Thoughts? I have three feet of 6061 5/8" round. Got it for free.
Was thinking about 7075 but the shipping is ridiculous.
Was thinking about 7075 but the shipping is ridiculous.
Gunsmithing Pillar Material...6061 or 7075?
- Thread starter JimT
- Start date
Re: Pillar Material...6061 or 7075?
You are not going to crush either one of them. Both would be fine. Free beats paying also
You are not going to crush either one of them. Both would be fine. Free beats paying also
Re: Pillar Material...6061 or 7075?
<----- Thinks that by the time the 6061 oxidizes, there won't be much steel left of the rifle action and barrel.
6061 will work just fine, and it beats paying.
<----- Thinks that by the time the 6061 oxidizes, there won't be much steel left of the rifle action and barrel.
6061 will work just fine, and it beats paying.
Re: Pillar Material...6061 or 7075?
Not that it really matters, and I've used a lot of aluminum pillars, but the oxidation process for aluminum starts immediately, which can/does propose a problem when bedding doesn't want to stick to it.
I do understand that "using what you have" and "free" go a long way.
Not that it really matters, and I've used a lot of aluminum pillars, but the oxidation process for aluminum starts immediately, which can/does propose a problem when bedding doesn't want to stick to it.
I do understand that "using what you have" and "free" go a long way.
Re: Pillar Material...6061 or 7075?
I like to machine my own from 300 series stainless.
No oxidation, better surface adhesion to the resin, and the surface finish stays nice forever.
I like to machine my own from 300 series stainless.
No oxidation, better surface adhesion to the resin, and the surface finish stays nice forever.
Re: Pillar Material...6061 or 7075?
Chad,
What are the ridges on the top of those pillars for? To allow for a controlled bedding depth over the pillar (and still leave pillar->action contact)?
Chad,
What are the ridges on the top of those pillars for? To allow for a controlled bedding depth over the pillar (and still leave pillar->action contact)?
Re: Pillar Material...6061 or 7075?
These are my thoughts regarding pillar bedding a rifle.
Epoxy shrinks when it cures. ALL epoxies shrink. The better ones keep it down to 1 or 2 percent. When this percentage is translated into a linear dimension it's going to be directly tied to the volume of material being used. A 1"x1" cube of the stuff is going to shrink less in total distance than a 10"X10" brick.
Going down this train of thought a little further, it would seem to me that since bedding a stock is nothing more than making a precision casting of the receiver, we want to try and manage for this shrinkage as best we can.
What I've done in the effort to respond to this is to write all my own inlets as 3D surface models using CAD/CAM software. I then machine the inlet accordingly and just enlarge everything by .05" so that I have an even film of epoxy between the action and the stock. The ribs in the pillars are part of this as they suspend the action above the floor of the inlet by that same amount. When cured the epoxy captivates the pillar so that it can't ever fall out/shake loose while still delivering the 1:1 contact between the pillar and the receiver.
I'm not actually compensating for any shrinkage. All I'm doing is attempting to ensure the shrinkage is uniform from one end of the bedding job to the other. Does it work? Honestly I don't know. It'd take some pretty sophisticated metrology equipment to be able to measure it and even then I think it'd be a "best guess" answer.
Initially it seemed like a bunch more work, but after getting used to the programming and seeing the finished results I'm going to stick with it. Rifles are shooting well, the finish work speaks for itself, and clients are happy.
Thanks.
C
These are my thoughts regarding pillar bedding a rifle.
Epoxy shrinks when it cures. ALL epoxies shrink. The better ones keep it down to 1 or 2 percent. When this percentage is translated into a linear dimension it's going to be directly tied to the volume of material being used. A 1"x1" cube of the stuff is going to shrink less in total distance than a 10"X10" brick.
Going down this train of thought a little further, it would seem to me that since bedding a stock is nothing more than making a precision casting of the receiver, we want to try and manage for this shrinkage as best we can.
What I've done in the effort to respond to this is to write all my own inlets as 3D surface models using CAD/CAM software. I then machine the inlet accordingly and just enlarge everything by .05" so that I have an even film of epoxy between the action and the stock. The ribs in the pillars are part of this as they suspend the action above the floor of the inlet by that same amount. When cured the epoxy captivates the pillar so that it can't ever fall out/shake loose while still delivering the 1:1 contact between the pillar and the receiver.
I'm not actually compensating for any shrinkage. All I'm doing is attempting to ensure the shrinkage is uniform from one end of the bedding job to the other. Does it work? Honestly I don't know. It'd take some pretty sophisticated metrology equipment to be able to measure it and even then I think it'd be a "best guess" answer.
Initially it seemed like a bunch more work, but after getting used to the programming and seeing the finished results I'm going to stick with it. Rifles are shooting well, the finish work speaks for itself, and clients are happy.
Thanks.
C
Re: Pillar Material...6061 or 7075?
Chad,
That is THE nicest looking pillar bedding / skim bedding job I have ever seen - It looks absolutley perfect!!!!
Chad,
That is THE nicest looking pillar bedding / skim bedding job I have ever seen - It looks absolutley perfect!!!!
Re: Pillar Material...6061 or 7075?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Buckey</div><div class="ubbcode-body">Chad,
That is THE nicest looking pillar bedding / skim bedding job I have ever seen - It looks absolutley perfect!!!! </div></div>
It looks so nice that it looks like it's injection molded.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Buckey</div><div class="ubbcode-body">Chad,
That is THE nicest looking pillar bedding / skim bedding job I have ever seen - It looks absolutley perfect!!!! </div></div>
It looks so nice that it looks like it's injection molded.
Re: Pillar Material...6061 or 7075?
Thanks gents.
All about the prep work.
Here's a Stiller I did recently
Thanks gents.
All about the prep work.
Here's a Stiller I did recently
Re: Pillar Material...6061 or 7075?
I use a mold release agent available commercially through MSC Industrial supply.
I use a mold release agent available commercially through MSC Industrial supply.
Re: Pillar Material...6061 or 7075?
Chad , you cheat with the NC programs !!
but if ya aint cheating you aint tryin to win !!
Awsome bedding indeed and the idea seems sound enough.
Now what are some of you guy's thoughts on pillar material being "too hard" , I talked with a builder that like aluminum over steels because that he feels their is a harmonic effect? who know , I've used 6061 , 7075 and 7068 aluminum , brass , 316L , 416 , 17-4PH and I personaly could not tell that one made a more accurate bedding pillar than the next.
I think that like anything else in screwing a rifle togther , its good to eliminate as many variables that "could" cause a problem later down the road.
I persoanly use 316L cause I have alot of it and it keep its finish nicely when the pillars are exposed to the public
Chad , you cheat with the NC programs !!
but if ya aint cheating you aint tryin to win !!
Awsome bedding indeed and the idea seems sound enough.
Now what are some of you guy's thoughts on pillar material being "too hard" , I talked with a builder that like aluminum over steels because that he feels their is a harmonic effect? who know , I've used 6061 , 7075 and 7068 aluminum , brass , 316L , 416 , 17-4PH and I personaly could not tell that one made a more accurate bedding pillar than the next.
I think that like anything else in screwing a rifle togther , its good to eliminate as many variables that "could" cause a problem later down the road.
I persoanly use 316L cause I have alot of it and it keep its finish nicely when the pillars are exposed to the public
Re: Pillar Material...6061 or 7075?
A picture from the Nesika Bay web page. They were in business long ago manufacturing rifles. Policies and proceedures were in place prior to that in the manufacturing of said rifles.
Just saying...........
A picture from the Nesika Bay web page. They were in business long ago manufacturing rifles. Policies and proceedures were in place prior to that in the manufacturing of said rifles.
Just saying...........
Re: Pillar Material...6061 or 7075?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">A picture from the Nesika Bay web page. They were in business long ago manufacturing rifles. Policies and proceedures were in place prior to that in the manufacturing of said rifles.
Just saying...........
</div></div>
HHhhhmmmm....
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">A picture from the Nesika Bay web page. They were in business long ago manufacturing rifles. Policies and proceedures were in place prior to that in the manufacturing of said rifles.
Just saying...........
HHhhhmmmm....
Re: Pillar Material...6061 or 7075?
I'll never be accused of having an original thought.
But I'll always be guilty of taking a good idea and improving it.
I'll never be accused of having an original thought.
But I'll always be guilty of taking a good idea and improving it.
Re: Pillar Material...6061 or 7075?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body">I'll never be accused of having an original thought. </div></div>
Thats most of us Chad. Our best ideas are the ones we borrowed
The wheel can only be so round.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body">I'll never be accused of having an original thought. </div></div>
Thats most of us Chad. Our best ideas are the ones we borrowed
The wheel can only be so round.
Re: Pillar Material...6061 or 7075?
Lets think this through. While we are doing that I will go launch some bullets down range.
Lets think this through. While we are doing that I will go launch some bullets down range.
Re: Pillar Material...6061 or 7075?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steelcomp</div><div class="ubbcode-body">Wht about thermal coeffecient of expansion between the mterials? </div></div>
There are some who use fiberglass pillars for all the reasons mentioned above.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steelcomp</div><div class="ubbcode-body">Wht about thermal coeffecient of expansion between the mterials? </div></div>
There are some who use fiberglass pillars for all the reasons mentioned above.
Re: Pillar Material...6061 or 7075?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steelcomp</div><div class="ubbcode-body">Wht about thermal coeffecient of expansion between the mterials? </div></div>
We have:
A steel or aluminum action.
A steel barrel made from a different alloy than the action.
A stock made of either a wood or synthetic material, sometimes a combination of both.
A polymer resin squished between them.
Screws made from yet another alloy of steel completely different from the action or the barrel.
A scope base that often doesn't match anything.
Rings.
The scope itself.
Nothing is the same, has ever been the same, and probably won't be. In practice if one goes "blackwater" with his bolt guns enough to where he's worried about thermal expansions of materials you've already got bigger problems, pressure, a scorched throat, fouled bore, etc.
If a smallblock chevy can run 100k miles with aluminum pistons I have to think our little bolt guns will be just fine.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steelcomp</div><div class="ubbcode-body">Wht about thermal coeffecient of expansion between the mterials? </div></div>
We have:
A steel or aluminum action.
A steel barrel made from a different alloy than the action.
A stock made of either a wood or synthetic material, sometimes a combination of both.
A polymer resin squished between them.
Screws made from yet another alloy of steel completely different from the action or the barrel.
A scope base that often doesn't match anything.
Rings.
The scope itself.
Nothing is the same, has ever been the same, and probably won't be. In practice if one goes "blackwater" with his bolt guns enough to where he's worried about thermal expansions of materials you've already got bigger problems, pressure, a scorched throat, fouled bore, etc.
If a smallblock chevy can run 100k miles with aluminum pistons I have to think our little bolt guns will be just fine.
Re: Pillar Material...6061 or 7075?
When I was in 8th grade shop class in 1965, we were shown a film on the nobility series of metals, and how galvanizing works.
I wanted to make the world's fastest filling bath tub.
I stepped up from 3/4" hot and 1/2" cold Copper pipes to brass ball valves with 3/4" and 1/2" cross section when open. I stepped up with galvanized steel bushings alternating with brass nipples.
Every time I turned on the water the first quart was dark rust color into the tub.
The problem was dissimilar metals. Stacking in series, the steel to brass boundary made a multi cell battery.
I replaced all the steel bushings with Copper or brass.
Then the water came out clean.
I had an octagon 25/35 barrel with rust bluing. I necked down a 30-30 case and put it in the chamber to see how it fit. The barrel sat on a shelf for years with the case in the chamber.
The hot water tank leaked and the basement flooded 1" and the air was humid. The barrel turned color from blackish blue to muddish red.
It was a dissimilar metal problem between brass and steel triggered by a week of humidity.
When my cousin pays $200k each for a Cat diesel engines in his tug boats, runs the coolant through a heat exchanger, runs the other side of the heat exchange trough salt water, the engines still get electrolysis. He pays a consultant to actively bias the engine Voltage.
When I design military equipment, the specification often has a paragraph on how dissimilar metal problems must be controlled.
When I build rifles, if steel is going to touch Aluminum, I want the Aluminum anodized, for the electrical isolation.
If I mill out a scope mount and do not have it anodized, I could electrically isolate it from the receiver at least .001" with non conductive shims, and glass bed in between. But the screws will still conduct.
Aluminum looks strong on yield strength per unit weight, but the stiffness is not so good compared to steel.
What does it all mean?
I use 3/8" steel tubing .030" wall thickness bought in 6' lengths and roughed up on the outside to grip epoxy ala Steve Wagner.
The steel is cheap, and works better for me as pillars compared to the brass, Aluminum, or stainless steel that I have tried.
When I was in 8th grade shop class in 1965, we were shown a film on the nobility series of metals, and how galvanizing works.
I wanted to make the world's fastest filling bath tub.
I stepped up from 3/4" hot and 1/2" cold Copper pipes to brass ball valves with 3/4" and 1/2" cross section when open. I stepped up with galvanized steel bushings alternating with brass nipples.
Every time I turned on the water the first quart was dark rust color into the tub.
The problem was dissimilar metals. Stacking in series, the steel to brass boundary made a multi cell battery.
I replaced all the steel bushings with Copper or brass.
Then the water came out clean.
I had an octagon 25/35 barrel with rust bluing. I necked down a 30-30 case and put it in the chamber to see how it fit. The barrel sat on a shelf for years with the case in the chamber.
The hot water tank leaked and the basement flooded 1" and the air was humid. The barrel turned color from blackish blue to muddish red.
It was a dissimilar metal problem between brass and steel triggered by a week of humidity.
When my cousin pays $200k each for a Cat diesel engines in his tug boats, runs the coolant through a heat exchanger, runs the other side of the heat exchange trough salt water, the engines still get electrolysis. He pays a consultant to actively bias the engine Voltage.
When I design military equipment, the specification often has a paragraph on how dissimilar metal problems must be controlled.
When I build rifles, if steel is going to touch Aluminum, I want the Aluminum anodized, for the electrical isolation.
If I mill out a scope mount and do not have it anodized, I could electrically isolate it from the receiver at least .001" with non conductive shims, and glass bed in between. But the screws will still conduct.
Aluminum looks strong on yield strength per unit weight, but the stiffness is not so good compared to steel.
What does it all mean?
I use 3/8" steel tubing .030" wall thickness bought in 6' lengths and roughed up on the outside to grip epoxy ala Steve Wagner.
The steel is cheap, and works better for me as pillars compared to the brass, Aluminum, or stainless steel that I have tried.
Re: Pillar Material...6061 or 7075?
<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: steelcomp</div><div class="ubbcode-body">Wht about thermal coeffecient of expansion between the mterials? </div></div>
We have:
A steel or aluminum action.
A steel barrel made from a different alloy than the action.
A stock made of either a wood or synthetic material, sometimes a combination of both.
A polymer resin squished between them.
Screws made from yet another alloy of steel completely different from the action or the barrel.
A scope base that often doesn't match anything.
Rings.
The scope itself.
Nothing is the same, has ever been the same, and probably won't be. In practice if one goes "blackwater" with his bolt guns enough to where he's worried about thermal expansions of materials you've already got bigger problems, pressure, a scorched throat, fouled bore, etc.
If a smallblock chevy can run 100k miles with aluminum pistons I have to think our little bolt guns will be just fine. </div></div>
Small block Chevys are built with therml expansion taken into consideration (on almost every moving part). If they weren't, they sure wouldn't go 100K mi.
So what you're saying is, you buy the most expensive barrel- bore honed to within tenths, you cut your chamber to as precise a dimension as possible (some within .0000X), you time your barrel, you cut the crown with the same precision, you weigh your powder to the n'th, weigh your bullets, measure your bullets to the thou, true your bolts and actions to microns...all in the effort to achieve as close to perfection as humanly possible... and then tell me the heat expansion of aluminum pillars vs. steel pillars doesn't matter? Some things in an assembly you don't have control over, but where you do, and especially something as simple as a pillar, why not? Are all those other micro tolerances really necessary?
Isn't that kinda like building that hot rod Chevy and putting the stock air cleaner on it?
Just asking.
<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: steelcomp</div><div class="ubbcode-body">Wht about thermal coeffecient of expansion between the mterials? </div></div>
We have:
A steel or aluminum action.
A steel barrel made from a different alloy than the action.
A stock made of either a wood or synthetic material, sometimes a combination of both.
A polymer resin squished between them.
Screws made from yet another alloy of steel completely different from the action or the barrel.
A scope base that often doesn't match anything.
Rings.
The scope itself.
Nothing is the same, has ever been the same, and probably won't be. In practice if one goes "blackwater" with his bolt guns enough to where he's worried about thermal expansions of materials you've already got bigger problems, pressure, a scorched throat, fouled bore, etc.
If a smallblock chevy can run 100k miles with aluminum pistons I have to think our little bolt guns will be just fine. </div></div>
Small block Chevys are built with therml expansion taken into consideration (on almost every moving part). If they weren't, they sure wouldn't go 100K mi.
So what you're saying is, you buy the most expensive barrel- bore honed to within tenths, you cut your chamber to as precise a dimension as possible (some within .0000X), you time your barrel, you cut the crown with the same precision, you weigh your powder to the n'th, weigh your bullets, measure your bullets to the thou, true your bolts and actions to microns...all in the effort to achieve as close to perfection as humanly possible... and then tell me the heat expansion of aluminum pillars vs. steel pillars doesn't matter? Some things in an assembly you don't have control over, but where you do, and especially something as simple as a pillar, why not? Are all those other micro tolerances really necessary?
Isn't that kinda like building that hot rod Chevy and putting the stock air cleaner on it?
Just asking.
Re: Pillar Material...6061 or 7075?
Because of this thread, I can finally guess why they put truck trailer panels together with double sided sticky tape:
http://trailer-bodybuilders.com/mag/trucks_deal_dissimilar_metals/
Because of this thread, I can finally guess why they put truck trailer panels together with double sided sticky tape:
http://trailer-bodybuilders.com/mag/trucks_deal_dissimilar_metals/
Re: Pillar Material...6061 or 7075?
<span style="font-style: italic">"and then tell me the heat expansion of aluminum pillars vs. steel pillars doesn't matter?" </span>
Oky doky. Short answer: NO, it does not matter.
Long winded dissertation to follow:
From the 27th edition of the Machinery's Handbook. Pretty much the most informative and painful little book to sift through when in search of absolutes pertaining to all things cool and manly.
Coefficients of Thermal Expansion (Begins on page 402)
-Table #8. Typical values of coefficient and linear thermal expansion for thermoplastics and other commonly used materials
Values are in in/in/Deg F x 10-5
Steel: .6
Aluminum: 1.2
-Table #13. typical thermal properties of various metals
Values are in uin/in-F*
6061 aluminum 13.0
7075 aluminum 13.1
303 stainless steel 9.6
To save everyone (including myself) the brain damage from having to read through a pile of engineering arithmetic click on this link and plug in the coefficient values. Be sure all your units are consistent. Metric/Celsius, Imperial/Fahrenheit.
Thermal Expansion Calculator
Now ask yourself that since you do have to worry about grains of powder, bullet concentricity, machine work, the associated metroloy, surface finish, and the marksmanship fundamentals (you forgot that one), is this REALLY something you want to stress over? Were talking 6 points to the right of the decimal point gents.
Never mind that if you think your RCBS/Lyman/Dillan manual/electronic scale is a qualified laboratory grade instrument you are only fooling yourself.
$200 bucks for a digital scale at Cabellas or a $2500 laboratory grade balance from Denver Instrument?
At some point a person should realize that your going to be far, far, far ahead in this game if you stop obsessing over things that you can't control and start focusing on things you can. Build a gun using good parts by someone who understands accurate gunmaking. Select/assemble the appropriate ammunition, and then shoot, shoot, shoot, and shoot some more.
I've been friends with Mid Tompkins, his wife Nancy, and both Sheri/Michelle since I was 19 years old. Lonnes Wigger and I used to shoot smallbore prone together once a week. Kyle Leibertrau is my young prodigy that I sponsor in Palma. David Karcher, the 2002 National SR Champion is my best friend.
These are all world class competitive marksmen with Olympic, World, National, and International marquee event wins on their resumes. They've forgotten more about tearing the X ring a new one than 99.999% of the shooting community will ever know. If you've ever seen a rifle built by Mid Tompkins you'll walk away scratching your head as to how the thing even hits the backstop (bless his heart) yet ALL of Mid's guns will deliver X counts well over 60% when in <span style="font-style: italic">capable</span> hands. I can promise you that if you begin pegging them with questions about thermal coefficients they are going to look at you like your from another planet. David might not since he's an engineer.
Save $17.39 on a K/N air filter.
<span style="font-style: italic">"and then tell me the heat expansion of aluminum pillars vs. steel pillars doesn't matter?" </span>
Oky doky. Short answer: NO, it does not matter.
Long winded dissertation to follow:
From the 27th edition of the Machinery's Handbook. Pretty much the most informative and painful little book to sift through when in search of absolutes pertaining to all things cool and manly.
Coefficients of Thermal Expansion (Begins on page 402)
-Table #8. Typical values of coefficient and linear thermal expansion for thermoplastics and other commonly used materials
Values are in in/in/Deg F x 10-5
Steel: .6
Aluminum: 1.2
-Table #13. typical thermal properties of various metals
Values are in uin/in-F*
6061 aluminum 13.0
7075 aluminum 13.1
303 stainless steel 9.6
To save everyone (including myself) the brain damage from having to read through a pile of engineering arithmetic click on this link and plug in the coefficient values. Be sure all your units are consistent. Metric/Celsius, Imperial/Fahrenheit.
Thermal Expansion Calculator
Now ask yourself that since you do have to worry about grains of powder, bullet concentricity, machine work, the associated metroloy, surface finish, and the marksmanship fundamentals (you forgot that one), is this REALLY something you want to stress over? Were talking 6 points to the right of the decimal point gents.
Never mind that if you think your RCBS/Lyman/Dillan manual/electronic scale is a qualified laboratory grade instrument you are only fooling yourself.
$200 bucks for a digital scale at Cabellas or a $2500 laboratory grade balance from Denver Instrument?
At some point a person should realize that your going to be far, far, far ahead in this game if you stop obsessing over things that you can't control and start focusing on things you can. Build a gun using good parts by someone who understands accurate gunmaking. Select/assemble the appropriate ammunition, and then shoot, shoot, shoot, and shoot some more.
I've been friends with Mid Tompkins, his wife Nancy, and both Sheri/Michelle since I was 19 years old. Lonnes Wigger and I used to shoot smallbore prone together once a week. Kyle Leibertrau is my young prodigy that I sponsor in Palma. David Karcher, the 2002 National SR Champion is my best friend.
These are all world class competitive marksmen with Olympic, World, National, and International marquee event wins on their resumes. They've forgotten more about tearing the X ring a new one than 99.999% of the shooting community will ever know. If you've ever seen a rifle built by Mid Tompkins you'll walk away scratching your head as to how the thing even hits the backstop (bless his heart) yet ALL of Mid's guns will deliver X counts well over 60% when in <span style="font-style: italic">capable</span> hands. I can promise you that if you begin pegging them with questions about thermal coefficients they are going to look at you like your from another planet. David might not since he's an engineer.
Save $17.39 on a K/N air filter.
Re: Pillar Material...6061 or 7075?
Beating this horse to the point of being unrecognizable I contacted a friend of mine who is a brilliant ME from a top ten school. He's been doing this sort of thing everyday for the last 30 or so years. I'm a high school graduate and keeping up with him is sometimes a challenge, so I'll attempt to offer his perspective as I understood it.
Lets take a two pillar arrangement.
The heat generated by a rifle is centered around just ahead of the chamber. This radiates outward towards the crown and back towards the tang. It shouldn't take a genius to visualize that the front pillar is potentially going to see more heat exposure than the pillar in the rear.
Now factor in that the front pillar is typically shorter than the one in the rear, which means there will be a difference in linear distance as things warm up. Should I be surface grinding/lapping my pillars to tolerances 6 figures to the right of the decimal so that the two end up with the same total linear distortion due to expansion from heat?
BUT we've not considered the guard screws which are made from a different material yet again, AND they too are different lengths. Never mind they are in tension and not compression like the pillars. Now factor that the receiver typically only engages the screw by 5-8 revs so until the screw normalizes in temp things are going to be all "screwed up." (pardon the pun)
Now consider than the stock is either going to act as a heat sink or a heat isolator/insulator. What's this do to our pillars and screws? Never mind the action since half the receiver sits in the stock and the other half is out in space. Is every bolt action gunmaker in the world degrading accuracy because we build rifles with the top half of the receiver sticking out of the stock? Seriously??
Now lets look at a three pillar arrangement typical of a single shot.
If thermal expansion is that critical then by the same argument we'd have to label every action manufacturer out there who produces a three screw action an idiot. The reason would be we are now faced with a teeter totter arrangement. That middle pillar isn't going to expand/elongate/contract at the same rate as the two out on the ends. We either end up with a tug in the middle a hunched up back like when you pet a cat, or a number of other scenarios. I personally don't think action manufacturers are idiots.
Enjoy your weekend.
C
Beating this horse to the point of being unrecognizable I contacted a friend of mine who is a brilliant ME from a top ten school. He's been doing this sort of thing everyday for the last 30 or so years. I'm a high school graduate and keeping up with him is sometimes a challenge, so I'll attempt to offer his perspective as I understood it.
Lets take a two pillar arrangement.
The heat generated by a rifle is centered around just ahead of the chamber. This radiates outward towards the crown and back towards the tang. It shouldn't take a genius to visualize that the front pillar is potentially going to see more heat exposure than the pillar in the rear.
Now factor in that the front pillar is typically shorter than the one in the rear, which means there will be a difference in linear distance as things warm up. Should I be surface grinding/lapping my pillars to tolerances 6 figures to the right of the decimal so that the two end up with the same total linear distortion due to expansion from heat?
BUT we've not considered the guard screws which are made from a different material yet again, AND they too are different lengths. Never mind they are in tension and not compression like the pillars. Now factor that the receiver typically only engages the screw by 5-8 revs so until the screw normalizes in temp things are going to be all "screwed up." (pardon the pun)
Now consider than the stock is either going to act as a heat sink or a heat isolator/insulator. What's this do to our pillars and screws? Never mind the action since half the receiver sits in the stock and the other half is out in space. Is every bolt action gunmaker in the world degrading accuracy because we build rifles with the top half of the receiver sticking out of the stock? Seriously??
Now lets look at a three pillar arrangement typical of a single shot.
If thermal expansion is that critical then by the same argument we'd have to label every action manufacturer out there who produces a three screw action an idiot. The reason would be we are now faced with a teeter totter arrangement. That middle pillar isn't going to expand/elongate/contract at the same rate as the two out on the ends. We either end up with a tug in the middle a hunched up back like when you pet a cat, or a number of other scenarios. I personally don't think action manufacturers are idiots.
Enjoy your weekend.
C
Re: Pillar Material...6061 or 7075?
CDixon, I work out of a Machinist's handbook quite often. You proved my point in showing that alum. expands at a higher rate than steel. It's not something to stress over...it's very simple. Almost fundamental. If trying to remove as many uncontrollable variables as possible, why use aluminum- from a theoretical stanadpoint?
I'm not talking about pillar design or layout, just material.
It's just a theory, and it's just a thread discussion on the internet...notihing to get stressed about.
CDixon, I work out of a Machinist's handbook quite often. You proved my point in showing that alum. expands at a higher rate than steel. It's not something to stress over...it's very simple. Almost fundamental. If trying to remove as many uncontrollable variables as possible, why use aluminum- from a theoretical stanadpoint?
I'm not talking about pillar design or layout, just material.
It's just a theory, and it's just a thread discussion on the internet...notihing to get stressed about.
Re: Pillar Material...6061 or 7075?
I don't stress over things .000001" on a rifle. Or anything for that matter since I don't have the six figures to the left of the decimal to buy and measure it anyway.
I don't stress over things .000001" on a rifle. Or anything for that matter since I don't have the six figures to the left of the decimal to buy and measure it anyway.
Re: Pillar Material...6061 or 7075?
You can move that decimal place ALOT and the gun shoots just fine. There comes a point of diminishing returns in the manufacturing world,decimal places cost money,and the inspection of said decimal place can and does sometimes cost more than the manufacturing.
+1 cdixon
I just wanted to kick the dead carcus....damn thing wasn't even a horse...its was a donkey !!
You can move that decimal place ALOT and the gun shoots just fine. There comes a point of diminishing returns in the manufacturing world,decimal places cost money,and the inspection of said decimal place can and does sometimes cost more than the manufacturing.
+1 cdixon
I just wanted to kick the dead carcus....damn thing wasn't even a horse...its was a donkey !!
Re: Pillar Material...6061 or 7075?
i'm just going to eliminate the stock completely and make a monolithic rifle. i just want to make sure that there isn't any differences in thermal expansion and/or electrolysis. oh if you guys only knew how far behind you are
i'm just going to eliminate the stock completely and make a monolithic rifle. i just want to make sure that there isn't any differences in thermal expansion and/or electrolysis. oh if you guys only knew how far behind you are
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