Hello Airgunners!
I get a lot of questions from customers concerning how I machine gun barreIs during my tunes or custom work. So I just wanted to post a picture of my barrel setup for machining threads or when machining the back end of a new barrel to fit the action. Although I have a large 12x36 lathe I prefer to use my mini lathe. The lathe that I am using is a 7x16 Micro mark metal lathe. I do not have a spindle spider on the back of my lathe, so I designed and built a fixture that has 8 brass tipped set screws to hold on to and secure the barrel in the lathe while allowing me to adjust it to dial in the barrel's bore. The barrel is dialed in so that the bore of the barrel is concentric to the axis of the lathe. Most gun barrels are not perfectly concentric to the outside diameter of the barrel. If the gun barrel bore is not concentric with the spindle bore of the lathe than there is high chance you can machine the barrel off center, which can obviously cause accuracy issues. In the pic below you can see the barrel protruding out from the aluminum fixture. Installed in the bore is a perfectly straight and perfectly fitting rod that is used to set a dial indicator on. Since the rod is perfectly aligned with the bore I can now manipulate my 8 brass tipped screws that surround the outside diameter of the work piece (barrel). As I move each screw it changes the alignment of the barrel. Once the rod that is protruding from the barrel is running true, I know that the barrel bore is concentric to the lathe spindle bore. I check and align the rod using the 8 brass tipped screws along different lengths of its body to get it as true as possible. The barrel you see in the pic already has threads cut into....I am just using it as an example for this post. I was able to dial this barrel down to half a thousands of an inch. I don't have quite a good camera setup yet for taking videos, but hopefully I can some time soon show you just how accurate you can come to getting a part really dialed in. Thanks for looking!
I get a lot of questions from customers concerning how I machine gun barreIs during my tunes or custom work. So I just wanted to post a picture of my barrel setup for machining threads or when machining the back end of a new barrel to fit the action. Although I have a large 12x36 lathe I prefer to use my mini lathe. The lathe that I am using is a 7x16 Micro mark metal lathe. I do not have a spindle spider on the back of my lathe, so I designed and built a fixture that has 8 brass tipped set screws to hold on to and secure the barrel in the lathe while allowing me to adjust it to dial in the barrel's bore. The barrel is dialed in so that the bore of the barrel is concentric to the axis of the lathe. Most gun barrels are not perfectly concentric to the outside diameter of the barrel. If the gun barrel bore is not concentric with the spindle bore of the lathe than there is high chance you can machine the barrel off center, which can obviously cause accuracy issues. In the pic below you can see the barrel protruding out from the aluminum fixture. Installed in the bore is a perfectly straight and perfectly fitting rod that is used to set a dial indicator on. Since the rod is perfectly aligned with the bore I can now manipulate my 8 brass tipped screws that surround the outside diameter of the work piece (barrel). As I move each screw it changes the alignment of the barrel. Once the rod that is protruding from the barrel is running true, I know that the barrel bore is concentric to the lathe spindle bore. I check and align the rod using the 8 brass tipped screws along different lengths of its body to get it as true as possible. The barrel you see in the pic already has threads cut into....I am just using it as an example for this post. I was able to dial this barrel down to half a thousands of an inch. I don't have quite a good camera setup yet for taking videos, but hopefully I can some time soon show you just how accurate you can come to getting a part really dialed in. Thanks for looking!