Sully2
Well-Known Member
When a metal object is heated, it goes to MMC which is Maximum Material Condition. The perimeter of the material grows larger...where as any hole within it goes SMALLER because the material around the hole GROWS.
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Bolt Diameters
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Canadian Bushman
Well-Known Member
I have researched this topic pretty thouroughly and i can tell you the condition you describe is an anomaly.
Typically the od and id will grow and shrink together.
We heat stainless sleeves of varying size and length and drop in carbide inserts with a .008-.012" interference fit pretty much on a daily basis so i can prove this is the norm.
It usually needs additional features or a stressed piece of matl to collapse a hole when heated.
Ive seen it happen before and tried like hell to define the condition, but the truth is its just not the norm.
Sully2
Well-Known Member
Thats laughable to call it an anomaly. EACH and EVERY piece of a jet engine undergoes this. EACH one.
With a piece of "thinwall" tubing as you describe BOTH walls expand because of the greater forces of the exterior FORCE the inner wall to go with it.
I dont consider the bolts from my rifles to be "tubing"
Canadian Bushman
Well-Known Member
It may be laughable to you but its pretty confusing to me after a decade of pressing in carbide sleeves, cylinder liners, bearing races, etc. etc.
Never did i state "thin wall." That is an assumption on your part.
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thexp2.html
http://www.webassign.net/question_assets/buelemphys1/chapter13/section13dash2.pdf
Temperature and thermal expansion
Never did i state "thin wall." That is an assumption on your part.
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thexp2.html
http://www.webassign.net/question_assets/buelemphys1/chapter13/section13dash2.pdf
Temperature and thermal expansion
Canadian Bushman
Well-Known Member
I tried to argue on accurate shooter that a barrels bore could possibly get smaller under certain heat conditions, but i eventually conceeded failing to provide ample evidence of a similar scenario.
I even constructed a scaled barrel and froze it then heated to 400 degrees and i could not prove the id "could" shrink when heated. Its growth was supeisingly linear, and always expanded when heated.
I even constructed a scaled barrel and froze it then heated to 400 degrees and i could not prove the id "could" shrink when heated. Its growth was supeisingly linear, and always expanded when heated.
Yes metal rings. I don't care how many years you have spent working on what, you are still wrong. I have heated hundreds of metal rings for the sole purpose of making the id larger. Get yourself a metal ring and a torch, it's real east to confirm what happens.
Sully2
Well-Known Member
Sully2
Well-Known Member
Any part of a rifle...barrel...etc..etc is a "thinwall" piece of material.
Get a piece of steel plate...say 1/2" thick. Drill a tight fitting hole in it...one that a force fit bushing might go in...and heat the plate up....real hot...and THEN try to get the bushing in it...YA cant! The hole went SMALLER
catamountsierra
Well-Known Member
If the bushing is brass or bronze, and is in the steel plate when things are heated, you won't be able to get it out because it expands more with the same change in temperature than the steel plate; brass and bronze have higher thermal expansion coefficients than steel. Stainless steel has a higher coefficient than carbon steel, so if you have a stainless bolt in a carbon steel receiver, I would expect that with enough heating and close enough tolerances, it would stick.
Canadian Bushman
Well-Known Member
A 1.25" barrel with a .243 hole going through it is thinwall? Whats thickwall?
Im guessing you didnt spend much time on those links i found for you. They actually explain that the growth of a hole in a plate, just as you describe, is related to the materials linear growth of its circumference. Basically the same idea Edd stated earlier.
Sully2
Well-Known Member
Toss some more items in the fire....If the bushings were made of monkey boogers they would slide in and out....
J E Custom
Well-Known Member
Toss some more items in the fire....If the bushings were made of monkey boogers they would slide in and out....
I was going to try and give an explanation for the problem, but after seeing this I am not sure that I can stop laughing long enough to type.
Ok after several tries I will begin.
In order to change the OD or ID of the action enough to cause the bolt to seize or tighten, the action would have to be heated hot enough that it would be very uncomfortable to touch. "BUT"with
a long cylindrical shape with large openings on one side and the bottom, the receiver could certainly move out of straight/true buy a few thousandths causing the binding. It would only have to move a few thousandths to bind if the receiver was extremely close to the same as the bolt.
With the large openings, one side of the receiver the solid side is much stronger than the side with the two large cutouts and any expansion would not be constant throughout the entire length. (Causing the action to warp toward the weaker side). This effect is the reason that most bench rest actions have a solid bottom (No magazine cutout).
Heating/cooling causes all things to expand or contract but this can be dealt with, with the proper clearance. In my opinion the problem is the shift of the action straightness over its length, not its girth.(Example; A uneven growth of .0005 per inch, would throw the action out of straight on a 7 or 8" action by .0035 to .004) there went the clearance if you started with .002 thousandths.
I hope my spelling and typing is not to bad. I am still laughing.
J E CUSTOM
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