Lout falls into the belleville rabbit hole!

[BallisticBill]

Part II
======
All springs used in this post are equal in every way. This is a washer | plain and simple.

Since series stack increase deflection for the same load would ()()()|||| be a better stack than ()()()()() [assuming relaxed height the same] since the piston movement would be less and therefore recovery would be quicker?????

With the ()()()|||| stack if opening time is reduced would that then mean a higher set pressure for needed for the same muzzle energy because the reg open duration is reduced and therefore air volume reduced?

I will be testing this out at some point but I want to get the current playtime research gun back together and scoped up today for some plinking.

I think your thinking is totally confused, I think.

The recovery and air mass are largely unrelated to the valve lift and dwell over 95% of the lift. The main factors are valve cross-sectional area and how this is limited at the end of the valve stroke.

The reg setting will be unaffected by recovery rate because the total volume of air is determined by relative pressure acting on the piston and on the valve, I.e the static forces at the end of the stroke.

The objective is to achieve a high flow rate, not to change mass of air passed. The best way might be to redesign the valve seat. If you want to improve rate of flow by changing the stack and you can get away with reducing the number of pairs and adding spacers, you would be better off using more, thinner washers. Then the sensitivity to small pressure changes would be increased. Isn't that what you are really looking for... more deflection over the pressure change at the very end of the stroke?

The downside with using fewer or softer washers is more metal fatigue. So it's speed vs longevity, I think.

 

[El Caro]

Particular attention when using stacks of Belville springs must be paid to the total movement you want from the stack which of course must be balanced with its strength. Wound up the stack may still produce the movement required and strength but be close or beyond the deflection maximum of the spring washers. The stack should ideally be made up of single cup to single cup spring washers for long life and consistency over that life.

 

[GUNFUN]

Yes I've had a bad night but I've been thinking . Stop reading now if you have low tolerance for rambling waffle. You have been warned.

I decided it's time I tried to understand bellevilles a bit more. I understand that it is bad news to over flex/deflect but without really knowing if I'm doing that or not apart from early failure of a spring I wanted to think about the load and deflection of mixing spring thicknesses.

My understanding of bellevilles comes from here (I have posted this in several places but thought it best to have the source of my madness here as well):

From that video I get :
Single springs in series ()()()
Increase deflection without increasing load.
One spring will deflect D for load L.
Deflection D is multiplied by the number of springs in series. ( = 1L=1D, () = 1L=2D, ()()()() 1L=8D

Springs in parallel (((
Increase load without increasing deflection.
Spring load L is multiplied by the number of springs in parallel, ( = 1L, ((( = 3L
Deflection D is the same as a single spring, ( = 1L=1D, ((( = 3L=1D or 1L=0.33rD

Parallel springs in series (())(())(())
Increase load and deflection.
Load L is multiplied by the number of springs in parallel, ( = 1L, ((( = 3L
Deflection D is multiplied by the number of springs in series
(( = 2L=1D 0r 1L=0.5D, (()) = 2L=2D or 1L=1D, (())(())(())(()) 2L=8D or 1L=4D,
((()))((())) = 3L=4D or 1L=0.75D

Thinking about mixing thicknesses
I'm using parallel stacking to replace thickness as an analogy that I can quantify in my thoughts.
() 1L=2D
(( 2L=1D or 1L=0.5D
(()) 2L=2D or 1L=1D
If I now apply 1L to this stack ()(()) I think it causes () to deflect 2D and (()) to deflect 1D therefore total deflection is 3D. Providing deflection is not excessive on a single spring this should represent a way of tuning a regulator to a small movement of the piston (fast recovery, low wear characteristics) for a given set pressure value.

Given that I have a bunch of bellevilles of differing thicknesses and a single thickness stack (using the springs in my collection) does not achieve my requirements for set pressure and movement I'm now thinking it's OK to mix spring thickness in the same stack, it may not be desirable but it's what I got available.

If you got here WOW well done! All input on this very welcome.

I went through this stuff finding better disc springs for my HW100 in about 2010.

I calculated the regulator piston force in Nm using the desired reg pressure, that gave me the force required to compress the disc spring stack. Then it was a case of selecting the right thickness of disc springs, it took me days to work it out.
My main concern was having a set of disc springs working in the optimum part of their stroke to ensure consistency and avoid disc spring fatigue.

Disc Spring Information - Springmasters

Disc Springs Characteristics supplied by Springmasters

www.springmasters.com

 

[sagalout]

Glad I asked instead of starting down that hole. Great info everyone, thanks.

 

[Blackmax]

I went through this stuff finding better disc springs for my HW100 in about 2010.

I calculated the regulator piston force in Nm using the desired reg pressure, that gave me the force required to compress the disc spring stack. Then it was a case of selecting the right thickness of disc springs, it took me days to work it out.
My main concern was having a set of disc springs working in the optimum part of their stroke to ensure consistency and avoid disc spring fatigue.

Disc Spring Information - Springmasters

Disc Springs Characteristics supplied by Springmasters

www.springmasters.com

Hi mate, be interested in what configuration you came up with for the HW100?

 

[GUNFUN]

Hi mate, be interested in what configuration you came up with for the HW100?

Hi Blackmax good to hear from you, I'm using the standard configuration (stacked in series and parallel) so I still have the frictional losses although I use copperslip to lube the disc spring faces in an attempt to keep the frictional losses consistent. The change was going to the 0.7mm thick disc springs in the photo below, from playing with the regulator pressure I can tell the disc springs are working in a much better part of their stroke at 85 bar.




Whilst I have your attention Blackmax let me take advantage of your deep HW100 knowledge, what do you think of the new design of the HW100 exhaust valve/breech block with the diecast port insert for better air flow?
I just order this new one and I'm going to do a direct comparison to the old one to see if it is more efficient or even consistent?

 

[Al Stevens]

Particular attention when using stacks of Belville springs must be paid to the total movement you want from the stack which of course must be balanced with its strength. Wound up the stack may still produce the movement required and strength but be close or beyond the deflection maximum of the spring washers. The stack should ideally be made up of single cup to single cup spring washers for long life and consistency over that life.

Yes.

 

[Blackmax]

Hi Blackmax good to hear from you, I'm using the standard configuration (stacked in series and parallel) so I still have the frictional losses although I use copperslip to lube the disc spring faces in an attempt to keep the frictional losses consistent. The change was going to the 0.7mm thick disc springs in the photo below, from playing with the regulator pressure I can tell the disc springs are working in a much better part of their stroke at 85 bar.

View attachment 339762


Whilst I have your attention Blackmax let me take advantage of your deep HW100 knowledge, what do you think of the new design of the HW100 exhaust valve/breech block with the diecast port insert for better air flow?
I just order this new one and I'm going to do a direct comparison to the old one to see if it is more efficient or even consistent?

Hi Gun Fun, good to hear from you too mate and thanks for your reply. I got some British made Belleville washers and tried them in HW100’s, I also got Rapid BT reg replacements. Although they were more consistent dimension wise, it didn’t make any real noticeable difference to the velocity consistency. Although I will say the HW100 has a reasonably generous operating regulator setting parameters.

The Rapid ones worked well and along with machining the correct float into the regulator collar (thanks @bucketboy) gave really good consistency with no input pressure effect.

I’ll message you about the other subject as it’s a different subject to the original post.

 

[DaveP796]

And also perhaps why I spent so much time machining the sodding things to be the same sizes (and this was 1975/6 FFS!).

ATB, ED

Allways keep an eye out for silver linings!

The market for precision spring washers might be about to boom - and you could be the in house Go To guy...

 

[keithy]

FX do tend to mix thicknesses in the stack
I've always used the same washers in the stack as I've thought that thicker springs over work the thinner springs ....

Fac guns have thicker belville's in the reg, maybe thicker washers in a mixed reg stack just shorten the movement of the whole washer stack particularly if used on the ends of the spring stack.

 

[Blackmax]

yet i have 4 gsx's and all came from factory with a top and bottom singular bellevilles that were thinner than the rest. perhaps you just didn't notice

Strange that, as Chris Whistler who owns Impacts Airguns confirmed they’ve only ever used the same size (thickness) Belleville washers in the stack on all their GSX models. I had a chat with him on Sunday and although configurations changed depending on power levels, they always used the same Belleville washers.

 

[Robbo]

Yes I've had a bad night but I've been thinking . Stop reading now if you have low tolerance for rambling waffle. You have been warned.

I decided it's time I tried to understand bellevilles a bit more. I understand that it is bad news to over flex/deflect but without really knowing if I'm doing that or not apart from early failure of a spring I wanted to think about the load and deflection of mixing spring thicknesses.

My understanding of bellevilles comes from here (I have posted this in several places but thought it best to have the source of my madness here as well):

From that video I get :
Single springs in series ()()()
Increase deflection without increasing load.
One spring will deflect D for load L.
Deflection D is multiplied by the number of springs in series. ( = 1L=1D, () = 1L=2D, ()()()() 1L=8D

Springs in parallel (((
Increase load without increasing deflection.
Spring load L is multiplied by the number of springs in parallel, ( = 1L, ((( = 3L
Deflection D is the same as a single spring, ( = 1L=1D, ((( = 3L=1D or 1L=0.33rD

Parallel springs in series (())(())(())
Increase load and deflection.
Load L is multiplied by the number of springs in parallel, ( = 1L, ((( = 3L
Deflection D is multiplied by the number of springs in series
(( = 2L=1D 0r 1L=0.5D, (()) = 2L=2D or 1L=1D, (())(())(())(()) 2L=8D or 1L=4D,
((()))((())) = 3L=4D or 1L=0.75D

Thinking about mixing thicknesses
I'm using parallel stacking to replace thickness as an analogy that I can quantify in my thoughts.
() 1L=2D
(( 2L=1D or 1L=0.5D
(()) 2L=2D or 1L=1D
If I now apply 1L to this stack ()(()) I think it causes () to deflect 2D and (()) to deflect 1D therefore total deflection is 3D. Providing deflection is not excessive on a single spring this should represent a way of tuning a regulator to a small movement of the piston (fast recovery, low wear characteristics) for a given set pressure value.

Given that I have a bunch of bellevilles of differing thicknesses and a single thickness stack (using the springs in my collection) does not achieve my requirements for set pressure and movement I'm now thinking it's OK to mix spring thickness in the same stack, it may not be desirable but it's what I got available.

If you got here WOW well done! All input on this very welcome.

Fecking nutter....love it!

 

[Robbo]

I didn't realise the importance of the size condition, configuration and lube used In the bellevilles regs on shot consistency. My hw100 reg bellevilles were degreased, and put back in standard configuration ()()(), and I think I lubed if with fine graphite or teflon powder. I hadn't got round to removing the antitamper on the hammer spring adjuster but I remember I was getting consistent 11.8fpe using jsb heavies. Although was losing air efficiency when I had the reg adjusted something low like 70/80bar. Never could get better than about 12fps on a shot string. I will have to take a break from springers and revisit the bellevilles and properly measure them.
Thanks for the brilliant thread and expertise

 

[sagalout]

The gun I was working on at the time ended up with ()()()()() all 0.52mm. A gun I stripped the other day had ()()()()()(, 10 at 0.42 and 1 at 0.6. The 0.6 faced the piston shoulder and I assume is only there as a spacer. The reg works extremely well and was only stripped out because the gun has a slow leak I ain't been able to find yet and the reg was the next logical place to look.

 

[Robbo]

Leaks as you know can be anywhere. When I was messing with my 100, apart from the usual small cylinder oring, the next usual suspect was from the place you screw the test manometer into, commonly when the manometer was being used sending me on a wild goose chase. The little washer with inbuilt oring you get with the manometer was to blame. The hw100 servicing replacement screw cap is way better than the crappie oring and ball held in with a grubscrew. Good luck with the search.

 

[Winkmyster]

I have been thinking about Belleville washer stack for some time and came to the same conclusion. You are putting a strong spring and a weak spring in series so the soft spring deflection will be greater initially allowing greater air flow for initially faster recovery in the reg. Nice write up.