell pics...and I am asking meself.."Am I the only one hollow grinding forged blades?"

 

So..just for the sake or my own curiosity..is anyonme else out there in the far reaches of creation, besides me..hollow grinding forged out blades?? Just curious...Besides this could be the start of a very interesting discussion...

 

JPH

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Hey Jim,

 

I am recovering from a hip replacement which was three weeks ago. To walk and do the rehab exercises, pain meds are mandatory. I do a lot of modest grinds on pukkos about 18" radii. Hope that helps.

 

Gary Toulomelis

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i used to but my hand sanding is better than my hollow grinding so i switched to flat 10+ years ago to make a fine finish more economical for me

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Interesting topic. For me anyway it seems that I morphed from a fifteen inch diameter hollow grind to a flat grind when I went from stock removal to all forged blades. Part of this may have been the ABS influence. Part of it may have been that I got into cutting competitions about the same time and a flat cut is preferable for a competition blade.

 

I'm not one of those purists that thinks that one blade geometry is best for all uses. I can see the advantages of both blade geometries but my preferred way of construction now includes a flat grind with a distal taper.

 

Gary

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I flat grind all my blades currently.

I don't like the super steep hollow grind I see on most factory knives and have not yet purchased a contact wheel large enough to do a large radius hollow grind I would like, especially on kitchen knives. Since I'm a part time bladesmith and mostly make hunting and camping knives that benifit from having a bit more "meat" behind the edge, the $200+ for a 15" wheel and another KMG arm to mount it on hasn't worked its way to the top of my tooling list yet.

 

I will be watching this thread as I am very curious to see where the discussion leads!

James

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When I find a 6-foot wheel I'll do it more often... (grin). I actually did a little edc out of forged 15n20 wth a 6" diameter hollow grind. Itty bitty blades do well with that.

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It depends on the blade. But yeah, I still hollow grind some of my forged blades.

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A lot of my scandies have been hollow ground, hunters absolutely love them.

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I got so used to doing a hollow grind years back that I had to re-teach myself how to grind a blade when I went to a flat grind. In my book they are two completely different skills. ;) Funny how we can get into a routine of doing things.

 

Gary

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Jim,

 

I have just started using a 17" diameter contact wheel ( a converted punch press ). I use the hollow grind to pre-shape some blades which will get finished on a platen ( flat ). I plan to use it for Japanese style blades where the carbon steel is on one side and left with a hollow grind. This grinder is fantastic I can grind wet or dry and go so slow the water stays on the belt.

 

Jan

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Well...as for yours truly...95% of what I do...I wind up hollow grinding on a 16" serrated wheel at 7200 SFM ..It's a screamer of a grinder...Now me being the "Dainty" sort I have a 5 HP motor on it and I don;t even slow it down and I really lean into the thing when I grind "big stuff"..I can rough grind out a 32" long sword from a forging in about 25 minutes ready to HT...

 

The other 5% of the work is either flat or cannel fround... I just hate to grind...even though I was more or less taught to flat grind by one of the best blade grinders that ever lived... the late Bob Engnath,,, Boy talk about a grinding Deamon....that man could do some serious grinding in all sorts of ways...

 

JPH

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Get yourself a radius platen and cooler =) I've got a 48" radius platen and cooler, though my little water pump died. running the radius platen without a cooler generates a lot of heat which can snap belts at the glue line.

 

Dont have any photos of my setup but here's the one from the guy who has been making them for KMGs Nathan over on bladeforums

 

http://i566.photobucket.com/albums/ss107/Nathan_the_Machinist/platten_wip/d.jpg

 

 

When I find a 6-foot wheel I'll do it more often... (grin). I actually did a little edc out of forged 15n20 wth a 6" diameter hollow grind. Itty bitty blades do well with that.

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I've thought of making one of those for years....

 

JPH, for whatever reason this forum seems to lean more flat-ground. I guess it's the emphasis on historical types like seaxes and petformance competition blades, plus the fact we have a lot of folks who work without grinders anyway. A flat grind is easy to drawfile, unlike a hollow grind.

 

I know, one can flat or cannel grind on a wheel as easily as one can hollow grind on one, and a lot of historic swords after the Viking age are large-radius hollow ground, but I'm cheap and wheels are not. (Grin!)

 

Plus it's just the current fashion. Ties are skinny again, so it must be flat-ground season...(insert rolling eyes here)

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I personally do an almost-flat grind, it always has a bit of convex to it, however slight. I have an order for a celtic blade that will have 2 massive fullers taking up at least 3/4 of the blade width, one could just about call it hollow ground with a wide edge bevel...

 

I've always loved the way a convex blade cuts.

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I agree with you George, most of my work is convex, I believe it gives a stronger more chip resistant edge. That's the way I learned and just never changed, but I'm considering making a griner for hollow, at least 12"

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Hollow ground blades can be just as strong as anything else imo, it's all in how it's done, edge thickness, wheel diameter, etc.

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I tend to hollow grind some styles of swords but I hardly ever hollow grind my knives, I think this is due to my hunt for historical plausibility rather than any like of dislike of a particular grind.

MP

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I love the hollow grind. Funny how it's gotten a bad rap... i.e. too fragile, hard to sharpen, etc. I love my 15" wheel for the KMG.

 

Get yourself a radius platen and cooler =) I've got a 48" radius platen and cooler, though my little water pump died. running the radius platen without a cooler generates a lot of heat which can snap belts at the glue line.

 

Dont have any photos of my setup but here's the one from the guy who has been making them for KMGs Nathan over on bladeforums

 

http://i566.photobucket.com/albums/ss107/Nathan_the_Machinist/platten_wip/d.jpg

 

 

Justin.. how do you like the platen? I've been thinking of getting one for a while. I have his flat platen.

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Don't really like grinders but have been lusting over some of the big wheel machines I have seen lately.

Something about 20 inch dia would be wicked!

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Don't really like grinders but have been lusting over some of the big wheel machines I have seen lately.

Something about 20 inch dia would be wicked!

yep... I'd at least like 30". But the 48 you get from the platen mentioned above is compelling. Just not sure I like the idea of the heat build up and having to fuss with water cooling.

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Watercooling rocks once you get used to it and set-up for it, especially on swords.

Makes a mess but sure helps to speed up the process, without getting in a rush, and you can do alot more without re-setting each time you have to dunk the blade, which also helps reduce the wanders and belt-edge gouges you have to go back and clean up once you get going again,

 

And, much finer belts can be used a lot easier as well, slow down the speed and you can polish away on a hollowgrind for an hour at a time if you want, makes for less stressfull and more accurate work.

 

It is damn messy though.

:0)

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Watercooling rocks once you get used to it and set-up for it, especially on swords.

Makes a mess but sure helps to speed up the process, without getting in a rush, and you can do alot more without re-setting each time you have to dunk the blade, which also helps reduce the wanders and belt-edge gouges you have to go back and clean up once you get going again,

 

And, much finer belts can be used a lot easier as well, slow down the speed and you can polish away on a hollowgrind for an hour at a time if you want, makes for less stressfull and more accurate work.

 

It is damn messy though.

:0)

Oh yeah I want to set up a water cooling system for that. I have all the stuff.. an irrigation micro-sprinkler, tank, pump etc.. just haven't set it up. But this platen is different.. it has an attached water jacket and ports for closed loop water cooling. It is for keeping the platen itself cool.. not the blade. I suppose I could just use the same water sprinkler system I'm eventually going to build and not buy the separate water jacket.

 

edit: Randal.. your post might just get my arse moving on installing that water sprayer.

Edited by Scott A. Roush

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Do it man, other than the mess it makes swordmaking a lot easier in a lot of ways.

 

Now the cooled platen thing I have never heard of before, but that sounds cool as well.... Cool...get it?

 

:0)

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That curved platen is thought provoking!
Thanks for posting that. It could be a good alternative to getting a really big wheel.

Like Randal I also use direct water cooling. It is handy when the edge gets thin and also helps to bind dust.
And it is really messy :-)

I attach some images of what it looks like when used for sharpening and hollow grinding (I use it for the flat platen as well).

 

_DSC0017_315942.jpg

 

IMG_0400.jpg

 

IMG_0401.jpg

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