Railgun question
- Thread starter Roy in NC
- Start date
G
Gary Walters
Guest
I was told
to use 65 inch pounds. Seems to work okay. That is not too tight. I do not know what to use with your set-up (gasket material)............GW
to use 65 inch pounds. Seems to work okay. That is not too tight. I do not know what to use with your set-up (gasket material)............GW
Depends on the bolts and what's between the barrel and the block...
... in my experience.
Dwight Scott had finer bolts (28 TPI I think) with a recoil shoulder on the barrel of his famous rail gun (7 points). He torqued his bolts to 40 inch pounds. Dwight had a V-block with nothing between the barrel and block. His concern was that the barrel could be receiving stresses from over-tightening the top.
I have a Young with the more course bolts (18 TPI I think), a recoil shoulder on my barrels and nothing between the V-block and barrel. I torque mine to 90 inch pounds. Guys with a similar set-up to mine who have torqued theirs lighter would have the gun throw shots until it got to the 90 IP range. It seems that the courser the bolt, the more torque is necessary for the top to hold the barrel correctly in the V. I have no experience with a rail gun that has the sleeved block; although Lester Bruno has been extremely successful with that type of set-up.
I have not been a big proponent of putting anything between the barrel and the block, but my rail gun barrels have the surface under the block turned to be round by my gunsmith (DS). I believe that using material between the barrel and block is only necessary as a compromise when the contact between these two items hasn't been "trued". There's a lot more to that barrel-block contact in a rail gun than how much to simply torque the bolts.
It seems to me that the most important thing to do is keep trying different settings until the gun shoots.
... in my experience.
Dwight Scott had finer bolts (28 TPI I think) with a recoil shoulder on the barrel of his famous rail gun (7 points). He torqued his bolts to 40 inch pounds. Dwight had a V-block with nothing between the barrel and block. His concern was that the barrel could be receiving stresses from over-tightening the top.
I have a Young with the more course bolts (18 TPI I think), a recoil shoulder on my barrels and nothing between the V-block and barrel. I torque mine to 90 inch pounds. Guys with a similar set-up to mine who have torqued theirs lighter would have the gun throw shots until it got to the 90 IP range. It seems that the courser the bolt, the more torque is necessary for the top to hold the barrel correctly in the V. I have no experience with a rail gun that has the sleeved block; although Lester Bruno has been extremely successful with that type of set-up.
I have not been a big proponent of putting anything between the barrel and the block, but my rail gun barrels have the surface under the block turned to be round by my gunsmith (DS). I believe that using material between the barrel and block is only necessary as a compromise when the contact between these two items hasn't been "trued". There's a lot more to that barrel-block contact in a rail gun than how much to simply torque the bolts.
It seems to me that the most important thing to do is keep trying different settings until the gun shoots.
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Jay Young
Member
I use 10 5/16"-18tpi bolts in my barrel blocks, I have done some for Dwights's
costomers with 6 1/4"-28tpi before as well, Both systems work well, I have never used a torque wrench on my rail but many people are starting out at 40" pounds and going up from there, As far as the gasket material goes, Try it both ways and see how it shoots, That is the ultimate test, <If it ain't broke don't fix it>.....J
Joe, Keep up the good shooting...
costomers with 6 1/4"-28tpi before as well, Both systems work well, I have never used a torque wrench on my rail but many people are starting out at 40" pounds and going up from there, As far as the gasket material goes, Try it both ways and see how it shoots, That is the ultimate test, <If it ain't broke don't fix it>.....J
Joe, Keep up the good shooting...
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Jay...
... sorry about misstating the TPI on your blocks. I did say that I was not sure. I do know that the ones on mine are not as fine as what Dwight used on his, and Dwight had fewer bolts. It is the combination of the finer threads and the recoil shoulder that had allowed Dwight to go lighter on the torque.
I do stand behind the inch pounds that I use on my ten-bolt V-block set-up and that I have both personally seen and witnessed with other rails that too light on the top will throw shots. But, your recoomendation to start light and work up is the best solution. Ultimately, it is what the target shows that is what matters.
I would believe that anything above 100 inch-pounds is overkill and could lead to damage.
... sorry about misstating the TPI on your blocks. I did say that I was not sure. I do know that the ones on mine are not as fine as what Dwight used on his, and Dwight had fewer bolts. It is the combination of the finer threads and the recoil shoulder that had allowed Dwight to go lighter on the torque.
I do stand behind the inch pounds that I use on my ten-bolt V-block set-up and that I have both personally seen and witnessed with other rails that too light on the top will throw shots. But, your recoomendation to start light and work up is the best solution. Ultimately, it is what the target shows that is what matters.
I would believe that anything above 100 inch-pounds is overkill and could lead to damage.
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Kirk Ethridge
New member
Recoil shoulder
do you turn down part of the barrel to create the "recoil shoulder"???
how much do you have to turn off the barrel to create a useable shoulder?
Thanks!
Kirk
do you turn down part of the barrel to create the "recoil shoulder"???
how much do you have to turn off the barrel to create a useable shoulder?
Thanks!
Kirk
R
Russ Hardy
Guest
Joe,
Is the turning of the barrel primarily to properly align the bore with the rail top, or to just give better (more even) contact between the barrel and block?
Russ
Is the turning of the barrel primarily to properly align the bore with the rail top, or to just give better (more even) contact between the barrel and block?
Russ
Thanks for the info guys! I was not looking for a specific number, but a good starting point in in/lbs. I had been using way too much torque for some unknown reason.
I am trying the rubber gasket material at the suggestion of a good railgun shooter in the region ( maybe he was just trying to eliminate some competition? ). I did use it with some success on a previous railgun.
Thanks again!
Roy
I am trying the rubber gasket material at the suggestion of a good railgun shooter in the region ( maybe he was just trying to eliminate some competition? ). I did use it with some success on a previous railgun.
Thanks again!
Roy
Recoil shoulder.
Dwight turns about an eighth off the outside of the barrel from the breech end to the front of the block in an attempt to have a consistent fit across the entire block. The block is also a V on the bottom and a square cut on the top so that when the barrel fits into the V the top block simply holds the barrel in the V without introducing any additional stresses from a poor fit.
The last thing is a relief of the front of the top block so as to not contact the recoil shoulder. This way only the V cradles the barrel and the top is there simply to maintain the barrel in that cradle.
Some of this might be theory, but I would say that it has had its successes.
This certainly can't hold a candle to tuner discussions or water in the barrel, but it is my modest contribution to the benchrest theoretical wars.
Dwight turns about an eighth off the outside of the barrel from the breech end to the front of the block in an attempt to have a consistent fit across the entire block. The block is also a V on the bottom and a square cut on the top so that when the barrel fits into the V the top block simply holds the barrel in the V without introducing any additional stresses from a poor fit.
The last thing is a relief of the front of the top block so as to not contact the recoil shoulder. This way only the V cradles the barrel and the top is there simply to maintain the barrel in that cradle.
Some of this might be theory, but I would say that it has had its successes.
This certainly can't hold a candle to tuner discussions or water in the barrel, but it is my modest contribution to the benchrest theoretical wars.
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