new to the trade - need help on ideas

[kyyyyle]

I am new to machining, and was fascinated when I went on a welding field trip to the local JC and visited the machine shop. There is this project I always wanted to get done, but I have no experience what so ever on designing or graphing out a diagram of what the part is going to look like. I am fairly neat with my drawings, but I have never taken a drafting class and don't know how to specifc threads and angles and what symbols to use. Anyways, what I wanted to do is I have this bored out cylinder (steel tube 3" OD and 2 " ID) I wanted to make a cap for one end that threads into the tube / pipe. I wanted to thread the outside of another piece of stock that will thread into it. The thing is I want the top of the cap (maybe like 5 - 10mm thick) to come out flush with the top/end of the tube. therefore, I have to get like a 3 inch long piece of stock (matching the OD of the tube) and then trim down the one end so it can be threaded into the tube, leaving the other end the same diamtere. Make sense so far? I also wanted to machine an allen head indent on the end so it can cleanly be screwed in....is this at all possible. Also, how do you obtain the pieces when determining the threads. You can't just get a 2" piece of stock the slides into the 2" ID of the tube and thread it because the threads will just slide past...that is where I have trouble....measuring and sizing threads...I wanted to have really DEEP and a lot of threads - maybe 40 TPI if at all possible. Any suggestions would be greatly appreciated, and if you want better information on the description above to understand it please contact me ! thanks - kyle !

[ViperTX]

Welcome.....

Draw it up freehand.....what it looks like from the side, end, etc.....

Are you planning on machining it yourself?

Well you most likely won't be using any dies.....so just specify the threads per inch and whoever turns and threads this will know what you want.

So, you have this length of 3 inch tube which I seriously doubt you can find one with an ID of 2 inch.....so, it will be solid stock that is bored out....then you plugging the end and then you're making some type of reducing coupler that will thread on the outer surface of the 3 inch tube and the end is reduced to an OD of 2 inch which be used as the plug for another 3 inch tube....and the purpose of this is ??

[kyyyyle]

no, I am not machining it myself. That is far into the future, but how does the machinist that is doing this for me know how deep the threads will be...is there a certain depth for certain TPI's? I already located a tube that is 3"OD and has a 2" ID. The end cap is described as this, it will screw in with the allen inset on the end and when it is screwed in, there will be a lip on the plug being screwed in so that when the threads meet the end, the end plug will screw in flush with the OD of the tube...so the tube will be internally threade and the plug (not cap) will be externally threaded. The plug will have the threads, but instread of being able to screw it in until the surface goes inside, I want to leave a lip on the plug so it stops from continuing to screw in, and that lip will be the same OD as the tube, so it looks good....does all this make sense?

[kyyyyle]

think of the plug this way, like an allen bolt, but a big one. It will screw into the tube, and when it bottoms out, the OD of the " big allen bolt" will be the same as the OD of the tube it is screwing in to....does that help?

[ViperTX]

Got it...

Well the machinist will determine the depth of the thread engagement based on it's use....usually anywhere from 50 to 80 % depth engagement....

[kyyyyle]

The attatched photo is like the idea I have, only it would be larger in scale. Then this piece would simply thread into an internally threaded pipe. The OD of the head of the bolt would be the same as the OD of the pipe/tube.