Mega Mold back contouring

[Jon Heimbruch]

Hi all. I am about to contour the back of the rim using the Mega Mold. I have read the process but want to make sure that I understand the process. This is what I plan to do. With the base flat raise the heel block to the same height as the tail block. Mark the general contour line on each block with the curved side of the abrasive bar. Place the abrasive bar on the spindle. Using the curved side of the bar sand each block to the correct contour, then progress to the side kerfing. I think this is the correct way to do this procedure. Do I indeed start out with the base flat? I know the process seems pretty straight forward but i want to make sure before I sand. Thanks for any feedback. Jon

[Dave Bagwill]

Yes, the base is flat, and as you said, you raise the headblock with shims to the same height as the tailblock. I use the back edge of the block, where it is glued to the rim, for the measurement. I pencil in some witness lines across the corners of the blocks and on the kerfing to make sure everything gets nice and even.

[Jon Heimbruch]

Thankyou very much Dave. I am discovering that the Mega Mold is awsome! I will proceed with the back contouring. I watched your video demonstration on the mold setup and sand ing the top to the correct angle. It was most helpful and it looks like it is going to be a straight forward procedure. Thanks again.

[George Welch]

Yes, the base is flat, and as you said, you raise the headblock with shims to the same height as the tailblock. I use the back edge of the block, where it is glued to the rim, for the measurement. I pencil in some witness lines across the corners of the blocks and on the kerfing to make sure everything gets nice and even.

Resurrecting this old thread, could the height adjustment screws be used (vs. shims) as well to match the heights of the head and tail block?

[ken cierp]

No ---- the adjuster screws are designed to establish a level plane or angle to the abrasive bar and shaft -- shims are used to level the rim edges to the base.

I suggest going over the conceptual information in this article

http://www.kennethmichaelguitars.com/neckangle.html

so that the "whys and what for" requirements of the MM are clear. The MM is a positioning/locating device that is far superior to the common free hand method of rubbing the rim on an abrasive dish.

[Daniel P]

Ken and George,

If you follow the KMG success kit instructions for the Mega Mold ( http://www.kennethmichaelguitars.com/rim.html), in which the top side of the rims is built flat to the bottom of the mold, you could follow the Mega Mold back contouring instructions here:

http://www.kennethmichaelguitars.com/contourfixt.html

In this case you do use the angle setting screws to match your neck and tail block heights in preparing for back contouring with the radiused Mega Mold sanding bar.

Hope I'm not confusing things.

[George Welch]

That's part of the confusion for me, actually

I know what I have to do now but was confused for a bit exactly as Daniel P described