Explaining what I want help with is easy. Explaining why I want it is a little more complicated. I'll try to stick with the "what" for now.
I'm looking for a way to create a longer version of the part indicated below. Perhaps as long as 12 inches maybe as little as 6 inches. The very short version of "why" is that I need to create a relatively large elevation change quickly. I try not to reinvent the wheel and this rest accomplishes what I want... just not enough of it.
Any ideas? I don't know if plastic is machinable, but if it is I might be able to stay with the existing rest as a base. If wood or metal is the answer then I will have to have two matching "adjusters" to go with the extension.
Thanks in advance for any help you are able to offer
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin
Your local smith or machine shop should be able to make a large bolt like that. Aluminum would be easy to work with and lighter, but won't withstand a heavy duty cycle like stainless would.
Because it's not your standard 60 deg thread, they may need to grind a tool bit to cut what almost appears to be square threads. But, that's no big deal.
I have a lathe, but not a mill here at the house. You'll need a mill or something to cut the channel for the locking screw. ...assuming that's really required. You could possibly engineer an alternate locking mechanism that won't booger your threads.
Also, one can only speculate about the top of the bolt that the rest affixes to unless you disassemble it and show pictures or a blueprint.
Another option is to replace the bolt with a smooth shaft that's just smaller than the minor diameter of the threads and has holes drilled horizontally through the diameter of the shaft about every 1/2" or so. Then, use a pin to hold the elevation.
You could drill and tap a larger jam bolt to help stabilize it.