What method is used to determine if and how far out of true the action threads are when truing an action?
Thanks,
Dave
Thanks,
Dave
Gunsmithing Thread truing - Action blueprinting
- Thread starter GasLight
- Start date
- Tags
- action blueprinting thread truing
Re: Thread truing - Action blueprinting
me thinks......it ain't the threads that are any great shakes , but the action face and bolt face get plumbed....
me thinks......it ain't the threads that are any great shakes , but the action face and bolt face get plumbed....
Re: Thread truing - Action blueprinting
so when someone says they have seen the threads as much as .030" out, then they are saying they had to take .030" off to completely clean them up?
BR, I agree, and typically wouldn't have other work done than what you say, I was just curious how the amount the threads are off is determined when they are trued up.
so when someone says they have seen the threads as much as .030" out, then they are saying they had to take .030" off to completely clean them up?
BR, I agree, and typically wouldn't have other work done than what you say, I was just curious how the amount the threads are off is determined when they are trued up.
Re: Thread truing - Action blueprinting
We use GTR's Action Blue Printing Jig and mandrels and bushings from PT&G, and dial in the receiver off of the bolt raceway. This ensures axial alignment of the receiver off of the bolt raceway, and then single point cut the threads until they are concentric to the bolt raceway/boreline. They never are, and we just keep advancing the cutting tool until we have completely re-cut the threads. All you see is newly machined, shiny metal surfaces on the threads, receiver locking lugs, and the receiver face or shoulder, and they are all cut absolutely square to the bolt raceway/boreline.
We use GTR's Action Blue Printing Jig and mandrels and bushings from PT&G, and dial in the receiver off of the bolt raceway. This ensures axial alignment of the receiver off of the bolt raceway, and then single point cut the threads until they are concentric to the bolt raceway/boreline. They never are, and we just keep advancing the cutting tool until we have completely re-cut the threads. All you see is newly machined, shiny metal surfaces on the threads, receiver locking lugs, and the receiver face or shoulder, and they are all cut absolutely square to the bolt raceway/boreline.
Re: Thread truing - Action blueprinting
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bolosniper</div><div class="ubbcode-body">We use GTR's Action Blue Printing Jig and mandrels and bushings from PT&G, and dial in the receiver off of the bolt raceway. This ensures axial alignment of the receiver off of the bolt raceway, and then single point cut the threads until they are concentric to the bolt raceway/boreline. They never are, and we just keep advancing the cutting tool until we have completely re-cut the threads. All you see is newly machined, shiny metal surfaces on the threads, receiver locking lugs, and the receiver face or shoulder, and they are all cut absolutely square to the bolt raceway/boreline. </div></div>
this is exactly how i did mine except i made my own mandrel, bushings and truing jig. if i remember correctly, i had to deepen the threads about .005" to get them completely true. if truing the threads is really needed, i don't know. i do know for now on if i have a say in it, i will start with a custom action from the get go and not even touch the receiver.
i have a feeling, many are screwing the receiver onto a threaded mandrel that is indicated in the lathe and only facing the front of the receiver.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bolosniper</div><div class="ubbcode-body">We use GTR's Action Blue Printing Jig and mandrels and bushings from PT&G, and dial in the receiver off of the bolt raceway. This ensures axial alignment of the receiver off of the bolt raceway, and then single point cut the threads until they are concentric to the bolt raceway/boreline. They never are, and we just keep advancing the cutting tool until we have completely re-cut the threads. All you see is newly machined, shiny metal surfaces on the threads, receiver locking lugs, and the receiver face or shoulder, and they are all cut absolutely square to the bolt raceway/boreline. </div></div>
this is exactly how i did mine except i made my own mandrel, bushings and truing jig. if i remember correctly, i had to deepen the threads about .005" to get them completely true. if truing the threads is really needed, i don't know. i do know for now on if i have a say in it, i will start with a custom action from the get go and not even touch the receiver.
i have a feeling, many are screwing the receiver onto a threaded mandrel that is indicated in the lathe and only facing the front of the receiver.
Re: Thread truing - Action blueprinting
If you only had to advance your single point thread cutter .005" to true the threads, then that was a relatively decent receiver. Most aren't anywhere near that good. We have had to go as much as .050" plus at times to remove all of the non-concentric threads on a receiver. You want to have freshly machined thread surfaces when completed, and you will want to advance the cutter until you achieve that goal, no matter how deep that you eventually have to go.
If you only had to advance your single point thread cutter .005" to true the threads, then that was a relatively decent receiver. Most aren't anywhere near that good. We have had to go as much as .050" plus at times to remove all of the non-concentric threads on a receiver. You want to have freshly machined thread surfaces when completed, and you will want to advance the cutter until you achieve that goal, no matter how deep that you eventually have to go.
Re: Thread truing - Action blueprinting
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">What method is used to determine if and how far out of true the action threads are when truing an action?
Thanks,
Dave </div></div>
Dave,
If truing in the lathe one must also remove taper, if there is any, from the threaded area and blank area just ahead of the lug abutments. You can go in with a small boring bar and just touch off at the front of the threads and make a clean up bore to the lugs being careful not to remove too much material. The main objective is to have the barrel threads, receiver threads, bolt and chamber concentric with the barrel bore and receiver center line. Once dialed in, you’re just looking for a clean up pass inside the receiver. Skim the lug abutment faces after your last boring cut. The major diameter of the threads are typically around 1.0625" and the minor around 1.0085” but, I have seen them at 1.058".
To clean up the receiver threads take small cuts watching the crest of the receiver threads as you go. Leave a small flat on top and you'll be fine. Once cleaned up, the receiver major thread diameter will be about 1.072” and the minor (ID of the receiver at the threads after clean up) around 1.018” As was said in a previous post, the receiver face, lug abutment faces and recoil lug faces being parallel are what's important. I've also used the PTG Tools and they are very good and easier to use. Tight fitting bushings in the receiver bolt raceway is an absolute must.
I’ve known guys that trued the receiver face and lug abutments in the lathe and ran a 1.0625” tap in the threads. Their rifles shot extremely well but, I couldn’t bring my self to use a plain tap in the receiver threads.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">What method is used to determine if and how far out of true the action threads are when truing an action?
Thanks,
Dave </div></div>
Dave,
If truing in the lathe one must also remove taper, if there is any, from the threaded area and blank area just ahead of the lug abutments. You can go in with a small boring bar and just touch off at the front of the threads and make a clean up bore to the lugs being careful not to remove too much material. The main objective is to have the barrel threads, receiver threads, bolt and chamber concentric with the barrel bore and receiver center line. Once dialed in, you’re just looking for a clean up pass inside the receiver. Skim the lug abutment faces after your last boring cut. The major diameter of the threads are typically around 1.0625" and the minor around 1.0085” but, I have seen them at 1.058".
To clean up the receiver threads take small cuts watching the crest of the receiver threads as you go. Leave a small flat on top and you'll be fine. Once cleaned up, the receiver major thread diameter will be about 1.072” and the minor (ID of the receiver at the threads after clean up) around 1.018” As was said in a previous post, the receiver face, lug abutment faces and recoil lug faces being parallel are what's important. I've also used the PTG Tools and they are very good and easier to use. Tight fitting bushings in the receiver bolt raceway is an absolute must.
I’ve known guys that trued the receiver face and lug abutments in the lathe and ran a 1.0625” tap in the threads. Their rifles shot extremely well but, I couldn’t bring my self to use a plain tap in the receiver threads.
Re: Thread truing - Action blueprinting
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I’ve known guys that trued the receiver face and lug abutments in the lathe and ran a 1.0625” tap in the threads. Their rifles shot extremely well but, I couldn’t bring my self to use a plain tap in the receiver threads.</div></div>
The whole concept is to produce a stress free assembly. Facing the reciever and not truing the threads is akin to taking a shower with a rain coat on.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I’ve known guys that trued the receiver face and lug abutments in the lathe and ran a 1.0625” tap in the threads. Their rifles shot extremely well but, I couldn’t bring my self to use a plain tap in the receiver threads.</div></div>
The whole concept is to produce a stress free assembly. Facing the reciever and not truing the threads is akin to taking a shower with a rain coat on.
Re: Thread truing - Action blueprinting
When I wanted to see the runout of the Rem thread on six receivers I threaded a piece of steel and screwed on the receivers while the spud was still in the lathe. Make a real good thread, I like to check the pitch dia. with wires or a thread mic (or both).
The six receivers that I checked were from 1 to 50+ (722) years old. Clean the threads before screwing them on. I indicated the receiver rear bridge area for runout and along the sides of the receiver for angularity.
Some were pretty good, one was so bad that runout at the rear was beyond the indicators range. Year of manuf or age made no difference.
If you are serious, true the threads on all actions used for serious rifles.
When I wanted to see the runout of the Rem thread on six receivers I threaded a piece of steel and screwed on the receivers while the spud was still in the lathe. Make a real good thread, I like to check the pitch dia. with wires or a thread mic (or both).
The six receivers that I checked were from 1 to 50+ (722) years old. Clean the threads before screwing them on. I indicated the receiver rear bridge area for runout and along the sides of the receiver for angularity.
Some were pretty good, one was so bad that runout at the rear was beyond the indicators range. Year of manuf or age made no difference.
If you are serious, true the threads on all actions used for serious rifles.
Re: Thread truing - Action blueprinting
If you faced the receiver while it is screwed onto the new barrel threads you just cut, wouldn't it be will be stress free even if you used a tap? Not that I would do anything like that, well except for maybe on a savage. I own a bunch that were cleaned up using a non-piloted tap that will shoot as well as any of my custom actioned guns. I actually think we are delving onto too much minutia in most instances of truing remingtons. I only use the PTG kit and think it works great, for something that probably does not matter anyway. Good barrel, good bedding, good glass....it will probably out shoot most of us.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AJ300MAG</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I’ve known guys that trued the receiver face and lug abutments in the lathe and ran a 1.0625” tap in the threads. Their rifles shot extremely well but, I couldn’t bring my self to use a plain tap in the receiver threads.</div></div>
The whole concept is to produce a stress free assembly. Facing the reciever and not truing the threads is akin to taking a shower with a rain coat on.
</div></div>
If you faced the receiver while it is screwed onto the new barrel threads you just cut, wouldn't it be will be stress free even if you used a tap? Not that I would do anything like that, well except for maybe on a savage. I own a bunch that were cleaned up using a non-piloted tap that will shoot as well as any of my custom actioned guns. I actually think we are delving onto too much minutia in most instances of truing remingtons. I only use the PTG kit and think it works great, for something that probably does not matter anyway. Good barrel, good bedding, good glass....it will probably out shoot most of us.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AJ300MAG</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I’ve known guys that trued the receiver face and lug abutments in the lathe and ran a 1.0625” tap in the threads. Their rifles shot extremely well but, I couldn’t bring my self to use a plain tap in the receiver threads.</div></div>
The whole concept is to produce a stress free assembly. Facing the reciever and not truing the threads is akin to taking a shower with a rain coat on.
</div></div>
Re: Thread truing - Action blueprinting
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OMJ</div><div class="ubbcode-body">
If you are serious, true the threads on all actions used for serious rifles. </div></div>
and if you are serious about your time, start with a quality aftermarket action
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OMJ</div><div class="ubbcode-body">
If you are serious, true the threads on all actions used for serious rifles. </div></div>
and if you are serious about your time, start with a quality aftermarket action
Re: Thread truing - Action blueprinting
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: eddybo</div><div class="ubbcode-body">If you faced the receiver while it is screwed onto the new barrel threads you just cut, wouldn't it be will be stress free even if you used a tap? Not that I would do anything like that, well except for maybe on a savage. I own a bunch that were cleaned up using a non-piloted tap that will shoot as well as any of my custom actioned guns. I actually think we are delving onto too much minutia in most instances of truing remingtons. I only use the PTG kit and think it works great, for something that probably does not matter anyway. Good barrel, good bedding, good glass....it will probably out shoot most of us.
</div></div>
i think a lot of guys thread the receiver onto a threaded mandrel and only true the face of the receiver. this does not ensure that the bolt face is square or centered to the chamber. does it matter? i can't say for sure with my limited experience. personally, i'd rather spend the extra time to eliminate as many variables as i can.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: eddybo</div><div class="ubbcode-body">If you faced the receiver while it is screwed onto the new barrel threads you just cut, wouldn't it be will be stress free even if you used a tap? Not that I would do anything like that, well except for maybe on a savage. I own a bunch that were cleaned up using a non-piloted tap that will shoot as well as any of my custom actioned guns. I actually think we are delving onto too much minutia in most instances of truing remingtons. I only use the PTG kit and think it works great, for something that probably does not matter anyway. Good barrel, good bedding, good glass....it will probably out shoot most of us.
</div></div>
i think a lot of guys thread the receiver onto a threaded mandrel and only true the face of the receiver. this does not ensure that the bolt face is square or centered to the chamber. does it matter? i can't say for sure with my limited experience. personally, i'd rather spend the extra time to eliminate as many variables as i can.
Re: Thread truing - Action blueprinting
A tap will clean up threads where the bore is egg shaped. The issue is that if the threads are canted to the axis of the bolt bore a tap will not correct it. The only way to make the threads concentric and straight to the bolt bore is by single point cutting them with a boring bar.
If the threads are canted the barrel won't have 100% contact with the face of the reciever when hand tight, even after the face if cleaned up. Heck you could conceivably make the joint worse. So when you torque the barrel tight something has to give for the barrel to mate up to the reciever face. Guess it depends how anal you want to be, It takes me longer to indicate in an action than to recut the threads.
A tap will clean up threads where the bore is egg shaped. The issue is that if the threads are canted to the axis of the bolt bore a tap will not correct it. The only way to make the threads concentric and straight to the bolt bore is by single point cutting them with a boring bar.
If the threads are canted the barrel won't have 100% contact with the face of the reciever when hand tight, even after the face if cleaned up. Heck you could conceivably make the joint worse. So when you torque the barrel tight something has to give for the barrel to mate up to the reciever face. Guess it depends how anal you want to be, It takes me longer to indicate in an action than to recut the threads.
Re: Thread truing - Action blueprinting
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AJ300MAG</div><div class="ubbcode-body">A tap will clean up threads where the bore is egg shaped. The issue is that if the threads are canted to the axis of the bolt bore a tap will not correct it. The only way to make the threads concentric and straight to the bolt bore is by single point cutting them with a boring bar.
If the threads are canted the barrel won't have 100% contact with the face of the reciever when hand tight, even after the face if cleaned up. Heck you could conceivably make the joint worse. So when you torque the barrel tight something has to give for the barrel to mate up to the reciever face. Guess it depends how anal you want to be, It takes me longer to indicate in an action than to recut the threads. </div></div>
i think the guys that use the tap will thread the action on a threaded mandrel that is dialed into the late. while on the threaded mandrel, they will true the face of the receiver. this should allow 100% contact between the barrel shoulder and the receiver face. this does not do anything to keep the bolt square or aligned with the chamber.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AJ300MAG</div><div class="ubbcode-body">A tap will clean up threads where the bore is egg shaped. The issue is that if the threads are canted to the axis of the bolt bore a tap will not correct it. The only way to make the threads concentric and straight to the bolt bore is by single point cutting them with a boring bar.
If the threads are canted the barrel won't have 100% contact with the face of the reciever when hand tight, even after the face if cleaned up. Heck you could conceivably make the joint worse. So when you torque the barrel tight something has to give for the barrel to mate up to the reciever face. Guess it depends how anal you want to be, It takes me longer to indicate in an action than to recut the threads. </div></div>
i think the guys that use the tap will thread the action on a threaded mandrel that is dialed into the late. while on the threaded mandrel, they will true the face of the receiver. this should allow 100% contact between the barrel shoulder and the receiver face. this does not do anything to keep the bolt square or aligned with the chamber.
Re: Thread truing - Action blueprinting
That is what I was talking about 300sniper, except using a freshly turned barrel. When you turn the new threads they are dialed in with the throat. facing the receiver screwed onto this barrel insures that the action face is concentric with the shoulder.
I am not saying that it is the best way, and do not use that method, as I see it as compounding errors, just that there will not be stress when tightened. I have screwed savage actions onto freshly turned barrels sans the recoil lug. I turn a shoulder and delete the barrel nut. Then used a cutter to lightly "true" the front of the action. On a savage I do not think it matters because of the floating bolt head. But on a remington I see it as possibly putting the bolt face more out of alignment, with no way of truing it to that line.
I have measured several actions cut using the PTG kit against an action that I trued in the lathe. I did not see enough difference to make me want to risk someones action. My machining skills just do not let me comfortably run a cutter into a blind hole. There is a lot going on when you do this and I do gunsmithing as a hobby not to get my blood pressure up.
One thing I wish that had been done differently on the PTG kit. I wish that the bolt way reamer was hollow and would mate over the tap mandrel. That way you would leave the tap screwed into the threads extending to the back of the action. Then the raceway reamer would slide over the mandrel and run through the action being fully alighned with the threads. It works the way it is, I just think that would be an improvement, but what do I know I am just a hobby guy.
That is what I was talking about 300sniper, except using a freshly turned barrel. When you turn the new threads they are dialed in with the throat. facing the receiver screwed onto this barrel insures that the action face is concentric with the shoulder.
I am not saying that it is the best way, and do not use that method, as I see it as compounding errors, just that there will not be stress when tightened. I have screwed savage actions onto freshly turned barrels sans the recoil lug. I turn a shoulder and delete the barrel nut. Then used a cutter to lightly "true" the front of the action. On a savage I do not think it matters because of the floating bolt head. But on a remington I see it as possibly putting the bolt face more out of alignment, with no way of truing it to that line.
I have measured several actions cut using the PTG kit against an action that I trued in the lathe. I did not see enough difference to make me want to risk someones action. My machining skills just do not let me comfortably run a cutter into a blind hole. There is a lot going on when you do this and I do gunsmithing as a hobby not to get my blood pressure up.
One thing I wish that had been done differently on the PTG kit. I wish that the bolt way reamer was hollow and would mate over the tap mandrel. That way you would leave the tap screwed into the threads extending to the back of the action. Then the raceway reamer would slide over the mandrel and run through the action being fully alighned with the threads. It works the way it is, I just think that would be an improvement, but what do I know I am just a hobby guy.
Similar threads
