Smaller longer ports for softer shot feel ?

[Shed tuner]

Dang, just search for "needle roller thrust bearings" on Fleabay.

They took a while to arrive but there's ten in a pack, complete with hardened washers.

Mine just arrived - look excellent for the money, and virtually no friction at all, even under pressure
Even with a rotating piston these should help cocking, where the piston cannot rotate freely as it does on firiing.

[Snooper601]

Mine just arrived - look excellent for the money, and virtually no friction at all, even under pressure
Even with a rotating piston these should help cocking, where the piston cannot rotate freely as it does on firiing.

What size did you get Jon? I could only find 10 x 24 which won't fit inside a TX, HW77 or LGV piston. Ok for a HW 80 and a PE but we need some 10 x 20 for 25-26mm pistons.

Cheers

John

[Shed tuner]

What size did you get Jon? I could only find 10 x 24 which won't fit inside a TX, HW77 or LGV piston. Ok for a HW 80 and a PE but we need some 10 x 20 for 25-26mm pistons.

Cheers

John

These are fine for the rear guide (30mm cylinder on HWs and TXs) - don't want any more weight in the piston than I already have...

[TopDog]

Mine just arrived - look excellent for the money, and virtually no friction at all, even under pressure
Even with a rotating piston these should help cocking, where the piston cannot rotate freely as it does on firiing.

Hi Jon

Your In Box is full! Was trying to send you a PM!

atvb
David

[Shed tuner]

Hi Jon

Your In Box is full! Was trying to send you a PM!

atvb
David

Cleared

[NickG]

Just my two penneth on the soft shot feel front, My early ally pistons had no bearing at the front just the o ring, I now do them with a delrin piston head, which carries the o ring and acts as a bearing, they are identical otherwise, weight ,length etc. The delrin head has a noticeably softer shot feel than the ally head, I think its because it has a softer landing when it finally comes to rest. Its a bit crude as a test, but you even notice the difference when you drop them on to a bench. Now going to experiment with polyurethane piston head , or make my own seals from polyurethane, just got to find some at the sight price . Oh another idea is to groove the face of the piston to take an o ring as a buffer.

[Artfull-Bodger]

Quick update on the bearings, I have now fired over 1000 shots through the BSA , took the end cap off last night to inspect the bearings, so far there is no sign of wear or marking on the bearings or the shims!

Accuracy wise we were hitting ping pong balls at 65yds with a 4x mag scope Sunday, my next test is to make up anew guide and bearings to go in my HW77, see what difference it makes on that rifle.

[TonyL]

Excellent! S' look in' good!

[Shed tuner]

Just my two penneth on the soft shot feel front, My early ally pistons had no bearing at the front just the o ring, I now do them with a delrin piston head, which carries the o ring and acts as a bearing, they are identical otherwise, weight ,length etc. The delrin head has a noticeably softer shot feel than the ally head, I think its because it has a softer landing when it finally comes to rest. Its a bit crude as a test, but you even notice the difference when you drop them on to a bench. Now going to experiment with polyurethane piston head , or make my own seals from polyurethane, just got to find some at the sight price . Oh another idea is to groove the face of the piston to take an o ring as a buffer.

Or a BSA head type buffer washer

[Black Beard]

If you put roller bearings on the spring guide with a reasonable preload they won't wear. All the huge forces of the surge and are absorbed by the mass of the piton/spring and the compression of the spring.

If you put them in the piston under the top hat most pf the force goes un to accellerating the piston's mass but the spring also has mass. The forces on the end of the spring inside the piston will be experienced by the bearing. And bigger than at the spring guide end. I think a plain acetal bearing washer would be better in the piston.

Also you don't feel the forces on the piston, you feel the forces on the back of the spring so it makes sense to put your roller bearing on the bit you feel.

[NickG]

Or a BSA head type buffer washer

I guessed that's what you were going for , I am hopefully going to simplify things a bit with a polyurethane o ring head , that will shorten the stroke at the same time ( for the hw97)

[bmp01]

If you put them in the piston under the top hat most pf the force goes un to accellerating the piston's mass but the spring also has mass. The forces on the end of the spring inside the piston will be experienced by the bearing. And bigger than at the spring guide end. I think a plain acetal bearing washer would be better in the piston.

I have a ball bearing arrangement under the tophat on my HW97 and 2 Tx200's, thus far no wear and no concerns. I don't think the forces are too big. I agree there is the compression force that goes into decellerating the piston and squashing the spring. The force can only be as big as the force provided by the spring, it'll just compress some more if the force goes up. The llittle bit of spring inertia to over come.... can't see the inertia of a few coils being very big.
At the trigger end there is the issue of spring surge - if the spring momentarily comes away from the trigger block there is the impact force when it lands again. I have run an INA radial bearing there, no problems but I think it was a bit noisier than plain washers....

PS sorry if this is a bit off subject - very interesting this port discussion.

Byron.