Nice offer Larry!! I love the family of woodturning!!
Thanks very much Mark. Yes, PM me and we can get a set out to you.
Yeah - Threads could be *cut* into just about anything.. The question would then be if they will hold up/ last/ stay in place... CA glue is often used to harden up / stiffen wood fibers so they don't fragment into pieces while cutting threads and could be used for hand chased threads as well. From what I have seen/viewed/read a harder, more densely grained species is preferred for thread chasing simply for the reason that the wooden threads don't break off while they are being formed (so they stay looking pretty) otherwise you may end up with jagged raggedy looking threads that can jam up on each other if the lid is just a tiny bit too tight fitting (wood movement) and essentially rip out all the threads in one go with the next twist of the lid. So, I would suggest that species itself is not the important thing, it is the condition and quality of the wood into which threads are being cut - You'd have far better threading results in hard maple than you would in red or white oak, even though oak is the harder wood - because of the nature of the wood's grain (diffuse porous maple vs ring porous oak)
That will definitely help account for the annual movement caused by the changes in humidity in our heated homes, if you allow extra clearance.
True. My understanding is that the positive rake provides for a cleaner cut in woods but that the angle differs depending on use (crosscutting, ripping, etc). And I imagine you won't want to use a positive rake blade cutting metal for safety's sake? Not a metal guy so I don't know anything about that subject.
Tapping threads is just screwing in a tap and backing out again, so no relief. Chasing threads on a wood lathe requires a relief area for the end of the cutting action. It provides a stopping point for the tool. Without it, it might try to keep feeding deeper. You could use a jig with no relief, since you're just backing out again, but the finish point might not be so clear.
So maybe I'll give this one a go and since I plan on using some pretty hard wood for some smallish boxes, or maybe adding a slice of hard wood to some just for threading (and contrast). Thanks John!
Here is an alternate to threading just turn about 5 to 10 degrees and lift off.
Segmented buckthorn with a walnut finial
Clever and very well executed. I honestly don’t know if I have the skills to do that.
Curious how you made the slots for the top dowels to fit into.
I mounted a small right angle pneumatic die grinder on my Delta cross slide with the top slide set to operate as the X axis and the Y axis used to center on the lathe bed. The index on the lathe is used to hold the work piece in place as you advance the bit into the work piece against a stop then remove the index pin and move the work piece by hand about 10 degrees, shut down the die grinder, move the piece back to the index point and back the die grinder out of the way. Move to the next index position and repeat. The size of the opening needs to be big enough to accommodate the die grinder and on the pictured vessel the opening is 3.875" ID.
My favorite type threaded lid is a single turn, same as a peanut butter jar. I use 4 TPI bottle threads cut on my CNC. Bottle threads are more tolerant of a loose fit to compensate for wood movement than 60 degree vee threads. AFAIK nobody makes a conventional threading jig with that coarse a pitch. Use the search function to see some samples.
I have turned several urns, salt shakers and other pieces that require a screw-on lid. I have used black or white PVC screw-on fittings, which are available in several sizes. PVC is easily turned on a lathe. A collar and a matching plug can be integrated into the turning to provide the desired joint. The PVC can be hidden or shaped to produce a contrasting feature. Urns and many other containers generally do not require a large opening for filling so very large fittings may not be required.
