re airstripper setscrew placement?

[Walther]

Hi Ive just finished a project for my .22
cr600w rifle.
Its a carbon fiber shroud aluminum airstripper .
i built it n my unimat db200 lathe mill.
Now the only thing  left to do is the set screw placement for the cone.
I dont want  to mess it up any suggedtions.

[aluminumfetish]

That looks fantastic ! Please fill us in on the rest of the project ?

[rsterne]

The best setup I have used is two rows of three setscrews at 120 deg. with a cone that is a loose fit inside the stripper (ie significant radial movement available).... By using a wooden or plastic mandrel inside the muzzle you can move the cone radially, axially, and angle it parallel to the bore.... That way you can guarantee concentricity with the bore.... Once you get it adjusted, you can just undo the top setscrew in each row, slide the cone fore and aft to a new position, and retighten just those two setscrews.... and maintain the radial and parallel alignment....



The ink lines on the wooden alignment tool are visual indicators for fore and aft placement.... When the setscrews are perfectly adjusted, the cone is held tightly in the stripper and the dowel will slide easily in and out with no more resistance than just the sum of the friction in the two parts separately.... ie minimal....



If your stripper is solidly mounted, and the cone perfectly concentric and parallel with the bore.... and a perfect sliding fit in the stripper.... Then just one setscrew should, in theory, be all you need....

Bob

[Walther]

That looks fantastic ! Please fill us in on the rest of the project ?

Thank you Im new here, which forum for builds??

[Walther]

Thank You Bob!
I knew you'd know exactly, Im rom CAF originally:)

I did my best to keep everything concentric by turning everything on aluminum mandrel that I turned first and made sure never to remove it from the three jaw chuck until all the turning was done. I used a adjustable reamer to for all the   hole finishing so Ive got everything fairly close tolerance fit. That said I'm a chef by trade (Although I did take a machineshop class  ⅓ credit course 1980 in grade 9), just always liked to build and machine stuff.
Really need a bigger lathe than my tiny Unimat db200.
I like the dowel trick, i'm going to borrow that idea and set screw layout.
After making this I see know why they cost so much to buy (especially in Canada) a lot of time to make them unless you have a cnc setup.
Those hatsans look nice and (and cheap in USA).  I just really wanted to do my own as I've got spare time right now as I am recovering from knee surgery and off work.

[Gippeto]

If you have a good fit, the burr raised by the grub screw will give you grief. I mill a slot on the cones for the grub screw to bear on...solves the issue.

Al

[rsterne]

The Hatsan stripper uses that, you can see it in the photo above.... and I agree it is necessary if the fit is close.... Not so much when you drill the hole in the stripper larger than the cone, with the intention of the setscrews adjusting the position....

Bob

[Walther]

If you have a good fit, the burr raised by the grub screw will give you grief. I mill a slot on the cones for the grub screw to bear on...solves the issue.

Al

Thank You for that . I will mill some slots in the cone next chance I get:)

[Walther]

I have add the 120' spaced set screws and completed integrated shroud as well as turned the co2 filler cap down for better clearance. I always use a brass bar to gently close it as I was never able to hand tighten it.
This is <500 fps rifle for Canadian rules and I really don't need more power. These rifle fyi in canada come with the LR700 21.6 inch barre,l hence looks a bit "snipery" . Honestly I woull love to put the 19 inch stormrider barrel on it to test fps difference as I understandlower power  co2 rifles don't benefit much from the barrel length past 18/19 ish inches.

[Walther]

Added the set screw slots:)

[Gippeto]

Nice work.

You might try boring the cone out for as far as practical. I use 3x bore diameter.



Al

[Walther]

Thanks Gippeto
Btw that is beautiful

[Hobbyman2007]

I am completely blown away by the quality of the machining seen here . I’m still learning how to use a lathe and find myself getting lazy when it comes to finishing . I really need to learn to slow down .great work guys .
Al, are you saying the ID of the cone should be 3 calibers  in size . I was under impression the closer to bore diameter the better with 1 to 1.5 caliber spacing .

[Gippeto]

The entrance to the cone should be as near bore size as you can get away with. The exit is bored out.

Think about what you're trying to accomplish with the stripper in the first place...strip off the muzzle blast and redirect it. The cone strips off the expanding gas column, but there's more following directly behind the pellet...that can be easily dealt with by slowing it down...by increasing the "pipe" diameter.

Does make for a larger stripper though.

Make sense?

Al

[rsterne]

that can be easily dealt with by slowing it down...by increasing the "pipe" diameter.

Excellent idea, Al.... 

Bob

[Walther]

I am completely blown away by the quality of the machining seen here .

I know your not talking about me.. I am chef by trade that took ⅓ credit machine shop course in 1980 If I can make something half decent , you can too. Just keep at it. For finishing I go 400grit wetsand to 600 then steel wool 00 and then buffing wheel with compound.
Cheers