The poppet valve stem) in my Marauder final came apart. The day beforeI had shot it 56 times. Then yesterday on the second all the air exhausted through the barrel. Have twists of o-rings, but no poppet. Placed one on order yesterday, but will take about six days to get here. Bummer! 
Marauder rifle poppet
- Thread starter Jonah
- Start date
It happens. I run custom hand made poppets in my marauder from delrin or peek sized .04-.05" over seat OD.
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Yes sir, bummer for sure. For a long time I put off making my own...with nothing more than a drill press at the time, it seemed like a daunting task. Then a situation like yours happened. My options, wait a week for one or try making one. I think the first one took me 2 hours to make, a lot of it spent flattening the sealing face by spinning it against sandpaper (drilled a hole in a wooden block and used it as a backer, passing the stem through the hole and spinning it with a handheld drill). But it worked out great and is still in service today with a lot of pellets in its past. The best part though was that I was back in business on the same day.
I know it's not for everyone but if you have the means to do it, give it a try. Delrin or PET-P are both good materials for a first attempt and they don't cost much. Even if not this time, get a stick and have it ready for next time. Why? Well, firstly the replacement is made just like the original so there's no reason to expect it will be any more durable. Secondly, if you have the material handy when disaster strikes, it's a whole lot easier to find the motivation.
It's just a plastic cylinder with a steel rod stuck in it
Good luck!
I know it's not for everyone but if you have the means to do it, give it a try. Delrin or PET-P are both good materials for a first attempt and they don't cost much. Even if not this time, get a stick and have it ready for next time. Why? Well, firstly the replacement is made just like the original so there's no reason to expect it will be any more durable. Secondly, if you have the material handy when disaster strikes, it's a whole lot easier to find the motivation.
It's just a plastic cylinder with a steel rod stuck in it
Good luck!
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+1 to what nevroustrig said, its a little daunting at first but I wouldn't have it any other way. Heres how I do mine..
Start with 5/16 or .3125" rod of delrin/peek..cut off roughly .5"-.6" in length, find a method to center punch a starting point for your drill (various methods to this, I just used digital calipers locked at the radius of the rod, then circled it around and around till I felt I was centered and then made an indent with the sharp edge of the caliper)...
Drill stem hole to .115"~ and a depth of roughly .25". I start the hole out at .05"~ personally, and with a small dreme bitl I correct the hole if its off centered until my calipers give me a good reading going around the poppet, then drill to final .115"~ OD.
Using a .125" hss drill blank (my preference), grind a few slots like the stock poppet for an adhesive to rest in (I use loctite), grind the tip away slightly to allow the next steps to go smoothly, apply adhesive and press the blank/stem into the poppet. I like to warm my poppet up a bit as to make the pressing procedure go a bit 'easier'. Let it cure...
Now you can true the poppet up so that the stem is truly centered by chucking it into a drill and running it on 600~ or so grit, then smooth it up with wet 600 and work up to 1000~.
You can true the face of the poppet using various methods, I use a small dremel grinding disc wheel and press it against the poppet face while its spinning in a dremel. Toss the poppet into the valve and chuck the rear stem into a driill, and burnish the two surfaces together with light pressure and 20~ spins in both directions, nervoustrig likes to use sharpie on the poppet face to check for trueness which I have yet to try but if I ever make another poppet, I certainly will.
Toss the new poppet into the valve, measure roughly .15-.25" of stem out the back (stock is .25", i run .15 to obtain additional hammer throw), take poppet back out, remove excess stem, give a 45 degree grind around the edge of the poppet so the hammer doesn't 'flatten' it further causing it to stick in the back of the valve, and you're good to go.
I personally thin my valve stems down in the area of the throat prior to pressing them in, this allows you to run larger ports and smaller seat OD's, which in turn results in better air flow while keeping the valve easier to open, only worth considering if you run ports larger than .157" in a stock valve..
Start with 5/16 or .3125" rod of delrin/peek..cut off roughly .5"-.6" in length, find a method to center punch a starting point for your drill (various methods to this, I just used digital calipers locked at the radius of the rod, then circled it around and around till I felt I was centered and then made an indent with the sharp edge of the caliper)...
Drill stem hole to .115"~ and a depth of roughly .25". I start the hole out at .05"~ personally, and with a small dreme bitl I correct the hole if its off centered until my calipers give me a good reading going around the poppet, then drill to final .115"~ OD.
Using a .125" hss drill blank (my preference), grind a few slots like the stock poppet for an adhesive to rest in (I use loctite), grind the tip away slightly to allow the next steps to go smoothly, apply adhesive and press the blank/stem into the poppet. I like to warm my poppet up a bit as to make the pressing procedure go a bit 'easier'. Let it cure...
Now you can true the poppet up so that the stem is truly centered by chucking it into a drill and running it on 600~ or so grit, then smooth it up with wet 600 and work up to 1000~.
You can true the face of the poppet using various methods, I use a small dremel grinding disc wheel and press it against the poppet face while its spinning in a dremel. Toss the poppet into the valve and chuck the rear stem into a driill, and burnish the two surfaces together with light pressure and 20~ spins in both directions, nervoustrig likes to use sharpie on the poppet face to check for trueness which I have yet to try but if I ever make another poppet, I certainly will.
Toss the new poppet into the valve, measure roughly .15-.25" of stem out the back (stock is .25", i run .15 to obtain additional hammer throw), take poppet back out, remove excess stem, give a 45 degree grind around the edge of the poppet so the hammer doesn't 'flatten' it further causing it to stick in the back of the valve, and you're good to go.
I personally thin my valve stems down in the area of the throat prior to pressing them in, this allows you to run larger ports and smaller seat OD's, which in turn results in better air flow while keeping the valve easier to open, only worth considering if you run ports larger than .157" in a stock valve..
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That's a very nicely detailed set of fabrication instructions there from ackuric.
About truing the poppet OD to the stem (chucking the stem in a drill and abrading the poppet OD), I just want to point out a couple of things. Firstly, this step is optional for the most part. As long as the sealing face is flat and smooth, it will work fine. It is necessary only if you are trying to reduce the poppet OD to the smallest possible size that it becomes necessary for the stem to be perfectly centered.
Secondly, if you're doing this step, don't attempt it by simply holding a file or sandpaper against the poppet as it spins. That will only remove material around the whole thing, making it smaller but not concentric to the stem. Instead what you want to do is slowly bring in your abrasive until it just kisses the high spots of the poppet as it spins. When I was making them on a drill press, I would load the valve stem in the chuck and get the poppet spinning, then bring in a spinning Dremel bit until it just touches the high spots. Eventually it will get to where you can feel and hear that it's taking off material from the full circumference. At that point you know the OD is true to the stem (as close as it’s going to get, anyway).
Preferably the bit is either a sandpaper wheel or a suitably sized cylindrical burr...something long enough to work the full height of the poppet at once. However if you have a steady hand and some patience, you can use one of the thin emery wheels and work it up and down until you've trued up the whole poppet. That actually leaves a pretty decent surface finish that doesn't require much smoothing. With that said, please note the sides of the poppet don't need to be pretty.
Also for what it's worth, I don't bother to knurl or heat stake or epoxy or threadlock the stem into the poppet. An interference fit is sufficient...something like a 0.004" undersized hole for Delrin or PET-P and just 0.002" or so for PEEK. I believe Motorhead has advised the same. For the end that's to be inserted into the poppet, I simply blunt it square against a piece of sandpaper and then very slightly break the sharp edge against a piece of 400 grit wet/dry paper. The idea is to maintain a blunt end so it doesn't act like a nail and drive through the poppet, but relieve the sharp edge so it doesn't cut a curl from the plastic as it is being pressed into the drilled hole. I then place a marking on the stem of the depth of the drilled hole, and put it in the vise and press it in to the depth of the marking.
About truing the poppet OD to the stem (chucking the stem in a drill and abrading the poppet OD), I just want to point out a couple of things. Firstly, this step is optional for the most part. As long as the sealing face is flat and smooth, it will work fine. It is necessary only if you are trying to reduce the poppet OD to the smallest possible size that it becomes necessary for the stem to be perfectly centered.
Secondly, if you're doing this step, don't attempt it by simply holding a file or sandpaper against the poppet as it spins. That will only remove material around the whole thing, making it smaller but not concentric to the stem. Instead what you want to do is slowly bring in your abrasive until it just kisses the high spots of the poppet as it spins. When I was making them on a drill press, I would load the valve stem in the chuck and get the poppet spinning, then bring in a spinning Dremel bit until it just touches the high spots. Eventually it will get to where you can feel and hear that it's taking off material from the full circumference. At that point you know the OD is true to the stem (as close as it’s going to get, anyway).
Preferably the bit is either a sandpaper wheel or a suitably sized cylindrical burr...something long enough to work the full height of the poppet at once. However if you have a steady hand and some patience, you can use one of the thin emery wheels and work it up and down until you've trued up the whole poppet. That actually leaves a pretty decent surface finish that doesn't require much smoothing. With that said, please note the sides of the poppet don't need to be pretty.
Also for what it's worth, I don't bother to knurl or heat stake or epoxy or threadlock the stem into the poppet. An interference fit is sufficient...something like a 0.004" undersized hole for Delrin or PET-P and just 0.002" or so for PEEK. I believe Motorhead has advised the same. For the end that's to be inserted into the poppet, I simply blunt it square against a piece of sandpaper and then very slightly break the sharp edge against a piece of 400 grit wet/dry paper. The idea is to maintain a blunt end so it doesn't act like a nail and drive through the poppet, but relieve the sharp edge so it doesn't cut a curl from the plastic as it is being pressed into the drilled hole. I then place a marking on the stem of the depth of the drilled hole, and put it in the vise and press it in to the depth of the marking.
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I haven't a clue, could be simple Crosman poppets, or he may make his own, if he does I would lean towards delrin being the material he uses as its quite inexpensive and great for sealing valves with little fuss.
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It appears Tim uses stock Crosman poppets, I have compared them to stock and cannot see or measure any difference.
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I would suppose no VMS, larger exhaust port and a bigger opening in the intake cap. I see no o rings either except the -118 on the outside. He uses a couple different spring rates in his valves also.
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