The Dreaded Airsporter Questions

[NOTSHARP]

I am giving an Airsporter Mk.6 some TLC, and would appreciate advice from the many here that have got the tee shirt.

Firstly, piston heads.

Mine came with the plastic (?) head, with the scraper ring fitted. Somewhere along the line, I have acquired a steel one.




I understand that the steel type was for export models. Also the scraper ring idea was unnecessary, and abandoned.

My questions are:

With a standard spring, is fitting the steel head worthwhile?
Would a standard plastic, or alloy, be the better option?


Any advice welcome - apart from scrapping it.







Steve.

[look no hands]

I've never actually seen a steel head (or plastic one) in any of the Beezas I've stripped, all of them have been alloy heads, personally I'd stick with an alloy head, that steel head looks too short as well compared to the plastic one,which would increase the stroke slightly (I can't see the hole for the cross pin.

[T 20]

The steel heads were export and FAC spec, Pete.

I'd go for the alloy head as the Nylon heads tend to swell up over time, it is possible to machine an alloy head up to accept a 28mm Diana seal and also increase the stroke a bit, but as the parallel loading taps on Airsporter leak like a sieve there's little point getting too carried away.

The Nylon head shown is normally found in a MK4 Airsporter and the pin hole is actually in the O ring groove.



All the best Mick

[evert]

What on earth were they thinking about when they added that scarper ring???

[Dornfelderliebe]

My Mk6 bought from new, never touched in-between and was refurbed by me four years ago came a nylon head which had no scraper ring. I replaced it with an aly version from John Knibbs. T20 is right the later loading taps leak like sieves.
When I can get my act together and work out what else is wrong I'll do an update on my attempt to have grooves machined and fit orings either side of the tap.
It was seized up. I used a screwdriver and hammer to push the piston down the cylinder after trying to squirt WD 40 every where to loosen it. Shades of the Meteor thread.
Perhaps some one should market the buffer washer material as a bonding agent.

[T 20]

What on earth were they thinking about when they added that scarper ring???

It's probably incorrect to call it a scraper ring as there would be nothing to scrape, the only thing I can think it was for was to act as a bearing to centralise the head in the cylinder ?





All the best Mick

[evert]

It's probably incorrect to call it a scraper ring as there would be nothing to scrape, the only thing I can think it was for was to act as a bearing to centralise the head in the cylinder ?





All the best Mick

Ok, but steel in steel? Isnt that asking for excessive wear?

[NOTSHARP]

The steel heads were export and FAC spec, Pete.

I'd go for the alloy head as the Nylon heads tend to swell up over time, it is possible to machine an alloy head up to accept a 28mm Diana seal and also increase the stroke a bit, but as the parallel loading taps on Airsporter leak like a sieve there's little point getting too carried away.

The Nylon head shown is normally found in a MK4 Airsporter and the pin hole is actually in the O ring groove.



All the best Mick

Many thanks for your reply, Mick.

The Mk6 drawing on the Knibbs site, does show the piston head, with the "support ring".
https://www.airgunspares.com/162435b...pportring.html

But, the piston head is shown as alloy.
https://www.airgunspares.com/catalog...7/category/678

I will go with the alloy, as you suggest.


Steve.

[NOTSHARP]

My Mk6 bought from new, never touched in-between and was refurbed by me four years ago came a nylon head which had no scraper ring. I replaced it with an aly version from John Knibbs. T20 is right the later loading taps leak like sieves.
When I can get my act together and work out what else is wrong I'll do an update on my attempt to have groves machined and fit orings either side of the tap.
It was seized up. I used a screwdriver and hammer to push the piston down the cylinder after trying to squirt WD 40 every where to loosen it. Shades of the Meteor thread.
Perhaps some one should market the buffer washer material as a bonding agent.

I have read of the leaky loading taps, but mine seems fine at the moment. No doubt that means it will leak in the future.

Did you get grooves machined, or is it a work in progress? I would be interested in the test results.


Steve.

[T 20]

Ok, but steel in steel? Isnt that asking for excessive wear?

The steel snap ring it hardened and a round cross section so tended not to gall, the MK4 Airsporter I bought with that piston head had an undamaged cylinder --- The rest of the gun was shyte though.

[NOTSHARP]

The steel snap ring it hardened and a round cross section so tended not to gall, the MK4 Airsporter I bought with that piston head had an undamaged cylinder ---

The rest of the gun was shyte though

.

They were not exactly precision made, where they.

Do you know of anyone attempting to button the piston in one?



Steve.

[T 20]

Do you know of anyone attempting to button the piston in one?.

That would be like putting lipstick on a pig, Steve.

I recently built a completely new lightweight piston for my Mercury (the same piston as an Airsporter) and I think I may have put a rear bearing on that one, but I don't think I've ever heard of anyone buttoning a standard Airsporter piston.




All the best Mick

[NOTSHARP]

That would be like putting lipstick on a pig

, Steve.

I recently built a completely new lightweight piston for my Mercury (the same piston as an Airsporter) and I think I may have put a rear bearing on that one, but I don't think I've ever heard of anyone buttoning a standard Airsporter piston.




All the best Mick

What's not to like.





Did you use a needle roller bearing, and did the theory work?



Steve.

[T 20]

Did you use a needle roller bearing, and did the theory work?



Steve.

Hi Steve

I normally cut a groove round the piston tail and fit a Delrin ring in the groove, on 25mm and 30mm cylinder guns I cheat and use the bearings from an AirArms TX piston, on others I machine up the bearing and I have used the Delrin snap rings from the forward/reverse clutch pack in a JCB gearbox before now.

Whatever gets the job done.

The piston tail bearings really come into their own to make cocking smoother as they prevents metal to metal contact on a high load area.




All the best Mick

[NOTSHARP]

Hi Steve

I normally cut a groove round the piston tail and fit a Delrin ring in the groove, on 25mm and 30mm cylinder guns I cheat and use the bearings from an AirArms TX piston, on others I machine up the bearing and I have used the Delrin snap rings from the forward/reverse clutch pack in a JCB gearbox before now.

Whatever gets the job done.

The piston tail bearings really come into their own to make cocking smoother as they prevents metal to metal contact on a high load area.




All the best Mick

More food for thought. I shall see how The Pig performs after I get the tlc done. I can feel a Winter project building.

If it is putting out 9-10 ft/lb, and smooth'ish, it shall remain, for ever, a pig.

Many thanks for your help.



Steve.



Steve.