Radius Platen

JT, what do you think about the heat? Could it be a problem? A belt will be sliding on the platen all the time (not just when you grind) and it will not be slow.
 
Heat is always a problem with things like this. Polishing the platen will help, but friction is friction. Running the belts as slow as will work efficiently and turning off the grinder when not actually cutting will keep heat down some ,but a big block of steel will heat up, and the thermal mass will keep it hot .

Something that may help would be to drill a series of 1/4-1/2" through holes about 1/4" in from the surface to aid with convection cooling.

If you wanted to go high tech, you could solder "U" tubes in alternating holes and add water cooling ( look at the ends of a AC radiator or car radiator for what I mean). Not really practical, but who ever accused me of being practical.
Stacy
 
piggybacking on the watercooling thing guys in the know with modding computers have been watercooling their stuff for years. Lots of websites sell pumps, waterblocks, radiators, and fans. For the most part kits suck but most guys use an oil cooler from like a 79 pinto (just throwing that out there as an example) from advance auto parts for $20 for the radiator.
 
I would be interested also, depending on final price. Sounds like something I have been wanting/thinking about doing for a while now. Never did get around to it... obviously. :-)
 
I'm also interested. I'd prefer a 30" radius to simulate a 5' wheel. I tried this once using Micarta faced with 304SS; worked okay but had some tracking issues because it was all hand ground, not really square to anything anywhere... :D
 
lel said:
JT, what do you think about the heat? Could it be a problem? A belt will be sliding on the platen all the time (not just when you grind) and it will not be slow.
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You know i don't really know how big a deal the heat problem is going to be. ya thy will get hot but how hot. i mean D2 can be tempered at 500 deg and still have a hardness of 60 RC. and say it onley gets to like 200 deg then thats 64 RC, you could hit 900 deg :rolleyes: and your still at 58 RC. what i need to know is what is the hole spacing on the KMG and how are the platens attached. I'm just thinking that i will put 2 threaded holes on the back but thy wont be all the way out to the ends but in a bit. this way you could bolt that to a flat bar that bolts to the kmg platen brackets.
 
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Jt, I am guessing heat is not a problem for the steel but for the belts. It'll melt the glue and they'll just disintegrate in a hurry.

Patrice
 
I wouldn't think that wear would be a problem on these as there is not much force being applied to them and the back of the belt is not very abrasive. Just my $.02 (valued at around $.01 right now)
 
any one have an idea on what radius i should put on the edge of the platen, this will determin the plunge cut radius.
 
Just a heads up fellas...I made one of these about a year ago and have used it heavily. I've had great results. The platen does get hot, but not hot enough to be a serious problem. I haven't had the splices come undone either (I even grind steel right out of the forge).

I'm looking forward to seeing the finished product.

Matt
 
JTknives said:
any one have an idea on what radius i should put on the edge of the platen, this will determin the plunge cut radius.
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I dont think you should put any radious on the edges. People can put their own on if they choose to.

My vote is for D2 steel at nearly full hardness.

I have hollow ground nearly everything for the last few years and I like my 14" wheel but I think about a 36" wheel would be preferred. If the wheel is too big there is barely a groove to land in and the blade will be more flat than hollow except on a big bowie type blade.
 
Bruce Bump said:
I dont think you should put any radious on the edges. People can put their own on if they choose to.

My vote is for D2 steel at nearly full hardness.

I have hollow ground nearly everything for the last few years and I like my 14" wheel but I think about a 36" wheel would be preferred. If the wheel is too big there is barely a groove to land in and the blade will be more flat than hollow except on a big bowie type blade.
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sounds good to me. ya that's a good idea about not putting the radius on them. should i make it just a hair under 2" or just leave it 2" wide.
 
I'd offer them in A2 and D2. D2 would last much longer. But D2 costs more and eats up cutters, so it would be more expensive. And depending on how much the user plans to use it, even mild steel would work for a while...

I'd leave it 2" wide
 
Would it be worth it to have them water-jet cut?
(edit: I change my mind, a cnc mill would do the trick)
 
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I was thinking about doing the same thing with a chunk of new, fully hard 5160 leaf spring cutoff that I got from a spring shop... however, I finally got around to grinding a couple of blades on my new homemade grinder with the 14.5" wheel and it is a big enough arc for what I'm doing.
 
My KMG has a 8 5/16 long platen there are two 1/4 -20 bolts 6 3/4 inches apart
one hole is 3/4 inch from the end.
You had mentioned Japanese kitchen knives earlier, considering they have no plunges in their grinds I would leave the edges square too.
 
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