Blueprinting custom actions...why?

[riflewoman]

Not sure what your company makes but .028 and .030 is pretty liberal tolerances.
But as has been stated the trick to make good consistent parts is in tooling setup and sequence of operations. Inspections has to be made, but inspecting quality in is a bad idea.
I have 35 years in aircraft engine and gas turbine design, our tolerances are tighter and the FAA has accepted FEM analysis as long as I have been in the business. There is of course also actual engine tests.

Worked as a structures engineer at your biggest customer. Our cert office didn’t accept FEM on the structure. They wanted to see the calcs. Perfectly fine with using it to get loads tho.


The .028 and .030 reflected the size of the parts. True position on a tooling hole not used as a datum or coordinated fastening hole in a part measuring 10 feet x7 feet isn’t that loose. And like I said, tighter can be indicated but it had to be justified.

 

[tomswede]

Worked as a structures engineer at your biggest customer. Our cert office didn’t accept FEM on the structure. They wanted to see the calcs. Perfectly fine with using it to get loads tho.


The .028 and .030 reflected the size of the parts. True position on a tooling hole not used as a datum or coordinated fastening hole in a part measuring 10 feet x7 feet isn’t that loose. And like I said, tighter can be indicated but it had to be justified.

Get it, size matters in tolerancing. Have worked some engine structures but mostly rotating parts during my career. At this point I end up reviewing a lot of drawings and advice on what can be made

 

[geo.ulrich]

Well, the Navy uses them, so...

https://www.navsea.navy.mil/Home/Wa...na/What-We-Do/Measurement-Science-Department/

that is my old employer until N.O.S.L. closed down

 

[geo.ulrich]

Yup... been there with the engineers in my design team. My normal markups were to loosen positionals to .028 and surfaces to .030. If they wanted tighter they had to justify it.

As for CMMs, never worked with any but they’re now so prevalent it’s hard to justify bespoke tooling. Finding a good operator on the other hand...more unicorns. And as for CMMs now being acceptable to the government. So far as I know, the FAA refuses to accept Finite Element Modeling of aircraft structure as “Stress Analysis”. Perfectly fine to use for developing internal loads however.

this thread seems to have become derailed, so I will ask a simple question. Being you don't think the modern materials warp much during machining or heat treating I have to ask how many " custom " actions have you actually checked. there seems to be two types of people commenting here . those that have and do check and those that haven't but think gee they cost more they must be perfect.....

 

[sdean]

Which parts need to be .0001 true on an action to make a difference on the target? Or .001 for that matter?

 

[Alex Wheeler]

The last thing I will say on this subject is that, theres too much assuming and not enough experience. Its very obvious whos measured them and who has not.

 

[riflewoman]

this thread seems to have become derailed, so I will ask a simple question. Being you don't think the modern materials warp much during machining or heat treating I have to ask how many " custom " actions have you actually checked. there seems to be two types of people commenting here . those that have and do check and those that haven't but think gee they cost more they must be perfect.....

Which parts need to be .0001 true on an action to make a difference on the target? Or .001 for that matter?

And that is the crux of the matter. What has to be true? How true does it need to be? The consensus amongst the fitters would be “dead on” I suppose. As it “just has to be to be accurate”. The idea that your sending a perfect bullet down a perfect bore that is perfectly concentric....just has to be “more accurate”. But is it? Where’s the data to back this up? Sure, a “trued” action properly and meticulously fir will shoot better, but is that from the truing or is it from the better fit? I will offer this, then I will retire from this thread, a bolt has to operate easily and that requires a clearance to the bolt body and the receiver. Maybe not much but it’s not zero. The lugs on the bolt when a cartridge is in the chamber, likewise. Does this affect the accuracy potential? Again how much is too much clearance?

No one here or on any other forum has EVER answered that question. Probably because there are way too many other variables in play. And here we are 20 years later, with all of the technology and knowledge on fitting this stuff up, we still do not know how much clearance or out of square is too much.

 

[johnfred1965]

After reading through this thread, here is my take away. The shooting analogy would be: Aim small, miss small. By setting tolerances tightly, production strives to make the best part possible, but if it isn't, it will only be off a small amount. If you design a part with tolerances to match your worn out machinery, you are going to get that much wider range of quality. Now, I was just a car builder, and the mantra was Zero defects in building our product. Everyone strove for that but with 4000 workers, someone always missed, but most did not. If our standards allowed for one defect a day, that is what we would have had.

A custom action will be much better than a production one. Will it be perfect? Maybe not, but again, the difference from perfection will be a small one. It is up to you and your GS to decide if it is a problem.

 

[tomswede]

And that is the crux of the matter. What has to be true? How true does it need to be? The consensus amongst the fitters would be “dead on” I suppose. As it “just has to be to be accurate”. The idea that your sending a perfect bullet down a perfect bore that is perfectly concentric....just has to be “more accurate”. But is it? Where’s the data to back this up? Sure, a “trued” action properly and meticulously fir will shoot better, but is that from the truing or is it from the better fit? I will offer this, then I will retire from this thread, a bolt has to operate easily and that requires a clearance to the bolt body and the receiver. Maybe not much but it’s not zero. The lugs on the bolt when a cartridge is in the chamber, likewise. Does this affect the accuracy potential? Again how much is too much clearance?

No one here or on any other forum has EVER answered that question. Probably because there are way too many other variables in play. And here we are 20 years later, with all of the technology and knowledge on fitting this stuff up, we still do not know how much clearance or out of square is too much.

Agree completely, I tried to state the same earlier, who knows what is sufficient and what is varies with the discipline. I know what I expect with my experience, others may differ.

 

[geo.ulrich]

Which parts need to be .0001 true on an action to make a difference on the target? Or .001 for that matter?

all of them other wise you start stacking error

 

[tomswede]

Many

this thread seems to have become derailed, so I will ask a simple question. Being you don't think the modern materials warp much during machining or heat treating I have to ask how many " custom " actions have you actually checked. there seems to be two types of people commenting here . those that have and do check and those that haven't but think gee they cost more they must be perfect.....

Many materials move when machined from internal stress. I work with some that has capabilities that makes it hard if not impossible to heat treat them stress “free”. The solution is to remove material slowly and have a good strategy to get the desired result. None of the action materials are in this class but the same approach can be used.

 

[geo.ulrich]

And that is the crux of the matter. What has to be true? How true does it need to be? The consensus amongst the fitters would be “dead on” I suppose. As it “just has to be to be accurate”. The idea that your sending a perfect bullet down a perfect bore that is perfectly concentric....just has to be “more accurate”. But is it? Where’s the data to back this up? Sure, a “trued” action properly and meticulously fir will shoot better, but is that from the truing or is it from the better fit? I will offer this, then I will retire from this thread, a bolt has to operate easily and that requires a clearance to the bolt body and the receiver. Maybe not much but it’s not zero. The lugs on the bolt when a cartridge is in the chamber, likewise. Does this affect the accuracy potential? Again how much is too much clearance?

No one here or on any other forum has EVER answered that question. Probably because there are way too many other variables in play. And here we are 20 years later, with all of the technology and knowledge on fitting this stuff up, we still do not know how much clearance or out of square is too much.

the answer is pretty simple as we are talking accuracy. just look at the bench rest records long and short range that would be the undisputed pillar of accuracy. if anyone here thinks that an off the shelf action is winning on a national level they are very mistaken... there is a lot more involved than just having a receiver body straight and square, but that one I will leave alone as there are few that have gone that deep. this has been done for way longer than 20 yrs. hell Brackney was writing articles in rifle magazine in the 70's and Dale Hutchinson in the 80's in P.S.... always seem odd people become involved in things and all the sudden they just figure out what was being done years before they started...and yes how square or tir has been tested many times over I still have firing pins and shrouds with crooked threads and crooked holes that were purposely bent to see what would happened to ignition....

 

[msinc]

Here's an idea....and I realize this one is way out there in left field somewhere but here goes....why not put the GD thing together and try it first????? Fixing a problem before you even know you have one seems....."different"{???} to me. Call me mucho muy loco, but arguing about a high probability non-existent problem seems even stranger.

 

[geo.ulrich]

been there already done, took a brand new off the shelf well known receiver assem. whole rifle. test fire dmn bolt is real tight, try it again bolts real tight with mediocre loads. recheck barrel all is fine. unglue action start checking hmmm receiver face is out a lot like more than 005. so now have to do all the tricks straighten out and set barrel back for headspace and reglue action. learned my lesson check before otherwise lose money....

 

[tomswede]

been there already done, took a brand new off the shelf well known receiver assem. whole rifle. test fire dmn bolt is real tight, try it again bolts real tight with mediocre loads. recheck barrel all is fine. unglue action start checking hmmm receiver face is out a lot like more than 005. so now have to do all the tricks straighten out and set barrel back for headspace and reglue action. learned my lesson check before otherwise lose money....

.005 is machining malpractice, how did the manage to do that badly? With proper tooling and sequence of operations .001 should be easy. Have 4 Remington factory actions, none of them close to that bad.

 

[geo.ulrich]

I agree it was one that fell through the cracks but it shouldn't have.. I am curious what are you checking the remingtons too.

 

[davidjoe]

been there already done, took a brand new off the shelf well known receiver assem. whole rifle. test fire dmn bolt is real tight, try it again bolts real tight with mediocre loads. recheck barrel all is fine. unglue action start checking hmmm receiver face is out a lot like more than 005. so now have to do all the tricks straighten out and set barrel back for headspace and reglue action. learned my lesson check before otherwise lose money....

Glued? Can I ask how you unglue an action? And was the brand new off the shelf well known receiver assembly one that is typically glued? I have an old 40-x I’d like to unglue but someone did a damn good job of it a long time ago.

 

[geo.ulrich]

put barrel in barrel vice then lay a clothes iron on top of action scope bases and just wait about 10 minutes grab fore end and pull down once you feel it move it will pop right off. some throw a wedge between barrel and fore arm or just leave it long enough it will just fall off...yes it was a state of the art br action

 

[PWS]

I’m a 1MOA=A-OK kind of shooter so can’t add anything other than thanks to all that have contributed to this conversation!

Threads like this one make AS a great place!

 

[Evan]

.005 is machining malpractice, how did the manage to do that badly? With proper tooling and sequence of operations .001 should be easy. Have 4 Remington factory actions, none of them close to that bad.

Haha. I worked QA and ran a CMM for a while and most all of the machinists I've worked with could only hold an honest, verified 0.005" tolerance across setups. In the same setup, much tighter tolerances can be held but the minute you unclamp it, it's not trivial to get it indicated back in down to the tenths. If you ask for tighter than 0.005", most machinists will need to make extras until they get enough that came out within spec unless all operations are made in the same setup.