It is raining today, so I decided to try to thread some 1/2 inch 304 rod that will be used to hold the carronade carriage together. A couple of machinists told me I would need a lathe to do it. I don't have a lathe, so I had to do it without one.
When I threaded the 3/8 rod for the 1" Brooks barrel, I knew I was at the limit of a typical threading die wrench. I came close to bending it. I also had issues getting the thread to start straight. If it doesn't start straight, the thread will not be concentric with the rod and evetually it will push metal outside of the diameter of the rod, at which point you can't really thread it any more.
So, I made a new threading die wrench with more beef and a guide to start the threads straight.
Here is how it works...
First, I tapered the end of the rod to make it easier to start the die onto the rod.
Then I welded two beads on top of the rod about 45 degrees apart and there is also one more that goes on the bottom about dead center to make it possible to actually hold the rod in a vise.
Without the weld bead the rod will just spin in the vice. The beads will get ground off later after the threading is completed. Since this part of the rod is burried inside of the wood, a little impefection will not be noticable.
Here is the home-made threading die wrench, made out of a 1/2 inch drive deep socket and a 1"x2" rectangular tube about 4 feet long for plenty of leverage. There is a hole drilled in the tube to accept a 1/2 inch bushing. The 1/2 inch bushing will accept a 3/8 inch busing and that will accept a 1/4 inch bushing, so it will fit more than one size of rod. The bushing makes the cut start straight.
Start the die by applying just a little force on the threader handle, and tap the die with a soft hammer. If you are applying the correct amount of force, the die will only turn when you tap it. You will have to do this routine for at least the entire first turn. Back off every 1/4 turn to clear the threads, and use plenty of oil.
Once the hammer is no longer needed, work the die in and out only a few degrees at a time. Every quarter of a turn or so, back it off a good 1/4 to 1/2 of a turn untill it feels clear of chips. When you think you are done, you will find that, due to the taper on the die a nut will stop about 3 threads short of the finish of the threaded area. Unless you want to go three more turns, you can just flip the die over so that the non-tapered end is doing the cuttting. It will cut fine backwards, and you will be able to finish the cut on the last three threads.
Stainless Steel Square nuts from "Bolt Depot"
http://www.boltdepot.com/product.aspx?cc=7&cs=99&cm=6------------------------
Changing subjects a bit... look what came back from the machine shop this morning... thank you Jamie from Westfield Tool and Die.