Building a HW35LGV

[thevoid]

It dosen't work like that with me Pete


I hate all this gun Snobbery, I'm just as happy working on a b2 as I am working on a 77k.




All the best Mick

I think the BBS readers have already established that as long as it has a barrel its fair game lol

[look no hands]

It dosen't work like that with me Pete


I hate all this gun Snobbery, I'm just as happy working on a b2 as I am working on a 77k.




All the best Mick

I know what you're saying Mick but this rifle gets peoples backs up when mentioned, all I will say is it's made far far away and is a damn good clone.

Pete

[TonyL]

For guys like Mick and Tone, it's a challenge and they'll do work on a gun because they CAN and they can totally transform it..

I could only merely scratch the surface compared to these guys.....degrease, de-burr, polish up, fit better components, relube etc.

There is another advantage to working on cheaper guns for us less talented / less well-equipped guys.....That if you had a play with a much cheaper gun and went too far and wrecked it, you wouldn't be as gutted.

My old 35 has been apart a fair few times, as it was a tired old, abused dog, and I could only make it better...it couldn't have gotten much worse.......Much more work required.....

Whereas, some of the HWs that I had Venom tuned are as they left Ivan and Dave. Some have had hardly any use in recent times, due to lack of time and they'd be wasted at my short home range.

You often hear of factory standard 20 year old 77s still being lovely and the springs being okay, so, to my mind, one that's been Venomed, and especially the Lazaglide, having been de-burred / honed etc. should be fine......

I would imagine that the issues that would occur in time would be the grease caking up and maybe the seals becoming brittle??

Best get that Predator Lazaglide out and give it an airing......

[T 20]

Well after doing a few practice runs with the Mig I glued the breech to the 25mm tube today and machined it up.

http://i1138.photobucket.com/albums/...6012006697.jpg

So now I have a 25mm ID tube welded onto the back of a HW35 breech with a 6.3mm long transfer port :- before welding I opened the transfer port to 3.2mm.

I aired on the small side with the transfer port just in case I ran into problems getting a full 71mm of stroke (I've done a 35 at 71mm before but not with a Walther piston).

The full breech and tube assembly :-

http://i1138.photobucket.com/albums/...6012006698.jpg

This is actually how I thought the Walther LGV breech assembly would be.


Now after a bit of polishing on the inside of the original HW35 cylinder the breech and tube slid in:-

http://i1138.photobucket.com/albums/...6012006701.jpg


I slid the Walther piston into the cylinder without a seal and then fitted a HW35 barrel and cocking arm to get some measurements.

I have 2.4mm clearance between the cocking arm and the rim on the piston so this could be reduced by 1mm to 1.5mm, this could be done by taking some metal off the front of the piston:-

http://i1138.photobucket.com/albums/...6012006703.jpg

But I only have 5,5mm in front of the front piston bearing to fit an O ring piston head so if I take 1mm off that I end up with a 4.5mm long piston head.
As the piston head will be screwed onto the piston sear rod I'd like to keep it as long as possible so that I have a good number of threads holding it on so I had a look to see if I could shorten the piston by 1mm somewhere else.

http://i1138.photobucket.com/albums/...6012006704.jpg

As luck would have it the Walther piston body is screwed onto the piston head, so I can just machine 1mm off the piston body and screw it back onto the head to shorten the piston by 1mm.

Folks who have found their Walther piston rod is not threadlocked into the end of the piston may also want to check that their piston body is threadlocked onto the end of the piston.



And after measuring the stroke with the standard length Walther piston rod it came out at 66.6mm :- it's a beast.





All the best Mick

[bigtoe01]

So you need to gain around 4mm by shortening the rod Mick to give you there 70mm you need?

How easy did the piston nose come away from the piston body?

[T 20]

So you need to gain around 4mm by shortening the rod Mick to give you there 70mm you need?

Hi Tony

Yes a 4mm or 5mm shorter rod should see me up at 70mm - 71mm stroke which is about as far as you can go with a HW35 before having to alter the woodwork.


Though it may be possible to gain a little more stroke by offset machining the cocking link hole on the barrel block so increasing the stroke radius.

How easy did the piston nose come away from the piston body?

I warmed it up with a gas axe and it unscrewed easily - easier than the piston rod thinking about it.






Al the best Mick

[bigtoe01]

Hi Tony

Yes a 4mm or 5mm shorter rod should see me up at 70mm - 71mm stroke which is about as far as you can go with a HW35 before having to alter the woodwork.

Though it may be possible to gain a little more stroke by offset machining the cocking link hole on the barrel block so increasing the stroke radius.

I warmed it up with a gas axe and it unscrewed easily - easier than the piston rod thinking about it.

Al the best Mick

if its still in pieces you could measure the threads for me please, then i can look into making up a direct replacement nose in Bronze maybe that will except the piston rod and an O ring

im going to guess at m22x1...the Germans seem to like fine metric threads a lot.

[look no hands]

This is like watching airgun brain surgery

Pete

[Weasle]

This Mick, is truly a brilliant piece of work.

Are you contemplating welding the revised breach / compression arrangement to the existing tube with a full penetration weld over the the mig weld area?

Would their be any benefit in also welding up - and then refacing - the face of the breach were the lock has worn the surface - as they all seem to do?

I cant wait for the next installment.

Cheers

Steve ( ;-)>

[thevoid]

Its all coming along nicely
http://i1138.photobucket.com/albums/...6012006701.jpg

In that picture, you just weld prepping and mig welding up then linishing flush?

Also given the 70-71mm stroke and 25mm(?) piston, what spring spac are you using?
interested in how the volume, spring and port = power.

[T 20]

if its still in pieces you could measure the threads for me please, then i can look into making up a direct replacement nose in Bronze maybe that will except the piston rod and an O ring

im going to guess at m22x1...the Germans seem to like fine metric threads a lot.

Hi Tony

You're spot on at M22 X 1



All the best Mick

[T 20]

Its all coming along nicely
http://i1138.photobucket.com/albums/...6012006701.jpg

In that picture, you just weld prepping and mig welding up then linishing flush?

Yes the rear of the breech has a slight chamfer on it and the original cylinder will have a larger chamfer on it so that I have a good V to weld into, this will all be machined down and then linished flush ready for fume bluing --- the idea is that I end up with a cylinder that looks completely standard.
I may also put a couple of plug welds below the stock line through the original cylinder onto the rear end of the new 25mm cylinder --- this will add a fair bit of extra strength and will also stop any vibration between the two cylinders.

Also given the 70-71mm stroke and 25mm(?) piston, what spring spac are you using?
interested in how the volume, spring and port = power.

I'll be using the standard LGV spring which comes in the 16 joule service kit for starters.

My 35 now has a transfer port about the same length as a HW77 and a 25mm cylinder bore.

The 70-71mm stroke is about the maximum I can get from a HW35 without woodwork alterations, so that is the max I can aim for.

John Bowkett used to shortstroke 77s by machining the piston back 8mm and threading and then fitting a 25mm long twin O ring piston head so reducing the stroke by 17mm.

So 81-17 = 64mm stroke so I may have a play with the standard LGV piston rod giving a 66.6mm stroke before going to the trouble of altering the piston and sear rod.






All the best Mick

[gibboj]

hi mick wat sort of flb are you going for on the 35/lgv . the reason i ask iv just short stroked one of my rifles to 70mm x 26mm and wot ever i did i could only get 10.2 flb but shoot fine . so then went for a 75mm stroke with all the same internals and got 11.2 flb right away and shoot just the same
atb john

[evert]

Have been following the different writings on transferports, seals, compression ratio etc, these are some of the better discussions on any of the airgun forums these days...

I have a short question:
Am currently tinkering with a 1980 hw35, with what seems to me to be crimped front end/barrel forks. The gun had a leather seal originally. If i deicide to sleeve the transferport dow, what would be the best diameter? I understand that smaller diameter means higher compression, but how smal can you go before it starts to reduce the air-flow too much?

[bigtoe01]

hi mick wat sort of flb are you going for on the 35/lgv . the reason i ask iv just short stroked one of my rifles to 70mm x 26mm and wot ever i did i could only get 10.2 flb but shoot fine . so then went for a 75mm stroke with all the same internals and got 11.2 flb right away and shoot just the same
atb john

70x26 is 37cc...you should have seen around 11 with that...is the rifle a .177?