F
frwillia
Guest
Yesterday was a really fun day. Shortly after noon, this was the situation - barrel was in metal cutting saw and I was getting ready to flip the switch and saw the old chamber off.
While it wasn't exactly a Mylanta moment, it was sure close. I flipped the switch and a few minutes later it looked like this. For all of you experienced folks, this might not be a big deal, but for a first timer, it was a moment of considerable trepidation.
From there on things got better and better. I got it aligned through the headstock. I used Gritter's method since there was nothing of the original chamber left. When I was done and had it like I wanted it, the muzzle OD was making a 0.013" orbit. Then it was ready to thread.
Many years ago I made a cross slide stop to use for threading. Not as elegant as the one on my South Bend, but it works just fine for getting the cross slide back to datum after disengaging the half nuts, or flipping the lathe in reverse, and giving the cross slide a wrist flip to clear the shoulder, or threads, as the case may be.
Also many years ago I pattern drilled the back of my lathe's cross slide so I can mount all manner of gadgets on it including a rear tool post.
The threading was routine. I had earlier gotten data from the factory threads, as suggested, and used that to get in the ball park, then worked my way into a nice thread fit a little at a time.
The chambering was a learning experience. I took advantage of the time to go to school on the process.
I spent the time chambering practicing hitting marks, cleaning the chamber, making a measurement, and so forth. By 2/3'd depth I could hit the marks to half a thou. The result was that by the time it was crucial to make that "last cut" and get the head space right it was a well rehersed process and worked perfectly. I'd recommend this to all first timers.
The attachment I made (a shamless copy of those made by many others) to take advantage of a dial indicator on the tail stock turned out to be a huge success. By the time I was done I could basically split the lines on the indicator dial and know exactly when the reamer would start to cut.
I locked the carriage in position and used it as a tail stock stop as was suggested by another on this forum. That worked extremely well and allowed me to be able to re-start the cut in the middle of the line where it ended, cycling the tail stock back a foot to get lots of room between cuts.
Necessity is the mother of invention, so I made a home made pusher and held the reamer from turning by using my second smallest lathe dog clamped on the flat. The pusher was a flat surface in the tailstock. I made a radiused piece to screw into the back of the JGS reamer (1/4-28 threaded hole) that pressed against the lubricated flat face. I believe it ended up with me making a reamer sized hole. With 0.025" to go, I tried gently to move the reamer in the chamber and it had exactly zero play which leads me to believe the chamber is properly sized. Since it was completed, I've tried brass in it and it seems to fit just like it should.
I figured that the assymetrical force to counter act the cutting torque was the enemy so I worked slowly at minimum rpm to a) minimze the chance of having an over size chamber, and b) maintain a continuous cut to obviate chips getting under reamer flutes. I terminated the cut by letting go of the lathe dog, backing off the tail stock, and letting the reamer rorate with the chamber till it was stopped, then I drew it straight out.
Intermediate inspections showed the chamber walls to be shiny smooth with no evidence of chip galling. there may be better ways to do it, but this worked for me.
Early in the process I was able to take cuts of as much as 0.050" with no problem. However, as the depth increased, the reamer seemed to fill with chips faster, doubtless because the cutting surface was increasing rapidly, and I began using 0.025" depth of cut as the rule between reamer cleaning sessions. I figured if chips were squeezing out the back, it was time to let go, back off the tail stock, turn it off, remove it and clean it. That is what I did.
I set a wide mouth plastic container of cutting oil and another of mineral spirits on the gear head. I swished the reamer in the mineral spirits and blew it off with compressed air, blew out the chamber with compressed air, visually checked for residual swarf and removed any if it was there, before dipping the reamer in the dark thread cutting oil, reinserting it, and taking the next cut. I developed a technique where I could slide the tailstock up against the carriage, hold the lathe dog, start the spindle, and "touch off" the reamer into a gentle continuous cut. This came together early in the process.
As time and finances permit, I "will" add a muzzle flush system, but a borescope and a better DIT are higher on the wish list.
I cut the bevels on the breech (OD and chamber ID) end the same size as those on the factory chamber.
When I was done it looked like this:
and this
As originally finished the action needed to be rotated an additional 110 degrees to point the barrel up. I left it in the headstock last night to think about it. This morning I decided to go ahead, adjust the chamber depth and face the breech end of the barrel to point the barrel up, which I did with no surprises along the way.
The rifle is all reassembled, scope mounted, and ready for a range trip. Alas, I have other commitments that will put off the range trip till at least Tuesday next week. It will be agonizing waiting that long to see if it shoots, but that's life.
I sure appreciate all that I learned on this forum. You folks sharing your experience and insight paid a huge part in making this a successful project.
Fitch
While it wasn't exactly a Mylanta moment, it was sure close. I flipped the switch and a few minutes later it looked like this. For all of you experienced folks, this might not be a big deal, but for a first timer, it was a moment of considerable trepidation.
From there on things got better and better. I got it aligned through the headstock. I used Gritter's method since there was nothing of the original chamber left. When I was done and had it like I wanted it, the muzzle OD was making a 0.013" orbit. Then it was ready to thread.
Many years ago I made a cross slide stop to use for threading. Not as elegant as the one on my South Bend, but it works just fine for getting the cross slide back to datum after disengaging the half nuts, or flipping the lathe in reverse, and giving the cross slide a wrist flip to clear the shoulder, or threads, as the case may be.
Also many years ago I pattern drilled the back of my lathe's cross slide so I can mount all manner of gadgets on it including a rear tool post.
The threading was routine. I had earlier gotten data from the factory threads, as suggested, and used that to get in the ball park, then worked my way into a nice thread fit a little at a time.
The chambering was a learning experience. I took advantage of the time to go to school on the process.
I spent the time chambering practicing hitting marks, cleaning the chamber, making a measurement, and so forth. By 2/3'd depth I could hit the marks to half a thou. The result was that by the time it was crucial to make that "last cut" and get the head space right it was a well rehersed process and worked perfectly. I'd recommend this to all first timers.
The attachment I made (a shamless copy of those made by many others) to take advantage of a dial indicator on the tail stock turned out to be a huge success. By the time I was done I could basically split the lines on the indicator dial and know exactly when the reamer would start to cut.
I locked the carriage in position and used it as a tail stock stop as was suggested by another on this forum. That worked extremely well and allowed me to be able to re-start the cut in the middle of the line where it ended, cycling the tail stock back a foot to get lots of room between cuts.
Necessity is the mother of invention, so I made a home made pusher and held the reamer from turning by using my second smallest lathe dog clamped on the flat. The pusher was a flat surface in the tailstock. I made a radiused piece to screw into the back of the JGS reamer (1/4-28 threaded hole) that pressed against the lubricated flat face. I believe it ended up with me making a reamer sized hole. With 0.025" to go, I tried gently to move the reamer in the chamber and it had exactly zero play which leads me to believe the chamber is properly sized. Since it was completed, I've tried brass in it and it seems to fit just like it should.
I figured that the assymetrical force to counter act the cutting torque was the enemy so I worked slowly at minimum rpm to a) minimze the chance of having an over size chamber, and b) maintain a continuous cut to obviate chips getting under reamer flutes. I terminated the cut by letting go of the lathe dog, backing off the tail stock, and letting the reamer rorate with the chamber till it was stopped, then I drew it straight out.
Intermediate inspections showed the chamber walls to be shiny smooth with no evidence of chip galling. there may be better ways to do it, but this worked for me.
Early in the process I was able to take cuts of as much as 0.050" with no problem. However, as the depth increased, the reamer seemed to fill with chips faster, doubtless because the cutting surface was increasing rapidly, and I began using 0.025" depth of cut as the rule between reamer cleaning sessions. I figured if chips were squeezing out the back, it was time to let go, back off the tail stock, turn it off, remove it and clean it. That is what I did.
I set a wide mouth plastic container of cutting oil and another of mineral spirits on the gear head. I swished the reamer in the mineral spirits and blew it off with compressed air, blew out the chamber with compressed air, visually checked for residual swarf and removed any if it was there, before dipping the reamer in the dark thread cutting oil, reinserting it, and taking the next cut. I developed a technique where I could slide the tailstock up against the carriage, hold the lathe dog, start the spindle, and "touch off" the reamer into a gentle continuous cut. This came together early in the process.
As time and finances permit, I "will" add a muzzle flush system, but a borescope and a better DIT are higher on the wish list.
I cut the bevels on the breech (OD and chamber ID) end the same size as those on the factory chamber.
When I was done it looked like this:
and this
As originally finished the action needed to be rotated an additional 110 degrees to point the barrel up. I left it in the headstock last night to think about it. This morning I decided to go ahead, adjust the chamber depth and face the breech end of the barrel to point the barrel up, which I did with no surprises along the way.
The rifle is all reassembled, scope mounted, and ready for a range trip. Alas, I have other commitments that will put off the range trip till at least Tuesday next week. It will be agonizing waiting that long to see if it shoots, but that's life.
I sure appreciate all that I learned on this forum. You folks sharing your experience and insight paid a huge part in making this a successful project.
Fitch
