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All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Engineering- Research & Development => Topic started by: Aldea6 on September 30, 2019, 04:31:10 AM

Title: O-ring groove machining
Post by: Aldea6 on September 30, 2019, 04:31:10 AM
Hi , I would like to put a hexagonal Lothar Walther barrel on one of my guns ; the problem is : how to machine the tiny groove inside the chamber of the barrel for the O-ring? What kind of tool is needed to do this operation on a lathe , or on a milling machine , as the bore is only .25" in diameter?

Thanks
Title: Re: O-ring groove machining
Post by: rkr on September 30, 2019, 08:21:26 AM
Quote from: Aldea6 on September 30, 2019, 04:31:10 AM
Hi , I would like to put a hexagonal Lothar Walther barrel on one of my guns ; the problem is : how to machine the tiny groove inside the chamber of the barrel for the O-ring? What kind of tool is needed to do this operation on a lathe , or on a milling machine , as the bore is only .25" in diameter?

Thanks

Have you considered putting the o-ring on the probe?
Title: Re: O-ring groove machining
Post by: rsterne on September 30, 2019, 11:49:06 AM
I grind my own tool from a piece of 1/4" square HSS lathe tooling.... using a grinder and a Dremel cut-off wheel to make the groove....

(https://i378.photobucket.com/albums/oo221/rsterne/22%20cal%20Disco%20Double/Porting%20and%20O-ring_zpsp3ahsefk.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20cal%20Disco%20Double/Porting%20and%20O-ring_zpsp3ahsefk.jpg.html)

Make sure it will fit into the bore without the heel touching, including when you advance the cutting edge into the groove.... Work slowly, and check your O-ring fit until you get it right, by inserting the O-ring in the groove and sliding the bolt into place.... If it's too tight, you will have to force it (or it won't go in)…. but don't go past the point of having some drag on the bolt as it enters the O-ring....

Bob
Title: Re: O-ring groove machining
Post by: Aldea6 on September 30, 2019, 02:10:42 PM
Thanks Bob, your explanations are a great help and the pic of the tool gives me a clear idea of what to do.
Title: Re: O-ring groove machining
Post by: Bill G on November 21, 2019, 06:01:33 PM
Bob is right on as usual.  The feel will tell the tale. You can DL a pdf of Parker o-ring hand book and get deminsions based on pressure ratings, static or dynamic ect. Great reference and gives you a deminsions target to sneak up on. In the end, you'll judge by feel more than likely.  Most of us do   ;D