Thoughts on this.
Using delrin for the valve-body. Obviously it’d be the thread taking the force of 3000psi. Reckon the material is strong enough?
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As MM mentioned…
…You can, just not by much without changing the characteristics of the thread.
Larger radius = Shallower thread or different thread pitch. Either will require a modification of the part it mates too = More work than it is just to make the part from a suitable material in the first place.
Why cant you round off the tip of you thread cutter so that you dont have the sharp corners at the bottom of the thread?
I’m imagining a 1200-pound weight hanging from a valve anchored in a bottle. You’ve got me worried about brass now. 😆
I build some valves with large stem diameters.
That cuts down on the cross sectional area of the material that threads into the bottle.
I even worry about the streingth of the brass.
When you cut threads, the sharp corrner at the root of the thread forms a ” stress riser”. Any sharp corrner in a stressed area cuts down on the effective streingth of the material.
“Stress risers ” can cut the effective strength of the material by a factor of 2 or more.
You avoid “stress risers” by using a radius, but you cant radius the root of the thread very much.
I worry about the streingth of the threaded end that screws into the bottle. I always calculate the cross sectional area and apply a big safety factor.
Theres 1200 pounds of force trying to push the valve out of the bottle!!
Mark
I think the tinsle streingth of the plastic is half of the brass.
Brass is a proven material for this application.
Also, does the delrin get brittle when it gets cold?
Will delrin “creep” under prolonged stress?
Too many questions about its use for high pressure.
I would not like to cut safety factors so low!
Mark
Hand-grenade territory, huh? 😆
It’s hard stuff, but it gives (hammered an 11mm p-t-p nut into a 10mm hole and it formed around it). I think if a thread was coarse and/or long enough it might hold for a while, but unless anyone else has tried it successfully I’ll give it a miss. Twas but a vague idea.
not only no, but HELL NO
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Awwww, c’mon, guys. None of you see Wall-e? That part when he’s outside the big spaceship? Whatcha gonna do when you don’t have a fire extinguisher?