Barrel Flute Finish

[Edd]

Ya' can't have a discussion with a closed mind.

I have a choice and I've chosen what I want.

I'm not really wanting to have a discussion about rifling anyway. I'm looking for information about barrel flutes.

 

[beakus33]

a cheap die grinder and a few cartridge rolls and those flute groves will look sweet as hell,better than a ball nose endmill or a wheel cutter.

 

[Edd]

My Rock Creek cut rifled barrel came from them with really nice shiny grooves.

Do they cut U shaped or V shaped grooves?

 

[gunwalker]

They are U shaped. I am working out of town should be home Wednesday evening and I will try and get a pic for you. The smith polished the barrel a bit but it is pretty close to how it arrived.

 

[Bart B]

Do they cut U shaped or V shaped grooves?

V shaped flutes weaken the barrel at the bottom of the flute where both flats come together at a sharp point. I don't know of any barrel "fluter" who would put in V shaped flutes.

 

[Edd]

V shaped flutes weaken the barrel at the bottom of the flute where both flats come together at a sharp point.

You have any data to support that? I can't think of any reason that would be true. In fact it seems a V fluted barrel would be stronger if the flute root diameter and barrel diameter is the same because the V shaped flutes would have more metal at the base of the flute. I have seen some V shaped flutes but I like the looks of U shaped better.

 

[Bart B]

Edd asked me about my comment that V shaped flutes are weak at their bottom:

You have any data to support that? I can't think of any reason that would be true. In fact it seems a V fluted barrel would be stronger if the flute root diameter and barrel diameter is the same because the V shaped flutes would have more metal at the base of the flute.

There's lots of materials with a slit in them but holes are put at each end so they don't tear further into the rest of the material.

The internet's full of data about such stuff. Read the part in the link below about the British Comet airplane with square window cutouts in the body and why they failed catastrophically but were fixed by making window cutouts with rounded corners that were much stronger.

Metal fatigue in engineering - Ralph Ivan Stephens, Henry Otten Fuchs - Google Books

 

[Edd]

Edd asked me about my comment that V shaped flutes are weak at their bottom:
There's lots of materials with a slit in them but holes are put at each end so they don't tear further into the rest of the material.

The internet's full of data about such stuff. Read the part in the link below about the British Comet airplane with square window cutouts in the body and why they failed catastrophically but were fixed by making window cutouts with rounded corners that were much stronger.

Metal fatigue in engineering - Ralph Ivan Stephens, Henry Otten Fuchs - Google Books

I've repaired many pieces of cracked metal and have drilled holes at the ends of cracks but we are not talking about materials with slits in them or square windows. We are talking about a V shaped groove in a round bar. What might make it easier for you to understand is to look at it in reverse. Consider a small round bar having pieces added to it instead of a large round bar having pieces removed.

 

[Bart B]

....but we are not talking about materials with slits in them or square windows. We are talking about a V shaped groove in a round bar.

Well, I'm referring to a V shaped cutout in metal that fractured at the root of the V. That's what square cutouts in metal have; a 90 degree V at each of the four corners. That's the best I can do. Go find a mechanical engineer that agrees with your point then have him give you his reasoning so you can post it for all to see. Then I'll concede my point and admit I'm wrong. The ball's in your court.

 

[bigngreen]

Most of the barrels I've gotten have had tooling marks in the flutes, not an issue since I sand blast or polish the barrel after chambering. If I ordered a prefit finished barrel I would expect it to be finished though. Next barrel may be a Hart so maybe I won't need to polish them

 

[Edd]

Well, I'm referring to a V shaped cutout in metal that fractured at the root of the V. That's what square cutouts in metal have; a 90 degree V at each of the four corners. That's the best I can do. Go find a mechanical engineer that agrees with your point then have him give you his reasoning so you can post it for all to see. Then I'll concede my point and admit I'm wrong. The ball's in your court.

A V shaped flute wouldn't be a 90° cutout. It also would have a small radius at the bottom and at both ends. Why is the ball in my court ? You are the one who made the claim about weakness. I asked for your data. I think I've explained sufficiently to show you why you are wrong.

 

[beakus33]

Well I'm gonna throw my 2cents worth in, personally I wouldn't want a v cut barrel for 2 reasons,first off I wouldn't want a sharp interior corner because it builds up heat and it creates a stress point.the flutes would have to about half as wide in the "v" as the"u" to get the same depth.also its a proven fact that with a root fillet in the bottom that it would have more strength.

 

[Edd]

If I ordered a prefit finished barrel I would expect it to be finished though.

How would they finish it other than while cutting the groove?

 

[Bart B]

A V shaped flute wouldn't be a 90° cutout. It also would have a small radius at the bottom and at both ends. Why is the ball in my court ? You are the one who made the claim about weakness. I asked for your data. I think I've explained sufficiently to show you why you are wrong.

Now that you've changed the shape of the V into a U with its upper arms spread apart to form an angle between them instead of being parallel, that's different. And now having a radius at the bottom, that will be stronger than a V shaped flute. I guess it depends on what type font one uses for letters to describe a shape. And how much detail's provided to make ones case.

But if that radius is too small, it'll weaken the metal too much at that point.