Crisp plunge lines?

[Geoff Flato]

I've only had those problems with dull or cheap belts.

 

[AVigil]

IMO, a platen radius has nothing to do with the "red" area, or rather, it doesn't help at all.

That depends on the technique being used. If you over hang the belt then no a radius makes no difference. If you leave the belt at the edge it will fold over the radius and give a perfect plunge at the bottom and at the top, on both sides.

This is something Bob Loveless recommend for a contact wheel and it works for for the platen as well.

Good thing is it still works if you decide to over hang the belt.

 

[javand]

That depends on the technique being used. If you over hang the belt then no a radius makes no difference. If you leave the belt at the edge it will fold over the radius and give a perfect plunge at the bottom and at the top, on both sides.

This is something Bob Loveless recommend for a contact wheel and it works for for the platen as well.

Good thing is it still works if you decide to over hang the belt.

I'll admit I haven't tried doing plunges the way you describe, although it seems like it would be somewhat limiting if you don't want the same radius for different size and thickness of blades.

Since much of what I do are very small thin pocket knife blades, which are very difficult to get good defined plunges, and I like sharp very tight radiused/square plunges, the way I described above works best for me, but as with all things related to this trade, YMMV, and there's a million different ways to skin a cat.

Thanks for the info Adam!

 

[AVigil]

I'll admit I haven't tried doing plunges the way you describe, although it seems like it would be somewhat limiting if you don't want the same radius for different size and thickness of blades.

Since much of what I do are very small thin pocket knife blades, which are very difficult to get good defined plunges, and I like sharp very tight radiused/square plunges, the way I described above works best for me, but as with all things related to this trade, YMMV, and there's a million different ways to skin a cat.

Thanks for the info Adam!

This definitely is more applicable to bigger and thicker blades

Merry Xmas Javan

 

[SamaraVolk]

No, Y or J-weight belts are fine.

I honestly think most of what people think are splice chatter are just problems in the low grits showing up in the finer grit passes, or using dull belts. 400 and above, I never use the belts more than once, and honestly, they're only good for a few passes per side on steel. Use one per knife, or two if necessary (although 1, and 2-3 passes per side is all you should need if you set up everything correctly at previous grits), and toss it. It's done. Any more attempt to use it is only going to cause problems. A bit of smearing, or streaking is possible from a splice or worn fine grit belt, but if you have any wobbles or faceting, it's a technique issue, not the belt. Try putting a new belt on, and making one firm pass per side, see if that doesn't fix the problem.

If you're shooting for a perfect "belt" finish, and not doing a hand rubbed satin finish, then you will get some light shadowing (smearing) and inconsistency from the splice, and potentially some wobble at the top of the grind if you don't use enough pressure making these passes, as the belt "cups" over the platen from the tension differential due to the shape of the tracking and drive wheels stretching the center of the belt more than the outside. The easiest way to remedy this in my opinion, is to make a final pass with a new 800 grit Awuka J weight belt, on a "soft" platen. This is a rubber/cork/hard felt lined flat platen (must be very firm, with a tiny amount of give or it'll burn out the tops of your grinds and edge worse), that at low speed, and low pressure, will "smooth" out any inconsistencies that you would otherwise take care of when hand sanding (which you would also do the final strokes of with a backed(rubber, cork, leather, whatever) sanding stick).

This is why so many belt finishes are often done with belts like the scotchbrite or cork belts, which accomplish much the same effect, albeit with a different finish.

Thank you. I use the corks like you said and I do like them. I will have to remember the advice of tossing the belts after one use. I've been too frugal with them.

 

[Ian Fifelski]

One way to get more out of cork belts is to load them with compound. It works nice for polishing when you don't want to polish on a buffing wheel, but rather the platen.