Gunsmithing The blueprinting debate. . .maybe this will help.

[LRI]

There's been a fair amount of recent chatter regarding the validity of working a receiver over.

This morning I started on a new job. I've got a Remmy 700 that has a scope base that doesn't fit quite right and the cst wants the base holes opened to 8-40.

Through the process of setting the receiver up to machine the hole locations (notice I didn't say drill) I decided to check a few things that <span style="font-weight: bold">normally I don't concern myself with since I machine them anyway regardless.. </span>

First step was to clamp the action in the vise and indicate to center based on the <span style="font-weight: bold"><span style="font-style: italic">outside</span></span> of the action. Basically its a simple process that involves bouncing the edge finder off both the fixed and moving mill vise jaws as they are a qualified surface, ground parallel, etc. From there I just split the difference and positioned the table to my center position. With a "wiggler" tool over the existing base hole I then made a simple visual reference.

The result was proof positive that the base hole is not on center with relation to the OD of the action. As the photo shows, the wiggler probe is crowding on the left side of the base hole.

Next step:

<span style="font-style: italic"><span style="font-weight: bold">Since we rarely care about the outside of the action when tuning things up,</span></span> <span style="font-weight: bold">I installed my centering mandrel into the Id bore and repeated the process all over again just to see what the differences were. With the wiggler over the existing holes it again shows the location out of clock position slightly. Tough to see in this photo but again its favoring the left side of the action.</span>

What this tells me:

In this particular case the OD and ID bore are pretty dern close to one another in terms of concentricity. I didn't measure it (because it has no bearing in this exercise) but the simple visual tells me they are probably within .005" of each other.



The scope base holes however are out of <span style="font-style: italic">clock </span>position. If viewing from the front of the action they are slightly behind 12 o clock. (11:58-ish. . .)

Probably not enough to hurt anything but again it's not "right". No worries since I machine my holes using a .125" endmill and just circular interpolate a round hole instead of hoping that a drill will run to the new center (it won't, it'll just follow the existing hole)

Now I gauge the hole using a .136" pin gauge to ensure my inside diameter is correct before I go blazing away with cutting threads for the new base screws.

Nothing really alarming, Just kinda emphasizes the fact that these actions, while pretty good overall, are in fact mass produced and its rather challenging to replicate perfection over and over again while still maintaining a price point that consumers will tolerate.

Enjoy your Saturday gents.

-C

 

[jrob300]

Re: The blueprinting debate. . .maybe this will help.

Thanks for the pictorial post. I'm very visual, so this helps a lot.

I can understand the out of clock on the base holes. Harder to understand when the front holes and back holes are not parallel to the action raceway. I've seen this before on a R700 action.

Also hard to understand why it's so hard to make two round objects around the same center. A local smith (who has a pretty good reputation, he does a lot of Lilja's work) told me it was because Remington buffs the outside of the receiver prior to bluing thus leaving it not quite round and not necessarily concentric to the bolt raceway.

Same smith told me that most truing operations are a waste of time on Tikka actions because they come really close from the factory and they don't buff or polish the outside of their actions. I've never actually seen this verified. Have you done the above on a Tikka? I know the smith who trued mine said it was as near perfect as he could measure.

John

 

[x ring accuracy]

Re: The blueprinting debate. . .maybe this will help.

Good write up. The over or under clocked rail screws is good info. Trued Remingtons shoot with the best, lack resale value according to some.

 

[mdesign]

Re: The blueprinting debate. . .maybe this will help.

Very interesting! I've seen holes "off clock" and not perpendicular before and it can really mess up getting your base on the action straight.

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

Different topic, same subject:

CZ 525 action that I'm working on for a friend. (Normally don't mess with these)

Take a good look at the threads. The color change says it all guys.

The steel used for these is garbage IMO. I had to cut the barrel off and bore out the tennon for fear of wrapping the receiver up like a twizzler in the vise.

This'll be a first and last. . .

 

[Jkob]

Re: The blueprinting debate. . .maybe this will help.

Just kind of wondering how you set the action up in the vise. How did you level it up. COuld it be you didn't have it levelled correctly and that is why the hole upears to be "off clock" as you say? There is not much surface to use to level a Remington 700 action when it needs work.

Jim

 

[BlackOps Tech]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gundoktr</div><div class="ubbcode-body">Just kind of wondering how you set the action up in the vise. How did you level it up. COuld it be you didn't have it levelled correctly and that is why the hole upears to be "off clock" as you say? There is not much surface to use to level a Remington 700 action when it needs work.

Jim </div></div>

I'm kinda wondering the same thing....Also, using the OD of a receiver to find the center and make the determination about whether the base holes are correctly placed isn't the most accurate/dependable method. Are you using the same method prior to "truing" receiver threads?

 

[stillbuster]

Re: The blueprinting debate. . .maybe this will help.

I read, and re-read this.
But is not the purpose of blueprinting an action to make the whole unit concentric to the bore, with as little variance on tolerances as possible? Not the OD of the receiver?
To make sure the action is level in the clamping mechanism wouldn't one use the action rails and the action mounting holes as a point of reference for level rather than the OD of the receiver?
If the scope mount holes are off center then would that not also make the action screw hole off center also?
an action can only go into a stock one way and that is determined by how the action screw holes line up with the stock, correct?
I see in the first picture that you have the mandrel locked up in the action already, wouldn't it be easier to indicate off of the sides of the mandrel?
Sorry so many questions, just trying to lern, or understand.

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Skunkworks</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gundoktr</div><div class="ubbcode-body">Just kind of wondering how you set the action up in the vise. How did you level it up. COuld it be you didn't have it levelled correctly and that is why the hole upears to be "off clock" as you say? There is not much surface to use to level a Remington 700 action when it needs work.

Jim </div></div>

I'm kinda wondering the same thing....Also, using the OD of a receiver to find the center and make the determination about whether the base holes are correctly placed isn't the most accurate/dependable method. Are you using the same method prior to "truing" receiver threads? </div></div>

Please reference my original opening post, the parts to pay attention to are now in bolt/italicized print.

I never said I used the OD of the action for establishing the center. I said I checked that first, then went to the ID using a mandrel to locate off of. I did it on the OD first just to <span style="font-weight: bold">see </span>how different it would be. In this case it turned out to be about .005".

I'm NOT using the outside of the action for anything other than something to hold onto.

Last. What the photo doesn't show is the previous set up where I installed a pinned recoil lug. I do this by sticking a B/S parallel in the raceway and holding it with a magnet, then indicating off the ground surface till I'm parallel with the X axis. Then I Drill for the lug.

Fixture the action in the vise with the bottom of the lug (I make all my own lugs) contacting the vise along the bottom. Then ALSO double check by again laying the parallel in there and indicating across its surface. Once I'm dialed it can't move.

No, there's no chance the action is out of clock position and I did not indicate anything off the outside of the receiver.

Sorry for the confusion.

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

Here's that finished CZ BTW.

 

[stillbuster]

Re: The blueprinting debate. . .maybe this will help.

I understand now. I should have read more closely. Basically you indicated off of the OD to answer how much difference measuring this way would show. Thanks.

 

[oldgrayone]

Re: The blueprinting debate. . .maybe this will help.

Good visuals. Thanks for sharing with us.

 

[BlackOps Tech]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Skunkworks</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gundoktr</div><div class="ubbcode-body">Just kind of wondering how you set the action up in the vise. How did you level it up. COuld it be you didn't have it levelled correctly and that is why the hole upears to be "off clock" as you say? There is not much surface to use to level a Remington 700 action when it needs work.

Jim </div></div>

I'm kinda wondering the same thing....Also, using the OD of a receiver to find the center and make the determination about whether the base holes are correctly placed isn't the most accurate/dependable method. Are you using the same method prior to "truing" receiver threads? </div></div>

Please reference my original opening post, the parts to pay attention to are now in bolt/italicized print.

I never said I used the OD of the action for establishing the center. I said I checked that first, then went to the ID using a mandrel to locate off of. I did it on the OD first just to <span style="font-weight: bold">see </span>how different it would be. In this case it turned out to be about .005".

I'm NOT using the outside of the action for anything other than something to hold onto.

Last. What the photo doesn't show is the previous set up where I installed a pinned recoil lug. I do this by sticking a B/S parallel in the raceway and holding it with a magnet, then indicating off the ground surface till I'm parallel with the X axis. Then I Drill for the lug.

Fixture the action in the vise with the bottom of the lug (I make all my own lugs) contacting the vise along the bottom. Then ALSO double check by again laying the parallel in there and indicating across its surface. Once I'm dialed it can't move.

No, there's no chance the action is out of clock position and I did not indicate anything off the outside of the receiver.

Sorry for the confusion. </div></div>

Although I do understand and appreciate the reason for your post and the time that you've invested in sharing, I do see a few set-up issues that can lead to inaccurate results. I'm not trying to troll here or stir the pot, but I wouldn't want those that view what they see as THE method that everything else should be compared to or as THE method that will yield the best results. Overall, I agree with a lot of what you're saying, but I'm a bit skeptical as to the accuracy of your findings based on your photos....I re-read what you said about the OD and must have missed a few details the first time around, but my other prior remark is in agreement with what Gundoktr said....

 

[300sniper]

Re: The blueprinting debate. . .maybe this will help.

it sounds to me like the parallel is placed flat across the raceway and used as the action's "level" reference. to me, that does make sense as one way of doing it.

i'd be curious how others decide what exactly is the true tdc on the action.

 

[Jkob]

Re: The blueprinting debate. . .maybe this will help.

Do you really think it matters if the base hole location is off a mere .005" or so? Also, it appears the threaded bore on the receiver is quite a bit bigger than normal. What is the new major diameter for the barrel to be?

 

[BlackOps Tech]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">it sounds to me like the parallel is placed flat across the raceway and used as the action's "level" reference. to me, that does make sense as one way of doing it.

i'd be curious how others decide what exactly is the true tdc on the action. </div></div>

I agree, but the "level" reference across the raceway is a rather short distance and therefore wouldn't be as accurate as a level reference taken over a longer distance. I use a ground and hardened "V" fixture that the receiver torques into rigidly and the center reference is taken from a ground/bushed mandrel in the raceway.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gundoktr</div><div class="ubbcode-body">Do you really think it matters if the base hole location is off a mere .005" or so? Also, it appears the threaded bore on the receiver is quite a bit bigger than normal. What is the new major diameter for the barrel to be? </div></div>

Absolutely .005" makes a difference and I would have fixed it as well. Typically I see the holes off between .012" and .018." I can't/shouldn't comment to the threaded bore diameter as I believe Chad said it is a CZ and I don't see them in my shop....

 

[300sniper]

Re: The blueprinting debate. . .maybe this will help.

thanks mike.

that is very similar to the way i was envisioning doing it.


edit: i was on my way to bed last night when i did some quick math (disclaimer: so i could be wrong

) but it looked like if the front or rear of the scope base was shifted over just .005", it would equal about 3 moa windage error. add in some twist and/or a more extreme angle and only get worse.

 

[BlackOps Tech]

Re: The blueprinting debate. . .maybe this will help.

What?! No drawing?!

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

I appreciate this being kept civil.

Thanks.


Now, riddle me this:

If I indicate off of a raceway that is roughly an inch wide exactly how is that any less accurate than building a device that inserts into the bore and also registers off the same raceway, only now is wider someplace else?

It would seem to me that all I've done is potentially (I'm not poking fingers, just asking) increase my margin of error because now I have to rely on a separate tool/devise that may/may not be as true as I want it to be.

A Brown and Sharp parallel set is ground pretty dern flat, parallel, and square. (Gawd I hope so anyway for what you pay for the damn things) That being said I would like to think that laying one in the raceway and sticking it with a magnet will provide me a good surface to indicate off of. The only reason I don't go off the raceway itself is because of surface finish. 9 out of 10 production actions, and most custom receivers are broached. The quality of surface finish varies considerably and rather than trying to "filter" all those little bumps and valleys it seems easier/more accurate to me to take the average via a hardened/ground/qualified piece of steel.

No?

As far as touting this to be the only way/best way to do all this work, I read through everything I wrote and I don't see that anywhere. Bold statements like that only piss people off and that is the furthest thing from what this thread is about. It's nothing other than showing an example to validate the extra work a gunsmith puts into an action to improve performance. That's it. I tell how I do something and why I do it that way-nothing more.

All the best,

-C

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gundoktr</div><div class="ubbcode-body">Do you really think it matters if the base hole location is off a mere .005" or so? Also, it appears the threaded bore on the receiver is quite a bit bigger than normal. What is the new major diameter for the barrel to be? </div></div>


The hole location isn't off .005". The difference between the OD/ID of the action is.

Look at the photo again. The minor hole ID for a 6-48 screw is around .113". Look at the wiggler. It's favoring one side by almost 2/3rds of the hole's diameter. 2/3rds of .113" is .034". 300 Sniper crunched some numbers and determined that .005" is worth 3MOA. Assuming the math is linear (cause I'm too lazy to do it myself) we'd be looking at something on the order of almost 20MOA now. Now complicate the matter further by recognizing that the induced cant of the scope is going to create some issues for elevation and windage. The optics aren't square to the bore and as the range increases the margin of difference is only going to increase. Ever shot a rifle at 300 yards and then at 1K+ on the same day in the same conditions with a scope/sight that isn't clocked right? It can drive you batshit in a hurry.

That's quite a bit of movement on a scope turret is it not?

-C

 

[BlackOps Tech]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body">I appreciate this being kept civil.

Thanks.


Now, riddle me this:

If I indicate off of a raceway that is roughly an inch wide exactly how is that any less accurate than building a device that inserts into the bore and also registers off the same raceway, only now is wider someplace else?

<span style="font-style: italic"><span style="font-weight: bold">It would seem to me that all I've done is potentially (I'm not poking fingers, just asking) increase my margin of error because now I have to rely on a separate tool/devise that may/may not be as true as I want it to be.</span></span>

A Brown and Sharp parallel set is ground pretty dern flat, parallel, and square. (Gawd I hope so anyway for what you pay for the damn things) That being said I would like to think that laying one in the raceway and sticking it with a magnet will provide me a good surface to indicate off of. The only reason I don't go off the raceway itself is because of surface finish. 9 out of 10 production actions, and most custom receivers are broached. The quality of surface finish varies considerably and rather than trying to "filter" all those little bumps and valleys it seems easier/more accurate to me to take the average via a hardened/ground/qualified piece of steel.

No?

As far as touting this to be the only way/best way to do all this work, I read through everything I wrote and I don't see that anywhere. Bold statements like that only piss people off and that is the furthest thing from what this thread is about. It's nothing other than showing an example to validate the extra work a gunsmith puts into an action to improve performance. That's it. I tell how I do something and why I do it that way-nothing more.

All the best,

-C

</div></div>

WOW. O.K.

It's the margin of error I'm referring to specifically. Didn't mean to ruffle your feathers, but you do tout <span style="font-style: italic">Investment Grade </span>firearms.

I believe I already expressed my appreciation for your willingness to share info, but historically there seems to be an <span style="font-style: italic">ooh-ahh</span> factor involved. That's why I made the comment about "THE" way to do things. If you're going to post things like this, you should probably be prepared for others to disagree with and question what you're doing. It doesn't mean I expect you to do it my way or anyone else's way, but my point is that your set-ups look/sound a little suspect to achieve the best results but they're painted with an allure of grandeur....

In an effort to squelch the escalation of a pissing match, this will be my last response on the topic....

 

[bohem]

Re: The blueprinting debate. . .maybe this will help.

Chad- The math that 300sniper did is indeed linear, it's just a similar triangle problem, same idea (in a different plane of course) that the 20 MOA base works on.

If it's off 0.001" over 3.6" then it's off 1" at 100y (3600 inches). I don't remember what the spacing for the midpoint of the 2 rears against the 2 front points are, but let's say for easy math sake that it happens to be 3.6" (this way I don't need a calculator).

If you have 0.034" of yaw runout along 3.6" on the receiver, then you're off by 34" at 100y.

For a totally factory rifle, this is one of the reasons that I like using the Leupold bases that have the rear ring snubber screws. You can put the optic in it's windage center and coarse adjust to within 1/2" and then dial and zero the turrets. With a P-rail and untrued mounts (assuming the rings and base are actually true, hardly the case usually) then you don't get to do this, you can shim or dial.

Skunkworks and Chad: Here's a thought I've been mulling over. Let's imagine that you have just the locking lugs and tenon joint to work from, there's no aft section of the receiver that supports the tail end of the bolt.

From a straight up geometry point, you could take the round receiver, chuck up where-ever you please and cut the threads, face, counterbore face, and recut the locking lugs to true, no dialing required. Now you have the tenon threads, receiver face and locking lugs all concentric and/or perpendicular to one another. UNLESS you removed it from the chuck, then you're boned and have to actually dial it back into place.

It appears to me (and I have limited experience building them, just from studying the geometry and applying some modicum of engineering knowledge) that you can take a rifle with an extremely tight headspace, provide an undersize bolt body, cut the tenon ring exactly how I described above, and let it "float" at the rear bolt support at the rear bridge.

When the case locks into place, a 0.0001" headspace (which is unnervingly tight) would mean that the most linear travel you could have on the bolt face would be 0.0001" across the case head. The case head is 0.473" for commonality sake.

0.0001"/0.473" turns out to be ~0.000211"/1", and that turns into the bolt being effectively off the axis of the bore by 0.00076" appx on it's total unsupported length.

I have a 700 receiver that is U shaped between the bolt support points, which means that unless you rebore the bolt raceway and either replace or sleeve the bolt, no matter what you do, the rear is going to have a less than ideal support level.

I don't have a raceway reamer, so I just lived with the rear support having minimal contact.

When the round fires, the bolt thrust on the face is going to stand that bolt straight back against the locking lug surfaces adn it's going to sit where-ever the contact planes on the lugs align. A little bit of clearance under the rear end of the bolt might not be terrible in that regard.

I'm not arguing that truing the threads and getting everything concentric is a bad idea, my point is simply that if you set the rifle up in such a manner then it will still shoot very well, the cost is that you need to have an extremely tight headspace and it's going to be next to useless in anything but a temp controlled shooting environment that has no dirt/dust or other elemental factors because with a headspace that tight, you're in trouble at the slightest issue.

A realistic headspace rifle is more like 10-20 times that tolerance, which makes your bolt have a lot more runout than is tolerable to any of us.

A similar thought goes into the bolt head, if you have the bolt face, nose, and locking lug surfaces all cut true to each other, then it seems that you can get away with a fair bit of runout over the bolt body and still have a rifle that shoots. Of my 4 Rem 700/7 actions, the best bolt was only out by 0.0006" of TIR from the bolt handle to the aft lug surface and it was round to within 0.0005", but the worst one is out of round by 0.003" and axial TIR is 0.0025"

Chad's method (from some other posts) seems to be essentially using a VMC in a very similar manner that most people cut the actions on a manual lathe. Bolt raceway indicator, dial it, then use the VMC's automatic capabilities to clean up the tenon.

Keeping in mind the lockup tolerances in the tenon region, I see no reason that either method is better or worse, what I do know from experience is that the VMC setup is more than likely faster. I've indicated a lot of race car pieces into a VMC for cleanup or rework, and compared to dialing them into a 4 jaw chuck manually, the VMC was a snap.

Also, for actually cutting the thing, once you pickup the thread and have it dialed in place, a push-button program speeds up things quite a bit and takes out the potential for human error, meaning that every 700 action coming out of the shop is consistent to within the tolerances of the VMC. For my own piece of mind, I would adopt this policy myself. Everything is trued to a 1.080x16 thread, Barrels can be threaded with minimal hand fitting, the manufacturing process just works smoother.

I'm not knocking the work that other known builders have and the quality of the results, I'm stating the fact that there's lots of ways to skin a cat, and by the tolerance stackup and potential to dial close and then just cut it, you end up with the same results on the tenon IFF (if and only if) you keep it in the fixture through the whole process.

I use the smurf-piss test on everything when I'm bluprinting it, before I set a headspace or move anywhere with the rest of the build, I lightly wipe on Dykem and check lockup and clearances. It's served me well so far, but then again, I've only built a few rifles as of yet.

I'm not trying to be sarcastic, I'm hoping that you guys with more build experience will discuss it and this might further the science a little more.

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

<span style="font-style: italic">It appears to me (and I have limited experience building them, just from studying the geometry and applying some modicum of engineering knowledge) that you can take a rifle with an extremely tight headspace, provide an undersize bolt body, cut the tenon ring exactly how I described above, and let it "float" at the rear bolt support at the rear bridge.</span>


Your exactly correct sir. I had this very conversation with a gent out in CA earlier this spring who is an avid BR shooter and knows all the big names in that game. I forget the smith but he described exactly what your talking about; aligning the bolt with the breech and the rear bridge.

Regarding how I tune up a receiver. Yes, I use a VMC. Instead of moving the part, I'm moving the tool. (which isn't exactly correct because with thread milling I'm doing both simultaneously) I don't claim it to be any better/worse than other more traditional methods. I like it this way because it gives me added flexibility and options that a lathe just cannot do.-Any Lathe that lacks multi axis live tooling anyway.

first. The "razor blade" lead thread has always bothered me. So, I've eliminated that by using an endmill as a thread mill for the first half rev or so. by doing this and fiddling with the offsets a bit I can go from no thread to a full thread form over the radius of the tool that I use to cut it. In this case a 1/4" end mill. Better/worse? No, but I like it and I'm sticking with it.

I use one tool to cut the face and the lug surfaces. Better? Not really but with one tool I know exactly what the distance is as there's no tool change (facing/turning tool and then a boring bar to reach down into the hole) which means I don't have any math or additional set up. Wizz the receiver face to a zero and then rapid the tool to the lug faces and wizz them at the same time. Quick, easy, and so long as stuff is square and surface finish is good, what difference does it make?

None.

Cutting threads:

With a Thread mill it affords a guy to program a variety of things. Where the thread starts/ends, taper, and any pitch/form imaginable. The better CNC milling centers are now being equipped with very precise encoders that are very, very good at determining location. What this means is the machine is verifying the exact tool location every step of the way, both in diameter and pitch. It just offers a potential for better accuracy and more flexibility. I'm not held back by any set number of gear combinations or having to swap out gear sets to do metric threading. You plug a value in your software and that's it.

Overkill for a silly bolt action receiver? Sure, but who cares? I'd be a fool to have the resource and not use it. CNC's are becoming more and more affordable so why not?

Sorry if I rustled trees and hurt peoples feelings. The entire motivation behind this thread was to show that factory, high production count, receivers do in fact have flaws that can result in a shooter scratching his head wondering why something isn't working the way it should.

-Nothing more.


All the best,

C

 

[wnroscoe]

Re: The blueprinting debate. . .maybe this will help.

 

[257speed]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body">Different topic, same subject:

CZ 525 action that I'm working on for a friend. (Normally don't mess with these)

Take a good look at the threads. The color change says it all guys.

The steel used for these is garbage IMO. I had to cut the barrel off and bore out the tennon for fear of wrapping the receiver up like a twizzler in the vise.

This'll be a first and last. . . </div></div>

Not to hi-jack, but how do you (accurately)indicate on the boreline in a 3-jaw chuck? That runout could just as easily be an O.D. problem as opposed to the threads not being accurate to the boreline.

 

[wnroscoe]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 257speed</div><div class="ubbcode-body"> Not to hi-jack, but how do you (accurately)indicate on the boreline in a 3-jaw chuck? </div></div>

 

[bohem]

Re: The blueprinting debate. . .maybe this will help.

257- If you cut the tenon using the method I asked about, simply truing the whole tenon up in 1 shot, then in the same fixture you can oversize the bolt raceway for a bushed bolt (or a PTG oversize bolt) this would completely negate the need to dial out on a 3 jaw chuck.

I don't know if Mr Dixon is doing that, it's just a potential work around to the problem of using a 3 jaw.

 

[treebasher]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 257speed</div><div class="ubbcode-body"> Not to hi-jack, but how do you (accurately)indicate on the boreline in a 3-jaw chuck? </div></div>

</div></div>

I dunno, but maybe one of those 4 axis CNC thingies...

 

[BlackOps Tech]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">257- If you cut the tenon using the method I asked about, simply truing the whole tenon up in 1 shot, then in the same fixture you can oversize the bolt raceway for a bushed bolt (or a PTG oversize bolt) this would completely negate the need to dial out on a 3 jaw chuck.

I don't know if Mr Dixon is doing that, it's just a potential work around to the problem of using a 3 jaw.
</div></div>

Sorry, but I have to ask....Why would you reference your rifle build on the OD of the receiver? Wouldn't it make more sense to fixture properly and avoid the hodge-podge 3 jaw work around? It really doesn't matter if a VMC or a manual machine is used, what matters most is how the process is set-up. I know I said I wouldn't respond to this post anymore, but I'm about to throw down a face palm....

 

[Hooper]

Re: The blueprinting debate. . .maybe this will help.

As long as it is a .308, it should shoot fine.hehe

 

[bohem]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Skunkworks</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">257- If you cut the tenon using the method I asked about, simply truing the whole tenon up in 1 shot, then in the same fixture you can oversize the bolt raceway for a bushed bolt (or a PTG oversize bolt) this would completely negate the need to dial out on a 3 jaw chuck.

I don't know if Mr Dixon is doing that, it's just a potential work around to the problem of using a 3 jaw.
</div></div>

Sorry, but I have to ask....Why would you reference your rifle build on the OD of the receiver? Wouldn't it make more sense to fixture properly and avoid the hodge-podge 3 jaw work around? It really doesn't matter if a VMC or a manual machine is used, what matters most is how the process is set-up. I know I said I wouldn't respond to this post anymore, but I'm about to throw down a face palm.... </div></div>

Where's the hole in the math that makes it hodge podge? If it's so blatantly obvious to "throw down a face palm" then can you please point out the point where the math/geometry of the proposal I made fails?

From my machining experience (which happens to be quite a bit more than my rifle building experience) the spider setup has always been a last resort. The structural integrity of an 8 pin spider pales in comparison to the integrity of a 3 or 4 jaw vice.

If the material was available to remove stucturally and by GD&T, then using the strongest setup that is easily attainable would make more sense would it not?

Here's the other question that I have regarding the spider method.

You are dialing the action around the bolt body support bushings (bolt raceway). If the action is U shaped (common) and you install brass bushings for the support rod, they may be very tight, but what guarantees their axis is aligned to one another? The rod right?

Let's assume the rod is the straightest thing here, since very likely it will be. Nothing is perfect, but for the sake of this discussion, the only "perfect" items are:

Lathe spindle/chuck rotation
Tailstock alignment
Indicator bar

The above 3 are the 3 common things between the setups.

You have the following 2D issue that I sketched poorly in MSPaint.

In order to deal with the localize U shape there must be some clearance either on the ID or the OD of the bushings with respect to the receiver and/or the indicator bar.

0.0001" of radial clearance on the 1/2" OD indicator bar/bushing turns into 0.002" by the end of the bar at 10" long.

This is just the clearance involved for a "tight fitting clearance fit" on the bushings in both the action and the receiver. And a double tolerance of 0.0001" on the bushing is pretty darn tight.

If you do the math regarding the realistically attainable tolerances on the bushings in the receiver and indicator rod, then I am now starting to question if dialing to zero TIR via the spider method is doing anything more than indicating a rod to zero runout even though the actual receiver may still have some hidden in the bushing tolerances.

Now you cut it, the runout goes away and it's the method of choice. Based on the idea of bushing the bolt to smooth up the action (or replacing the bolt body) I'm still not understanding how the spider is actually any difference, when the spider can be masking some runout anyway.

It seems to just be another way to skin the proverbial cat.

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

For sake of clarity.

The three jaw chuck you see in my photos is not for a lathe, isn't installed on a lathe, nor can it even be installed on a lathe.

It's a 3 jaw chuck built into a rotary indexing head that clamps to the table on a vertical machining center (CNC Mill).

Using a mandrel that is not in anyway dissimilar from what is conventionally used in a lathe when tuning up a receiver I stab the bore and then indicate up the sides in the X/Y axis. Once I'm "straight up" (meaning parallel with the spindle) I'll sweep the OD of the mandrel to establish my center.

From there it's what I described earlier.

I have a table that allows me to adjust the part in whatever direction I need to go so that the receiver will point straight up the spindle CL when I'm done.

I don't need to clamp/fixture on the rear of the receiver. The only machine work I'm doing is up in the ring area. The rest is just along for the ride. If I were rotating the part and only had point contact (spider, brass tipped bolts, etc) then it'd be different, but in this case its of no consequence. Using point contact for something like this would be a poor choice as it would certainly invite tool chatter and result in very poor surface finish. A basic fundamental in any machine operation is rigid work holding. My mill weighs close to 12,000 lbs and the fixture is a "svelt" 175lbs. The machine sits on a 10" thick slab of crete with 5/8 rebar on a 10" grid. Newton's basic law of things wanting to stay still or moving until influenced certainly applies here. What I'm saying is I think my set up is pretty sound.

The proof whether if this does indeed work is when you lap the lugs. The ONLY reason I lap the lugs these days is because it serves as an inspection process to qualify that all lug surfaces have optimum surface contact. If something was off or out of alignment it would become immediately apparent when only one bolt lug, or only a portion of one bolt lug, touched the lug face of the receiver. Thus far I've been ok as I've never had that happen.

It's said the greatest form of flattery is imitation. I didn't just conjure this idea up from thin air. It is exactly how Nesika Bay Precision machines all the receiver ring features on their actions. I know because I was once a production manager for the company. The only difference being with that application a Kurt Vise sits on it's side with V blocked vise jaws. (I personally thought a mill with a horizontal spindle would have been better/easier.) Since all the cylinder blanks on Nesika's are OD ground concentric to the bore prior to any features being added it was an easy and repeatable set up. For me its a bit more work because I'm building guns off a variety of actions.

If my set up was bad/poor it would immediately show up with poor surface finish and the inability to hold to a number. IF I had issues like that then it'd be pretty foolish of me to keep trucking along hoping for a different result. (the ol insanity definition. . .)

Hopefully that cleared the skies on this matter.

All the best,

-C

 

[subgunr]

Re: The blueprinting debate. . .maybe this will help.

C Dixon

There is alot of talk about "fixing" a action from you and others above and on previous post. Time spent,machinery, fixtures needed,tooling required etc etc..

As you were the production manager for Nesika , how long, in actual machine time, does it take to make an " already true" action and bolt assembly from raw material. Im sure that info would fall under the production managers job knowledge.

That info would let others compare time required to fix an action or just build a new one.

Regards,
sub

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

A great of that depends on the complexity of the action.

A Remington style push feed is far simpler to produce than a control round feed, three position safety type action. Far less parts in a Remmy.

Regardless, here's what your looking at:

Starting with nothing more than a stick of material and programming already proofed and ready:


You'll drill the bore at around 4" per minute. I don't know the set up time as we bought our blanks from an outside vendor in Kent, WA.

Honing the bore takes probably about 5-10 minutes per part.

Cylindrical grinding the OD off of centers is probably about 3 minutes per part chip to chip.

EDM-ing the raceways is what kicks your but. a 1/16 per minute is about as fast as you can push that wire through the material. Especially when it's 7-10 inches long. Chip evacuation and flushing becomes a real biche sometimes. Figure about 15-20 or so minutes per receiver for that op.

Now you have a blank ready to turn into a receiver.

Now, bear in mind that Nesika actions were(are?) made with programming that is a bit different than conventional generic FANUC style language. It's all based on variable macros that allows ONE master program to be edited via use of variables to add/change/delete features in a particular action for a particular application or desire by the customer. Because of this a great deal of care has to be taken during manufacturing by someone who's "johnny on the spot" with use of a CNC control. Stick the wrong variable in and your just as likely to friction weld a CAT50 tool holder into your mill table as you are to make a good part. It's not a bad way to program but it does someone able to wade out into the deep end of the gene pool to operate.

1st op, adding all the features to the receiver ring. About 30-45 minutes per action. The way we cut the helical ramps for the bolt is a bit different. In the interest of keeping proprietary things proprietary I'm not going to elaborate. Its an innovative and novel solution that still allows for everything to be done in one operation.

2nd op, adding the guard and scope base screw holes. About 5-8 minutes per action.

Now your off to the heat treat oven. 15-5ph is an air quench stainless. Cook it and then bring it out of the oven and stick a fan on it basically. Pretty nice stuff to work with.

Now its post heat treat operations that include the ejection port, the tang, magazine mortises, etc.

Depending on the configuration this gets broken down into a couple different set ups and takes about two hours of run time to complete.

Now the action is basically all machined and ready for fitting.

Bolts:

Bolts from Nesika begin as a chunk of bar stock. They are machined from one piece of pre heat treated 4140. No welded/soldered handles.

you turn it, grind the OD then deep hole drill the ass end for the fire control. These also came as blanks from the same vendor in WA.

Now you profile the lug face, bolt face, and the cocking cam features, profile the handle, thread mill the handle for the knob (different op/set up) and then add your extractor, ejector. (depending on the style depends on the addition of another op)

A Nesika bolt is basically a 4/5 operation depending on the extractor configuration.

In comparison a control feed action is a bit more work. Shrouds have more parts, extractors are more difficult to make, triggers are integrated usually, the bolts are more complex, etc. (which is why most stick with push feed style actions)

Hope this helped.

C

 

[subgunr]

Re: The blueprinting debate. . .maybe this will help.

C

Good info, intresting reading. Lets call it 8-12 hrs for the "full monte" work over. Then add the donor used receiver/bolt assembly, price TBD.

How long does it take a top tier "custom action maker" to manufacture a receiver/bolt assembly from raw materials. Raw materials price TBD.

Then we have a good baseline comparison to get a "true" action both ways...in hours invested.

thanks,
sub

 

[300sniper]

Re: The blueprinting debate. . .maybe this will help.

i think that is going to be a tough comparison. you are trying to compare working on a single part to something made in quantity on a full assembly line and quality control all the way though.

i think what you really need to compare is the purchase price for a rem700 and the cost of a full truing job to the price of an aftermarket action that is ready to go out of the box. be sure to include all comparable features such as recoil lug, trigger, extractor, finish (parkerized, polished ext.), bolt fluting, side bolt release and scope rail ect.

 

[subgunr]

Re: The blueprinting debate. . .maybe this will help.

I dont believe so...
Looking for hours, time spent only.
Not cost in dollars.
Certainly the features need to be similar, I guess I figured that went without saying.

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i think that is going to be a tough comparison. you are trying to compare working on a single part to something made in quantity on a full assembly line and quality control all the way though.

i think what you really need to compare is the purchase price for a rem700 and the cost of a full truing job to the price of an aftermarket action that is ready to go out of the box. be sure to include all comparable features such as recoil lug, trigger, extractor, finish (parkerized, polished ext.), bolt fluting, side bolt release and scope rail ect. </div></div>


300 is spot on IMO.

I charge $800.00 for a fully blueprinted Remington 700 action. That's doing every possible thing I can to it to make it feel and function on par with a more "marquee" custom action. I make all my own parts (except the springs, screw that!)

Lipstick on a pig for sure.

Dollars and cents is ultimately what matters but the ascetics and function are also very important in this game.

Assuming that I'm not crazy for charging this and I don't think I am as the parts list alone comes close to $400 bucks it can quickly come to a point of diminishing returns from the chair of the customer.

Lets call a Remington a camaro with a plain jane SB engine. I'll toot my horn for a moment and assume what I'm doing is great and wonderful. So now we have a camaro with a big block.

I say if your willing to go that far, skip it all and head straight for the "corvette" (custom action) for about the same money (total investment between the original purchase of the stock Remington rifle/action and the added parts/labor)and get exactly what your after the first time.

I've said this to numerous folks who've called wanting all this work done. Most are/were unaware that a custom action is within their grasp. For some, they have a pet affection for a Remington and that's what they want.

To each his own. We exist in a service industry so I'm only hurting myself if I don't offer the options.

Point is comparing the differences is an apple/orange sort of thing because there are features inherent to custom actions that a Remington just doesn't have and isn't realistic to try and install. Primary extraction being the top of the list IMO. For instance, a Defiance action has a ton of PE. You can't modify that into a Remington. Not very easily anyway as you'd have to redesign the bolt as well.

Hope this helped.

C

 

[Jkob]

Re: The blueprinting debate. . .maybe this will help.

I still don't buy the procedure for levelling the receiver. Come on, the top hole is off .005"

I'll raise the bullshit flag on that one.

 

[300sniper]

Re: The blueprinting debate. . .maybe this will help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gundoktr</div><div class="ubbcode-body">I still don't buy the procedure for levelling the receiver. Come on, the top hole is off .005"

I'll raise the bullshit flag on that one. </div></div>

i probably wouldn't use the method he is using to level it but i do understand it and agree that it is one way to do it. now my questions to you are: did you read his original post? did he say that the hole was only .005" off? does this look like only .005"?

 

[TXHunter]

Re: The blueprinting debate. . .maybe this will help.

Big +1 on the PE feature. IMHO, a custom push feed action with a well designed strong PE feature and an M16 style extractor in the bolt is just as good as any controlled feed claw. The religious argument is then reduced to the whole controlled feed piece and whether or not you need to be able to cycle your rifle while hanging upside down. Add to that the fact that most CF 's have been modified to allow for tossing a round on top of the mag and sending it into battery so now they are half push feed anyway and the original Mauser interference fit between the claw and the bolt is gone so that the claw can just as easily pop off the rim of a sticky as any other extractor. A camaro will always be a camaro and a corvette will always have a higher resale value. And to extend the analogy, it is pretty common knowledge that a high end vette will outrun most of the german toys. I vote custom push feed all day long.

 

[LRI]

Re: The blueprinting debate. . .maybe this will help.

One thing to consider regarding a PF vs CRF is that with a non rotating extractor the ejection port side raceway is blocked when the bolt is in battery.

A nice added safety feature in the unfortunate event that a case "sneezes". Also nice is that if the guy designing the bolt is on his game he'll install the gas checks in the bolt to align with the extractor when in battery. this way there's no "old faithful" geysers of gas pressure being shot anywhere close to the shooter, optics, stocks, etc. It'll vent out the bolt, hit the inside of the extractor and disperse.

Also figure in the typically larger shrouds (3 pos safety) behind the rear bridge and it makes for a receiver that's pretty safe if something lets go.

Most (not saying all) pushfeed actions don't pay quite as much attention to this aspect.

All the best,

C

 

[CS223]

Re: The blueprinting debate. . .maybe this will help.

Dredging up this topic from a while back.

If I understand correctly the process is summarized as follows:

Level the action in the vise using a parallel in the bolt way as a reference plane such that X & Y at zero insures that the Z is true vertical.

Using the action mandrel, locate the true center of the action (bolt raceway) by indicating off of either side of the mandrel & splitting the difference. Correct the mounting holes to #8.

Question #1. If the bolt raceway is canted in respect to the OD of the receiver, how do you correct your setup for it? Swivel base on the vise? Or don't bother because the scope base is normally fitted to the radius of the receiver?

Question #2 What about the action screws? What if they are off axis in relation to the receiver bore line? Do you not worry with them and allow the action bedding to correct for the OD variance?

From what I can wrap my head around, once the action is trued to the bolt raceway, the front of the receiver face and the bolt lug face becomes your reference point, the lug face is especially important now when it comes to the bedding because it will be perpendicular to the bore line & the stock center-line. If the receiver OD is a little canted, the bedding will correct for it providing you seat the recoil lug to the pocket face in the stock.

It's logical that the scope rail mounting screws should be corrected based on the bolt raceway. Though the result may be that the radius on the underside of the rail may not conform precisely to the top of the receiver which could be corrected with bedding the rail. If instead enough clearance is left in the rail screw holes to allow the rail to move to conform to the receiver OD, then nothing has been gained by truing the holes since the rail follows the OD of the receiver which is/may be off axis to the bolt raceway. So is it worth all the effort?

I guess the Holland rail system would be the optimum means of correcting for the bore axis/scope axis issue. In lieu of that, it seems that correcting the screws would also require bedding a one piece rail, or bedding individual rings/ring mounts using a mandrel in the rings to keep them aligned.

Comments? Please, I'm not trying to start an argument, just trying to wrap my head around the issue.