Dusty Stevens
Hollow Point Dispenser
Thats real nice. I need one for my 13" south bend
pics of my first benchrest build in progress
- Thread starter savet06
- Start date
Did a mock tenon and thread today and I am very happy with the results.
Chamber reads just under .0005 runout. I am just not sure I can get below that point with this setup but I am going to give it my best!
I had originally bored out the spindle to 1.220 but I may go back and add another .010 so I have a bit more room to move the barrel. I should still have enough metal beneath the threads of the spindle but it is getting close! I am running into a bit if binding if I try to snug up the thrust bearing too far but I am able to hold tolerances well for turning and threading.
Chamber reads just under .0005 runout. I am just not sure I can get below that point with this setup but I am going to give it my best!
I had originally bored out the spindle to 1.220 but I may go back and add another .010 so I have a bit more room to move the barrel. I should still have enough metal beneath the threads of the spindle but it is getting close! I am running into a bit if binding if I try to snug up the thrust bearing too far but I am able to hold tolerances well for turning and threading.
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MilGunsmith
Member
Are you using straight diameter barrel blanks? If they are tapered, there should be plenty of room in the spindle.
I will be running hv and lv taper barrels so I will give it a try. Maybe the taper on the barrel will start before the spindle bore.
Made a reamer holder tonight and wanted opinions on the design.
with this style from the reading I have done a rounded insert in the tailstock is the best way to keep things floating.
Made a reamer holder tonight and wanted opinions on the design.
with this style from the reading I have done a rounded insert in the tailstock is the best way to keep things floating.
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Jerry,
Your post on the south bend heavy ten thread means a great deal to me as I try to move forward with my benchrest career. I want to do the very best I can with the set up that I have as there is little chance I will get permission from the boss to acquire another lathe at this point or any in the foreseeable future!
Before I put a $300+ barrel in this setup should I reconsider and go back to a steady rest or is there a way to avoid putting the barrel in a position of stress with the half headstock.
It would seem that Chet's idea of only having a very small portion of the barrel in the 4-jaw would allow it to pivot without inducing that stress...at least not to as great an amount as chucking it fully in the jaws would. I am a pimple on the ass of those of whom I would call "gunsmiths" and want to learn all that I can. This has been a really fun project regardless and I have learned alot already.
Thanks,
Mike
p.s. I have also re-thought the knurling on the reamer holder and will likely only have the very end left with a pattern on it. Don't want any reason for the tool to be in my hand any longer than need be if something goes wrong! It just made it easier to screw it into the body of the holder.
Your post on the south bend heavy ten thread means a great deal to me as I try to move forward with my benchrest career. I want to do the very best I can with the set up that I have as there is little chance I will get permission from the boss to acquire another lathe at this point or any in the foreseeable future!
Before I put a $300+ barrel in this setup should I reconsider and go back to a steady rest or is there a way to avoid putting the barrel in a position of stress with the half headstock.
It would seem that Chet's idea of only having a very small portion of the barrel in the 4-jaw would allow it to pivot without inducing that stress...at least not to as great an amount as chucking it fully in the jaws would. I am a pimple on the ass of those of whom I would call "gunsmiths" and want to learn all that I can. This has been a really fun project regardless and I have learned alot already.
Thanks,
Mike
p.s. I have also re-thought the knurling on the reamer holder and will likely only have the very end left with a pattern on it. Don't want any reason for the tool to be in my hand any longer than need be if something goes wrong! It just made it easier to screw it into the body of the holder.
JerrySharrett
Senile Member
Mike, on the reamer holder, if it were me I'd remove the knurl. It looks pretty but it might grab you. I set my cross slide/compound to where I have an elbow rest, for my left arm, on it somewhere. Then I hold the reamer holder handle by its extreme end in the middle joint of my index finger. That way if the reamer grabs for any reason the handle simply jerks out of its hold.
In the various barrels I have done I've only had one reamer grab and jerk loose . That was on a 25/264 Win Mag Imp reamer and what happened was a piece off a flute on the reamer fractured and bound the reamer in the chamber.
Back many years ago while I was walking through the Eastman machine shop, one of the guys caught his sleeve on a protruding block welded on the side of a pipe he was polishing on a Monarch 10EE lathe and it wound him up. Luckily the 10EE was in belt drive range, not low range, was turning only about 50 rpm or so and the spindle stalled before he got would to his shoulder. It still tore away part of his forearm and one of the two bones there. This is a gristly story but very true. Just a caution of how to dress and how to stand clear around any machine tool.
"one of the guys caught his sleeve on a protruding block welded on the side of a pipe he was polishing on a Monarch 10EE"
No sleeves, no rings, no watches. Apron has a velcro tab that is under the primary material.
So is there a way to avoid the stress being induced as mentioned in the other thread?
Mike
No sleeves, no rings, no watches. Apron has a velcro tab that is under the primary material.
So is there a way to avoid the stress being induced as mentioned in the other thread?
Mike
JerrySharrett
Senile Member
Are you talking about barrel stress?
Some people use a piece of copper wire between the barrel and chuck so the barrel does not deflect. I use an aluminum ring that I machined and cut with a slitting saw.
Ben
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JerrySharrett
Senile Member
This copper/aluminum wire method works, if you do it correctly, to reduce of eliminate bending the barrel if you are using a spider and chambering through the headstock. If you are using the wire method in this "new" mid-bed headstock chambering method, you are going to get unwanted movement as the barrel constantly slides to relieve the twisting it endures.
Boyd Allen
Active member
It seems to me that the wire would not be needed if the mid bed headstock is holding the barrel with an inboard spider, that is similar to what some are using to allow shorter barrels to be chambered through their headstocks. Also, given the typical weight of competition benchrest barrels, I would think that twisting due to their being driven from their muzzles would be minimal, as long as cuts were light. Chet seems to have gotten excellent results with his.
And for my machine there is no such thing as a heavy cut really. At most I can take .010-015 (.020-.030 total removal) at a time with barrel steel. The belt just cant handle much more than that and .015 is probably pushing it! Aluminum is a different story fortunately.
Just no need to take much more anyway. I am in no rush.
Just no need to take much more anyway. I am in no rush.
coyotechet
Chet
confused: barrel constantly slides to relieve the twisting it endures.
I am confused as to barrel sliding and twisting. I can put a .0001 test indicator ( Brown & Sharpe 7023-3) on Deltronic fitted pin in the bore or on a turned tenon or on the flat spot near the 4 jaw chuck at the head stock after I have indicated the barrel in to the nearest .0001. Then turn the barrel by hand or in back gear or at a speed of 304 RPM /470 RPM / 740 RPM and the indicator needle barely wiggles less then .0001 most but less then .0002 anytime. So please someone explain to what and when is the barrel sliding and twisting.
I know that I am not a Machinist but I know that I know how to set up and read an indicator and how to test one to see is it is reading right.
Here is one of my testing of indicators so that I can trust what I am reading.
Chet
I am confused as to barrel sliding and twisting. I can put a .0001 test indicator ( Brown & Sharpe 7023-3) on Deltronic fitted pin in the bore or on a turned tenon or on the flat spot near the 4 jaw chuck at the head stock after I have indicated the barrel in to the nearest .0001. Then turn the barrel by hand or in back gear or at a speed of 304 RPM /470 RPM / 740 RPM and the indicator needle barely wiggles less then .0001 most but less then .0002 anytime.
So please someone explain to what and when is the barrel sliding and twisting.I know that I am not a Machinist but I know that I know how to set up and read an indicator and how to test one to see is it is reading right.
Here is one of my testing of indicators so that I can trust what I am reading.
Chet
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Dusty Stevens
Hollow Point Dispenser
Im trying to figure out how it has different stress than a thru spindle outboard spider setup. Looks to be exactly the same- 2 points of contact.
JerrySharrett
Senile Member
confused: barrel constantly slides to relieve the twisting it endures.
I am confused as to barrel sliding and twisting. I can put a .0001 test indicator ( Brown & Sharpe 7023-3) on Deltronic fitted pin in the bore or on a turned tenon or on the flat spot near the 4 jaw chuck at the head stock after I have indicated the barrel in to the nearest .0001. Then turn the barrel by hand or in back gear or at a speed of 304 RPM /470 RPM / 740 RPM and the indicator needle barely wiggles less then .0001 most but less then .0002 anytime.
I know that I am not a Machinist but I know that I know how to set up and read an indicator and how to test one to see is it is reading right.
Here is one of my testing of indicators so that I can trust what I am reading.
Chet
View attachment 15912
In the pictures I've seen of the mid-bed half headstock setup, or lack of a better description, the barrel CAN be "wrenching" if it is chucked on both ends and the alignment of rotation is not perfect between the headstock and this mid-bed thing. There will be an insignificant "torqueing" effect being chucked on both suspension points, simply wrenching. In a mid-bed steadyrest the barrel is allowed to slip axially, even the same misalignment error.
In a through the headstock setup, the barrel could be held in a "bend" but that bend is not wrenching simply rotating in space, or in the spindle bore if you please.
Dusty Stevens
Hollow Point Dispenser
If a barrel is held in a chuck and a spider i cant see the difference in it being held in a chuck and a spider
Joe Woosman
Member
I don't see the sliding and twisting happening either unless the floating headstock were not in line with the main headstock by a substantial amount.
Dusty Stevens
Hollow Point Dispenser
When its dialed in its no different than a spider on the end of a spindle. When the barrel runs true it just dont matter
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coyotechet
Chet
The key word here is CAN. I believe Jerry is correct when he says (the barrel CAN be "wrenching") . Because it does that me 4 to 5 times to adjust the barrel in. I first set the Half head stock on the bed ways loose run the barrel thru it to a center in the tail stock to align the barrel then adjust the 4 set screws to the barrel, then tighten the half head stock to ways. Now I go the 4 jaw chuck and loosen jaws to remove the bind if any then back to the adjusting the spider then back to the 4 jaws doing this the 4 or 5 times before I make the final .0001 or close adjustment at the spider. I can now and have set a dime on edge on the half head stock then cut and thread the barrel with out having the dime fall. It took me the better part of a year to get the half head stock aligned to the lathe spindle before I got it to run smoothly with out bending. Lots of hard work time and words to get it to this point. Would I do it again KNOW WAY but I really enjoy the one I have and will keep it for ever. I can adjust a barrel in with the half head stock to .0001 or close to it which is something that I can not do the common steady rest. (Speaking for myself only)
P.S. I now do most all my barrel work thru the head stock of my Heavy Ten which is way faster and easier.
P.S. I now do most all my barrel work thru the head stock of my Heavy Ten which is way faster and easier.