Gladius Semi Balanced Valve - Didn't Work Out

[JumboPellet]

I thought I'd share this, some might find it interesting...

In an attempt to get away from having to use a crazy stiff spring in my Hatsan Gladius project gun, I decided to try and machine a valve poppet with a balancing piston on the far end to reduce opening forces (semi balanced). A .028 through hole vented HPA to behind the piston, which all sat in a new one piece valve body.

At the end of the day, outside of the gun, it did work! Installed into the gun, it ended up as a wash and didn't contribute anything of significance. I knew the barrel/TP pressure would rise on the shot cycle and eventually cancel out the piston force, but didn't expect it to happen so sharply as to render the concept completely useless. Interesting result (to me at least).

If anyone is curious on specs:

Hatsan Gladius .25

Valve Throat  :  0.262"
Valve Stem    :  0.122"
Valve Area     :  0.04222"  (Throat - Stem)
Force @2100  : 89 lbs

Piston Size     : 0.262"
Piston Stem   : 0.177"
Piston Area    : 0.03027
Force @2100  : -63 lbs


At least these projects help improve my machining skills 

[oldpro]

 Well I can certainly see the issue but without revealing to much of my own work I wont say exactly why online but if you call me ill explain your issue. As long as you keep it to yourself as well.

[rsterne]

Nice job on the machining, Jeremy.... Keep at it, you'll get it eventually....

Bob

[jarmstrong]

As a power plant mechanic (in a former life) my brain just went WOW, you guys are genius! When you get the engineering fine tuned  as I'm sure you will, I would be honored if either one of you two GENTLEMEN would like to sell me one for my .22 cal Gladius. I have a brand new valve and the piece it screws into, and would send to you if you like. If only I can figure out how. VERY AWESOME WORK
PS: and Bob I have learned much from your work and willingness to share with all of us , Thank you  to you also.
Jack

[JumboPellet]

Jack, agreed, I've learned a LOT from Bob's work and willingness to share. My .25 Glad is up to 90FPE shooting slugs, but reducing that #40 hammer spring is the next target of opportunity.

Travis's words are also encouraging. But I also understand he makes a livelihood on this knowledge and I'm just a basement hobbyist figuring it all out. So I'm going to do some more reading/research and see if I can crack it. If not, I may have to just call him (or optionally buy an Mrod and use one of his valves) 

There's a lot of crossover here from the paintball world https://www.google.com/patents/US7624726, but as others know, the fine details are the hard ones to figure.

Thanks for the encouragement!

[Gippeto]

Before you abandon it...can you increase the passage size beyond .028"? When the stem is struck, the volume behind the piston is increased....reducing the pressure and force. Increasing passage size should make a difference.

Nice bit of work.

Al

[JumboPellet]

Al, agreed. There's about .025 of plenum behind the piston. If you figure about 0.050 - 0.070 in poppet movement during the shot, the force will reduce significantly due to the gained volume. Unfortunately,  i work hardened the stem (O1 steel). I attempted to ream it out tonight using a number drill and only succeeded in ruining the bit. I'll have to make a new stem. Stay tuned...

Regards,
Jeremy

[jarmstrong]

  could enlarging the balance plenum help? Less percentage of change from at rest volume to full stroke volume

[shorty]

It's the HPA "refill" of the balancing poppet and not really the plenum behind it. As the balancing poppet opens, the pressure from the main poppet pushes it closed "too fast" because the hollow stem and (exit port " right behind the balancing poppet" ) is too small reducing the air pressure behind the pressure reducing poppet as it opens (can't refill the dead space fast enough).

If you hardened it already, you have a chance at using a kolbalt bit or a diamond tip bit. I go cheap and use a masonry bit. For the port right behind the pressure reducing poppet, you can grind.

Love the design and I found the same in paint ball guns too back in 2004/2006. Great work....

[jarmstrong]

the cobalt bits drill bits work good. I use Sno Seal boot sealer for lubricant, It works well, drill bit gets hot and the wax melts and runs down the bit .
Ya, I concur bigger ports, faster fill more balance

[JumboPellet]

Update, I got another stem turned and bored the transfer passage to .062 with 4 .040 exit ports behind the piston.  This gained me 120 fps to 1050 fps on a 33.95 JSB. So definitely lends some support to the thought. Overall though, the valve is still using the same spring as before (.055 wire) and making a bit less power, so some more work needs to be done. The valve stem is .125 so I don't think I can go much more than .062 and have it last any length of time. So going bigger in the current arrangement isn't very viable. I'm going to try and flip it around in a Cothran style arrangement to get a larger occlusion and plenum space. There's a lot more room on that end of the valve.

Few more hours on the Chinesium 7x16 and I should have some more data. Stay tuned...

[oldpro]

 Jeremy your setting so close to transonic you wont see much improvement regardless of what you do so you will either need heavier ammo or back it down to a lower power setting and see what the changes do from there.

[JumboPellet]

Yea I know, I'm just using that as a rough benchmark as I have a tin of them on the bench. The JSBs tended to shoot best dialed back to around 970. The prior valve was pushing 47g BBTs ~950 fps (~1100 on the JSBs). I'm very content with that power level. Just looking for a new arrangement to lighten the spring load. The load/wear on the trigger and cocking lever are the main concerns long term. So it wasn't the 'bit less power' part, it was the 'still needs the .055 spring' part. If the next go around shows promise, I'll crony some slugs as well.

The prior valve was a .250 throat with 0.100 stem. This one is a .262 throat with a .125 stem. Roughly equivalent in total area.


Regards,
Jeremy

[blackdiesel]

Just wondering what performance goals are you seeking?  What kind of shot count are you getting at this power level?

[ackuric]

Great work Jeremy. Glad you're not giving up! Failure is just a step towards success. Soon you will have to start a new thread titled "Gladius Semi Balanced Valve - Worked it out".

I like to get my spring wire down towards .042-.047 in diameter if/when I can. .055" must pack a good punch!

-Matt

[JumboPellet]

Originally, I acquired a Seig mill, lathe and tooling from an estate sale (price was right, someday hope to have better) and wanted to learn how to machine and create this kind of stuff. As well as modify them, etc. The performance levels are pretty much there for me to shoot slugs. I can get a full clip out of a fill (9 rounds) , but am also using a different air tube with a Huma regulator on a ~80cc plenum. The rifle is heavy and pretty impractical to take into the field, so is pretty much bench only. Essentially, it's become how I spend my downtime when not working 

[JumboPellet]

Some new results and update for this weekends work. I reworked things so that there's now an occluding piston inside the valve. The piston is .189 and the valve seat remained at .262 with the stem at .125. The vent passage was drilled to .040 and two perpendicular .028 holes were drilled through the stem.

First test was with the .055 spring that I was previously using with the standard valve:

JSB 33.95g       1143 fps
BBT FN 51.2g    960 fps
Rat Sniper 45g  1001 fps

I'm really happy with those numbers! But the gun is using mountains of air, like ~15 bar per shot. So I suspect the valve is just giving me dump shots. It's possible the hammer was bottoming out also (max poppet lift was .140).

Next I made a smaller spring out of .049 wire and the results were very similar.  I quickly tried a .039 spring I had laying around and the velocity of the JSBs dropped to 940 fps. Maybe a little too soft. This week I'll pick up a some .042 wire and try that. Maybe little red riding hood will like that spring just right 

If that doesn't work, or air usage stays crazy high, I'll try reaming out the vent passage to .050 to create some more back pressure to help close the valve faster.

Things are looking much more promising now, but some more tuning needs to be done.

[oldpro]

.040 should be your max lift and going above that means your throat and TP are to small. If your trying to make power with a small air sample like I see in this post your over dwelling the valve and need to up the available volume to not use so much air. I would suggest a :290-300 valve throat and .190 or larger TP to supply the needed air to raise the amplitude of the pulse signal to the pellet.

[JumboPellet]

TP for this round was .193, but the valve body is ported at .250 so I can easily go up to full bore with a TP swap. The poppet was made out of .312 drill rod. That's where the .262 came from, to allow enough seating surface on the peek seat. I have to make a new seat anyway, I'm going back to delrin as the peek seat leaks when left overnight. When i remake it, ill open that up. Will have to source some larger O1 first.

With the .039 spring, air usage was pretty good, but the power was down a bit low for slinging slugs. Over dwelling is almost certain. Wish i had a way to measure it. I also suspect my hammer is too heavy at 75g (stock was 50 for the gladius). Which isn't helping either.

But it's showing promise for the original goal, which was to reduce the overall spring rate required.

Thanks for the tidbits!

[oldpro]

 I don’t think you need to change the TP size but valve throat is far to small and your absolutely correct the hammer and spring combination is most likely far to much and will be even more so when you get better into balance with the larger throat size. BTW your machine skills are awesome!!!