What's the force needed to slide a Spool in a marker?

[Pneumagger]

Right now, in my quest to make a electropneumatic valve for the Automag, I am stuck on a few things. One of which is choice of solenoid - so many options!

Does anyone know what the weight of sliding a spool is? I realize spool weight is variable depending on the design and gun, but here are some facts about mine:

Spool sleeve (bore) Diameter: .20"-.35"
2-3 orings of an unknown material sealing tight enough to hold 200-400psi.

The design should be pneumatically balanced in the open and closed positions, so there will no forces from the pressures. Only forces should be from the friction/tension of orings.

What kind of oring material should I use anyhow? Do you guys think that both a Stainless spool and stainless valve body matreials would work well together?

[fastev]

What kind of oring material should I use anyhow?
We use viton o-rings at work where there is friction between surfaces. They seem to hold up pretty well compared to EPDM and silicone.


Do you guys think that both a Stainless spool and stainless valve body matreials would work well together?
If you go that route be sure to have good lubrication between the surfaces. If you have tight tolerences, and I'm assuming you will, you might run the risk of gauling. Stainless gauls very easily, so it might be wise to use a different material for one part.

[Pneumagger]

We use viton o-rings at work where there is friction between surfaces. They seem to hold up pretty well compared to EPDM and silicone.


If you go that route be sure to have good lubrication between the surfaces. If you have tight tolerences, and I'm assuming you will, you might run the risk of gauling. Stainless gauls very easily, so it might be wise to use a different material for one part.

I'm thinking of having the Spool coated in Tungsten Disulfide. Pretty much the best dry coat lubrication in existance. They claim that lubrication is not required, but I will lube for the orings sake.

Or i was considering using a Brass heat fitted sleeve as the bore...But that could be expensive to produce and not as durable. How would Hardcoat anodized aluminum sliding on itself or Stainless work out? I assume a little better than just stainless on stainless.

Also, what should the surface finish be between the sliding surface while still being economically machinable?