HW35 With Rotating Piston

[TonyL]

It just looks like every other 35k, Gav, but it's lazerglided and long stroked.
:

A bit like your B2 looks (just) a little like any other B2 eh, Mick.

[T 20]

I still have a few tidy up jobs to do on the gun, I designed the piston to have 2mm clearance with the cocking arm, the Knibbs seal I used turned out to be 1mm shorter than a Weihrauch seal so cutting the clearance down to 1mm --- a quick file of the cocking arm will sort that, or I'll just get a new genuine seal.

Well it turned out that the Knibbs piston seal was moving fore and aft on the piston by .75mm so by simply cutting a circular piece of 1mm gasket paper and fitting it into the piston seal before fitting to the piston put me back to the designed 2mm clearance.

So all I ended up doing to the cocking arm was to polish the foot which fits inside the cylinder.

The barrel looks like it could do with checking for straight and given a quick tweak, it's also crying out for a barrel weight come cocking aid, so while I have the .22" barrel off I may as well fit my spare .177" K barrel and run a chrono string with that.

Yep, the barrel was bent, but it isn't now but while I was refitting it I noticed the barrel latch was a little bit stiff and wasn't engaging correctly so I polished the three unseen sides of it until it worked as it should do.

I also polished the spring ends and lubed the gun before reassembly, as the chrono test yesterday was run with the gun dry except for a smear of silicon oil on the piston seal.

Following another chrono session the gun is now locked in the naughty cupboard with a copy of the 1968 firearms act reflecting on the day's events --- I'll definitely be coil squashing in the morning.

[pigeondave]

So all I ended up doing to the cocking arm was to polish the foot which fits inside the cylinder.

Have you done this because its a rotating piston or should this be done as a matter of course, when the rifle is in bits?

Which bits did you polish? Any chance of a pic with arrows please.

[TonyL]

Nice one, Mick.

I hope you get the tinkering time today to free it from the naughty step

Pigeondave....always a good idea to them.

[T 20]

That looks great... I've seen some good setups.. a guy in the states sent me pics of his when I was setting mine up.. he had a 5' Fish tank which was awesome.

I experimented with a piece of 12" galvanised chimney, that I hung the parts in vertically, and hooked up a wallpaper steamer to the side of. I was hoping to combine the rusting and 'boiling' into one unit that didn't take ages to boil like the tank I was using.... it didn't work. The rusting was aggressive at the bottom where I sat the acid, and it didn't really steam that good either. I think it would work with a much larger chamber, well sealed.

Well it may look great, Donald, but I've not had much success in rusting with it using acid fumes.

Strangely, using hydrochloric brick cleaning acid the metal struck black in the cabinet but never actually produced red rust. --- This black never got any thicker over ten sessions in the fume cabinet.

So today I changed tack and gave up with the fume bluing and changed to rust bluing, by turning the heat up in the cabinet and putting a pellet tin full of water inside it became a damp box.
I'm now using a saturated water/Ammonium Chloride solution to coat the metal before placing in the fume cabinet to rust --- instant success.

[Bluefan]

Brick acid ain't wot it used to be Ive heard brick is say it's only like tcp now and not much more harm if you gargle with it. Glad the new approach is working out .

[thisisdonald]

I was using neat hydrochloric!! You used to be able to buy it on ... I've still got a little left.. dangerous stuff!!
You had to keep a close eye on rusts, I pitted a Vulcan barrel really badly in a matter of a couple hrs.. atmospheric conditions must have changed because I was getting a nice fine rust in about 8hrs on previous days. It's a dark art sure enough!
My dad bought me a copy of angiers book a couple years ago, there's loads of paint on rusting recipes there. Pm me if you want some pdfs

[arnie2b]

Well it may look great, Donald, but I've not had much success in rusting with it using acid fumes.

Strangely, using hydrochloric brick cleaning acid the metal struck black in the cabinet but never actually produced red rust. --- This black never got any thicker over ten sessions in the fume cabinet.

So today I changed tack and gave up with the fume bluing and changed to rust bluing, by turning the heat up in the cabinet and putting a pellet tin full of water inside it became a damp box.
I'm now using a saturated water/Ammonium Chloride solution to coat the metal before placing in the fume cabinet to rust --- instant success.

This solution gives in the right hands a Johnsons(does/did most of Purdeys/H&H stuff) type black within a few hours(big hint) not a month.
It really is good and great for helping you out of the sticky stuff.

There are gunsmiths who have analyzed this/similarly working rust bluing solution and use it all the time.
The more time you put in to it the better the result.

[TonyL]

Wow!

I've just had a good read of those instructions and it sounds very good.

One to have a go at one day when time finally allows to properly play with many more things airgunnery!

[T 20]

This solution gives in the right hands a Johnsons(does/did most of Purdeys/H&H stuff) type black within a few hours(big hint) not a month.
It really is good and great for helping you out of the sticky stuff.

There are gunsmiths who have analyzed this/similarly working rust bluing solution and use it all the time.
The more time you put in to it the better the result.

Ah, very interesting but two of the old guns I'm bluing at the moment have cylinders which are sealed to the breechblock with solder and I'd be loathe to go anywhere near them with a blowlamp.
Besides which I seem to have cracked the job by switching from acid fume bluing to rust bluing using Ammonium Chloride --- I managed three rustings today.

One of the items I'm bluing is the barrel weight for this rotary pistoned HW35 which should finish the front end off nicely.


All the best Mick

[arnie2b]

Ah, very interesting but two of the old guns I'm bluing at the moment have cylinders which are sealed to the breechblock with solder and I'd be loathe to go anywhere near them with a blowlamp.
Besides which I seem to have cracked the job by switching from acid fume bluing to rust bluing using Ammonium Chloride --- I managed three rustings today.

One of the items I'm bluing is the barrel weight for this rotary pistoned HW35 which should finish the front end off nicely.


All the best Mick

The difference between 60 and 240(iirc) degrees is quite substantial and it's very safe till you get to smoking stages of the solder then you don't have much time left.
You'd have to be a numpty to bugger that one up.
I use a laser IR thermometer to avoid that one.

[T 20]

You'd have to be a numpty to bugger that one up.

That'll be me then.

I could bugger anything up without even trying.

[T 20]

One of the items I'm bluing is the barrel weight for this rotary pistoned HW35 which should finish the front end off nicely.

Like so :-

image.jpg

[Bluefan]

Very nice Mick I likes it .

[TonyL]

Cop an eyeful of that!

Lovely, Mick, just lovely.