This post is meant to assist novices or people who have not made a lot of pepper mills using this mechanism. I use this mechanism that has an aluminum 5-sided shaft because with this mechanism a knurled knob is not required on the top of the piece. These comments assume that the general directions furnished with the pepper mills are used for drill sizes and depth of drilled hole. See other pepper mill post for photos of examples.
Use of Salt:
The Crush Grind mechanism, made in Denmark, has a ceramic grinding element that should work well grinding salt as well as pepper and spices. I have had one returnerd, however, and what I saw was that rock salt was being used. The large pieces of had salt must have lodged into the grinding mechanism, caused the shaft to bind or freeze up and any hard turning of the top section may have stripped the plastic pentagon-shaped receptacle. The mechanism has two parts.
The part for the top section of the mill has three prongs that have to be compressed slightly to fit into the 7/8″ hole that needs to be drilled at least 1-1/4″ deep. If the shaft is trimmed to project more than 1-1/4″ above the bottom section, this hole in the top section needs to be correspondingly deeper. If the top will not meet up with the bottom section when pressed down on the shaft, it may be that the hole is too shallow. The top is a friction fit over the shaft from the bottom section, and removing the top is a pulling action that will tend to pull the upper mechanism out of the hole it is placed in. This is where a slot cut in the wall of the hole will help. If the slot is positioned just right, the three compressed prongs will expand into the slot, making it extremely difficult for the top section to be pulled from this insertion hole. A tool is now being sold to make this slot in the top section. Alternately, you can make your own–see the photo provided.
If there is too much friction or if the shaft is frozen, the shaft may strip the hole as described above or the entire top mechanism may spin. On softer woods, the vertical fins on the top mechanism do not have to be cut or shaved off. This will help to stabilize the top section in the hole. For added insurance, I use epoxy glue placed in the hole before the top mechanism is inserted. Using any kind of glue with a plastic-to-wood connection can be problematic, but it makes me feel that I am doing all that I can to make the mills work well.
The top mechanism sits proud of the bottom of the top section, functioning like a tenon when it fits into the hole drilled for the bottom section. This fit must be snug while the top can spin freely. Too loose a fit and the top section will wobble in the too large hole. To compensate for the possibility that the exact size hole will be too large because of drill bit wander, I use a 1″ diameter bit and after the hole is drilled, use a small gouge to enlarge just the top 1/4″ of the top of the drilled hole in the bottom section and “dry fit” a top section in the enlarged hole to test for snugness.
The bottom mechanism fit must overcome a small ledge formed when the bottom hole is stepped down to a smaller hole. This is a tight fit and it helps to grind down the two compressible tabs on the bottom section a bit, so when the bottom section is pressed into the hole, the mechanism is not prevented from insertion by this ledge. I use a Beal Buff extension tube between the headstock and tailstock to aid in pressing the bottom mechanism into the holes drilled in the bottom section. On the headstock, I use a chuck that when closed, will permit the hole of the bottom section to fit over the closed jaws, and the shaft will still be able to extended in the hollow of the closed jaws. This is easier shown and done than explained. A slot can also me made for the two compressed tabs in the bottom section, but the bottom mechanism and shaft is in no position to be pulled out when overcoming the friction fit of the top section when it is removed.