GTA
Airguns by Make and Model => Diana Airguns => Topic started by: JimG on February 21, 2017, 11:15:48 AM
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Anyone know or can suggest what the torque values in inch pounds are for the 3 stock screws on a synthetic stocked Diana 34? Having accuracy issues and trying to track down the problem. Thanks.
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Don't know of a torque setting but I go ~1/2 turn past snug also Blue Loctite on the first 3 to 4 threads and let sit overnight. PS clean threads male and female threads with a mild solvent to remove any oils or lube from mating surfaces
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I don't have a torque but I do have a suggestion. Remove the screws. Put a star washer onto the screw followed by a flat washer.
The flat washer protects the gun from the star washer which in turn helps keep the screw from backing out. I don't use Loctite on my guns. I do use Vibratite VC-3 on some stock screws.
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What I do with my springer is get the screws snug, mark the scope ring to the scope and dove tail and see it that moves and check crown...if that's good and nothing visual I use cotton bud to see if it snags any tiny burrs that can throw off my shots. Find out which pellet it likes to shoot. Side play on the breech can also make you shoot inconsistent. Investing on a crony eliminates guessing.
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It doesn't really matter. Just snug with Loctite and you'll be fine. German guns are made from good steel hardware, sized appropriately, so you don't have to worry about strippage, as long as you use an appropriately sized tool.
If you don't have a good feeling for 'snug', by all means torque it, but it's largely unnecessary.
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15 in-lb on my Diana 34 and others.
Seems to work.
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I believe that would be INCH-POUNDS.
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OK, here's what I did. I checked the breech seal via the tissue test. I have a good seal. Checked barrel pivot tension. Seemed good, but I adjusted it slightly tighter. Put a dab of moly on the detent. While I know this has nothing to do with accuracy, I put some moly on the cocking shoe as it seemed to be very dry. Cocks smoother now. What I call the stock screw yoke on the front of the compression tube was not loose in any way. I then went by HW's torque specs and tightened the rear screw first to 40 in lbs. It has never been that tight before. Was around 18-20 in lbs. I then tightened the two front screws to 20 in lbs. They actually have always been 20 in lbs. First two shots were about 2" high at ten yards, then it started grouping very well. I then shot at 30 yards and found that it's now shooting like it always has before. Likes FTS, SuperDomes, and Ramjets. I'm not the best spring piston shooter, but I managed 5 shot groups of 1/2 to 7/8 inches including any fliers. Better than the 1 1/2 to 3 inch groups prior. Not sure what I did that fixed it but at least it's good now.
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I believe that would be INCH-POUNDS.
Of course. :-[
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I have my front D34 screws set at 25 inch pounds and the back screw set at 22 inch pounds. Be careful with torquing the screws down too tight. My stock split when I torqued the rear screw down to 35 inch pounds.
There was a great thread on this subject some time ago where Hector Medina gave a great write up on how to tune the stock screws. I have captured some of this discussion in the following>
Actually, you do not need screw cups nor loc-tite.
Get some flat washers that fit the wood cavity bottom exactly, get some star washers to go with them. Degrease one side of flat washers. Do NOT degrease anything else.
Glue degreased side of the flat washers with very little Gel CyanoA to the wood, then place the star washers between screw and flat washers and tighten to 20-35 in-lbs depending on the size of the screw.
Wait 24 hours to use gun.
Remember that in 3 screw breakbarrel actions you need to tighten the front/side screws and then TUNE the rear action/trigger screw tightness to the pellet / energy level you are using.
You're done.
When I started shooting breakbarrel airguns about 17 years ago, I started with the locally available Mendoza's.
Old designs and obsolete ideas (think '40's Barrakuda airguns made to diesel on purpose to achieve the advertised power level), one of the things I learned early on was that the tension in the rear screw (that usually is also part of the trigger guard attachment hardware) played an important part in the vibrations of the action in the stock when the shot is released which in turn, dictate the vibrations of the barrel and therefore exactly WHERE the muzzle is pointing at when the pellet exits.
Years later, when we started the special runs of Dianas, the 34 came across and I revived all the old tricks. One of these was the metal washers, another the tuning of the rear trigger guard/action screw.
Wood can compress, but if held between two solid steel walls, it compresses less than when it can be "squished sideways" So the idea of the washers is to get a solid steel wall (made by the screw head supporting the washer) and the receiver. It works with European Beech in a nice manner because it STILL allows some dampening action (as opposed to pillaring the bedding screws as Ed does that "FIXES" everything in place rigidly) and therefore the guns shoot smoother. It will not work as well in Malaysian tropical hard woods, or with Black, Circassian, Claro, or French Walnut, nor with Hard Rock Maple. The shortness of the fiber and the WEIGHT of the stock are an integral part in how the masses dampen the recoil and vibrations of the power plant.
Star washers are designed to "bite" into the flat washers and the screw head, properly used they are as good as the Nord-Loc/Dyna-Loc thingies.
SO, that is why it works.
HOW to tune your bedding; it is REAL SIMPLE:
Once a pellet and an energy level has been chosen, tighten the front screws to about 25 in-lbs, tighten the rear screw to the same torque.
Now, shoot a group of three shots.
Tighten the rear screw 1/4 turn.
Shoot another group. If the size of the group goes down, tighten another 1/4 turn.
Repeat until the group starts to grow or when you reach 35 in-lbs.
Now tighten the front end screws to the same tightness and check that the groups have not grown.
If they do, then loosen the rear screw by 1/4 turns till you get the optimum group size.
Sometimes it will surprise you how much the groups change, and also how little rear action tension some rifles need.
IF your rifle needs less than 25 in-lbs rear screw tension, then use blue loc-tite. It is uncommon, but it does happen.
One caveat: this technique works best in rifles where the front screws are ANGLED (about 75% of all breakbarrels). IF your screws are perpendicular to the stock, you may need too much tension in the rear screw. Do NOT exceed 35 in-lbs.
I would still try different torque settings. I know that my wife's HW95 takes a LOT LESS than 22 in-lbs in the rear screw to achieve its optimal grouping, and then I DO use loctite (the blue liquid) to keep everything in place. But that is just ONE rifle that is different from yours.
The factory has to specify what they feel works best for most and with an eye to "white book of good practices" philosophy using AVERAGE wood, but they cannot know what is going on in YOUR gun. Only YOU can do that. Paraphrasing what someone's signature says: "No guru can look through your eyes".
In GENERAL it is not a good idea to exceed the 35 in-lbs because this damages ANY wood, and you really cannot "recover" compressed wood with any structural integrity. You can raise dents and knocks, sand them over and refinish, but that does not entail structural functions.
IMHO, getting the most out of your gun is more important than following factory specs.
Another thing to consider is whether through repeated tightening and loosening you have already LOST some wood in those critical areas, either through compression or abrasion. In that case, the "wicking" CA idea can be extended using sanding dust to increase the wood and allow for proper tensioning of the screws. If you have lost wood, then Ed's "pillar bed" idea is worth a slow, long, look because you may have no other options, apart from getting a new stock and putting the washers in from the start before any damage has come to the thin wood sections.
I know how frustrating these things seem, sometimes taking a break, a long deep breath, shooting another gun, and sleeping on it may help.
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While I appreciate your advice and reply Fred J, I don't have a wood stock. Mine is synthetic as I had mentioned in my first post.
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Fred, can you post a link to details about pillar bedding?
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. PS clean threads male and female threads with a mild solvent to remove any oils or lube from mating surfaces
What solvent do you recommend? Is 90% Iso good enough?
-Y
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While I appreciate your advice and reply Fred J, I don't have a wood stock. Mine is synthetic as I had mentioned in my first post.
The same idea of the flat washer and the star washer still applies. For that matter, so does the methodology they Fred explained in tightening your stock screws. Your torque values may be different due to the different masses of plastic and beech wood, but the methodology should be the same.
-Y
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While I appreciate your advice and reply Fred J, I don't have a wood stock. Mine is synthetic as I had mentioned in my first post.
Jim;
Synthetic does not mean invulnerable. It may mean more consistent, but the actions and vibrations of each action are unique to that action. So, even if the stock is mechanically more resistant and uniform, it still does not mean that the BEST setting is the factory setting.
Taking care and adding a few flat washers, IF your gun did not have them already, hurts nothing.
And the methodology works. I use it all the time with LGV's as well as Dianas.
It really is up to YOU to make the best of YOUR tools.
JMHO
HM