How would a guy get his hands on the cad for the power adjuster? That thing sure looks trick and would love to make one for my QB ...Originally Posted by remtom1200
How would a guy get his hands on the cad for the power adjuster? That thing sure looks trick and would love to make one for my QB ...
SHAWN
It sounds like your hammer is hitting too hard and keeping the valve open... I would reduce the force of the hammer spring and/or up the valve spring force.
Normally, the hammer spring has just enough force to propel the hammer and exceed the force required to open the valve (which is resisting with valve spring plus compressed air). If the valve spring isn't strong enough, it doesn't have enough strength to close the valve once the hammer hits it. If the hammer spring doesn't have enough strength, or the valve spring is too strong, it doesn't open the valve.
I wouldn't be surprised if you are going supersonic with your pellets... and you're losing a LOT of air.
I'm not sure why you modified the valve for use at 1500psi? Not necessary and has gotten you were you are now. Can you return it to it's stock form?
I'd say I care- but I'd probably be lying...
Bling would be nice
But this would be nicer
http://www.airgunhome.com/agforum/vi...586&highlight=
or this if you like lower tech
http://www.airgunhome.com/agforum/viewtopic.php?t=7459
Last edited by SeanMP; Jan 16 2012 at 07:50 PM.
Sean
At last...Here is my QB78D PCP conversion. At 2700psi I am getting 30 strong shots down to 1000psi. All my grief was being caused by the spacer I had added to the hammer spring,as well as port size a little too large for this application. Spacer was removed completely and hammer lost a little weight too by lathe. Port hole closed up from #18 to #20 drill size. I have no chronograph to check speeds at this point. As rsterne had mentioned the hammer spring is very sensitive to adjustment which I experienced during this conversion. Accuracy is stunning over my springers. I found myself walking to the target to see where the new hole was, surprisingly POI was almost through the same hole on most shots and no flyers at 20 yards. I am impressed!
If you figure that one out, be sure to let us all know. ;)
Drilled through the reciever to mount mine.
Al
There must be some formula or somethin to determine how thick the wall of the choke band must be to squeeze the 15mm barrel to desired tightness? I have no idea but trial and error to find this out.
For every mile of road, there's two miles of ditch
Bravo...Nice work on the adjuster.
Keep your head down though, Eric has been trying to convince Al to go into production on those adjusters for years...you may be next
Sean
Ya I bet there is. The first place I would look is "The machinists handbook" or "machinery's handbook" I personally like the former but it hasn't been produced in 50 yrs and they are worth a fortune.
But I think you could could sneak by with a thumb rule. Calculate the cross section of material in % of the barrel OD. If you match it with an equal % cross section of material on the choke you should achieve something close to equal squish and stretch.
However I would figure out what weight gives the best barrel harmonic. Then you can tailor the interference fit to give you the desired .001 squish
Sean
IMG_0415.jpgIMG_0420.jpgIMG_0417.jpgAdjuster is now finished and WOW what a difference with all the adjustment! Do they make 5min loctite blue?lol I wanna go do some more shooting but have to wait now
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