Help stripping and sorting a HW35k

[Mr.Fixit-Norm]

Happy Birthday Norm.

Swiftly developing into a most excellent thread with all the expert engineer input. Rated accordingly.

Thanks Tony, I shall have to resist spending anymore of it in the shed today

It’s nice when you start a thread that people find interesting and informative, gives one a nice warm fuzzy feeling inside

I reckon between all the great people on here along with the good humour ( most of the time ! ) and incredible wealth of knowledge, this must be the best forum in the world

Norm

[Shed tuner]

Ah --- I knock sleeves in from the breech side on break barrels, Jon.

I also make the reduced port from brass with a slight taper but I finish the cylinder end into a Venturi before smearing with Loctite and knocking it in from the front.

From the above the force acting on the sleeve when firing at 1000psi is 0.02 X 1000 = 20 Lbs.

Obviously at 1500psi there'd be a force of 30 Lbs trying to push the transfer port out on firing, so as long as the force needed to knock the transfer port into the cylinder exceeds this it should never move --- mine haven't so far.

All the best Mick

yeah, people seem to massively over-estiamte the forces involved.. and expecially with longer ports, the chance of it coming out is pretty low. Fair enough on sloping port guns, but it just feels right to kock em in from the rear if you can

[T 20]

it just feels right to kock em in from the rear if you can

Dirty boy.

[TonyL]

It’s nice when you start a thread that people find interesting and informative, gives one a nice warm fuzzy feeling inside

I reckon between all the great people on here along with the good humour ( most of the time ! ) and incredible wealth of knowledge, this must be the best forum in the world

Norm

Absolutely, Norm.. And a nice Boinger Bash meet must surely be your next aim.

[TonyL]

it just feels right to kock em in from the rear if you can

Dirty boy.

Chortle, chortle.......!

[T 20]

yeah, people seem to massively over-estiamte the forces involved

Yes Jon.

From a quick calculation the cross sectional area of a .22" pellet is 0.038" and the cross sectional area of a HW35 piston is 1.095".

So if the cylinder pressure reaches 1000psi on firing there's 1095 Lbs force trying to push the piston back, but only 38Lbs force acting on the pellet to propel it up the barrel.





All the best Mick

[Mr.Fixit-Norm]

Absolutely, Norm.. And a nice Boinger Bash meet must surely be your next aim.

Sadly a bit of a way for me to go these days, and not easy with a dog at home.

[u.k.neil]

Indeed!

Hope you're keeping well, sir.

We are well mate, thank you, but keep getting older.....


Neil

[TonyL]

We are well mate, thank you, but keep getting older.....


Neil

Great to hear that you're keeping well, Neil. And that getting older lark is far preferable to the alternative.

[TonyL]

Sadly a bit of a way for me to go these days, and not easy with a dog at home.

Appreciated, Norm. But it would be great to meet you if you could make it and our furry friends are always welcome. Are you planning any tinkering time today?

[Mr.Fixit-Norm]

Appreciated, Norm. But it would be great to meet you if you could make it and our furry friends are always welcome. Are you planning any tinkering time today?

Hopefully !
I might do as Mick suggested and reassemble it as it is and see what power it’s putting out pre any tweaking and tuning. The only thing would be trying to get that spring back with the amount of preload, although I’m sure I can rig something up as I’ve done it in the past.

I’ve got a large sash clamp and I’d previously used small blocks of wood with a recess cut in them for the barrel and end block.

I may sort that horrible cut end of the spring out first though !

Norm

[u.k.neil]

Just for your information, Chambers Gun Spares have in stock standard mainsprings and piston head adaptors and synthetic seals if you need to replace the original leather washer.


Neil

[T 20]

Just for your information, Chambers Gun Spares have in stock standard mainsprings and piston head adaptors and synthetic seals if you need to replace the original leather washer.


Neil

The piston head adaptors are somewhat crap, Neil, they shorten the stroke and add a lot of weight to the already heavy piston.
The better option when changing from a leather seal to a synthetic seal on a HW35 is to buy the complete synthetic piston.
The synthetic sealed piston is lighter than the standard leather sealed piston and gives 4mm more stroke than the leather sealed piston --- win win.


Anyway, what you doing with your address as Hinckley, I thought you were going back over the A5 ?




All the best Mick

[Mr.Fixit-Norm]

Just for your information, Chambers Gun Spares have in stock standard mainsprings and piston head adaptors and synthetic seals if you need to replace the original leather washer.


Neil

Way ahead of you there Neil , first thing I did when I got it was go to the chambers site and see what was available. I was surprised how many different springs and tuning bits they do for it !

What I like is you can see all the parts in the exploded diagrams so you know what you’re looking at when you start working on it.

Luckily it’s got the synthetic piston seal already, it doesn’t look in bad condition but I’m changing it anyway. My tinbum kit should be on its way soon so in the meantime I’ll reassemble it, chrono it then strip it back down and start cleaning and polishing

I’ve never seen a record trigger block in the flesh so to speak and I’m impressed with its design. Seems a good idea to have a trigger unit that can be totally removed as one unit, and makes fettling of the rest of the mechanism much easier.

Right, off to the workshop now

[u.k.neil]

The piston head adaptors are somewhat crap, Neil, they shorten the stroke and add a lot of weight to the already heavy piston.
The better option when changing from a leather seal to a synthetic seal on a HW35 is to buy the complete synthetic piston.
The synthetic sealed piston is lighter than the standard leather sealed piston and gives 4mm more stroke than the leather sealed piston --- win win.


Anyway, what you doing with your address as Hinckley, I thought you were going back over the A5 ?




All the best Mick

I have done mate, just haven't updated my profile on here.


Neil