Flattening the Blocks

The next day after the blocks are glued I mark the outline. Then I work to get the ribcage, minus the ribs flat. It is pretty flat on the bottom just by the way the ribs were glued on. The top is fairly flat just by the way they were cut out. But if the surfaces are going all over the place, the glue join to the plates not be as good as it should be. I use a secret weapon.

I guess it's not secret if I tell you, but it is a used up cutoff wheel. We use a couple a month, on average, at work for cutting hardened bars of M2, A9, S7, H13, good hard steel. They are dirt cheap. It think they are only made of some kind of rubberized clay and diamond dust. They start out maybe 2 foot diameter, and when they get about half that they are too small to use, the wheel won't make it through the stock, the vise gets in the way. So we throw them away. They work great for sharpening stuff, and are much easier, and faster to use for this task than sandpaper.

I lay the wheel down on my glass top, and start with the bottom where the back will glue on. I rub it in a figure eight pattern, and switch it end to end, so I don't get it tapered. I work a little, and then check the pencil lines, and see where the blocks are being cut. Usually on the bottom it doesn't take long before it is smooth and flat. You can watch the progression as the pencil lines wear away.

On the other side it is flat from the bottom block to the top corners, so I do the same for that side as I did for the others. I may find that one block is too high, so I'll file it down, because files work best on the end grain. When I get it satisfactory, it is time to get the top half of the upper block. That is easy to do with the diamond wheel. Just rub it sideways on the wheel, pushing down on the upper block area, and letting the other side rest on the edge of the upper corner blocks. Here is where you might need a file to start the taper on the block. Soon that will be done, and it is ready to be marked up again.

This one ended up 1-3 tenths of a mmm short from the upper corner down, and maybe a couple tenths high at the neck. Close enough. I may glue a little strip on one corner near the inside where about 3 mm didn't clean up.

When marking the outline it is best to have a centerline drawn on both side, and the ends of the end blocks. Then no matter if your holes are off slightly, you can be assured that the outline at least started out somewhat symmetrical. This pattern has a top hole that is oval, and the bottom hole through the mould is drilled on an angle to the side, must have had chips under it. But with the lines drawn I got them in the right place.