Tx200 mk2 spring specs

[cooper_dan]

I just happened to measure a standard one yesterday.

Active coils = 23
Active Length = 200mm (this doesn't include the collapsed coils at one end)
Coil OD = 20.7mm
Coil outer dia = 3.24mm
Coil inner dia = 14.22
Mean dia = 17.46mm

In my TX, 84mm stroke, 11 ft-lb in 0.177, gives 37% efficiency. Very good springs.

[TonyL]

That was a Mk.3 spring, Mick.

I just happened to measure a standard one yesterday.

Active coils = 23
Active Length = 200mm (this doesn't include the collapsed coils at one end)
Coil OD = 20.7mm
Coil outer dia = 3.24mm
Coil inner dia = 14.22
Mean dia = 17.46mm

In my TX, 84mm stroke, 11 ft-lb in 0.177, gives 37% efficiency. Very good springs.

Any chance you could post this information on the Mainspring Data Thread please, gents?

[Phil Russell]

I just happened to measure a standard one yesterday.

Active coils = 23
Active Length = 200mm (this doesn't include the collapsed coils at one end)
Coil OD = 20.7mm
Coil outer dia = 3.24mm
Coil inner dia = 14.22
Mean dia = 17.46mm

In my TX, 84mm stroke, 11 ft-lb in 0.177, gives 37% efficiency. Very good springs.

So as to avoid any confusion, can you confirm that the above spring measurements are for the Tx MK2? I will then add them to the database.

The current database entry reads:
Air Arms TX200 Mk1/2 21 (20.75)od 3.25 wire diam 207 / 220 length 23 active coils Source from Forum so very close to your posting.

Cheers, Phil

PS what is mean diameter? I can see it is id plus wire but I have not seen it quoted before.

[Murphy]

IIRC the standard mk2 spring is the FAC mk3 spring.

[joffy]

IIRC the standard mk2 spring is the FAC mk3 spring.

maybe without the collapsed coils

[Murphy]

maybe without the collapsed coils

From memory they have the same part number.

[FPoole]

maybe without the collapsed coils

I have used the MarkI piston in my FAC MarkIII. In normal tune it shot 8.44 Exacts at 900 fps and with just the change to the MarkI piston, it dropped to 790 fps. It would seem the FAC MarkIII spring is very close to the same performance as the original MarkI/MarkII spring.

[Phil Russell]

Thanks for the information. I have added it to my post in the Mainspring thread. I also noticed that I had not put the Tx MK3 data there so I added that.
Interesting about 'mean diameter' as well ... I learn something every day.
Cheers, Phil

[TonyL]

Cheers, Phil.

Having read Jim's excellent article on using the TX Mark 3 in a Walther LGV conversion and having witnessed the "weedy" appearance of this spring from my own Mark 3 and also seeing how Jim's suggested conversion works so well in Vernal's LGV, I have high hopes for this spring for a few projects.

If the ID of the piston (and spring room) allows when I get round to stripping it, I think this spring will be at the top of my list for my old school HW50 fettle.

[cooper_dan]

So as to avoid any confusion, can you confirm that the above spring measurements are for the Tx MK2? I will then add them to the database.

The current database entry reads:
Air Arms TX200 Mk1/2 21 (20.75)od 3.25 wire diam 207 / 220 length 23 active coils Source from Forum so very close to your posting.

Cheers, Phil

PS what is mean diameter? I can see it is id plus wire but I have not seen it quoted before.

Yes that was for an OEM Air Arms mk2 TX200 spring with the collapsed coils. Purchased some time last year.
The length I measured was 'active length' so it doesn't include the collapsed coils at the end. They would add about 10mm I guess to the total length. Next time it's apart I can check.

Mean diameter is the diameter at the axis of the wire if that makes sense. i.e half way between outer dia and inner dia. That's the number needed to calculate the spring constant (k).

I have a spreadsheet that calculates efficiency of my competition TX200. I know it should be between about 36-40% when it's all working well. If it drops much below that I know there is something wrong. So I know to check the seals and spring etc. Sometimes this gun gets stripped and rebuilt twice a week (if it's a wet weekend with 2 shoots on) so it's worth doing. However the TX is mega and has only come up short twice in about 18 months.


Make Air Arms
Model TX200
Date 22/4/19
Active coils 23
Length 200
Coil OD mm 20.7
Coil dia mm 3.24
Mean dia mm 17.46
Coil ID 14.22
Stroke 83
Preload 12
k 8.923

Pellet speed fps 770
Weight grain 8.44
Power ft-lb 11.11
Joules 15.07

Spring Rate fitted N 107
Spring rate cocked N 848
Average rate N 477
Recoverable energy Joules 40

Efficiency % 38.0

[TonyL]

Some excellent, in-depth information there, Dan.