Mini QDV pilot
Posted: Sat Oct 31, 2009 7:03 am
Well I am making a fairly small QDV as a pilot. I have thought of two ways of doing so, i have no pictures as of yet, nor do I have diagrams. I tried two things both having failed i will describe these briefly:
Failure one: I drilled a hole into a 10mm threaded rod and then tapped M10 threads into two pieces of alli, that had an OD of 13mm. I tried brazing these to a piece of pipe with an ID of 13mm using special alli braze. One side came out nicely, the other too too much heating melting and deforming the pipe.
Failure two: I wanted to use a similar concept but with threaded parts all the way through. I tried using an 8mm threaded alli rod that could have two spacers on either end that were to be threaded with M10 threads and have inside threads of M8 so that the rod with the hole would be threaded into them and they in turn would be threaded into a pipe with M10 internal threads. This failed because i drilled a hole too large(i didn't want to make a piston under 5mm, thats too fiddly) and so the walls of the threaded pipe twisted of in the threading process.
Now I will try version two again but with larger pipe. The problem is that i only have threading apparatus up until M10 and so i though i could do the following:
Take a threaded rod, alli or steel, and turn down the middle until it is 7 or 8mm in diameter, then drill a hole of 5mm down the middle and cut ports in the part that was "hollowed out". Turn the hole thing into an internally threaded pipe(thick walled being preferable) and then putting some kind of fitting there where the hollowed out part with the ports is, to connect ti to the pilot area of my piston cannon. I then make a piston with a diameter of 7 or 8mm, or what ever the diameter of the hole is, put two O rings on it and tada, i have a perfectly working QDV pilot.
Now knowing the parameters of my apparatus i ask for advice and comments to improve on my method. I am sure is better ways to do it to have less fiddly work todo. However I do insist on a QDV as a pilot(perhaps, if it is impossible i will change that a a hammer/blowgun valve.
Thanks in advance, and happy spudding.
Failure one: I drilled a hole into a 10mm threaded rod and then tapped M10 threads into two pieces of alli, that had an OD of 13mm. I tried brazing these to a piece of pipe with an ID of 13mm using special alli braze. One side came out nicely, the other too too much heating melting and deforming the pipe.
Failure two: I wanted to use a similar concept but with threaded parts all the way through. I tried using an 8mm threaded alli rod that could have two spacers on either end that were to be threaded with M10 threads and have inside threads of M8 so that the rod with the hole would be threaded into them and they in turn would be threaded into a pipe with M10 internal threads. This failed because i drilled a hole too large(i didn't want to make a piston under 5mm, thats too fiddly) and so the walls of the threaded pipe twisted of in the threading process.
Now I will try version two again but with larger pipe. The problem is that i only have threading apparatus up until M10 and so i though i could do the following:
Take a threaded rod, alli or steel, and turn down the middle until it is 7 or 8mm in diameter, then drill a hole of 5mm down the middle and cut ports in the part that was "hollowed out". Turn the hole thing into an internally threaded pipe(thick walled being preferable) and then putting some kind of fitting there where the hollowed out part with the ports is, to connect ti to the pilot area of my piston cannon. I then make a piston with a diameter of 7 or 8mm, or what ever the diameter of the hole is, put two O rings on it and tada, i have a perfectly working QDV pilot.
Now knowing the parameters of my apparatus i ask for advice and comments to improve on my method. I am sure is better ways to do it to have less fiddly work todo. However I do insist on a QDV as a pilot(perhaps, if it is impossible i will change that a a hammer/blowgun valve.
Thanks in advance, and happy spudding.