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All Springer/NP/PCP Air Gun Discussion General > Machine Shop Talk & AG Parts Machining

Spring Guide Question

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Daysailer:
I have a 'friend' that made a spring guide for a HW30S.
An 'advisor' suggested that it be made just loose enough that when clean of any grease or lube, it will slide into the spring with just gravity pulling/pushing it.

The 'advisor's' reasoning was that the guide will swell slightly with the grease/lube and fit perfectly after that happens.

The spring and guide have been lubed with light grease and left for a few days, cleaned and then retested for fit and the guide still slides all the way in with just gravity for force.

Maybe I am just a bit dense (or opposite) but some version of nylon/plastic/delrin swelling from lubrication ????   
My thought would be that plastics of this type of material should be basically inert to any kind of lube I can think of (from my unlearned knowledge base), and be unchanged from exposure to it.

Was the advisor correct?    Or have we misread the tuning threads that suggest that the spring guide should fit snuggly in the spring before installing  ??


Thanks to all for time you have taken on this forum, and others, to educate those newbies, like me, and help us learn and enjoy our sport.
ds

CharlieDaTuna:
I would suggest that it be just a little tight because the spring expends as it is being compressed. If the guide is made out of a synthetic material like Delrin or Nylon it will not be affected by lubricants.

airiscool:
What lube, and plastic was your friend using ? Depending on what use the lube was originally intended for, some lubes have a swelling agent in them to keep synthetic seals tight.

Also, some plastics swell around oil and some don't.

Many years I worked in a boatyard that also had a boat store. We had one of the first run of Lazer sailboats. These small boats had a two-piece alumimum mast. The two sections slipped together with Teflon bushings in the slip joint. The factory had used  a light coating of some type of oil to retard oxidation of the alumium. After a couple of days we couldn't get the mast sections apart. We shipped the mast back and the new mast had been switched to nylon bushings. The factory stopped using Teflon bushings and the problem never happened again.

As Charley pointed out, the nylon wouldn't change size with oil contact.

Paul.

Daysailer:
Paul,
Thank-you for your enlightening post.

I own a Laser built in 1977.  In fact, just got back from sailing 'Tuf Nuf ?' this afternoon. Winds strong enough to plane at will.   It was interesting to hear about the growing pains that Bruce Kirby went thorough to perfect his incredeble design.  Over 100,000 built now and an Olympic class.  The mast bushings are still nylon, but we are now using UHMV tape, very thin, to shim the mast joint to get a smoother mast bend to improve preformance., and help get them apart after a days sailing.

I do not know exactly what the Spring Guide is made of so there is a chance that my experience with plastics is incomplete.  This post is to try and fill in my knowledge as it applies to airguns and the "advice" I recieved that the plastic guide would grow with exposure to lubes.  I have found nowhere else in my exhaustive research that mentions this happening to properly fitted spring guides.

Do you know if any of the aftermarket spring guides are made from Teflon ??

Thanks for sharing your experiences.....back to icing my knees from todays 'water dancing' in my Laser.

ds

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