How to Make a Shepherd's Shrink Cup, Part 4 (Fitting the Bottom)

Let's continue with the most difficult and risky part. It's necessary to carve a groove with uniform depth on a hardly accessible inner wall of the cylinder. The groove should be (thickness of the bottom piece)+(depth of the groove) from the bottom, so in my case 5mm+1,7mm. You can use a drawing compass to draw the line:

The groove can be cut with a small knife or a gouge. It will not be perfectly horizontal but it doesn't need to be. It is better to cut the groove slowly with several turns. You can draw a line on the blade with a thin marker as far from the tip as the depth of the planned groove, so that you don't cut deeper than necessary.

Draw a few pencil marks as far from the thin groove as the depth, towards the bottom of the cup. Then take a small pocket knife or a 3mm carving gouge and cut diagonally at 45 degrees towards the groove. Also this can be done slowly and gradually. The groove will show you exactly when to stop cutting.

When the groove is ready, prepare material for the bottom - a straight plank of softwood (spruce or pine) at most 0,5 cm thick. Softwood can be compressed a little, so the risk of cracking the cup while drying is lower.
Trace the inside of the cup onto the board and add a guide line on both the cup and the bottom, so that you know how exactly to fit the bottom back. Add another line around it using the same distance as the depth of the groove.

Cut the bottom with knife or saw. If the bottom is too wide somewhere, sand it off with coarse sandpaper, because it's easy to cut off too much with a knife. Then cut away the lower corner by 45 degrees. The bottom should look like this:

Put the cup (without the bottom!) into a pan with water and boil it. Then turn off the cooker and weigh down the cup so that it is submerged. Porous woods will soak quickly while dense and hard woods will take longer time. Some pieces will be ready in 10 minutes while others (like fir burls) must be boiled for hours.
Pull the cup out occasionally, dry it and try to put the bottom into the cup. Use the guide lines to align it properly. If the bottom seems just a tiny bit larger than necessary, then it is in fact the right moment. Put one end into the groove and use brute force to push the other end in. If you do it right, the bottom will snap in nicely and loudly.
(If you were not lucky and the bottom split, you can still carve another and have a second try.)
Wrap the cup into a piece of cloth or paper and let it dry slowly. Check the drying cup from time to time.

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