- Joined
- Dec 18, 2019
- Messages
- 7,295
Being the stubborn guy that I am, I thought I could duplicate a high pressure air fill probe that I have. The probe needs to be capable of dealing with 350 bars of pressure, which when you think about it, is a heck of a lot. Designed something up in FreeCAD and thought I was good. Then I stared at the design and decided to make some changes. I was going to use a parting blade to form the o-ring grooves and thought better of it. I'll be making a rounded groove for the o-ring to reduce the chance of stress risers. I also changed some of the internal wall thicknesses to make them a little bit thicker.
First is V1.
Then V2
Not quite sure what to do with the o-ring depth at the moment. I'm going to have to play that by ear.
Decided to make this piece out of 1144 steel, rather than 303. Both machine pretty well. Anyways, this is what I have done so far.
Piece on the bottom is what I am trying to duplicate. The body is about 7mm and 8mm. I used some sharp MoMax to shave down the steel, taking small cuts to reduce the deflection. My tail stock is centered, sort of kind of, for larger pieces but at these diameters, it's not centered enough. So this is with the part sticking out in the breeze. (About 4:1 stickout). You can see the bur I raised when reducing the diameter to 6.95mm. Functionally, I don't think it matters, but I'll knock it down.
I managed to get it to fit the female Foster fitting very snugly so that's good. Like no wiggle at all.
Now I need to grind some rounded o-ring groovers. I designed it to be 0.9mm radius. Have some HSS that I will use. The o-rings are NBR90 1.5(CS) x 4(ID), pretty small. Not shown, but already done, is a 1" deep 3/32" diameter hole. Had some excitement with that. My first piece I broke a drill. This is the second piece. Once I used a known good new drill, and peck drilled, it was no problem. Besides messing up the turning, the last tough thing is drilling the cross hole. It's only 1mm in diameter. I'll attempt to mill a flat, and spot it, then attempt drilling the hole. I bought three drills... I hope I don't have to make this piece over again. I get the idea of doing the hard stuff first, but this hole is intimidating.
First is V1.
Then V2
Not quite sure what to do with the o-ring depth at the moment. I'm going to have to play that by ear.
Decided to make this piece out of 1144 steel, rather than 303. Both machine pretty well. Anyways, this is what I have done so far.
Piece on the bottom is what I am trying to duplicate. The body is about 7mm and 8mm. I used some sharp MoMax to shave down the steel, taking small cuts to reduce the deflection. My tail stock is centered, sort of kind of, for larger pieces but at these diameters, it's not centered enough. So this is with the part sticking out in the breeze. (About 4:1 stickout). You can see the bur I raised when reducing the diameter to 6.95mm. Functionally, I don't think it matters, but I'll knock it down.
I managed to get it to fit the female Foster fitting very snugly so that's good. Like no wiggle at all.
Now I need to grind some rounded o-ring groovers. I designed it to be 0.9mm radius. Have some HSS that I will use. The o-rings are NBR90 1.5(CS) x 4(ID), pretty small. Not shown, but already done, is a 1" deep 3/32" diameter hole. Had some excitement with that. My first piece I broke a drill. This is the second piece. Once I used a known good new drill, and peck drilled, it was no problem. Besides messing up the turning, the last tough thing is drilling the cross hole. It's only 1mm in diameter. I'll attempt to mill a flat, and spot it, then attempt drilling the hole. I bought three drills... I hope I don't have to make this piece over again. I get the idea of doing the hard stuff first, but this hole is intimidating.
