New Grinder Attachments at the Bladeshow

I think the blade stays cool enough that it doesn't need to be dipped in water during the entire beveling and polishing process. The guy doing the demo didn't dip the knife in water even once. The bearings on the wheels get cooled too.
 
Shouldn't build up any more heat, and maybe a bit less, than grinding on a standard flat platen, with this config.

You still will have to dip the blade regularly if grinding hard.

I've got a water cooled flat platen (Nathan's with a chiller) and while it really helps prevent heat build up when grinding really thin stuff, most of the heat in the blade isn't coming from the platen or the belt itself, it's being produced by the grinding process itself, i.e. abrasive grains shearing metal from the blade, no matter how you slice it (pun intended) you're going to get heat generated from any type of machining process, you can remove it quickly with coolant as an example, but there's no way even a liquid nitrogen cooled platen would keep heat from being a concern when finish grinding, because the belt isn't conductive enough to carry away the heat quickly enough.

On top of that, in this application, you've got rubber (an insulator) between you and the platen, adding another layer of isolation between where the heat is being generated (on the grinding surface of the work), and the potential heat sink of the platen.

The cooling of the platen is just to keep it from getting hot enough to melt the rubber and pop belts I'd imagine, no doubt it's effective, but necessary because of friction to keep this thing from wearing out quickly.


Demos of this type are often done with non hardened blanks, that are never intended to be finished. Even hardened, if your working with a thick blank, for the sake of demos you very well may not take it down to what most of us consider to be acceptable thickness at the edge before sharpening. I wasn't there, so I can't speak to that, but I have zero doubt that you'll still have to dip a 1/8" thick or thinner blade that's hard, regularly when finish grinding.
 
I can't see this being any different than a large contact wheel for cooling, and I still have to dip blades in the bucket hollow grinding...
 
Hopefully somebody will post a demo video, I can't exactly figure out how that attachment makes it so easy to grind blades, maybe it's just me? And I agree, there is no way you won't have to still dip the blades in water or set up some type of sprayer system to grind totally wet.
 
Thanks! Looks interesting but I'm sceptipcal of anodized alu construction, even hardcoat will take a beating grinding blades. Hopefully somebody who buys one will post a real world review.
 
As much as i like the idea of this rotary platen and the fact it's carbide, that is a lot of $$ to come off of for it.... I picked up an entire setup at the show for the price of this platen.... 2hp baldor, small wheel attachment, flat platen, fully adjustable arm, and it tilts 90 degrees....
 
That thing is impressive.

Question: Why would you need a carbide platen if you are running a rubber belt over the surface?

Also, doesn't a rotary platen run much cooler anyway?
 
The carbide platen provides a low friction and wear resistant backing to the rubber belt so that the bevel is closer to a flat grind. I didn't have an infrared thermometer or a positive materials identification gun, but from what was told it was a fully hardened cts-xhp blade. It didn't have any heat discoloration after he finished, and people were coming up and touching it to see how cool it stayed. It did seem like he was making a point of using a new belt for each demo, and he was running the grinder at half of it's full speed. I did try sliding the jig over the work rest a bit and it was smooth as butter. There's definitely a limit to the length of knife you can grind with this jig, but I'm sure Travis or Jerry or the fine folks at Hardcore Products will happily make you an XL work rest for another $1-2k.

nosaj750, did you happen to pick up an ÜberGrinder? I saw it at the show and it seemed pretty neat. It looked like an aluminum frame KMG with a bunch of TW-90 features. I thought it was interesting that Burr King was adding features that were directly competing with the TW-90 (90 degree flip and surface grinder).
 
AVigil said:
That thing is impressive.

Question: Why would you need a carbide platen if you are running a rubber belt over the surface?

Also, doesn't a rotary platen run much cooler anyway?
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I think carbide would shed heat through convection more rapidly than say a glass backer. That might be why.
 
I think the comparison at the end was kind of disingenuous. The bevel ground on the rotary platen is convex, they then ground it on a flat platen to show the scratches, of course there will be a difference because they are two different geometries.

I have honestly never understood the use of platen chillers on flat platens. If they are set up correctly with the belt just barely touching the platen when running, I have never had a platen get anything hotter than warm to the touch and as javland said above almost none of that heat reaches the blade. Radius platens benefit from cooling because there is more friction in that setup.

I also don't understand the use of carbide, when hardened tool steel should hold up fine and can be re flattened many times before it would need to be replaced. I would think that would be a big cost saver.

I do think the jig is pretty slick by being able to grind both sides without removing the blade from the clamp. I think that is the most innovative part of the whole product.
 
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I think the cool factor is maybe a 6 or 7, and the practicality for me would be a 1 or 2. It is virtually useless for profiling with the extra plate on the right side and the lever all in the way and not much more room on the left till you run into the plate and tooling arm as it comes so far up due to the fan. Pretty much the only use I see would be using if for bevels. Glue some leather to an extra platen plate and swap it out on your platen and you have the same thing.
 
JMJones said:
I think the comparison at the end was kind of disingenuous. The bevel ground on the rotary platen is convex, they then ground it on a flat platen to show the scratches, of course there will be a difference because they are two different geometries.
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My understanding is that the bevel ground on this platen is flat (from the carbide/rubber platen) and the rotary part just drives the air cooling mechanism. Is this correct?
 
No it cant be flat because the rubber belt has give to it. It will make a convex grind.
 
The rubber belt rotates between the abrasive belt and the carbide platen. The carbide platen is there to provide a flat backing to the rubber. The cooling mechanism cools the carbide platen because rubber rubbing on metal produces a lot of heat from the friction. I overheard the guy doing the demo saying that they had to use carbide because steel was wearing out too fast, or maybe the rubber was wearing too fast against steel.

I kind of want to try the leather platen idea now. For cork belts, what progression is used to get a mirror polish?
 
Yeah, this simple solution gives great finish to Trizact 237 at higher grit. Especially compared to my ordinary flat platen. For finishing work (and sharpening) it doesn't wear too quickly.

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anyone with a rotary platen knows how fast the wheels wear out. they end up dished/concave rather quickly. it's hard to tell how the fan is being spun, but if it is a wheel with fan blades built in it's going to be expensive to replace.
 
What do you mean the wheels wear out? I haven't noticed any wear on mine, but I don't use it as much as some I imagine. The worst thing about mine seems to be the heat the bearings generate, which I assume I could resolve with higher quality bearings.
 
well, before i designed and built my own i started a thread and asked for advice. several makers on here informed me of the issue. so i made my wheels larger(4'') to reduce rpm, and i made them from steel to reduce wear. maybe its just the guys who put more time on the rotary. i believe one person said they replace theirs twice a year. i would have to assume that folks willing to drop the coin on this attachment1. are going to be using it a lot. 2. can afford to replace worn parts anyway. if i were buying it i would want to know the price of those parts though, especially that back side wheel.
 
I built mine as well which is why I was curious. I remember your thread now and how you used larger diameter wheels.

I just can't see where the wear is coming from or how it's different than 2" platen wheels.
 
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