Simplified Balanced Valve

[mann]

I had a slight set back broke the stem flush off in the head I was able to remove it with a left handed bit I think the hole in the stem was too large I can't get it seal completely I was getting air out the exhaust hole not alot so after I burnished the poppet several times it wasn't getting any better thought maybe my oring groove and oring were leaking and broke the stem when maching a new groove redrilled the stem with a smaller hole and got a new oring on the stem only one that fits good is a viton so I'll see what happens had to make a new stem also that's what I get for being in a hurry

[mann]

Drilled cross hole by hand that was fun only did the one side

[mann]

Wow my new oring seals up and it opens really easy just have to get the poppet to seal all the way  maybe if I cut another groove up so the air has a place to get around in the thimble idk

[mann]

The viton oring seems to work on the poppet though so that's a plus

[rsterne]

Yes, you only need to drill one side of the stem.... I have a 0.047" hole down the stem and a 0.031" hole through one side in the exhaust port area....

Bob

[mann]

I can get it to seal by first pushing should air through the exhaust of the valvewhich tells me I need to drill a bigger hole threw the stem and poppet I'm at .040 any other ideas

[rsterne]

I presume you mean "shop" air, not "should" air ?.... as in you are adding backpressure to get it to seal?.... I think more likely you have an incomplete seal on the poppet.... I can't imagine the size of the vent would make any difference to sealing.... Tack got his to seal up OK....

Bob

[mann]

Yeah I had it sealed up but I just blew the threaded stem out the back of the valve when I tapped the valve open oops just needs some good burnishing

[mann]

This valve hates me I had trouble getting it sealed with the ss poppet must be something in the seat I used peek poppets in other valves and they have sealed up

[rsterne]

I just blew the threaded stem out the back of the valve when I tapped the valve open oops

 

Cut out a small disc of 220 sandpaper, stick it on the poppet seat with double-sided tape, and the use the poppet to sand the seat in the valve body by pulling gently on the stem while chucked in a portable electric drill.... I follow that by burnishing with "Solvol Autosol", a very fine abrasive polish.... and then just the clean plastic poppet.... Clean carefully between each step, of course.... I also undercut my PEEK poppets by 1 deg. to force the sealing margin to the very outside edge....

Bob

[oldpro]

 If you guys get this to work Ill be shocked but Im certainly rooting for you!!! Go Team! I tried this over a year ago I have the valve at the shop Ill show you how I made it work and that was cutting off the lower section of the poppet and re sleaving the upper to 3/16ths I believe. Ill show pics on Monday of the thimble and poppet. It just wont work at the 80% ratio

[rsterne]

Mine is 71% ratio on the diameters (50% on the area)…. I guess we'll see in a few more days....

Bob

[mann]

I'll glue the stem back in sand the valve seat and I've been using real fine metal polish that I've used to get my other valves to seal the seat is really shiny it just not quite good enough yet so I'll have to sand and retry

[mann]

I cut 2 lines in the lower part of the poppet to help get air in the thimble it's slams shut faster now  to

[rsterne]

I noticed that.... I have a few thou gap between the large end of the poppet and the ID of the thimble.... a lot of area, compared to the size of the vent hole in the stem.... but I can do that if necessary....

Bob

[mann]

I did everything you suggested Bob I just can't get it to stay sealed up up completely all the time . It will be good at lower pressure hit it with the hammer and it starts leaking again . I also tried a heavier poppet spring and under cut the poppet

[Motorhead]

I did everything you suggested Bob I just can't get it to stay sealed up up completely all the time . It will be good at lower pressure hit it with the hammer and it starts leaking again . I also tried a heavier poppet spring and under cut the poppet

Suggest paying attention to travis and his past comments ..... someone with first hand experience generally offers sound advise.

[mann]

Thanks for the word of encouragement

[rsterne]

I guess Tack's success in his pumper was an anomaly....  …. I'll find out for myself in a few days when I get a chance to finish mine....

Bob

[PakProtector]

If the poppet is not cut square to the stem, no amount of polishing the seat is going to help. Had some fun with an SS valve. Started its first charge and found it leaking out the exhaust. Got it to 1k psi, and as it hissed away at me, I gave the stem a small tap through a dowel. KA-POW! No more leak. Keep your fingers away from the exhaust port if ever doing this... It would likely take your hide CLEAN Off...

On Bob's idea, I would suggest starting with a lighter balance/smaller amount of help. Work up...while y'all are at it, just keep in mind stability margin and Q...it could be that some resistance is needed to remove energy from the system.
cheers,
Douglas