Savage 99 restification project
- Thread starter Ian
- Start date
F
freebullet
Guest
That would be real interesting with an integral can.
F
freebullet
Guest
Nice!
I think your getting every dollar back out that lathe purchase already.
I think your getting every dollar back out that lathe purchase already.
Ian
Notorious member
I'm for sure getting every dollar's worth out of that Cheese-grade, brazed carbide tool set!
It basically paid for itself in equivalent gunsmith fees when I threaded a few of my barrels and did a couple of crown jobs.
...and tax stamps.
It basically paid for itself in equivalent gunsmith fees when I threaded a few of my barrels and did a couple of crown jobs.
...and tax stamps.
Stonecrusher
Active Member
Looking good! Now time to make some threads.
Let us know what prison to send your mail to......
Ian
Notorious member
Cutting the minor and roughing the shoulder. I left about .005" on the shoulder because the barrel contacts the bottom of the hole in the receiver as well as the front, so it's a very precise fit, too close to measure.
Scratching in the threads. I did that under power, and having .010" margin to disengage the half nuts on a 12-pitch thread proved not anywhere near enough, so I made all the rest of the threading passes by manually turning the chuck.
Another shot of the threading setup. I had to turn the cross slide to the left due to the compound crank interfering with the tailstock at full thread depth. I could have extended the form tool to give clearance, but I wanted choke up on it as close as possible to reduce flex. Glad I did, it cut very cleanly even turning the chuck by hand.
Finished threads. They're exactly .8985" OD, .8330" minor, and .0425" wide..was supposed to be .0430" but I did one more spring pass, oh well. I ground the form tool .039" wide and relieved it to the thread angle, plus a couple degrees so that I could dial in some windage with the compound to widen the cut. I also broke the corners of the tool very slightly so as to not burn up the tool or create stress risers at the root of the threads.
Scratching in the threads. I did that under power, and having .010" margin to disengage the half nuts on a 12-pitch thread proved not anywhere near enough, so I made all the rest of the threading passes by manually turning the chuck.
Another shot of the threading setup. I had to turn the cross slide to the left due to the compound crank interfering with the tailstock at full thread depth. I could have extended the form tool to give clearance, but I wanted choke up on it as close as possible to reduce flex. Glad I did, it cut very cleanly even turning the chuck by hand.
Finished threads. They're exactly .8985" OD, .8330" minor, and .0425" wide..was supposed to be .0430" but I did one more spring pass, oh well. I ground the form tool .039" wide and relieved it to the thread angle, plus a couple degrees so that I could dial in some windage with the compound to widen the cut. I also broke the corners of the tool very slightly so as to not burn up the tool or create stress risers at the root of the threads.
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Ian
Notorious member
The proof of the puddin's in the eating...
The red arrow points to the spot where the feed ramp thins the metal out a lot and has been pushed forward. I will peen that back into place and cut the barrel shoulder back a few more thousandths. I don't want the end of the barrel to actually contact the receiver when done, but I do want it to seat fully on the shoulder and have about .002" clearance at the back after torquing the barrel in place.
Very happy with how this turned out and that I was able to exactly and cleanly duplicate the factory threads for a very good fit.
The red arrow points to the spot where the feed ramp thins the metal out a lot and has been pushed forward. I will peen that back into place and cut the barrel shoulder back a few more thousandths. I don't want the end of the barrel to actually contact the receiver when done, but I do want it to seat fully on the shoulder and have about .002" clearance at the back after torquing the barrel in place.
Very happy with how this turned out and that I was able to exactly and cleanly duplicate the factory threads for a very good fit.
Ian
Notorious member
Well, I was scratching my head pretty hard after realizing that without a QCTP there wasn't enough height adjustment to run the tool upside down and get anywhere near on center with it, so threading away from the chuck was out of the question. I cut a .049"-wide relief at the barrel shoulder (tool width +.010"), to full depth plus a couple thousandths, hoping that I'd have enough fudge factor to pop the half nuts, but even at 60 rpm, no way Jose'. I didn't want to make the relief any wider because the OE barrel was threaded all the way to the shoulder and I was already giving up nearly a full thread as it was. The speed control circuits of the motor drive have some residual energy in them, so hitting the kill switch doesn't stop the spindle power immediately, it winds down under power after about a full revolution, and there's no spindle brake or leadscrew clutch, so the half-nuts are the only "right now" carriage stop. If you've ever cut 12-pitch threads right up to a precision shoulder under power you can imagine the pucker factor. Not gonna happen for me. I have enough meat on the barrel for two more tries if I screwed something up, but it took me nearly an hour to grind and hone the thread tool under 10x magnification and I wasn't about to risk crashing it. Hand power was the only option I had left, good enough for .002" DOC passes which is about all the setup could handle anyway due to flex.
Pistolero
Well-Known Member
Necessity is the mother of invention. I have done odd things like this in the past,
just what is needed to get it done. The key is the gearing between spindle and cutter,
so hand turning will work fine. And as you said, stiffness is an issue on a lot of setups,
and with that necessarily wide a cut, you can only expect a light pass to work smoothly
with no chatter.
I finally figured out that this is why you run the compound in at 29 deg on a std 60 deg thread,
to cut on one side and let the other side just float, less load on the cutter that way than
a straight in plunge, which I did when I was teaching myself to thread, before I got the South Bend
"How to run a Lathe" book as a Christmas present from my wife.
Besides, I often only go .002 or so per pass with a normal V thread, too. 12 TPI is 0.083
per rev. Yeah, that can be a problem running at a shoulder and trying to thread up
close to it. Is there a reason you couldn't pop the half nut open, or just too quick
to be comfortable? Not sure if you had to stay engaged and back up by reversing
the chuck.
Of course, three full threads will carry full axial load, so all the rest are not strictly
necessary for strength. I have verified this on an Instron machine, too. You can break
a 165,000 psi high strength steel bolt screwed into 6061T6 aluminum every time in tension with three
threads engaged. Had to prove it to another engineer one time. Broke four before he
would relent that it wasn't a fluke. 2.5 threads pulled out of the aluminum. Purely an
area ratio thing.
Have you done anything with the chamber at all? Rough out with a drill, I suppose.
Bill
just what is needed to get it done. The key is the gearing between spindle and cutter,
so hand turning will work fine. And as you said, stiffness is an issue on a lot of setups,
and with that necessarily wide a cut, you can only expect a light pass to work smoothly
with no chatter.
I finally figured out that this is why you run the compound in at 29 deg on a std 60 deg thread,
to cut on one side and let the other side just float, less load on the cutter that way than
a straight in plunge, which I did when I was teaching myself to thread, before I got the South Bend
"How to run a Lathe" book as a Christmas present from my wife.
Besides, I often only go .002 or so per pass with a normal V thread, too. 12 TPI is 0.083
per rev.
Yeah, that can be a problem running at a shoulder and trying to thread upclose to it. Is there a reason you couldn't pop the half nut open, or just too quick
to be comfortable? Not sure if you had to stay engaged and back up by reversing
the chuck.
Of course, three full threads will carry full axial load, so all the rest are not strictly
necessary for strength. I have verified this on an Instron machine, too. You can break
a 165,000 psi high strength steel bolt screwed into 6061T6 aluminum every time in tension with three
threads engaged. Had to prove it to another engineer one time.
Broke four before hewould relent that it wasn't a fluke.
2.5 threads pulled out of the aluminum. Purely anarea ratio thing.
Have you done anything with the chamber at all? Rough out with a drill, I suppose.
Bill
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