Diana Chaser barrel...
 

Diana Chaser barrel end o-ring sizes?  

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marflow
(@marflow)
Joined: 2 years ago
Posts: 634
2019-02-20 23:40:13  

the .22 caliber o-ring seems to be a 009 or at least it fits fine but the .177 is a bit odd I'm thinking it is a 1.42mm x4.7mm

any thoughts or the real sizes

the 1.42 x 4.7 is a hard size to find cheaply but it is a size

Mike


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nervoustrigger
(@nervoustrigger)
Joined: 2 years ago
Posts: 184
2019-02-21 00:23:21  

On the .177 CP1-M, my notes say 1.5mm x 4.5mm.  Same barrel as far as I know.  I didn’t have that size so I used a -008 with the OD abraded down to be a slip fit into the groove.  It seals perfectly to the bolt and has held up great for thousands of pellets.  Just placed it on a snug-fitting drill shank and spun it in the drill press while hitting it with a Dremel polishing wheel.  If it sounds like too much trouble, it was nice having it fixed in minutes as opposed to waiting days for an order of O-rings. 


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 2 years ago
Posts: 288
2019-02-21 10:46:52  
Posted by: marflow

the .22 caliber o-ring seems to be a 009 or at least it fits fine but the .177 is a bit odd I'm thinking it is a 1.42mm x4.7mm

any thoughts or the real sizes

the 1.42 x 4.7 is a hard size to find cheaply but it is a size

I don't know for sure if this is the size you need, but if you are sure, then these guys have superb service:

https://www.theoringstore.com/index.php?main_page=product_info&cPath=368_912_913&products_id=24126&zenid=d182649fe569b3551055a0aec5aaca7e  

Hope this helps.

 

 

 

 

HM


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marflow
(@marflow)
Joined: 2 years ago
Posts: 634
2019-02-21 15:04:33  

the O-ring Store is my go to place for shopping and for just sizing info

so after doing some measuring the .177 o-ring is not 1.5mm in CS and it is not 8mm in od

now the o-ring store shows a 1.42mm x 4.7mm and the od would be 7.54 and that is what it looks like after some measuring

so the O-ring has none in stock but you can find them

Hector a note to you, I bought 2 Chasers from PA when they were on sale, both the boxes were damaged by the cocking handle

a hole straight through the foam and cardboard and ever through the one owner manual I got, one owner manual was missing altogether

so some protection is needed to be added to the box for shipment to the customer and or the sell like PA and the manuals could be or should be put in the fabric cases or something else

thank for your time

mike

Mike


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nervoustrigger
(@nervoustrigger)
Joined: 2 years ago
Posts: 184
2019-02-21 16:07:39  

Really strange they would use an oddball O-ring like that.  Does the bolt probe measure 4.7mm to match it?

I will measure the probes on my CR600W and CP1-M tonight and report back. 


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marflow
(@marflow)
Joined: 2 years ago
Posts: 634
2019-02-21 17:56:25  

you know I didn't measure the probe

the main body is 4.68+-mm the step down is 3.73+-mm and the tip is the tip and because it is hard to measure in the breech that is the best I can do

it looks like the bolt just presses against the o-ring as the sealing surface instead of the o-ring probe interface

so maybe perfect isn't needed

 

Mike


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JiminPGH
(@jiminpgh)
Joined: 2 years ago
Posts: 296
2019-02-21 19:07:36  
Posted by: marflow

you know I didn't measure the probe

the main body is 4.68+-mm the step down is 3.73+-mm and the tip is the tip and because it is hard to measure in the breech that is the best I can do

it looks like the bolt just presses against the o-ring as the sealing surface instead of the o-ring probe interface

so maybe perfect isn't needed

In fact, perfect is not needed.  I was experiencing bolt flip on firing with my Dianas, which I didn't experience with my Snowpeaks.  Hector Medina told me the Dianas have a closer tolerance oring than the Snowpeaks.  He also taught me a trick.  The cocking slot is cut with a slightly negative angle, and if I pull back just a bit after chambering a round, no bolt flip, and no blow-by.  The breach-end oring size is not as critical as one would assume.

 


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nervoustrigger
(@nervoustrigger)
Joined: 2 years ago
Posts: 184
2019-02-21 19:42:55  

Okay yeah I was interested primarily in the portion that seals to the O-ring...in this case the 4.68mm portion.  And indeed that closely matches the diameter of both my SPA guns (4.67mm).

I may be splitting hairs but I like the O-ring to have a slight interference fit to make sure there's no blowby when it fires so I'd be more inclined to go back with a M1.5 x 4.5.  That amounts to only 6 or 7 thousandths of an inch of interference, a bit more than the thickness of a sheet of copy paper.


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marflow
(@marflow)
Joined: 2 years ago
Posts: 634
2019-02-21 23:28:39  

no I think the 1.5 x 4.5 would be fine with the OD turned down that .5mm

od ball stuff is used all the time, I have a IZH 53m and the trigger adjustment screw is 4MM x .50 thread and it is a flat blade grub screw and hard to reach   that screw size is harder then hell to find impossible really i'm going to make one for no better reason other then  the factory screw bugs me, the dies is here just need the screw

I would think that all manufactures would use common sizes in most of the parts that they can to save money but it ain't so 

Mike


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nervoustrigger
(@nervoustrigger)
Joined: 2 years ago
Posts: 184
2019-02-22 00:36:31  

I hear you on the oddball stuff in the general sense, I just didn't think it was something SPA was in the habit of doing.  I've replaced most of the O-rings in all 3 of my SPA guns and didn't have to resort to ordering nonstandard sizes...granted some of them I was able to replace with AS568 (inch) sizes because the dimensioning isn't all that particular in some locations.

Regarding reducing an M1.5 x 4.5 O-ring by 0.5mm...that wouldn't be necessary, right?  The difference is only perhaps 0.07mm which is a gnat's eyelash 🙂


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marflow
(@marflow)
Joined: 2 years ago
Posts: 634
2019-02-22 14:11:13  

yes your right I can't add it seems total od is 7.5mm but the 4.5mm ID is at the pellet size and the factory o-ring will pass a pellet with not touching

it doesn't matter in reality if it works it works

take care

mike

Mike


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