Ninja regulator - replacement ball for valve seat

[nervoustrigger]

Hey guys, this is just a quick heads up about a replacement valve seat for Ninja regulators.

If you've had a rifle with a Ninja bottle for a length of time, you may be aware the little ball on the end of the regulator piston will eventually wear and cause the regulator to creep.  If somehow it manages to get bad enough, it may even cause the output pressure to climb high enough to pop the 1.8k burst disk.



It's possible to knock out the ball from behind, flip it over, and reinstall it to get some more life out of the regulator, though eventually it will have to be replaced.  I just received some Delrin replacements from McMaster...100pcs for less than $5.  Here's a disappointing attempt to photograph the OEM ball and the Delrin replacement side by side:



I'm not sure what the OEM part is made of but the color and the way it cuts makes me think it's nylon.  The Delrin part seems to be harder so I hope it will prove to be more durable.  Time will tell.  All I can say at the moment is that it cured a creeping regulator this evening.

[Tater]

Nice fix/upgrade Jason. 

[sb327]

That’s good info!

What size ball did you order?

I’ve made a couple of regs and using a ball would be a lot easier than cutting that tiny disk and getting it to stay put.

Dave

Edit:  4mm ball

[vdwb]

Nice fix Jason. Since you ordered a bag of 100 pc you may have some for sale?
Dennis

[mackeral5]

Hey guys, this is just a quick heads up about a replacement valve seat for Ninja regulators.

If you've had a rifle with a Ninja bottle for a length of time, you may be aware the little ball on the end of the regulator piston will eventually wear and cause the regulator to creep.  If somehow it manages to get bad enough, it may even cause the output pressure to climb high enough to pop the 1.8k burst disk.



It's possible to knock out the ball from behind, flip it over, and reinstall it to get some more life out of the regulator, though eventually it will have to be replaced.  I just received some Delrin replacements from McMaster...100pcs for less than $5.  Here's a disappointing attempt to photograph the OEM ball and the Delrin replacement side by side:



I'm not sure what the OEM part is made of but the color and the way it cuts makes me think it's nylon.  The Delrin part seems to be harder so I hope it will prove to be more durable.  Time will tell.  All I can say at the moment is that it cured a creeping regulator this evening.

Awesome find.  Thank you for sharing.

[Motorhead]

I lathe turn a small cylinder with a semi-round end that replaces the ball ... made from PEEK
Makes for one snappy reset reg and zero creep.
Same deal finding the OEM ball WAY TOO SOFT wearing and set point drifting Way Too Much.

Nice fix !!

[oldpro]

 The ninja ball is nylon and will deform also if you use high pressure output on your regulator. One other mid I do is open the bleed hole in the regulator up to allow quick refresh for the high power guns that pull a lot of plenum air.

[nervoustrigger]

Hi Scott, I remember you saying you’ve rebuilt them with a PEEK seat.  I’m going to try that one day when I’m feeling unjustifiably confident so I can get knocked down a peg or two!  I don’t know, maybe with such a small seat it won’t be too hard to get it to seal.  I’ll have to look into how to part off a piece that small.
 
By the way I forgot to mention that I went ahead and lightly polished the face of the orifice down inside the regulator body in case it was contributing to accelerated wear on the ball.  I don’t think it was…the original ball actually looked decent under magnification.  It was just imprinted very slightly and uniformly.  Based on others I’ve inspected, I would not have expected it to creep like it was doing but clearly the two surfaces weren’t happy with each other.
 
I’ll report back sometime down the road on how well the Delrin holds up over time.  Meanwhile I can only say it’s working better than expected.  I figured it would need a break-in period but it appears to have settled in with nothing more than the handful of sho I needed to dial in the hammer spring tension over the chronograph.

[nervoustrigger]

Dennis, send me a PM with your address.

[nervoustrigger]

Travis, thanks for confirmation on the nylon.

FWIW, this regulator had been running at just 1100psi and it had maybe 1500 - 2000 pellets through it when it began creeping. 

[nervoustrigger]

A follow up observation…the creeping had prompted me to twiddle with the hammer spring tension in an attempt to minimize the first shot variance.  Apparently that placed it up near the velocity plateau and efficiency had gone out the window.  I could sorta tell by the muzzle report but I wasn’t aware of how bad it had gotten.  After replacing the ball and getting the regulator set back to the original pressure (1100psi), the shot count has almost doubled and it’s back to its very pleasant demeanor.
 
Also according to the following resource, Delrin (acetal homopolymer) has a compressive strength twice that of Nylon 6/6 (16,000psi vs 8,000psi at 10% deformation) so hopefully that will translate into substantially better longevity.  We will see.  Meanwhile this will become a standard upgrade/service item any time I have a Ninja regulator opened up.  Four cents for some peace of mind.
 
https://www.polytechindustrial.com/products/plastic-stock-shapes

[oldpro]

 Jason fantastic write up and explanation!

[YEMX]

I am certainly glad for this post!!  I've got a Ninja (and clones- we'll have a look-see) reg I can upgrade, as it will see relatively high output pressure for most of it's life.  Nervoustrigger- any chance I could buy some of those Delrin balls from you?

[nervoustrigger]

Thanks Travis, I just hope it helps someone solve a fairly common and frustrating problem.  Right now my sample size is just 1 so I don’t want to get too excited yet.

Tom, just PM me your address.  FWIW, I’ve tried at least half a dozen clones and all had a flat seal.  If memory serves, the pocket is too shallow to accommodate a ball.  However they will generally accept a Ninja piston (from the $15 rebuild kit) if you’re so inclined. 

I usually flatten and smooth the seal on the clones and they do well after that is done.

[Mr. Panther]

Excellent information Jason +1

[nervoustrigger]

One thing I should mention for the sake of completeness:  it’s entirely possible that swapping to a harder material may make creeping worse.  Fundamentally, creep is just a situation where air slowly seeps through microscopic imperfections in the valve seat.  Eventually the pressure will rise to the point it squishes the seal against the seat and completely halts any further transfer of air.  So if a hard seal can’t compress to conform to the seat, creeping may get worse.
 
What that means is, both surfaces need to be high quality.  The Delrin balls from McMaster appear to have a very nice, uniform finish when viewed under magnification so I don’t think they will be a contributor.  Just take care to not to damage the business end of the ball when pressing it in.  It takes a pretty good bit of force to pop it in.  The way I do it is to trap the ball against a piece of wood (clean and flat) and give the opposite end of the piston a sharp tap with the butt of a plastic screwdriver handle.  Don’t do it on your lovely dining room table because the ball is likely to leave a dent.  That’s what we want, the wood absorbs the abuse so the ball retains its shape.
 
That leaves the part it mates to, the orifice down in the regulator body.  It needs to have a similarly high quality finish.  This is a machined part so there is an opportunity it will have concentric machining marks and/or surface scratches.  The good news is, Ninja seems to take care in this critical area from what I’ve seen.  But just be aware of it and give it a close inspection with a 5x loupe or something similar while you have it apart to swap the ball.

[nervoustrigger]

A post from John/fuzzygrub yesterday reminded me about this topic.  I've since swapped to the Delrin in 3 other rebuilds and they all worked great straight away.  It will be a while though before I get a sense of how much longevity is improved.
 
Meanwhile I also took apart a couple of generic regulators that had begun to creep.  Sure enough, the seats were clearly worn when viewed under  magnification.  Unfortunately neither of them is designed to accept a ball seat like Ninja, and well...not really designed to be replaceable at all based on how tenaciously they were held but I managed to get them out without damaging the piston.  Then I turned a couple of PEEK stubs per Scott's suggestion and pressed them in and polished them out to 7000 grit.  They now come up to the setpoint quickly and stabilize.
 
The job is certainly easier with a lathe but I'm pretty sure it can be done with a drill press if you take care.  Then make a simple jig for sanding (flattening) the sealing face.  Take a piece of wood approx 3" x 3" x 1" and drill a hole in the center that matches the narrow portion of the piston.  Pass the piston through it and use it as a guide to sand it against a piece of sandpaper glued to a flat surface.  Rotate the piston on occasion as you go to account for any play or lack of perpendicularity in the drilled hole.  Worst case, you'll end up with a face that is ever so slightly convex but symmetric about the center of the circle so it will seal fine against the orifice.

[mackeral5]

This is a great post, thank you for blazing the trail then giving us all a map.  I have used the McMaster delrin balls on 2 regulators thus far.

[Motorhead]

PEEK IT ... LOL 
 Those regs done with the material are still stable and creep free. if you can get the prep and surfacing correct the reset is snappy and stable.

Good job on revisiting this modification 

[Blutroop]

What kinds of polishing compounds and/or sandpaper are y’all using?