[pontius]

Maybe manufacturers intentionally made them concave because flat it too finicky to acheive. I think that for various reasons, when dragging a peice across an abrasive on a flat surface, there is a natural tendency for more material to come off around the perimeters than in the center, leaving the table convex which is real bad.

In my experience, dead flat and concave do not leak but convex is an obvious and emediate problem. It's possible that they were taking reed warpage into consideration, but it's just as likely that mass producing with a slight convavity elliminates the possibility of a convex table and gives an overall better success rate.

 

[pontius]

They are not intentionally concave. They are left concave because they still play well enough with a concave table. They are concave because the facings are milled and done quickly. They are "allowed" to be convex because this gives the cut off material some place to go. So its not a goal, its an exception. I prefer not to make that exception.

If it's because of poor QC (milled quickly), wouldn't at least 50% of the non-flat tables be convex rather than concave? I always see concave rather than convex on original pieces. Or are you suggestion the convex ones go in the re-grind machine?

 

[pontius]

In the milling process, the surface heats and expands due to the heat from the cutting operation. Once it returns to room temp, the outer layer shrinks more, leaving a concave surface.

I'm confused. Wouldn't that leave it convex?

edit: Ok I think I get what you are suggesting and that seems to maybe make sense. This is the first plausible scenario I can imagine for concave tables that were not intentionally ground that way.

If you have a dead flat grinding surface, how else can you get concave results? Convex results can easily happen if there peice is not kept perfectly secured and not able to move or wobble during the process.

 

[pontius]

Flat is good. . Concave within reason is good. Convex is very very very VERY bad. If I was mass producing mouthpieces, employing blue collar craftsmen to churn out pieces, knowing that there are going to be +/- variable results from the target, what kind of table do you think I would shoot for?