Ok heres the scoop on the "beefed up" platen.
I added an extension for a few reasons. First my platen didnt come out far enough, it didnt even reach the belt. Second, it wasnt perpendicular to the belt. And third, the edges are rounded, which makes it difficult to grind on the side of the belt. IMO the platen is a really bad design on this grinder.
Here we go! I would do a few things different a second time around, so I hope you don't mind me being a bit long winded here to explain!
1. First I got some 2"x 3/16" steel from Home Depot. I would do 2" x 1/4" instead if you can find it. Then I cut it dwon to two 10" lengths. IMO just use 1pc of 3/16" or 1/4", with a ceramic or hardened steel liner (added later) the 1 piece of steel will be fine.
2. Then setup the platen as you normally would, but back it off at least 3/16-1/4" from the belt, or enough to stick the 10" piece of steel between the platen and belt. Line up the steel with the BELT, not the platen. The platen is not parallel to the belt (at least on mine). Then mark with a sharpie where the steel should be on the platen, draw a line along the side of the steel down the platen on both sides.
3. Next I C-clamped the platen and steel together on the drill press and drilled 2 holes through it. I think it was a 11/64" bit. Then remove the c-clamps and steel. Next drilled through the holes on a platen with a slightly larger bit. This will give you a little "play" when you JB weld the platen and steel later.
4. I picked up a countersink at sears and countersunk the holes on the STEEL. Make sure you countersink the correct side, I did the wrong side and had to do it all over again! Then put a pair of flathead bolts and fastened it with a washer and nuts. IMO I would add some JB Weld to hold this together if doing it again. Just be sure you have the steel lined up where it needs to be, no going back once this stuff hardens.
Heres what it looked like when done:
Now the ceramic platen liner. This is a bit easier.
1. Got a ceramic liner from USAKnifemaker.com. Great people, great service. First I used a sanding block with 60 grit paper and rubbed on the platen. Particularly to make sure the screws were flush with the platen. Hold the ceramic on the platen to see if its flat. Then I scuffed up the surface of the platen with 36 grit paper (actually an old belt). Also scuffed the glass, but very slightly. Cleaned it with Acetone. USAKnifemakers recommends using rubbing alcohol.
2. Then I used a L-square to make a straight line across the platen at the bottom to mark where the screws should be drilled. Drill two holes through the platen. Then I put two socket head screws and a pair of nuts. This is to prevent the ceramic liner from dropping into the drive wheel. If you dont get the screws lined up, you can use a file to ground one down to make it even. I got lucky, actually drilled it twice, second time it lined up perfect.
3. Then I held the platen flat in my vise, but I would imagine a better way is just to put the belt grinder assembly in the flat position, aka parallel with the workbench. I didnt have much room on the bench, so I held it in the vise.
4. Then lots of JB Weld! I put it on about 1/16"-3/32" thick. Put the ceramic platen on, then move it around a bit to make sure there are no air pockets. Push it down with a little pressure (not a lot!) to squeeze out the air pockets. Dont clamp it or push too hard, you want some cushioning there.
5. I let it sit for 24hrs before trying it out.
Too bad mine is only about a week old as well!
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