After a request by Travis Daniel, I am posting this photo of the platen I use. It was made by Bader, for me and I've found it to be very useful. You can go ahead and hollow out your tangs on a rest, first. Then put on the platen and start to flatten them out into a taper. If you need to hollow more out of the middle of the tang, you have the 8" wheel just below the platen. Very handy. Works for me, anyway! As you can see, I machined a small slot into the arm that holds the grinding wheel (and a matching tongue into the upright mount for the platen) so that I can just drop the platen arm into place an go to work. Use the serrated wheel, not the smooth wheel, which is shown, however. You can put a nut on the end of the platen arm where it is machined into a rod and threaded and protrudes through the wheel arm, if you like. Sorry, i'm tired, having just returned form the Solvang show. I hope it makes sense!
Note, also, the pyroceram on the face of the platen plate. You can get it from Tracey Mickley at
http://usaknifemaker.com/ceramic-gla....html?___SID=U. It cuts flatter and cooler than the steel platen. Just epoxied in place. Maybe I used "JB Weld?," or something like that gives a super bond. I believe it's Knife and Gun Supply's white epoxy, in the little jars, though. Has worked for 3-4 years.
Oh....this was built for me, by Bader, many years ago and I don't know if they'd be interested in making another one. You can figure it out, though, or have a local machine shop put one together, I'm sure, if interested. I can supply more photos, if anyone is interested and wants to build something like this. Some makers just use the bottom wheel of their platen to hollow out the tang and do fine - so whatever works for you......
https://www.dropbox.com/s/3mibgbgnc47qq1d/DSCN2342.jpg