The baker Max flow disco valve

[antithesis]

I'll skip over the fact that they didn't tap the holes for mouning this, it is so far a repurposed 2240 valve with a modded disco cap. That was an error on them and I'm sure Mr Baker will make it right.

But my quandary is the fact that they milled the sealing edge at the front of the throat dead flat. I haven't worked with a flat mating surface for a valve seat yet, and besides cleaning it up more, what kind of approach should I take on a flat seat as far as poppet design goes?  Would my usual mrod or 1377 poppet be ok? Should I go with something other than flat? Concave even like Timmy mac1 once suggest? I'm really got no idea what to do here

[rsterne]

For a flat valve seat, you can either make the poppet face flat or very slightly concave.... either will work fine....

Bob

[antithesis]

In a case like this, since the full closing pressure is being spread out a little more on the valve seat instead of the lip the poppet face normally seals against taking the total force,  do you think I would have a little more trouble achieving a good seal with harder poppets, and maybe do well to try something like a 1377 poppet or similar material as opposed to the mrod poppet or a handmade peek one?

The thing that really shocked me is that they didn't even use a disco poppet, they used a cut off co2 valve poppet....with the brass body and polymer insert. I found this to be remarkably cheap, and the only explanation being that it saved them the time of cleaning up the seat more by using a very soft poppet face material.   I can make all of this work, I basically wanted it for a brass bodied alternative to an aluminum valve, I don't like aluminum valve components due to corrosion, and of course I like the funnel style front cap. But this is pretty shoddy and an excuse to get fast money out of a 2240 valve, and I had honestly come to expect a little more.  If I had at least gotten a tapped body ready to install and a properly milled seat and poppet I could swallow the 50+ dollars..I still have heard nothing and I hope very much they make this right.


Oh one more thing....if I make the poppet slightly concave to increase the pressure  pushing on the sealing area by  decreasing the contact area, would I be increasing the closing force as opposed to making it contact the throat itself...?

Hope Im explaining that right , and I will make an illustration if I'm not..

[rsterne]

Yes, by using a concave poppet the sealing diameter will always be the OD.... However, it won't change when the poppet beds in, unless it is soft enough to bell outwards, of course.... If you use a tapered poppet, to seal on the edge of the throat, I would break the corner so that you don't have knife edge which will bed into even the hardest poppet material until the force divided by the (annular) seat area equals the compressive strength (both in psi) of the poppet material....

Bob

[mackeral5]

Yes, by using a concave poppet the sealing diameter will always be the OD.... However, it won't change when the poppet beds in, unless it is soft enough to bell outwards, of course.... If you use a tapered poppet, to seal on the edge of the throat, I would break the corner so that you don't have knife edge which will bed into even the hardest poppet material until the force divided by the (annular) seat area equals the compressive strength (both in psi) of the poppet material....

Bob

This is fairly straightforward for DIY.  I haven't been able to make concave poppet bases, so this method is my go-to for peek poppets on flat seats.

[antithesis]

Yes, by using a concave poppet the sealing diameter will always be the OD.... However, it won't change when the poppet beds in, unless it is soft enough to bell outwards, of course.... If you use a tapered poppet, to seal on the edge of the throat, I would break the corner so that you don't have knife edge which will bed into even the hardest poppet material until the force divided by the (annular) seat area equals the compressive strength (both in psi) of the poppet material....

Bob

This is fairly straightforward for DIY.  I haven't been able to make concave poppet bases, so this method is my go-to for peek poppets on flat seats.

I am a bit concerned about the wedging effect here.   Any recommendations for a starting angle to use provided I'm using standard ketron 1000 PEEK?

[antithesis]

Yes, by using a concave poppet the sealing diameter will always be the OD.... However, it won't change when the poppet beds in, unless it is soft enough to bell outwards, of course.... If you use a tapered poppet, to seal on the edge of the throat, I would break the corner so that you don't have knife edge which will bed into even the hardest poppet material until the force divided by the (annular) seat area equals the compressive strength (both in psi) of the poppet material....

Bob

This is fairly straightforward for DIY.  I haven't been able to make concave poppet bases, so this method is my go-to for peek poppets on flat seats.

I am a bit concerned about the wedging effect here.   Any recommendations for a starting angle to use provided I'm using standard ketron 1000 PEEK?

Would it be something like an angle that is very shallow almost flat, to minimize encroachment of the center of the poppet face protruding into the air flow?

[rsterne]

I would suggest you ask Motorhead, he uses slightly tapered PEEK poppets....

Bob

[Motorhead]

I would suggest you ask Motorhead, he uses slightly tapered PEEK poppets....

Bob

Only when i know the throat is concentric to the stem hole.  if the TIR ( total indicated run out ) is not dead nuts it won't seal. In those cases a slightly concave angle on poppet head on seat side works better which places the sealing margin at poppet heads O.D. rather that throats I.D.   Sealing to throat OPENS EASIER than Sealing at poppet O.D. ... just a matter of area.

[antithesis]

I would suggest you ask Motorhead, he uses slightly tapered PEEK poppets....

Bob

Only when i know the throat is concentric to the stem hole.  if the TIR ( total indicated run out ) is not dead nuts it won't seal. In those cases a slightly concave angle on poppet head on seat side works better which places the sealing margin at poppet heads O.D. rather that throats I.D.   Sealing to throat OPENS EASIER than Sealing at poppet O.D. ... just a matter of area.

Scott,

Pm sent but then I saw this so disregard

[mackeral5]

Yes, by using a concave poppet the sealing diameter will always be the OD.... However, it won't change when the poppet beds in, unless it is soft enough to bell outwards, of course.... If you use a tapered poppet, to seal on the edge of the throat, I would break the corner so that you don't have knife edge which will bed into even the hardest poppet material until the force divided by the (annular) seat area equals the compressive strength (both in psi) of the poppet material....

Bob

This is fairly straightforward for DIY.  I haven't been able to make concave poppet bases, so this method is my go-to for peek poppets on flat seats.

I am a bit concerned about the wedging effect here.   Any recommendations for a starting angle to use provided I'm using standard ketron 1000 PEEK?

Would it be something like an angle that is very shallow almost flat, to minimize encroachment of the center of the poppet face protruding into the air flow?

Wedging is a real concern--it can happen if the 2 sealing surfaces are too close to being parallel to each other.  Also the what Scott mentioned about throats being perfectly centered on the stem, this is critical for easily achieving a seal.  for example, if you drill out a throat with hand tools, in many cases the throat moves off-center due to the valve exhaust port.   it is possible to move the sealing surface a bit when cutting the angle on the mouth of the throat.  Challenging, but not impossible to do.  it is best to not have to do this, by maintaining a throat that is centered on the stem...

[antithesis]

Yes, by using a concave poppet the sealing diameter will always be the OD.... However, it won't change when the poppet beds in, unless it is soft enough to bell outwards, of course.... If you use a tapered poppet, to seal on the edge of the throat, I would break the corner so that you don't have knife edge which will bed into even the hardest poppet material until the force divided by the (annular) seat area equals the compressive strength (both in psi) of the poppet material....

Bob

This is fairly straightforward for DIY.  I haven't been able to make concave poppet bases, so this method is my go-to for peek poppets on flat seats.

I am a bit concerned about the wedging effect here.   Any recommendations for a starting angle to use provided I'm using standard ketron 1000 PEEK?

Would it be something like an angle that is very shallow almost flat, to minimize encroachment of the center of the poppet face protruding into the air flow?

Wedging is a real concern--it can happen if the 2 sealing surfaces are too close to being parallel to each other.  Also the what Scott mentioned about throats being perfectly centered on the stem, this is critical for easily achieving a seal.  for example, if you drill out a throat with hand tools, in many cases the throat moves off-center due to the valve exhaust port.   it is possible to move the sealing surface a bit when cutting the angle on the mouth of the throat.  Challenging, but not impossible to do.  it is best to not have to do this, by maintaining a throat that is centered on the stem...

I still have all intents on making my own stem and slightly concave poppet for this, but Mr Baker did contact me and established that I did in fact get the co2 valve.

NOW I'm not one to tell the man about his job, but the factory 2240 screw still don't seem like enough for bulk fill co2 to me.  I didn't mention that but is my logic sound in believing you need additional reinforcement even with tube bulk co2, without me going to crunch the numbers?

[rsterne]

I agree, bulk fill on CO2 should not be used with the stock factory screw, IMO.... Remember that at 120 *F the pressure if CO2 is about 1800 psi.... Leave it in a hot car, and the loads are similar to a Disco on HPA.... and need the same three 8-32 screws....

Bob

[antithesis]

I agree, bulk fill on CO2 should not be used with the stock factory screw, IMO.... Remember that at 120 *F the pressure if CO2 is about 1800 psi.... Leave it in a hot car, and the loads are similar to a Disco on HPA.... and need the same three 8-32 screws....

Bob

Even with one 8-32 would be better than that &^^& one crosman uses. ..and still not enough imo. ..if any of you numbers guys wanna join in and establish the safety margin of one 8-32 screw and potential shear force with warm co2?

I can never find a vapor pressure diagram for co2, despite it being a refrigerant gas and I used to work in HVAC.....I can't find the info anywhere

[rsterne]

Filled to 100% of capacity by weight, 1900 psi at 120 *F.... That is why CO2 tanks are rated at 1800 psi, and have a 3K burst disc fitted.... Here is a link to an actual test of the stock Disco 8-32 valve screws....

https://www.gatewaytoairguns.org/GTA/index.php?topic=72672.0

Bob