Leather Covered Platen

C

Cooter DeGraw

Joined
Jan 13, 2005
Messages
44
Some time ago the AR15.com website produced what I thought was an excellant 5 part tutorial on knife making--grinding the blade to finishing the grip. At one point the maker installed a "leather covered platen" on the grinder to stop the "bounce" that occurs when the blade crosses the point where the belt was joined---supposed to to give a smoother finish when using the finer grit belts. Would someone care to help me/enlighten me further. I am trying to gain skills and need all of the advice/help that anyone would care to give.
Thanks, Tom Hollowell (aka Cooter)
 
I tried graphite tape. I liked padding it gives. The problem is that it becomes uneven too fast. Try leather and let us know how it works.
 
Hi Cooter.I have tried leather,mouse pads,ceramic platens (Darren Ellis at Ellis Custom Knifeworks ) & have stayed with the ceramic.You still have to replace the ceramic but not nearly as often.Like alexmin said " they become uneven too fast". I really liked they way the mouse pads worked for doing convex grinds and still use them but they only last for one grind.I buy the biggest ones I can find and cut into strips & use double sided tape to adhere. I can get 4 foam platen backers from each mouse pad so it isn't too bad cost wise.Leather does reduce the bump-bump-bump you can get from some belts but you'll need to replace often.Ceramic is permantly glued to my platen now,thats what I do :)
 
Cooter, I did that tutorial.

I have tried rubber (mouse pads), graphite tape and leather. Leather was the only thing that worked consistently for me. Graphite gets too uneven too quickly and the rubber is too soft for my needs. One, leather is reasonably stiff so it maintains the "flat" part of the grind. Two, it is easily replaceable using some Barge, or similar contact cement. Three, it eliminates the "bump" from the butt splice, especially on fine grit belts allowing for a very smooth finish. Four, it is stiff enough at the edges to do plunge cut finish work while allowing the belt to roll over the edge. Using Norax belts in combination with a leather covered platen works wonders.

Just keep a spare platen around with leather and put it on when ready to finish. I have found that I can draw file the leather to keep it smooth as long as I do not let pitting get too deep. I can get quite a few blades out of one piece of leather.
 
A soft platen is something I just can't understand. They start getting uneven almost the first blade you do.
I'm on my grinder as much as 1-2 hours per day, sometimes more, year 'round.
I've been on the same glass platen from Darren Ellis for two years.
There's no bump.
There's no wear.
You can't use it for profiling, however. That would just be stupid. Use your round rubber wheels for profiling if you're of the stock removal breed.
I've never had to replace it.
It's perfectly flat everytime, if you want something flat.
Use sharp new belts so you don't need to ram your piece into the platen. Let the belt do the work.
 
Something else to consider is felt. I've been using it for years. It will wear out in a few months but I just love it. I use 1/2" industrial grade felt.
 
+3 for the pyroceram. I've not seen anything to beat it.

For flat surfaces that's the way to go. Anything else will leave an uneven surface as it gives under pressure. If that's what you want like for concave blades, then fine, but if you want truly flatter surfaces then pyroceram.

You can use a slack belt for concave edges.

It has additional values as it takes heat from the belt and workpiece, and makes for about 65-70% less friction. That will help the life of your grinder motor and bearings. It's commonly used for the doors of wood stoves, so it handles heat just fine.

Make sure your platen is FLAT when you epoxy that stuff on. It will crack otherwise.
 
I use the double sided 3M exterior tape. which will take up any variables in the steel platen, even though you should flatten as best you can.
No epoxy mess, and I did break one once, not paying attention to a wrench in my hand! and it was a bi--h to get off! Holds rather well, I'd say! And easy to apply!
 
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