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 Post subject: HW50 air tube trouble
PostPosted: Sat May 11, 2019 8:56 pm 
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Location: Woodstock, Ontario
Hello forum members,

I am having some issues with my HW50. After experiencing some 'hard to cock' frustration I took my rifle (less than 2 tins of pellets fired) to a fellow who was able to take it apart and peek inside.

We see that the problem is a scored air tube and piston. :(

I wonder if anybody has a spare air tube body, or if the body from a sub-495 ft/sec rifle will fit my 'registered' rifle.

I think that I will be able to save the piston, but fear the air tube may be too deeply scored to save. I hope to get it to a polishing expert late next week, but am not hopeful.

I appreciate any thoughts that the air gun crowd has to offer.

Regards,


Stewart


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PostPosted: Sun May 12, 2019 5:49 am 
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This is a rather commom problem with some Weihrauch models, amongst them the HW50 and HW30. I don't understand why the company never addressed this problem, but anyway we have to live with it. I have an HW30S with the very same issue, but it was only slightly scored, or ''galled''. I only had to re-polish the tube and cocking arm, and lube with moly paste, and it's OK for now.

What you may try on yours is to file the scored surface down a bit, and then glue a thin (1/32'') piece of plastic on it. Check the clearance before gluing so the cocking arm doesn't get stuck in between the tube and U-shaped ''retainer'' welded on the tube. Also mirror polish the cocking arm where it contacts the tube, and make sure to polish the arm's end where it engages the piston to remove any sharp edges. You will want to polish the piston's slot where the arm's end engages, and use a good quality grease to lube the contact surfaces. Moly paste (or tungsten, what I use now) is best, but any good quality high-pressure grease would do. I personnally would have no problems repairing that, but it always depends on your skills and experience with mechanical repairs.

If you still want to replace the tube, there is no difference between a full power and a low power one to my knowledge, this is the main spring into the tube that makes the difference in power. If you replace the tube, you'll just have to swap the internal parts and you'll be good. Don't know where you could get a new tube though. HTH.


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PostPosted: Sun May 12, 2019 7:45 am 
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stewbud wrote:
We see that the problem is a scored air tube and piston.

I wonder if anybody has a spare air tube body, or if the body from a sub-495 ft/sec rifle will fit my 'registered' rifle.


Airmec gives good advice. Can you post pictures of the damage?
Depending on where and how deep the scoring is the solution/prognosis could change.
These rifles have common galling problems on the exterior of the compression chamber where the cocking arm linkage articulates. If your rifle has internal galling the solution would be different, but not unsolvable as it could be deeply honed and fitted with oversize seal if necessary. More details will lead to a better diagnosis.

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PostPosted: Sun May 12, 2019 8:28 am 
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Gents,

My problem is internal galling of the cylinder.

It looks like a small piece of metal (perhaps a burr) got rolled up by the end of the piston and scored the inside of the tube.

I will try to get a picture, but there is not much light down there.

The scores are not on the portion of the assembly that seals, so a polish may fix me up.

The score is on the top of the tube, directly across from the cocking slot, which may preclude the use of a small hone.


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PostPosted: Sun May 12, 2019 10:13 am 
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stewbud wrote:
Gents,

My problem is internal galling of the cylinder.

It looks like a small piece of metal (perhaps a burr) got rolled up by the end of the piston and scored the inside of the tube.


I will try to get a picture, but there is not much light down there.

The scores are not on the portion of the assembly that seals, so a polish may fix me up.

The score is on the top of the tube, directly across from the cocking slot, which may preclude the use of a small hone.


OK, inside the tube. This is quite different from the very common outside galling problem affecting these rifles.

I once bought a used air rifle which was badly scratched inside the compression tube, in the ''compression zone'' of the tube. I was able to repair it using JBWeld: it held up good, and I never had another problem with it after. I saw small engines and diesel engines cylinder walls repaired that way in the past, with good results. Probably the same technique could be used to repair yours, and polishing and buttoning the piston would prevent the problem from happening again IMO. It's not an easy job, but if well done, it may well last the life of the rifle.


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PostPosted: Sun May 12, 2019 10:38 am 
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Thanks for the tips folks.

I will keep you informed as the repair moves forward.


Stewart


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PostPosted: Mon May 13, 2019 9:05 am 
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When I was polishing the scratches out of the cylinder I expected to see everything inside polished - because that what I was assured would be done when the folks at Air Gun Source in Peterborough installed a Vortek spring for me.

Nothing of the sort was done, so I guess it was just a spring replacement. :(

I wonder why it took so long to do the work.

They get no thumbs up from me.


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PostPosted: Mon May 13, 2019 2:45 pm 
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Just curious if you took it to where it was purchased, or contact Weihrauch about the issue. You may be qualified for repairs or replacement if the issue is in fact a factory issue.

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PostPosted: Tue May 14, 2019 3:08 pm 
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Gents,

My 'guy' called me just after lunch and asked me to come over and get my rifle.

It went together with my backyard hone and the Vortek 12 ft.-lb. spring and all is 'back to normal'. ;D

Thanks for your interest and comments.


Stewart


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PostPosted: Tue May 14, 2019 4:44 pm 
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Glad to hear!!!

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PostPosted: Tue Jun 04, 2019 9:23 pm 
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Fyi, if it does it again, and for other readers: You can sand the bad spot smooth(er) and put buttons on the piston. Ideally, which is what I do, you fill in the damage with moly. I have some stuff called DFL-1 from a place online: tinyurl.com/y9pydolz
You fill it in and sand it down like bondo and you're golden. Again you use buttons on the piston and your problems are over forever. Grease it anyway, but if you don't use buttons you need to grease more often. You can use motor oil too, which is much easier to get in there, but use thicker stuff and even more often. If oil then ideally store the gun horizontal upside down so the oil pools in that spot where it's needed.
Usually the cause of your problem is the aft top edge the piston has a sharp edge that digs into and scrapes the tube right where you said it did, so at the very least I hope he rounded that edge so it'll be far less likely to happen again. A lack of lube can do it too, or using silicone lube can do it. Never put silicone in there, even if it says that's what it's for. People sell stuff for one reason; profit, so be wary. Example; Bayer used to sell Heroin as medicine for kids. There's lots of example out there but Silicone Spring Oil is one of these things. People often put whatever silicone lube in there because there's a vicious rumor that real oil or grease should never be used. A rumor started by someone selling silicone. I believe Beeman started it, but if not he's the #1 rumor spreader and made a lot of $ from it, at our expense damaging fine guns.
The attached pix is of a home you can make from materials around the house, which is the best hone for springers imo, and far far better than store bought hones. The trigger and cocking slots don't bother it.
You may also have, or have in the future, the problem airmec described. Some Weihrauch guns came with a button, or slider, to fix this linkage scraping problem, and I recall Maccari selling one if needed. Otherwise just make one. If your tube was damaged from not having one then sand the damage smooth and ideally fill it w/ moly like above and the problem is solved. The piston buttons and linkage slider both reduce cocking effort and noise, but you should really be able to tell a big difference in cocking. Be sure to grease those two wear spots either way.


Attachments:
Tube sanding 1.jpg
Tube sanding 1.jpg [ 90.38 KiB | Viewed 305 times ]
Tube sanding 2.jpg
Tube sanding 2.jpg [ 136.25 KiB | Viewed 305 times ]
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