JSAR SS Valve is better than ever!

[nervoustrigger]

Continuing to research and brainstorm…
 
I ran across this article https://www.parker.com/literature/O-Ring%20Division%20Literature/Static%20Files/frictionestimation.pdf which ranks O-ring friction (whether break-out or running friction) factors in order of importance:
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TABLE A6-1 FRICTION FACTORS (IN ORDER OF IMPORTANCE)

Code: [Select]

TO INCREASE FRICTION       FACTOR                     [b]TO DECREASE FRICTION[/b]
 
Increase                    Unit Load (squeeze)        Decrease
Increase RMS                Surface Finish (metal)     Decrease RMS
Increase                    Durometer                  Decrease
Decrease                    Speed of Motion            Increase
Increase                    Cross Section of O-Ring    Decrease
Increase                    Pressure                   Decrease
Omit                        Lubrication                Use
Decrease                    Temperature                Increase
Decrease                    Groove Width               Increase
Increase                    Diameter of Bore or Rod    Decrease
Decrease                    Surface Finish (O-Ring)    Increase
Stretch O-ring              Joule Effect*              Compress O-Ring
Lower Durometer of O-Ring   Coefficient of Friction#   Increase Durometer
* Refer to rotary seals.
# A minor factor and should be ignored in design work other than for ultra high speeds
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Of particular interest is the coefficient of friction being at the bottom of the list so I guess we can shelve that idea.  However I see a few things in the top half of the list that are feasible to try:
 
1.       Polish the walls
2.       Reduce the durometer (may require backup ring or tighter tolerances to prevent extrusion failure)
3.       Use an O-ring with smaller cross section (obviously that means fabricating new parts, or perhaps some industrious person could fill the groove with J-B Weld and grind a shallower groove).
4.       Use lubricant.  Parker has a product called Super O-lube that is touted to alleviate stiction.  The MSDS says it’s dimethyl siloxane based so it’s some sort of silicone lubricant.  Is there a secret ingredient in the sauce, I don’t know.  I would use Super Lube (the oil #51004, not the grease) because it’s slick and I have a bottle

[triggertreat]

Very interesting Jason.  We are dealing with 1mm O-rings now so not much to work with on surface tension to begin with.  I'm still in favor of the correct lube and a hard hammer strike.

[Motorhead]

Very interesting Jason.  We are dealing with 1mm O-rings now so not much to work with on surface tension to begin with.  I'm still in favor of the correct lube and a hard hammer strike.

No so much HARD But FAST ... being the valve opens easy enough, it just seems to prefer a fast slap than a more gentle nudge.

[oldpro]

 Keith Im sending you the heavier(40G) Buffer Hammer it will almost eliminate the Stiction.

[nervoustrigger]

Yeah regarding a smaller cross section, I agree.   Not desirable to leave the realm of common off-the-shelf sizes but that design element ranks high on the list so I didn’t want to dismiss it.
 
http://www.applerubber.com/products/microrings/
What is a MicrOring® Seal?
As a general definition, a MicrOring® seal is any O-ring that measures less than 1 mm in either inside diameter or cross section.  Apple Rubber offers MicrOring® seals in more than 2,000 sizes…
http://www.applerubber.com/src/pdf/microrings.pdf
 
 

[triggertreat]

Keith Im sending you the heavier(40G) Buffer Hammer it will almost eliminate the Stiction.

Thanks Travis, you did remember.  Looking forward to that.


I wonder how FP-10 would work.  It's not affected by temps and doesn't require being shaken before use.  I know it is slick stuff.  I'll probably clean the poppet and try this once the hammer arrives.

[shorty]

I'll throw this out there. I have been working on some really neat thin film coatings. This morning I coated some of my concept valve parts.

The coating trial was to see if I could coat the ID of a part. It works 

The idea would be to have a smoother surface and lower COF between brass to o ring.

These pic's of the parts are under high magnification. The ID of the sleeve id .25" and on the piston is .08". What a beautiful coating.

and another good article on dynamic o orings situations.
https://www.physics.harvard.edu/uploads/files/machineshop/epm_oring_handbook.pdf

[PCPhack]

Brass can be grabby anyway, so I like the idea of the friction surface being something slicker.

[mann]

What about HBNR are they harder or softer  and do we want harder orings or softer the chart has me confused

[oldpro]

I'll throw this out there. I have been working on some really neat thin film coatings. This morning I coated some of my concept valve parts.

The coating trial was to see if I could coat the ID of a part. It works 

The idea would be to have a smoother surface and lower COF between brass to o ring.

These pic's of the parts are under high magnification. The ID of the sleeve id .25" and on the piston is .08". What a beautiful coating.

and another good article on dynamic o orings situations.
https://www.physics.harvard.edu/uploads/files/machineshop/epm_oring_handbook.pdf

 Tim you have the correct approach the issue has to be addressed at the thimble not the poppet. I have tried a variety of orings and lubes and the only way around it is to just waste the first shot or use our buffer hammer and hit it fast. I was told that a thin film Teflon coating would wear out quickly under those pressures and have looked at parleen and Diamond coating also. 

[shorty]

The coatings I have been working with is a nano ceramic suspended in a polyurethane. Today I also added a sub micron PTFE dispersion to it.

Although,
I do have a PTFE coating made for aluminum and stainless that uses a chromic/phosphoric accelerator to maximize adhesion and hardness of the PTFE.  Problem is, it is extremely hard to deposit on an ID as a very thin conformal coating. Super slick and great adhesion though.

It's not your ordinary PTFE coating.

It was just a thought.

[mann]

So my mds hammer with peek striker that I can run recessed weighs about 35 grams and hit it hard and fast . Should I polish the thimble up too

[oldpro]

So my mds hammer with peek striker that I can run recessed weighs about 35 grams and hit it hard and fast . Should I polish the thimble up too

Only if your not taking material away from thimble

[mann]

I'll use a q tip and real fine metal polish that I have it doesn't seem to remove any material as long as I don't use a Dremel

[Motorhead]

When it comes to breaking "Surface Tension" a microscopically rough surface such a crosshatch has less drag than a polished one.

[triggertreat]

When it comes to breaking "Surface Tension" a microscopically rough surface such a crosshatch has less drag than a polished one.

That's true.  The reason dimples are on golf balls sorta thing.

[Rallyshark]

When it comes to breaking "Surface Tension" a microscopically rough surface such a crosshatch has less drag than a polished one.

Yep, it is the same principle with racing slicks, vs treaded tires.  The smooth slicks put more material in contact with the pavement.  I guess the goal here would be the reverse of the tire thing.  You want minimum surface contact required to seal.  I think in this case, the solution will come with finding contact surfaces that can seal, but are in minimal surface contact on a microscopic level.  That along with tuning for a fast strike.  That's my pseudo scientific interpretation  

[triggertreat]

I sure am looking forward to the all new gen 2 SS valve.  Shouldn't be too much longer now, I hope.

[mann]

Is it going to be a retro fit to the old valve or completely new

[triggertreat]

Is it going to be a retro fit to the old valve or completely new

Completely new SSV2.  They made an all steel poppet, and are using peak or something for the seat.  A little different, but should be a good one that won't leak or break.  It's coming in the new Raptor.  Travis said there would be a deep discount for previous SSV1 owners.