Understanding valves [beginner]

[WobblyHand]

I have a 1322 valve that I have taken apart to understand it.  Also am modeling it in FreeCAD.  My apologies, I don't even know the correct terminology yet.  Is there a write up of valves and terminology?  Some kind of primer?  Eventually I want to get to the point of making valves, but one has to start somewhere...  My model doesn't have the Crosman sealing cone, it is a flat top valve.  I really don't know much about this stuff, so please pardon my trivial questions.  I only used calipers to measure things, I will end up using a micrometer to confirm some values, although it is tough to get good readings inside the bore.

First silly question, is the intake air sealing done on the conical part or the flat part?  Does anyone know the valve angle?  I'm guessing 60 degrees, but that is eyeballing it, at the moment, I don't have any way to measure it.

The plastic pieces are delrin or something like that?  I have seen where advanced users use peek.  For the poppet, it appears the seal is on a knife edge.  I have yet to model that side of the valve.  Is this angle critical?  For the poppet shaft, what are typical clearances?  Through the housing and for the air path?

Does anyone have a section view of this or other valves?  Dimensions or drawings?  I'm plodding along with this drawing, sort of to understand things better, and getting a little bit of CAD practice.

Moderators, if this is the wrong place for this post, please move it (and let me know where it went ).

[Spacebus]

A PCP valve might be an eaiser starting point since they don't (usually) have a check valve on them.

[WobblyHand]

Probably, but, I don't have a spare one to take apart, yet.  I'm just starting out, trying to understand the terminology and basic aspects.  So I'm roughly attempting to draw what I have, with looking at how it is made/machined.  I have machining capability, but have yet to figure out the order of operations to make something like this.  I'd make any valve at this point, just to get some experience at it.  I'd have to grind my tooling, so it's best to figure out most of the operations and then proceed to mess it up 

Don't have an idea of the tolerances, just yet, nor the inner dimensions to any degree of precision.  If I practice some, I will remember how to use the half ball hole gauges again.  The bores are too small to use a standard telescoping bore gauge.  No gauge pins or inside micrometer here either, so it's tough to get the inside measurements right.  I do know that it all has to fit, so there is some sort of bound - like a slip fit.

[WobblyHand]

Here's some more of the valve, the other half.  Need to do the poppet and the knife edge seal.  Sort of subtracting it out of the body, kind of like one might machine it.  Those are pseudo threads, real helical threads make the poor computer work hard for little benefit.  Was a little tricky to line them up.  Still need to enlarge the area around the poppet shaft, got to measure that first.

[Rob M]

very good cad work, this in the modern era may be a more important skill than machining.. As far as understanding the valve , i think your animation pretty much explains it. theres good youtube resources explaining it well




the plastic parts in a 1377 are nylon. The taper does the sealing on the check valve as I recall.
Something you overlooked in the rear drawing was the thrroat. the throat is a larger diameter section below the transfer port section , as you have it drawn , air could not passs the valve stem,

[sb327]

I made a couple of sketches with notes.

PLEASE BE AWARE. This is not intended to be all inclusive. The op asked about the basics and that is all I’m attempting to portray. The notes are only my opinions and very GENERAL in nature.

There are other combinations of poppets and seats. A ball in a seat can be a poppet.

Dimensions are not always critical to function. For instance, id of a plenum is not as critical to function as the wall thickness is to safety.

Lots to go over but here are some basics.

Dave

[WobblyHand]

very good cad work, this in the modern era may be a more important skill than machining.. As far as understanding the valve , i think your animation pretty much explains it. theres good youtube resources explaining it well




the plastic parts in a 1377 are nylon. The taper does the sealing on the check valve as I recall.
Something you overlooked in the rear drawing was the thrroat. the throat is a larger diameter section below the transfer port section , as you have it drawn , air could not passs the valve stem,

Thanks for the complement, it was and continues to be a struggle.  It wasn't that long ago that I learned CAD. 

Hadn't overlooked the throat (so that is what it is called!), simply hadn't drawn it yet.  Actually, I don't know what the dimensions are just yet.  The pic was but an instant in time of an unfinished model.  There appears to be a knife edge that seals the poppet as well that is not in there.  This modeling stuff for me is difficult, sometimes it is harder than the machining itself.  Messed things up this afternoon and nearly busted the model.  For some reason, the settings in the file were really far from the defaults and every operation started chewing up memory.  Just figured out how to fix the file so I can work on it some more.  Before I fixed it, the file would take 20 minutes to open... 

[WobblyHand]

I made a couple of sketches with notes.

PLEASE BE AWARE. This is not intended to be all inclusive. The op asked about the basics and that is all I’m attempting to portray. The notes are only my opinions and very GENERAL in nature.

There are other combinations of poppets and seats. A ball in a seat can be a poppet.

Dimensions are not always critical to function. For instance, id of a plenum is not as critical to function as the wall thickness is to safety.

Lots to go over but here are some basics.

Dave

Thanks Dave.  Even the labeled bits help a new guy like me.  There's a jargon to learn, which I don't know yet. 

The Crosman valve uses a flat poppet but uses a machined knife edge in the body for the poppet seat.  Maybe tomorrow I can finish that part of the model.  Now that I have my CAD program defaults under control... 

[sb327]

I was aware the Marauder used that type seat (knife edge) but am not familiar with the model you are working on.

Good luck.

Dave

[WobblyHand]

It's a 1322 valve, Crosman classic pumper.  Took it out of my 1322 when I flat topped it a few years back.  Been sitting in one of my airgun parts bins.  Thought I'd take it apart and figure out how it worked.

[Spacebus]

I made a couple of sketches with notes.

PLEASE BE AWARE. This is not intended to be all inclusive. The op asked about the basics and that is all I’m attempting to portray. The notes are only my opinions and very GENERAL in nature.

There are other combinations of poppets and seats. A ball in a seat can be a poppet.

Dimensions are not always critical to function. For instance, id of a plenum is not as critical to function as the wall thickness is to safety.

Lots to go over but here are some basics.

Dave

These are helpful, thank you.

[WobblyHand]

Here's a little bit closer.  Still don't have the correct dimensions for the seat nor the clearance for the poppet.  I don't know how to draw springs with flattened and ground ends. 

[nervoustrigger]

Regarding valve terminology, here's a PCP diagram I drew up a while back after several searches left me empty handed.



Basically the only difference relative to the valve you're modeling is that it lacks a check valve...a pumper stores its air in the valve whereas a PCP has air in both the valve and the reservoir.

[WobblyHand]

@nervoustrigger , thanks for the diagram.  It helps to know what the nomenclature is.  I need to estimate some of the ID'S and depths of my 1322 valve to finish up this model.  That means finding some pins or drill bits to fit check the holes. 

For giggles, once it is complete I will try to machine one.  It will be a test of my abilities, but will be fun to try.  If I don't deviate from the original design, maybe I will be able to get it to work.  If it's a flop, I hope to learn from the experience.  Have to start some where...

I started out with airguns because of interest.  This lead me to machining, which took me into another rabbit hole.  I've poked my head out of that hole and found the AG rabbit hole again.  We'll see what happens next!

[Nvreloader]

WH
A good set of ball mikes and or half ball mikes, I use both types
called small hole gages comes in very handy,
in sizes from 1/8" to 1/2" usually comes as a set of sizes,
along with pin gages that come in several sizes,



Full ball type


1/2 ball type


HTH's
Don

[WobblyHand]

WH
A good set of ball mikes and or half ball mikes, I use both types
called small hole gages comes in very handy,
in sizes from 1/8" to 1/2" usually comes as a set of sizes,
along with pin gages that come in several sizes,



Full ball type


1/2 ball type


HTH's
Don

I have a decent set of half ball gauges.  I find them tricky to use, however, as they have a small amount of spring to them.  On the other hand, I think I have mastered the telescoping gauges pretty well.  Usually within a few tenths from measurement to measurement on the telescoping gauges.  I had to practice that a lot when I was making a back plate for my lathe.  Bought a couple of bore gauge references to practice on.  I have a couple of different sizes, like a go no go set, which is useful for developing the correct feel for measurement.  Really helps to have "ground truth" when learning to measure inside diameters. 

Would be nice to have inside mikes, but they are out of my price range.  Don't use them often enough to justify buying them.