Tuning Reg stacks

[bchannell]

I watched an older Ernest Rowe video on the Imp Mk2 w/pp and he was using 3 different thickness washers in a strange stack. He used .38-.45 and .55
Stacked
)()()()()()(

In this order
.55 .55 .45 .55 .45 .55 .45 .55 .38 .55 .45 .55

Now this brings up many questions.
1) disregarding the two end washers, as long as the pairs stay the same, the placement of the .55 .38 pair doesn't matter?

2) the use of one .38 seems meaningless. By that I mean, even at moderately low pressures the .38 will flatten completely. I can't imagine another .45 would change it much?

3) the .45s would take a lot of the travel and the the .55 kick in that could be good in making adjustment less finicky.

4) the reg would have lots of travel

One thing to remember is the .45s do not go completely flat before the .55 start moving. Same with the .38, but by the time the .55s move, it is surely flat.

I don't understand what is gained by two thicknesses, other than spacing vs travel of the entire stack. Is all this just to fine tune the length of the stack and not much else?

I'm trying to learn spring stack theory, are my observations correct?

 

[MongooseV8]

I think most people that measure washer thickness try to get all the same thickness, or at least pair them together.

Which video of E.Rowe are you referring? I know at least one video he is just experimenting with washers and doesnt actually advocate people mix-n-match thicknesses.

 

[bchannell]

Here's the vid, it's for an M4, my typo above, but anyway.
He says it's the best stack he's found
He's the master of airguns, and I in now way am saying anything bad toward him, just trying to learn from an engineering standpoint how these washers would work.