Millennium Pumper Production - *The Beginning* - And The Lousy End

[QVTom]

Yep, I got one from McMaster that moves in 500 psi increments.   Was only 10$ so I didn't expect a lot.

Tom

[CarsonRatSniper]

I'm going to tear down the lower tomorrow to rework the pump slot...I think I have another gauge I can try.
I screwed the gauge directly into the Prod adapter so I'm 3cc's short on volume compared to your build Bob. When I air it up I will just pump it 75 times from empty and see what it reads.
The hammer is only 54 grams (Prod hammer) and is lacking the added mass/weight of the cocking knob...maybe there's not enough dwell due to the light hammer. I figured the cocking knob will add another 5-10 grams and bring it close to a 2240 hammer in weight.
I am hoping the light/fast hammer will help with efficiency. I don't think the light weight will be an issue on an 1800 psi fill.
I'm going to bore the Delrin TP out to .250" in the center and use a piece of poly tube to get a good seal while waiting for the Teflon rod to arrive - the issue is the TP recess on the barrel/breech I have on the gun is at 1/4" and the tube/valve exhaust face is at 5/16" = I need the delrin spacer on the valves exhaust port to center the poly tube.

I should have data to post by noon tomorrow.

Mike

[rsterne]

Your volume should be about 10% less than my 28cc, so 10% fewer pumps (eg. 70-72 to 1800 psi) would be my expectation.... If your slot is a bit shorter (swept volume larger) or your altitude lower (I'm at 2500') you could have fewer pumps, of course.... Also, your reservoir might be a fraction shorter than mine (longer check valve or valve front, or smaller valve front ID or volume), which would build pressure faster.... Bottom line is, it is what it is, and fewer pumps is better....

Bob

[CarsonRatSniper]

Ok, dead empty with 70 pumps got me to the red line above 2000 psi - confirmed by slight valve lock on the first shot...the gauge is accurate.

Still had TP leak as I didn't get a chance to make a new one...the PTFE rod shipped today, so I will have that in a few days.
At 1400 psi a 37gr Spitzer gave 715 fps...a second shot from 1100 psi gave 695 fps.
There's more in it due to the TP - I'm getting a puff of air in my face when I shoot it, so there's some power loss there.

The main issue is the 54 gram hammer doesn't have the mass to give enough dwell @ 1800 psi. The brass bushings I made for the Mrod trigger took care of the sear drag and I tapped the hammer 8-32 and installed a side cocking bolt to it.

Bob, how many grams was your hammer on your build? We're just going to make our own hammers. I was thinking 70 grams including the cocking knob weight. What do you think?

Mike

[rsterne]

Here is the original hammer from my Millennium Pumper, with stroke adjustment and integral guide.... The spring is longer than stock, likely a QB7X spring or 2.25" long equivalent....





Unfortunately, I don't have a weight, but that guide looks to be 3/16" x 3" long.... My hammer weight calculator, for a hammer with no waist, and a guide of that size, gives a weight of 74 grams.... Initial testing was done with the striker recessed into the front of the hammer as much as 0.20", giving a stroke of 0.80", but the hammer was striking the back of the valve body, so I reduced the recess until that no longer occurred.... I ended up with a recess of about 1/8", but there was no difference in performance between that and having the striker flush with the end of the hammer, only a difference in required preload.... (less travel = more preload)....

If you don't have enough hammer strike, and your hammer weight is anywhere close to 70 grams (including guide and/or handle) then you likely need a longer (~2.25") hammer spring.... Although you are only running 1800 psi, you have a slightly larger throat in the valve than I used, which may require more hammer strike to unstick the poppet, depending on the sealing diameter.... I now use a loose hammer guide, held down by the front end of the spring, and a solid hammer with no adjustable striker, getting the extra travel by either shortening the stem, a recess in the hammer face, or a combination of both.... You need a minimum of 0.150" lift possible without the hammer hitting the back of the valve, to make sure it never hits.... At 1800 psi, the valve only opens about 0.060", but that increases as the pressure drops to about double that on the last usable shot....

Here is a photo of the loose style of spring guide I use now (that one is 7/32"), which doubles as a cocking indicator (it protrudes though the hollow RVA screw when cocked).... These parts are from my .30 cal Disco Double, before I fitted the rear cocking knob.... Note the recess in the hammer face.... Hammer and guide weigh 77 gr.... Your side cocking hammer won't need the indicator feature, of course....



As in any regulated gun (which the MP will be when tethered), you want to try various hammer strikes to verify that you can max out the gun at 1800 psi.... You are looking for something like this when you plot velocity vs. preload, with the heaviest pellet....



That will tell you two things.... One, what the absolute maximum FPE (the plateau) is with the heaviest pellet.... and Two, how far you need to back off the hammer strike to avoid wasting air.... That point is the "knee" of the curve, on the above graph about 4.5 turns out.... You should NEVER use more preload than that.... Tuning for multiple shots starting from 1800 psi will require even less preload, of course....

Bob

[CarsonRatSniper]

Thanks!

My Challenger hammer is around 82 grams with the guide (very similar to yours - I used yours to model mine from when I built that gun).

I'll make the assembly at 80 grams. The spring is a .045" wire x 2" long x .360" OD - its a 10# spring IIRC - its plenty for my Challenger @ 70 ft lbs but that valve has a .250" throat not the larger throat of the Millennium valve.

I will be back at it Friday morning...results by next week.

Thank You Sir!

Mike

[westtexasrancher]

How did I miss this awesomeness. 

[rsterne]

I would suggest you try a QB spring.... Being just over 2.3" long, it will require a longer RVA and/or deeper hole in the hammer, however.... It is about 0.33" OD.... Alternately, you may be able to find a 2.25" long spring of your specs....

Don't forget, hammer weight only affects Momentum (dwell), not Energy (lift and knocking the poppet off the seat).... The hammer energy can only be increased by the spring, preload, or travel.... For a larger throat/seal area, you need more energy to unstick the valve at a given pressure.... Only the residual energy and momentum after that occurs are available to create lift and dwell....

Bob

[CarsonRatSniper]

WOO HOO! My fill nipple prayers have been answered!

Yes, they cost much more than what I had budgeted but I *like* them! These are going on the Millenniums.

Fully captured pin plus a sintered filter.



Mike

[rsterne]

VERY nice, Mike.... Who makes and sells those?....

Bob

[SeanAT]

VERY nice, Mike.... Who makes and sells those?....

Bob

http://www.ansgear.com/Bob_Long_Filtered_Fill_Nipple_Black_p/boblongfilteredfillnippleblack.htm

Here's a different brand of captive valve fill nipple that's a little cheaper but doesn't have the filter...

http://www.ebay.com/itm/Custom-Products-CP-Fill-Nipple-/331425093864?pt=LH_DefaultDomain_0&hash=item4d2a7998e8

[CarsonRatSniper]

I just ordered 10 of them from ANS Gear...this is the only fill nipple that Jack Haley would use in his guns, so I figured they *had* to be worth the cost!

Mike

[rsterne]

Note the comment on the website linked to about the screw on dust cap sticking in place if there is a tiny leak in the check valve.... Worth consideration?....

Bob

[Sfttailrdr46]

You can always drill a small bleeder hole in the screw cap

[dyotat100]

That is a good price on the CP ones. I just ordered 6. Those are what I use on my builds.

I have a Haley and it doesn't have one of the those fill nipple on it. I will have to look and see what it is.

[CarsonRatSniper]

I found an old post on the Yellow from 2010 where either Jack or someone had said that's all he used on the Haley builds...

I read the cap issue and it becoming stuck if the fill nipple leaks - I planned on drilling a *tiny* bleed hole in the cap somewhere to alleviate that becoming an issue.

Mike

[QVTom]

Mike before you drill a bleed hole I'd check to see how tight the threads are.  It's hard to believe that a threaded cap would be air tight unless (thinking as I type ) it's not the thread but the two faces making the seal. 

Neat fitting, is it 1/4 npt?

Tom

[dyotat100]

My Haley has a CP products on it. I think they are a newer than 2010 product. 

I snatched up all 6 that the like had above. They are normally $15. I usually get them from CP and the best they have done is $12 ea when I bought 10.

[CarsonRatSniper]

Tom, the fitting is standard 1/8" NPT for a fill nipple...not sure what the thread for the cap is.

I will see how tightly the cap fits on...they shipped today and should be here by Monday of next week.

Doug - Yeah, it might be...I was on *internet search mode* when I ran across the link to the Bob Long fill nipples on the Yellow. I may have gotten my information mixed up but Haley was mentioned with these somewhere.

Here it is! It was 2012...Jack said he only used 'these' and they were $15...he probably meant the CP's...

http://www.network54.com/Forum/79537/thread/1349466952/Source+of+HPA+fill+nipple+with+captive+check+valve-

[QVTom]

The threads look huge on my computer screen  LOL