Rotary Platen...

[kvehikite]

Rotary platen. I have never used one and therefore have no experience with it. What advantages are gained by its use? I guess I'm asking if it's worth the investment? Looking for some opinions.
Thanks,
Ken

 

[Matt Rochester]

Seems like I hear people using them for convex grinds. They are a stiff slack belt if that makes any sense.

 

[javand]

It's also incredibly useful for handle work, where a slack belt no matter how stiff, is too flexible.


I use the rotary platen for most handles, where I'm shaping the inside of a recurve portion. On slipjoints, where radiusing the whole handle and bolster on the flat platen causes whichever portion is lowest to grind further, you can get back in there and match the thickness of the scales using the rotary platen, and get consistency that's hard with a slack belt. That probably doesn't make a whole lot of sense, but you'll definitely know what I'm talking about when you see it.

 

[kvehikite]

Seems like I hear people using them for convex grinds. They are a stiff slack belt if that makes any sense.

Yeah, I get that much from what I've seen. I also figure it keeps the belt cool. Seems that it would be more of a finishing step, but just looking for thoughts on the "need" or "want" factor.

 

[Matt Rochester]

I have been thinking of making one especially if they are handy on the handles!

It's also incredibly useful for handle work, where a slack belt no matter how stiff, is too flexible.


I use the rotary platen for most handles, where I'm shaping the inside of a recurve portion. On slipjoints, where radiusing the whole handle and bolster on the flat platen causes whichever portion is lowest to grind further, you can get back in there and match the thickness of the scales using the rotary platen, and get consistency that's hard with a slack belt. That probably doesn't make a whole lot of sense, but you'll definitely know what I'm talking about when you see it.

 

[kvehikite]

javand, it does make since. Using the slack belt is frustrating trying to chase it as it's pushed around (if that makes any since). I can see how you can find a happy medium with something like the Beaumont rotary palten with it's varying lengths of slack.

 

[javand]

It's not just the varying lengths either, it's the "backing" factor. It allows you to work gently, or control the cut with just enough reinforcement that you grind consistently where you want as opposed to the geometry of the existing handle material controlling as with a slack belt. Don't get me wrong, you still need a slack belt for the final blending, but typically I'll run the rotary platen, and then slack belt off the top of the belt where it rides between the tension/tracking wheel and the rotary platen. You can pretty much set the radius on the handle material with the flat platen, then switch to the rotary and refine the internal radiuses, and blend with the top slack portion, in one operation.


And yes, it's also awesome for doing convex grinds or rolling a convex edge, after roughing in on the flat platen.


Anyway, I was skeptical about these things for a long time also, but once you use one, you'll use it every time. It fills a very important niche between the flat platen, and slack belt. Of course, some styles of knives or construction wont benefit from these.

 

[jdm61]

One of the early comments that I heard about the rotary platen is that unlike a slack belt, when you grind your handle, the pins/bolts end up flush and not staying a bit proud. It is also very good for convexing your edges. Is it necessary? No. Is it expensive? Hell, yes. Will you ever regret buying it? No.

 

[kvehikite]

All good stuff. Thank you. This is the kind if info I was looking for.