? chucking up a barrel ?
- Thread starter Hal
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akshooter
Guest
little as possable , no more than 5 times the diamater . no.
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frwillia
Guest
How much do I let the breech project from the chuck? As little as possible. In this picture the finished (and chambered if it matters) tenon is 0.734" long (for an -03 Springfield). The breech projects about 1-1/2" from the face of the chuck jaws.
Pictures will help. This shows my chambering setup - you can see how little of the breech projects.
Most important, do "not" chuck the barrel directly in the chuck jaws. Use a method that allows the barrel to pivot in the jaws when you adjust the muzzle end using the spider
on the other end of the headstock otherwise all you are doing is bending the barrel when you adjust the spider on the other end. I happen to use a piece of #4 bare copper ground wire bent into a circle, like this:
I got the tip to use the copper wire on this forum and it works really really well. It's easier to align the barrel with the 4J and the copper wire than it is with the spider chuck I made.
Fitch
Pictures will help. This shows my chambering setup - you can see how little of the breech projects.
Most important, do "not" chuck the barrel directly in the chuck jaws. Use a method that allows the barrel to pivot in the jaws when you adjust the muzzle end using the spider
on the other end of the headstock otherwise all you are doing is bending the barrel when you adjust the spider on the other end. I happen to use a piece of #4 bare copper ground wire bent into a circle, like this:
I got the tip to use the copper wire on this forum and it works really really well. It's easier to align the barrel with the 4J and the copper wire than it is with the spider chuck I made.
Fitch
adamsgt
Jerry Adams
frwillia
It looks as if you drilled and tapped your spindle for the outboard spider bolts. My lathe has at least as much spindle extending as you have and I would like to know how you drilled and tapped the spindle. Did you do it while the spindle was on the lathe; if so what did you use to drill and tap?
It looks as if you drilled and tapped your spindle for the outboard spider bolts. My lathe has at least as much spindle extending as you have and I would like to know how you drilled and tapped the spindle. Did you do it while the spindle was on the lathe; if so what did you use to drill and tap?
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frwillia
Guest
Did it with the spindle right in the lathe. I sort of wandered into doing it almost by accident, but it was a piece of cake to do it. I originally made an outboard spider out of aluminum. It clamped to the spindle using 4 set screws.
The outboard spider was rather precisely made and one day, as I was going to install it I noticed that the 4 set screws had perfectly marked the spindle with locations where I could drill and tap it and replace the outboard spider with spider screws threaded into the spindle - an advantage because it permits working on shorter barrels.
With that thought in mind I very carefully center punched the holes (very lightly, didn't want to screw up the spindle bearings), then center drilled the punch marks useing my smallest center drill in my 14.4V DeWalt battery operated drill. That was followed by a starter drill bigger than the tip web on the tap drill, and then a tap drill for a 3/8-16 tap.
Why 3/8-16? I had the bolts in the drawer and they use the same size hex wrench as the spider bolts in my spider chuck so I only need two hex wrenches on hand when aligning barrels in the head stock.
With all 4 holes drilled, I put the 3/8-16 tap in the DeWalt, set it to it's slowest speed (gear ratio), dipped it in tapping fluid, stick it in the hole, checked the alignment by eye, pushed on it a bit and pulled the trigger. Tapped the hole in about 10 seconds. Backed it out, blew the chips off, rotated the spindle a quarter turn, dipped the tap in the tapping fluid and did the next one. All told, from deciding to do it till the holes were done was about 10 to 15 minutes. The electric drill tapping method isn't something to try for the first ever time in your life on your lathe spindle, but I use the drill for that a lot, and it works just fine.
The real trick was in having them marked by the set screws. When I saw, and got the idea, I knew it was as good as done. And it was.
So then I hunted around and found some 3/8-16 SOCS of an appropriate length in a drawer, drilled and tapped a short piece of 3/4" rod to hold them in the 3J, made the 4 brass tipped spider screws in the picture, and it was done. The brass tips are glued into the spider bolts with Red LockTite.
I've used the 14.4V DeWalt to run taps in lots of times. As long as the tap is bigger than 1/4-20 (which must be the easiest tap on the planet to break) it works great.
Fitch
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frwillia
Guest
No, the tap isn't going to bind in a situation like this if one just powers it right on through. Lack of torque will let it bind and that can be a problem. Safest to just go for it. The section being tapped is pretty thin so I just want the drill to power right on through. The odds of the drill having enough torque to break the tap are pretty small with a tap this big, so I leave it set for drill mode and go for it. With the tap dripping in high sulfer cutting oil, the actual time it's cutting is maybe 2 seconds in a job like this, then it's through, the torque drops fast, and it's time to get off the switch to let it stop. You might feel like a handful of TUMS before doing it the first time, but it works great.
You can always tap the hole by hand, that will work too, but that's not how I did it.
Fitch
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frwillia
Guest
I had polished the barrel between centers. Didn't want to scratch it, so I wrapped it in tape. The tape worked great.
Fitch
Wayne Shaw
Active member
I wrap the barrel with newspaper, tape it together. Tear off what you need if it gets in the way.
jackie schmidt
New member
I have noticed something from reading threads and looking at pictures of various set-ups. That is, most chamber the barrel after the threading, etc.
Since the first thing I do is rough in the tenon and then establish the chamber, after which I do all of the subsequent machining operations. I am curious as to why most ream the chamber after the other operations.
Since the first thing I do is rough in the tenon and then establish the chamber, after which I do all of the subsequent machining operations. I am curious as to why most ream the chamber after the other operations.
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mike in co
Guest
'cause i don't have the experience you have......don't trust just numbers yet, and have to get the recvr/bolt in the picture for the final cuts of the chamber.....
(i think you have more march scopes, than i have done chambers from beginning to end)
mike in co
(i think you have more march scopes, than i have done chambers from beginning to end)
mike in co
Mike Bryant
Active member
I have a barrel in my lathe right now that I didn't get finished today. I cut the tenon almost to diameter and then drilled and bored out most of the chamber. Then ran the reamer in. I lack just a little having the reamer run in to full depth. I'll check the runout on the neck Monday and if the neck needs to be indicated in a little to get it to as close to zero runout as I can get, I'll tweak the adjustment screws on the chuck a little to get it there. Then finish turning down the tenon diameter and thread it to fit the action, cut the cone for clearance and the last thing will be to run the reamer in the rest of the way to full depth to just close on a go gage. The action is a new action and hasn't been put into a stock yet, so pretty easy to test it on the barrel. I prefer having most of the chamber reamed before doing the threads and cutting any clearances as if something goes wrong with the chamber, then you haven't wasted any time on doing the threads. Run out on the neck when I quit was about two tenths runout. I'll check it again Monday when I start back on the barrel.
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frwillia
Guest
I am confused. If my understanding is correct, what counts is the relationship of the chamber (and by association the bullet), it's concentricity and alignment, with the throat and the angle of the bore immediately after it - they are what define the symmetry or lack of it when the bullet hits the bore. How this recentering to have zero runout will have any beneficial impact on the relationship of that nearly finished chamber with the bore completely eludes me. The pilot is going to follow the bore no matter what, and unless something really awful has happened, the barrel should not have moved enough to affect primer strike in any significant way. In fact unless some alignment technique I've not heard of was used, I'd expect the reamer to be near perfectly centered at the breech face because the tenon was rough machined after the barrel was aligned, so recentering could make the primer strike move off center.
I can see doing an elaborate realignment where one centers the throat, then adjusts the muzzle to center the chamber at the breech, then the throat, and so on till the reamer is exactly on the lathe axis (avoiding any issue with off centering the primer strike), but what good this does is a mystery to me. The reamer has been tracking the bore, so the end result of this late realignment of the barrel to the chamber which has aligned itself with the bore in the breech end of the barrel, would approach what one gets if Gordy's approach is used to start with (aligning the bore at the breech end regardless of where the muzzle points).
This is a sincere question, this post left me completely adrift, I know I'm missing something here but I don't know what it is. What am I missing? How (the physics of bullet bore interaction, or rifle dynamics, or <?>) is it expected to affect group size? If it does end up with the same alignment that Gordy's approach would have given, one could just start that way and avoid the hassle, couldn't they?
Thanks
Fitch
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JerrySharrett
Senile Member
If I were in Mikes situation, I too would check the entire setup for movement and runout. If anything were amiss, I'd really give everything a relook. If something had moved that would mean stress somewhere had relieved itself, and that is not good.
As to which element of the chamber end is finished first, I challenge anyone to convince me which is most important to be finished first, tenon shoulder, tenon shank, or chamber. In any order of completion, each element is held to the nearest thousant in its relationship with the others. For example, the tenon shoulder position relates directly to the chamber shoulder, just as the chamber shoulder relates directly to the tenon shoulder. Chicken or egg??
Some of these flimsy tailstock indicator setups I have seen pictures of may require other considerations. My tailstock has a micrometer dial that is as accurate as can be made. It is no more nor no less accurate than the micrometer dials that determine the other measurements. .
As to indexing, except in unique situations, like lettering, proper alignment of the barrel blank in the original setup eliminates that potential screwup.
Mike Bryant
Active member
When you use a full length blank, both ends of the bore are belled slightly from lapping. If you use any of the belled end for dialing in the barrel, you are getting a false reading. The muzzle end isn't that critical, but if it's off much, it may be hard to get the barrel to zero when you start shooting it. With using an indicator to dial in the barrel at the projected throat of the chamber, I'm just picking that point as the most important place for the barrel to be indicated. With drilling and boring out the chamber end any belling is done away with by the chamber. Since you are running a dial indicator point on lands and grooves, you can get it as close as you can, but when you check on the neck of the chamber when you get close to finishing the chamber, it's easier to get the neck dialed in if you didn't quite get it right when you indicated on the lands and grooves.
Just remember no matter how you go about getting your chamber, the final word to how good a job was done is how the barrel shoots on paper. Probably a lot of what we do as gunsmiths when setting up a barrel, probably only has an effect between our ears. Do a bad job though and you'll find out about it as the barrel won't shoot.
Just remember no matter how you go about getting your chamber, the final word to how good a job was done is how the barrel shoots on paper. Probably a lot of what we do as gunsmiths when setting up a barrel, probably only has an effect between our ears. Do a bad job though and you'll find out about it as the barrel won't shoot.
Butch Lambert
Active member
Fitch,
I use a very loose bushing on my reamer in order that it doesn't follow the bore, especially if it is a little crooked. That will also make the base of your chamber somewhat larger.
Butch
I use a very loose bushing on my reamer in order that it doesn't follow the bore, especially if it is a little crooked. That will also make the base of your chamber somewhat larger.
Butch
JerrySharrett
Senile Member
By the time I am chambering the breech end, I have already cut the barrel blank off to finish length plus about 3/8-1/2 inches of finish length.
I use Dan Liljas BASIC program to establish barrel weight and length for where I want it to finish. For 100/200 barrels I use the Bruno Medium blank which is 29" long. By shifting the cut off points I can get a 22" barrel that is anywhere from about 4# 5 oz to 5# 5oz. This allows me to indicate the muzzle (outboard) end at point that is 1/2" or less of the finishing place for the muzzle.
JerrySharrett
Senile Member
Why??