(Login HectorMedina) from IP address 189.154.95.197
My Dear Friends;
It gives me great pleasure to inform you that the special piston tests were concluded.
We will have 4 different models, as the new T-05 trigger that displaces the old T-01 needs a longer stem to accommodate the plates system that replaced the old 3 balls system.
Therefore, there will be 4 models:
T-01 Full Power
T-01 International
T-05 Full Power
T-05 International
The Full Power pistons are designed to use heavy-for-caliber pellets, that is from 9 grains in 0.177" and upwards, as well as the 16 grain in 0.22" and onwards.
The International will be setup and should be spaced to yield 12 ft-lbs. Spacing will depend on the rifle, but do not worry, it's easy to do. The International Piston will shorten the lock time by 1/2, so it is a very pleasant sensation to shoot a D-54 with these. It is an "instant" shot, rather than the usual release-distension-thud we are all used to. Those that have shot a FWB300 know what I am talking about.
All 4 kits will need a Jim Maccari spring and guide, but no TopHat, as that is already included inside the piston.
If anyone is interested, post here to add you to the list of the first production run.
Cost will be US$80 per piston + Sh & Hdlg. and we estimate to be shipping around the middle/end of August.
Pistons will be built of 70,000 PSI yield tool steel and will have high temperature ORings.
When you look at the Diana seal, or the other seals in the airgun industry, they are cupped seals, that means that there is a dead space that can NEVER be compressed. This dead space is critical to obtaining the most of the airgun, especially with heavy for caliber pellets. O-Ringed pistons eliminate the dead space. Of course dry-fires are not survivable, so if you're planning in dry firing your gun, do not put one of these pistons.
Also, the O-Ring gives a better seal with less friction, so that enables the gun to transfer more energy to the pellet with less spring force.
A TopHat inside the piston guarantees that your spring will not go crooked prematurely.
It also adds weight to balance out the heavy for caliber pellets.
Spacing is done by inserting calibrated steel washers between the guide's end and the piston's beginning, this pre-compresses the spring and gives you more "power".
Pictures were posted here a long time ago . . . now go to sleep, or stay awake and look for them! LOL!
This is the goal we've been working towards the last year and a half.
To be quite frank, the main problem with the FWB300 is that it is limited to 6-7 ft-lbs. No problem in Germany, where they shoot Mini-FT matches at that power with the max distance being 30 meters. BUT totally non-competitive for International/WFTF and even less for AAFTA power levels.
There are other things from the FWB that we are borrowing, like the O-ring seal, they used a METAL seal but those guns were handmade and cost, in their time, TWICE of what a current D-54 would.
We MAY put out an International cocking lever, because since the stroke is shortened, the fulcrum point can be moved and the multiplication can be much higher, therefore cocking the gun will be a breeze. That is under study, I cannot promise nothing yet.
Don't worry about selling your 52, you may yet be convinced to get a 54, LOL!
the materials people are doing right now, the pistons MAY be buttoned from the start.
As it is, the piston relies on its weight to make a very sudden compression. Of course you can swiss-cheese the piston if you want, it's steel and the only hardened part will be the stem (hardened and then drawn, the 70,000 lbs/sq.in. yield strength is a fabrication parameter for quality acceptance).
But my suggestion would be to shoot whatever pellets you want to shoot in it first, then tune the MV to whatever power level you want to comply with, and then, if you want to swiss cheese it, fine. Go ahead and start all over again! LOL!!!
Cross-hatching the cylinder is something I completely frown upon, it turns the guns more into diesel guns than airguns. It does NOT affect the efficiency or the seal of the compression chamber it just adds chemical energy to the shot cycle.
First, thank you for your involvement in this and other projects involving Diana air weapons. Having someone with your knowledge and experience as a liason between us, the buying public, and Dianawerks owners and engineers can only lead to positive results. Will there be a list of what JM spring will work/ are recommended for which piston? I know he only has a few offerings, but it would be nice to know which one to order specifically for each piston. Can these pistons be buttoned, by JM's old school buttons or elsewise? Will the pistons be "turn key", ready to drop in? Will installation by the consumer/end user void any factory warranty? Will spare O-rings be available as replacement parts?
Jim is having some health issues solved, but as soon as he is well, I'll start pestering him, as I want a special set of springs made for these pistons.
In principle, the piston will take directly the Monolith spring and guide, you can just not order the TopHat. If we get Jim to make the springs, then we will make everyone aware of the fact.
As I answered Warren, Pistons MAY come already buttoned. It all depends on a wear test that's a long term test and we do want to get it right.
IF the pistons come buttoned, you will need to fit them to your rifle, it is added work, but I feel it could be worth it.
Pistons will be as turn-key as possible, for a while I debated getting airgunsmiths registered in the program, but then decided that most people here are knowledgeable enough to not need that. For other users, I may just suggest a good airgunsmith in his area for installation, or get a flat rate package form the USPS and send the gun to any of the good airgunsmiths.
Any installation of a non-Diana part voids the warranty, in this sense, I would suggest getting a used gun. Though, talking of 54's I seldom see one for sale.
O-Rings will be hard 90 Durometer rings and yes, there will be plenty in stock, though experiences show that as long as you follow a consistent maintenance program, you will probably need a ring after 3 years of intensive shooting.
No really, good Whiterock laying hens. Barring that offer I am not able to make a firm commitment due to finances, HOWEVER, I do want a "T-01 International" piston.
Heck I will just sell the Chickens and send you the money, please put me down for one, my 48/52 desirves one.
John Blount
tnairguns at yahoo.com
The new piston is slightly heavier than the factory piston. It has been tested with 10.5 grains in 0.177" rifles and 18 grains in 0.22" rifles. Stability and consistency are much better, no twang. International models will have a shortened lock time. Full Power models have the same lock-time. NO weight saving, on the contrary, there is a piston weight increase. This is necessary to keep the stability of the platform.
They MAY be buttoned, if we define that the buttons actually wear OUT the metal receiver, then we will not button the pistons.
Very interested in a international spring weight for my 54. Smoothness counts and for practical purposes should be enough. Main interest is 25 yd benchrest. Thanks for your help.
Do you have any data showing the performance increase over stock on these pistons?
theoretically, if you can ensure a consistent O-Ring seal, then the standard deviation between shots would drop and if the seal is consistently better, the average FPS will jump. On the flip side, because you're using a heavier piston, the performance of lighter pellets will suffer as they would have already left the barrel before the piston has made its full travel?
Only the data from the prototypes, and that was how we came to the realization that the piston needed to be more substantial if what was wanted was good, rock-steady performance with heavy for caliber pellets.
Shot to shot SD is usually already good in Dianas. Usually in the region of 3-4 fps from a full power gun. So, that means that SD is only about 1/2% of MV, few PCP's can keep that, even regulated guns push to achieve that kind of consistency.
You are right and I have always said so. Unless you go for an International piston, you will not be able to use lightweight pellets effectively. Too much power and too sudden a pressure spike for that. I doubt that the lighter pellet would have left the barrel before the piston reaches the end of the travel, that is not how this piston works. I am not saying it is impossible, just that it is not what the pistons are designed for.
Most probably, IMHO, the sudden pressure spike would deform the pellet skirt, blowing it out and creating a very high friction area. Unless very hard pellets were used, tin, or the High Antimony pellets out there. This would transform a lot of energy into heat that would be dissipated in the barrel, but not into useful Kinetic Energy.
to you all, Hector has his hands full with his work, and his air rifles besides WHY would someone with his knowledge be participating in this forum
because he loves the Diana brand, his passion and our benefit is that he participates in this forum
if I know 10% of air rifles of what Hector know's I would be a partner to Tom Gaylords' blog at PA and teach, give him time to return to the Dianawerks forum
he will be back because the Diana brand is in his blood
I may have missed this. What was the reason for the new pistons??
If a new spring and stuff is needed, and the O ring will need
to be replaced every few years, what was the big advantage to the new pistons??
The Full Power version is needed if you want to use heavy for caliber pellets without breaking the mainspring every few thousand shots. Heavy for caliber pellets are simply too stressing of the spring when you use the factory piston that is too light. A heavier piston has substantial advantages when you want to use 0.177"'s in the 10 grain region, or .22" 's in the 18 grain region.
The International pistons are needed because the traditional way of reducing the power in a spring gun lengthens the lock time incommensurately to the power needed. The gun then becomes too difficult to shoot well. It takes forever for the pellet to leave the barrel and you move the POA in that time. The Int'l pistons will solve that problem.
We are considering issuing an increased fulcrum cocking lever, so that the other advantage is that you get a reduced cocking effort for those 120 shots FT matches.
That is why we feel that the pistons fill a valid market niche, because they solve two different needs of the shooting fraternity.
![[linked image]](http://s54.photobucket.com/albums/g113/spanishintn/?action=view¤t=Picture159.jpg)
