billet how can you tell?

[Dave C]

so I'm building an AR and was looking at parts on line and found a buffer tube that listed it was made of billet. then I started thinking I'd never seen one listed as billet before. then I started asking my self what is too stop someone from just saying something is made of billet or how can you check or verify it is what they say it is. or do we just take it at face value and have faith. I guess you could say I have trust issues. anyway if anybody has two cents to throw in I'd love to hear it.

 

[rhodesbe]

I could be speaking out my bottom here, but:

In manufacturing, 'billet' is a raw material form. 'Bar stock', 'strap', 'billet', etc... Billet means it is machined (from a single piece) rather than forged, cast, or molded.

Generally, forging and casting include break lines or sprue marks. You can 'see' the transition lines between the halves of a die. Forging leaves hammer marks. Unless the part is 'machined, all over' which then removes these clues.

There may be a better answer to give, but unless it is a very coarse buffer tube, you might not be able to tell if it is indeed 'billet' or not without cutting it, or getting an NDI person to check it for you.

EDIT: When it comes to complex, low volume, narrow tolerance pieces like an AR buffer tube, it is often cheaper to machine from billet than invest in progressive forging equipment and casting operations on a piece that ultimately needs to be machined anyway. The billet claim is prolly legit.

 

[aviator41]

Well, kinda.

You can have a drawn billet, a forged billet or a cast billet. "billet" just means 'from one piece'

For example, a forged lower is a billet lower that gets its initial shape by forging hammers. a cast billet lower is formed by melting the metal into a mold. both are machined to finish. Then you have drawn billets. that's where an extruded block of metal is machined to make the finished product. The initial block is extruded through a former, but it just comes out as a somewhat basic shape like a block.

So really, as long as the piece isn't made from parts that are joined together in some fashion (welded, soldered, glued, riveted, screwed, etc), it can be considered a billet piece.

Dead giveaway is a joint. Been a long time since I've seen a non-billet buffer tube.

 

[rhodesbe]

^^^ Cool, thanks!

 

[HiredHand]

This reminds me of a discussion that I read about aircraft grade aluminum.

 

[zodiacflyer]

What was the general idea of that discussion?

 

[stick4]

Billets start out as billets. Something that begins as a casting or forging is not what I think of as billet. I machined some items that had to be machined in a certain way according to the direction of the grain. The idea was to maximize the strength of the part. The lab tested the metal & gave me the grain direction of the raw stock sample I took there. They can't read grain direction of castings and I don't think that forgings are uniform in that regard either. Point being, when advertising a product being billet, the implication is that there's a pretty certain absence of voids or weak areas in the item. Billet = Strong as you can get for the material it's made from.

 

[aviator41]

I have to disagree on that. Billet isn't as strong as you can get. the advantage of forging it to mash the molecules together, creating a MUCH stronger base metal by creating longer crystaline metal formations. Nascar engine components are forged, then machined. Of course, they are also steel and we are only talking about a buffer tube here.

However a good example would be jet engine vanes (something a know a little about) - they are forged and machined exclusively due to the tremendous pressures and g's needed to keep them from coming apart. A basic extruded billet that has been fluxed to determine grain direction would never stand up in the compressor of a jet engine. they're not even used on the cold side. I cant imagine any environment more harsh than one found in a turbojet - especially one that is afterburning. Maybe the Apollo Engines.

A quick google search for "forged billet" brings up everything from AR uppers and lowers to racing engine components to Extreme duty tools and other critical (and expensive) parts and items.

truth be told though, the buffer tube would never really be subject to the forces that would cause any of these to fail. chances are better that it wou'd rip from the threads of the upper before failure. I'd be perfectly happy with a buffer tube in any of the configurations mentioned.

I do agree with Rhodesbe - billet it the most cost effective way to make this part and most likely a genuine claim. I'd be comfy with that.

 

[HiredHand]

What was the general idea of that discussion?

That is mostly a marketing gimmick.

 

[stick4]

Billet isn't as strong as you can get. the advantage of forging it to mash the molecules together, creating a MUCH stronger base metal by creating longer crystaline metal formations.

Your post makes a lot of sense. I didn't work with forgings and actually had I thought about it I would have reached the same opinion. My head was stuck on the billet castings term which was new to me. I did work with some castings but none were used in critical strength areas of aircraft to my knowledge. My bad, I only got it half right. Thanks.