Operation TX

[T 20]

Seeing as I'm hosting the AirArms Owners Club charity meeting next month I thought it would be a good idea if I bought an AirArms gun to use over the weekend.

So I bought a cheap MK2 TX200 in .22" flavour off our very own Edbear for the princely sum of £125, so giving me something to tune and play with.

Now here's the twist, rather than me just lathing loads of new parts up I've decided to see what could be acheived using easily available off the shelf parts at minimum cost --- This should allow anyone who can strip a TX to replicate what I'm up to.

Now even though the MK 2 TX has a relatively short stroke I thought I'd shorten it a little bit more and I'm told that the HW77 piston seal is more efficient than the AirArms seal --- so I bought a piston allowing for both. :-


http://s1138.photobucket.com/user/mi...tml?sort=3&o=4


Now the LGV seal has a central tit that would restrict flow on a TX with it's central port so I dug a 25mm Weihrauch seal out the spares box. :-


http://s1138.photobucket.com/user/mi...tml?sort=3&o=6


And this picture shows the difference in piston lengths (LGV on right) :-


http://s1138.photobucket.com/user/mi...tml?sort=3&o=5


The difference in piston lengths with the Weihrauch seal fitted measured at 7.8mm, so with the original TX MK2 stroke being 84mm, fitting the LGV piston should drop the stroke down to 76.2mm.


Well I had a little bit of time this afternoon so I threw my TX together (bone dry) and ran a quick chrono string to see where I was going.

Results :-

Hobbies 645 ft/s = 10.99 ftlbs

Superdomes 604 ft/s = 11.75 ftlbs

Jumbos 550 ft/s = 10.75 ftlbs


The above results are just from changing the piston and removing 4mm of preload from the spring.

If I get a little bit of time in the week I have a few other little tweaks I'd like to try involving shedding a little weight from the piston by way of removing the 6 gram steel top hat and turning the spring round as I have three collapsed coils on the front of the spring which I calculate to add 11 grams to the overall piston weight.


So there you are this is my starting point and I'll play around to lower the power a bit more and to see if I can make the gun sweeter, though in all honesty it feels really nice how it's running now.




All the best Mick

[TonyL]

Excellent, Mick.

And, as you say, so easy for anyone to do without access to specialist machinery / lathe etc.

As you say, I bet it's already very nice, but even better with a little more fine tweaking.

Cheers for sharing.

[Gugglebox]

Thank, this is a perfect thread for me as I'm leaning towards a TX and looking forward to a tinker. I look forward to seeing how the experts do it.

[Shed tuner]

Perfect... that's the thing with tuning a TX; they are such a good base, just sorting the seal and the stroke makes a gun gun excellent.

Not that you are likely to be short of ideas, but in keeping with the no machining / moderate costs, I'd also consider

- Roller thrust rear needle bearings (about £2.50 of the 8ay), make cocking smoother
- beer can piston sleeve
- new tight fitting Custom guides (cheating on the no machining, I know, but if they are available "off the shelf"....)
- LGU seal - they seem quite a bit more efficient in most guns that the HWs
- centre floating guide

I would say consider gluing a sleeve into the port, but it doesn't look like you have any slam, and if you are considering lightening the piston, taking the port down may introduce some bounce with tighter port... unless you want to shoot FAPs (I would !), in fact I'm not even sure I'd lighten it at all...

[T 20]

Excellent, Mick.

And, as you say, so easy for anyone to do without access to specialist machinery / lathe etc.

As you say, I bet it's already very nice, but even better with a little more fine tweaking.

It seems really nice how it is Tony

The big surprise is that my first test run with a reduced stroke showed Superdomes running over 12 hence the removal of the 4mm spacer.

It certainly feels a lot better than standard but I'll let the AirArms lads have a play and give their opinion.

I'm a bit out of practice with this tuning lark as I haven't done much for two years now --- nice to get back in the swing of things.

Perfect... that's the thing with tuning a TX; they are such a good base, just sorting the seal and the stroke makes a gun gun excellent.

Not that you are likely to be short of ideas, but in keeping with the no machining / moderate costs, I'd also consider

- Roller thrust rear needle bearings (about £2.50 of the 8ay), make cocking smoother
- beer can piston sleeve
- new tight fitting Custom guides (cheating on the no machining, I know, but if they are available "off the shelf"....)
- LGU seal - they seem quite a bit more efficient in most guns that the HWs
- centre floating guide

I would say consider gluing a sleeve into the port, but it doesn't look like you have any slam, and if you are considering lightening the piston, taking the port down may introduce some bounce with tighter port... unless you want to shoot FAPs (I would !), in fact I'm not even sure I'd lighten it at all...

That's the idea Jon

I buy everything in and make absolutely nothing that can't be bought.

If anything doesn't work or is a waste of money I'll post that on here as well.

If I decide to sleeve the transfer port down I'll try to source the tubing from the rack in B and Q.

Obviously I'll need to swap all the guts out into a .177" TX at some point to see how it all works in the Ladies calibre.

The total cost of parts so far is about £35 plus shipping and you end up with a spare LGV seal, if you could find a source of LGU Pistons the price would be about £24 plus shipping which has got to be a bargain.

I'm not sure if the beartrap would work with the LGV/LGU piston as my TX has had it removed.



All the best Mick

[TonyL]

It seems really nice how it is Tony

The big surprise is that my first test run with a reduced stroke showed Superdomes running over 12 hence the removal of the 4mm spacer.

I'm a bit out of practice with this tuning lark as I haven't done much for two years now --- nice to get back in the swing of things.

I buy everything in and make absolutely nothing that can't be bought.

If anything doesn't work or is a waste of money I'll post that on here as well.

The total cost of parts so far is about £35 plus shipping and you end up with a spare LGV seal, if you could find a source of LGU Pistons the price would be about £24 plus shipping which has got to be a bargain.

All the best Mick

Looking very efficient already then, Mick.

Out of practice....nah! Once you've got it, you've got it, Michael, and that you most certainly have! And that two years basically corresponds with the Bash concept, so you've been pouring time and effort into that.

Excellent plan re using bought in parts, so that many more people can replicate, and what a great value for money tune it's proving to be.

[Shed tuner]

I'm not sure if the beartrap would work with the LGV/LGU piston as my TX has had it removed.

All the best Mick

@ ~76mm stroke and a MK2 comp tube, it will work fine. MK3, it won't catch.

In .177, I think you'd be pushing it with that stroke and a std port

[T 20]

Thank, this is a perfect thread for me as I'm leaning towards a TX and looking forward to a tinker. I look forward to seeing how the experts do it.

Hi Gugglebox

The TX is far easier to work on than a HW77/97, the only advantage with the 77/97 being the shorter transfer port but this can easily be sorted on the TX if needed.



All the best Mick

[shauny]

Seeing as I'm hosting the AirArms Owners Club charity meeting next month I thought it would be a good idea if I bought an AirArms gun to use over the weekend.

So I bought a cheap MK2 TX200 in .22" flavour off our very own Edbear for the princely sum of £125, so giving me something to tune and play with.

Now here's the twist, rather than me just lathing loads of new parts up I've decided to see what could be acheived using easily available off the shelf parts at minimum cost --- This should allow anyone who can strip a TX to replicate what I'm up to.

Now even though the MK 2 TX has a relatively short stroke I thought I'd shorten it a little bit more and I'm told that the HW77 piston seal is more efficient than the AirArms seal --- so I bought a piston allowing for both. :-


[url]http://s1138.photobucket.com/user/mickfurniss/media/image.jpg2_zpsm2qhj0gd.jpg.html?sort=3&o=4[/ur
Now the LGV seal has a central tit that would restrict flow on a TX with it's central port so I dug a 25mm Weihrauch seal out the spares box. :-


http://s1138.photobucket.com/user/mi...tml?sort=3&o=6


And this picture shows the difference in piston lengths (LGV on right) :-


http://s1138.photobucket.com/user/mi...tml?sort=3&o=5


The difference in piston lengths with the Weihrauch seal fitted measured at 7.8mm, so with the original TX MK2 stroke being 84mm, fitting the LGV piston should drop the stroke down to 76.2mm.


Well I had a little bit of time this afternoon so I threw my TX together (bone dry) and ran a quick chrono string to see where I was going.

Results :-

Hobbies 645 ft/s = 10.99 ftlbs

Superdomes 604 ft/s = 11.75 ftlbs

Jumbos 550 ft/s = 10.75 ftlbs


The above results are just from changing the piston and removing 4mm of preload from the spring.

If I get a little bit of time in the week I have a few other little tweaks I'd like to try involving shedding a little weight from the piston by way of removing the 6 gram steel top hat and turning the spring round as I have three collapsed coils on the front of the spring which I calculate to add 11 grams to the overall piston weight.


So there you are this is my starting point and I'll play around to lower the power a bit more and to see if I can make the gun sweeter, though in all honesty it feels really nice how it's running now.




All the best Mick

hello mate,where did you get your lgv service kit ? thanks.. shaun.

[T 20]

hello mate,where did you get your lgv service kit ? thanks.. shaun.

I was given it Shaun.

Originally I was going to build up the front of the TX piston with weld then machine it to take a 25mm Weihrauch seal which would have reduced the stroke by about 4mm.

Being given the LGV service kit allowed me to have a play without any lathe work which would be of more relevance to most TX owners.

I understand the kits are available through Armex but would need shipping to your local RFD due to the VCR act.

The price I quoted of £24 plus shipping is direct to your door from a German supplier.



My next door neighbour had a couple of shots with my TX earlier to see what he thought of the firing cycle --- when I asked him what he thought he replied, " I give up, how have you made this one recoiless."

I was going to have another play with the piston weight tonight but unfortunately I ended up working late but I will have another play this week.



All the best Mick

[NickG]

I was given it Shaun.

Originally I was going to build up the front of the TX piston with weld then machine it to take a 25mm Weihrauch seal which would have reduced the stroke by about 4mm.

Being given the LGV service kit allowed me to have a play without any lathe work which would be of more relevance to most TX owners.

I understand the kits are available through Armex but would need shipping to your local RFD due to the VCR act.

The price I quoted of £24 plus shipping is direct to your door from a German supplier.



My next door neighbour had a couple of shots with my TX earlier to see what he thought of the firing cycle --- when I asked him what he thought he replied, " I give up, how have you made this one recoiless."

I was going to have another play with the piston weight tonight but unfortunately I ended up working late but I will have another play this week.



All the best Mick

The.22's are very soft aren't they, I put my shortest stroke lightest piston in Maz's .22 and it barely moves , he is bringing it t0 the AA bash. Be nice to shoot them side by side,
I have been simplifying things on the piston front, by modding a standard piston for light weight, and o ring by glueing an ally o ring head on the front, that's the same size as the seal, and using a long latch rod to keep plenty of spring room.

[Lanky94]

I used an LGV seal in my .22 TX 200 with the piston skirt removed. I just machined the 'tit' of flush and re-tested. It produced the same fps/power as it did with the tit on.

Is the LGU seal the same as the LGV, but without the tit.?

[Snooper601]

No, it has a negative tit in the centre that's bigger than the port.

Cheers

John

[shauny]

I was given it Shaun.

Originally I was going to build up the front of the TX piston with weld then machine it to take a 25mm Weihrauch seal which would have reduced the stroke by about 4mm.

Being given the LGV service kit allowed me to have a play without any lathe work which would be of more relevance to most TX owners.

I understand the kits are available through Armex but would need shipping to your local RFD due to the VCR act.

The price I quoted of £24 plus shipping is direct to your door from a German supplier.



My next door neighbour had a couple of shots with my TX earlier to see what he thought of the firing cycle --- when I asked him what he thought he replied, " I give up, how have you made this one recoiless."

I was going to have another play with the piston weight tonight but unfortunately I ended up working late but I will have another play this week.



All the best Mick

ok, thankyou mick. shaun

[T 20]

ok, thankyou mick. shaun

No problem Shaun

I was going to have another play with the piston weight tonight but unfortunately I ended up working late but I will have another play this week.

Well I couldn't leave it alone so I had another little play today by shedding a little bit of weight from the piston.

Now when I got the TX from Ed :-

The piston weighed 237grams
The top hat weighed 11grams
The 2 collapsed spring coils added 7.4grams to the piston weight.

So the all up piston weight of the TX piston was 255.4grams.


Now the LGV piston weighs in at 252grams so as first tested with the LGV piston the overall piston weight was as follows :-

The piston weighed 252grams
The top hat weighed 11grams
The 2 collapsed spring coils added 7.4grams to the piston weight

So the overall piston weight was 270.4grams


Today I turned the spring round putting the collapsed coils to the rear and substituted a Nylon top hat for the steel one giving the following :-

Piston weight 252grams
Nylon top hat 2grams

So as of today I have an all up piston weight of 254grams.

After a chrono session the velocities are about the same as before losing 16grams in piston weight but the recoil feels to be just a little less than before.

I doubt I'm going to mess with the gun anymore unless my planed plinking session shows up any problems --- it's running nice enough for me.



All the best Mick