How I set up my Carothers C-Plate and Radius Platen/Chiller

Matthew Gregory

Matthew Gregory

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@Nathan the Machinist and I have spoken in the past about my issues with my KMG grinder, and the wretched QC of the stock C-plate was certainly an aspect of those conversations.

As soon as I saw that Nathan was producing a precision C-plate, with a third wheel attachment option, a light went on, and this was how I chose to apply it - not like it's the only way to use the third wheel setup, but this is how I chose to:


I used three grooved idler wheels, purchased from Midwest Knifemaker Supply. I'm not sure how necessary it is for all three to be grooved, but I did it anyway.

I think it's pretty important to point out that this could be awfully dangerous if someone weren't careful. Power transmission belts and grooved idler wheels are going to be unforgiving if something were to be pinched between them. By 'unforgiving', I mean possibly permanently debilitating. Know what you're doing before you do it. Maybe do a search for 'degloving' before duplicating this setup, just to be sure you get it. In fact, a really smart person would figure out how to make a guard for a setup like this. Seriously.

You could easily remove the platen assembly and just run the belt as a 'rotary platen' setup, I'm sure.

The power transmission belt is a 320J20 belt, you can get them all over the place. I got mine from Amazon.

I also bought a C-plate and axles for my 'standard' flat platen (mine happens to be carbide), and it's the first time my KMG has had perfect tracking with a platen.

Hope this helps!
 
Pretty interesting setup there Matthew. Very nice! I might give that a shot. I've always wondered how a rubber belt over a radius platen grinds.
 
Another way to use this setup would be as a rotary platen, for a $290 investment.

3 grooved wheels from Midwest Knifemaker = $145
1 precision C-plate = $60
1 3rd wheel adapter = $25
3 precision axles and nuts = $30
1 belt = $30

No need for a platen at all, and it’s a superior slack belt grinding platform.

The rotary platen I got from KMG was built exactly the same way my grinder from them was - poorly.

-Holes were drilled and tapped without being perpendicular.
-Shitty bolts for axles were crooked.
-Tensioning wheel axle was actually proud of the assembly plate, and made the whole assembly sit skewed if it was in the position I use it most,
-Massive burrs on every drilled hole - I had to disassemble, deburr, and reassemble the entire thing before I could even use it. The burrs were so big that the axle wouldn’t rotate on the tool arm.
-Belt generated tremendous heat because it applied uneven tension due to all the wheels being skewed in relation to one another.

All for $180 MORE than this setup. :confused:

...just a thought.
 
Matthew Gregory said:
Another way to use this setup would be as a rotary platen, for a $290 investment.

3 grooved wheels from Midwest Knifemaker = $145
1 precision C-plate = $60
1 3rd wheel adapter = $25
3 precision axles and nuts = $30
1 belt = $30

No need for a platen at all, and it’s a superior slack belt grinding platform.

The rotary platen I got from KMG was built exactly the same way my grinder from them was - poorly.

-Holes were drilled and tapped without being perpendicular.
-Shitty bolts for axles were crooked.
-Tensioning wheel axle was actually proud of the assembly plate, and made the whole assembly sit skewed if it was in the position I use it most,
-Massive burrs on every drilled hole - I had to disassemble, deburr, and reassemble the entire thing before I could even use it. The burrs were so big that the axle wouldn’t rotate on the tool arm.
-Belt generated tremendous heat because it applied uneven tension due to all the wheels being skewed in relation to one another.

All for $180 MORE than this setup. :confused:

...just a thought.
Click to expand...


Good idea!

If someone wants to save some more money, here's another supplier of these ribbed wheels. Three wheels for a total of $109.

https://www.ebay.com/itm/Ribbed-Bel...y-Platen-Use-with-J-Ribbed-belt-/232598449076
 
Thanks for all the great info Matthew and everyone... great link on the wheels Stromberg Knives Stromberg Knives gonna have to snag some.

Definitely gonna use this w/ the chiller, but I wonder if using a koolmist on the inside of the rubber belt would help things at all. Gonna have to play around w/ that!
 
I would worry about abrasives forming a slurry with the mist and prematurely wearing the wheels and platen face, but I worry about all sorts of shit.
 
Matthew Gregory said:
I would worry about abrasives forming a slurry with the mist and prematurely wearing the wheels and platen face, but I worry about all sorts of shit.
Click to expand...

No that's a good point, more so now that I have these nice/rare AIM Industrial platens to care for =) but IIRC that's why Nathan says you either want to use a belt all the way wet or all the way dry - but not in between, and since I normally grind wet anyway I guess that's why I got thinking that direction. May try it out and see how it goes, worse case it won't work =) Your idea w/ the silicone spray sounds excellent too, I have some of that stuff laying around.
 
So if I want to flat grind, but use high grit belts without bump. And I also want to do better convex grinding. I would want the setup you gave, but flat instead of radius platen for flat grinding, and remove platen for convex grinding?
 
Yes except with a flat platen it will still be slightly convex due to belt flexion. Maybe not enough to matter but it's much easier to get that nice machine satin with the belt/flat platen setup in my opinion.
 
Because of the ‘give’ that the belt has, even with a flat platen the results are somewhat convex. This is true with the Moen platen, as well, which is really all this is.

Good technique is still necessary, as you would expect, but the point is that, just like grinding on a rubber contact wheel, a given abrasive is somewhat more aggressive and also smoother in use. Smoother, referring to how it feels to grind on it.

I found, oddly enough, that my flat platen setup benefitted from using pyroceramic as a platen material. Ran smoother and cooler. I cut my pyroceramic platen to 1-7/8” wide, so it’s exactly the same width as the power transmission belt. It lets me ‘drift’ the edge of the belt for cleaning up plunges.
 
I need to point out that none of this is original thinking on my part. I’m relying on all sorts of help from friends, and brainstorming with people that are leaps and bounds brighter than I am, all the while feeding off of work and ideas of others. I really can’t take credit for this, other than perhaps taking that information and experimenting with it.
 
Matthew Gregory said:
I need to point out that none of this is original thinking on my part. I’m relying on all sorts of help from friends, and brainstorming with people that are leaps and bounds brighter than I am, all the while feeding off of work and ideas of others. I really can’t take credit for this, other than perhaps taking that information and experimenting with it.
Click to expand...
Matthew, Is that ribbed belt you used the same size as the one on the Beaumont rotary platen? I have a rotary platen that I use every couple months for something and I wondered where I would ever get replacement belts because Beaumont charges a lot for their parts. Thanks, Larry Ps I use Nathans platens and chillers too...love them. LL
 
Thanks John and Matt. In regards to the Moen platen: yes, that's kind of what I'm going for, but less expensive and suitable for a lower volume maker such as myself.
 
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