by jimmyk » Thu Jan 01, 2015 7:24 am
Helimac81,
Here is the procedure for the Staley tune. I keep a lot of important stuff stored away on the computer for times like this. Hope it helps.
Jimmy
Poor man's M-Rod, P-rod, etc. "Regulator" explained (Long)September 7 2011 at 8:03 PM bsta
September 7 2011 at 9:17 PM
By bstaley (Login q1q)
adm
________________________________________
Poor man's M-Rod, P-rod, etc. "Regulator" explained (Long)September 7 2011 at 8:03 PM bstaley (Login bstaley)
YF
First of all, despite the title, this mod is not a Regulator at all. Truth is I don't really know what you would call it. Maybe one of you can come up with a good name.
(if you are already intimately familiar with m-rod p-rod tuning skip the next 2 paragraphs)
As most of us are aware the M-Rod and P-Rod have a number of adjustments that allow us to tune our guns to suit our desired purpose. Both guns have a hammer spring preload adjustment and a stroke length adjustment. By changing and balancing these 2 settings you can raise or lower the 'sweet spot' and to some extent the velocity. Also changing the ratio of stroke to tension can have an effect on the efficiency as well. Both guns also have a Transfer Port, who's main function is to limit the flow of gas resulting in flatter, more efficient shot strings by limiting the peak of the sweet spot. On the P-rod the port diameter is fixed, and in the M-rod it is adjustable, which allows for optimizing shot strings over a wider range of target velocities without having to modify a fixed port.
All of these adjustments allow those who can understand how they all interact to achieve some very impressive shot strings, but it usually involves lots of trial and error, and lots of pellets over the Chrony. For many this can be a very frustrating process, so many just live with far from optimum settings, or spend good money to send their guns to one of our fine tuners to do it for them. Also since the settings are very precise, it is hard to change the settings to achieve a different tune and then return to a previous tune, without a lot more time consuming tweaking and chrony time not to mention expensive pellets.
This mod makes use of two of the existing adjustments, namely Spring Tension and Hammer Stroke length, but completely changes the usage of the stroke adjustment. It also eliminates the need for a restrictive transfer port to flatten the curve, so the transfer port can be set wide open in the M-rod, and drilled out or replaced with Poly tube in any of the other platforms. It achieves this by re-tasking the Stroke adjustment setting to instead precisely control the maximum amount the valve is able to be opened by limiting the hammer stroke to a fixed distance.
This mod is really so simple that I really didn't expect it to work as well as it has proven to. For lack of a better term, I'll call it a buffer for now. this buffer could probably be fabricated as one piece by those so inclined, but I just used standard o-rings to fashion my prototypes. The air tubes of these guns are designed around standard o-ring sizes, so the o-rings fit the tubes perfectly and stay put with just friction to hold them in place. The "buffer" forms a stiff but somewhat flexible tube that surrounds the valve stem. In effect, it just becomes a secondary valve return spring, with a much higher spring rate, or stiffness, than the one inside the valve. The buffer limits the travel of the hammer by contacting the outer edges of the hammer, but does not interfere with the smaller diameter striker which is the adjustable piece normally used for adjusting stroke length. So when the striker hits the valve stem, everything works pretty much the same as stock, UNTIL the hammer body comes in contact with the buffer. At that point the Buffer pretty much overwhelms all the other factors involved, absorbing the remaining hammer energy and limiting the valve opening based on how far the striker extends beyond the end of the hammer body (the number of CW turns from full CCW)
The buffer also then becomes, in effect, the stroke length adjustment. Since I wanted to use the highest recommended pressure fills, in my testing, I only used the minimum number of O-rings needed to give me the range of adjustment I wanted. This results in a longish stoke. Using more o-rings (a longer buffer) than I did would result in a shorter stroke which might also be advantageous, but I haven't experimented with that. One could also experiment with different types or o-rings or even quad rings. I would assume that varying the stiffness of the buffer would have some effect on the resultant string as well.
To install the mod you just need to disassemble your gun far enough to remove the hammer assembly, which you can find detailed elsewhere I'm sure, although I was actually able to insert the o-rings into the sear opening in the bottom of the marauder tube and manipulate them into place with a small screwdriver without having to remove the hammer. For the P-rod, my buffer consisted of 4 '113' o-rings, which should also work in Disco/22xx tubes. For the M-rod I used 3 '211' o-Rings. (i hope those are the right ones) Just insert the o-rings into the rear of the Air tube and push them forward so they stack up against the face of the valve. The resulting buffer should extend at least a little bit further from the valve face than the valve stem does, and even further if you want to go with shorter hammer strokes. That's it, you're done. Just re assemble and you're ready to go.
While you're in there though, you should also open up the M-rod transfer port to wide open. In any of the other platforms you'll probably want to put in a larger diameter transfer port, by drilling out your stock one (.11 works pretty well for the p-rod) or replacing it with freezer poly tube. This isn't required for the mod to work but if you are interested in higher velocity tunes the stock port will limit how high you can go. M-rod owners may also want to take this opportunity to tighten the grub screw on the top of the hammer that puts pressure on the little plug that adds friction to the stroke adjustment. Mine was pretty loose when I first tried this and over just a few shots, this adjustment would slip enough to noticeably affect velocity.
If you want to try this mod on a Disco or 22xx, you'll also need to replace the stock hammer with a P-rod hammer. I have heard that they will work in these guns, but I haven't verified this. If you have the proper equipment, you could probably modify a stock hammer to add an adjustable striker to it as well. You will also need some way to adjust the hammer spring tension and access the stroke setting in the hammer. You could probably use a p-rod end plug by drilling and tapping a new hole for the top screw, or a Melon or similar power Adjuster would probably work well too. I'm sure anyone who tries this on one of those platforms will be able to figure that part out better than I.
The main advantage of this mod is that it just makes tuning the gun so much easier. It almost makes it impossible to get a "bad" tune. Now the only 2 adjustments you need to worry about are the spring tension and the stroke adjustment. Although they do have some effect on each other, you can for the most part consider them independent adjustments.
Use the Spring tension adjustment to raise (cw turns) or lower (ccw turns) the sweet spot of your string. A good starting place would be whatever setting you were using before installing the mod and just fine tune it from there.
Use the Stroke length adjustment as your Velocity control. Turning it CW will raise your velocity and CCW will lower it (the opposite of what it used to do). I start at full CCW and then dry fire a few times, adjusting CW after each shot until enough air is being released to fire a pellet at reasonably low velocity. Depending on the length of the buffer, when set at full CCW, the striker may not even engage the valve stem at all and no air will be released.
I usually start tuning by filling the reservoir to a pressure that I know will be somewhere in the middle of my sweet spot. Fire a few shots over the chrony, adjusting the stroke adjustment in or out until you reach your target velocity. This setting is very sensitive, 1/8th or even 1/16th of a turn can make a noticeable change in velocity and 2-3 turns from where it first engages the valve stem is probably the effective range. If you go too far CW, the buffer will be taken out of the equation entirely because the hammer won't ever travel far enough to hit it.
Once you get the velocity about where you want it, finish filling the reservoir to your desired fill level and shoot a string over the chrony. The resultant sting should look just like the shot string from any well tuned PCP. You should get a smooth rise to a fairly consistent velocity for a large number of shots, followed by a smooth drop in velocity. If the sweet spot isn't where you want it, increase or decrease the spring tension accordingly, and if the velocity needs a little tweaking make very small changes in the stroke adjustment.
Once you get the Spring tension set where you want it, you can pretty much ignore it too. I have my sweet spot set up so that my usable shots at my highest power tune start right around the peak fill pressure. I then just use the stroke adjustment to change my velocity. The sweet spot will drop a little bit as you tune to lower velocities, but only by about 100-200 psi over a pretty wide range of velocities.
Once you get a feel for the new adjustments you can pretty much tune to any desired velocity with just a chrony and a few pellets. I have also found that the settings are fairly well repeatable. If I record my settings, make changes and then reset back to the original settings, the resultant shot string will be very close.....but again, the stroke adjustment is sensitive, so it will only be as good as your ability to exactly match the setting.
Don't expect this mod to give you the BEST possible shot string. I'm sure there still is room for tweaking so you'll probably still have to work if you want the best possible shot string. But it will generally get you to a VERY GOOD shot string with almost no effort at all once you get used to it. With this mod you really can make use of multiple tunes in your gun without having to worry about how hard it will be to get back to a previous tune.
So if you give this a try let us know how it works out for you. I'm especially interested in how well it will work with different calibers of m-rod as well as the Disco and 22xx platforms. If you use CO2 let us know how it works and how best to tune for CO2. I'd also be interested to see if adding an HDD to this mod improves the shot strings even further.
