how are barrels made/how to make barrels

[Drcemento]

just seeing all these brass builds over on the sheridan forum, and having a few ideas stewing around in my head, I put it to the experts, cause i cant wrap my head around it

how are barrels typically made?
solid chunk of aluminum or SS drilled, bored and polished to a final diameter or do you start with a pipe and bore it out?

what about brass - I see that some off the shelf seamless sizes are close - how is palmer making his .... 1/8" wall brass tubing and boring out the inside to final diameter?

how do you get from a bored finish to a high hone and get a barrel that is exactly .686 and not .689

what would a lathe set up that could do that look like - my limited knowledge tells me boring something 14" to that kind of tolerance is not easy...

what size lathe would be required to make say a 14" barrel?

its allot but this has been a burning bunch of questions I've had for a long time....

[DocsMachine]

how are barrels typically made? solid chunk of aluminum or SS drilled, bored and polished to a final diameter or do you start with a pipe and bore it out?

-Both.There's several different ways: Older Tippmann barrels, for example, were simple extruded tubes that they machined for threads and then honed. Cheap and simple.

A lot of manufacturers today drill and then ream thickwall tubing. Less of the material winds up as chips, compared to drilling from solid; it's faster so a machine can produce more per hour, and the machine requirements aren't as stringent.

Drilling from solid arguably gives the best and straightest bore, but really, it's the kind of thing that only precision metrology can even discern. It also requires expensive tooling (a gun drill, natch) a lot of horsepower at the spindle, high pressure coolant (typically 1,000 psi or better, in order to flush the chips out of the deep hole) and more of the material winds up as chips. (The flip side to that argument is solid is far more common, and is thus cheaper thanks to economies of scale. Precision-drawn tubing is typically more expensive since it's more of a specialty material, but those costs can be offset by a higher part-per-hour rate, and so on.)

what about brass - I see that some off the shelf seamless sizes are close - how is palmer making his .... 1/8" wall brass tubing and boring out the inside to final diameter?

-One of the big benefits to brass is that it "draws" well- that is, you can force it through a die fairly easily, and "swage" it to a fairly precise size. I believe most of a typical Palmer's brass is more or less off-the-shelf sizes, and that he has barrel material custom-drawn. (Too expensive for you and I, but Palmer's uses miles of it a year.)

That's why J&J and old BOA barrels were "assembled"- that is, you had a tube, and the threads and collars and whatnot were added and soldered on. The tubing was probably close to or actually off-the-shelf, so all they had to do was cut it to length, add the threaded collars, run a hone down the bore, plate it and sell it.

As paint has gotten smaller, anyone making a brass barrel today has to either machine out smaller diameter, or locate some custom-extruded.

how do you get from a bored finish to a high hone and get a barrel that is exactly .686 and not .689

-High quality CNC equipment, sharp tooling and the fact you're making thousands at a time. You and I try to make a barrel on an old home-shop lathe, and yeah, the bore ain't gonna be great, and even with a good reamer, the finished bore might be off a couple thou.

But a modern CNC turning center with an accuracy measured in millionths? No sweat.

A properly used reamer can do that, plus there's things like roller burnishing, the classic flex-honing, and probably others.

what would a lathe set up that could do that look like - my limited knowledge tells me boring something 14" to that kind of tolerance is not easy...

-You'd be surprised. A quality gun drill can help produce a 28" steel rifle barrel accurately enough to place two bullets through one ragged hole at a hundred yards. 14" of aluminum is child's play.

It's worth noting, however, that a big part of the reason most manufacturers are providing their markers with 2-piece barrels, is because it's WAY easier to make two 7" pieces than it is one 14"- especially when one of them never actually comes in contact with the ball.

Now, I don't know everything about making barrels- most of the manufacturers consider that sort of thing to be a trade secret, and other than using terms like "gun drill" and "roller burnish" as advertising blurbs, they try to keep that sort of thing under wraps.

I suspect that most manufacturers, especially of 2-piece barrels, start with a thickwall tube, probably precision drawn to spec (meaning the bore is more concentric with the OD than typical extrusions, and just give it a quick ream, hone or polish, and anodize. Modern CNC machinery with quality tooling can produce a bore probably pretty close to ready-to-anno right out of the box.

You and I with our manual stuff? Maybe not so much.

what size lathe would be required to make say a 14" barrel?

-Well, to start with you'd need at least 14" of carriage travel.

It's not really a "size" thing. You need specialty tooling, a good machine to turn it- accuracy, power, travel, etc. and it all needs to be set up well. It's by no means impossible, but really kind of tricky for us home-shop guys.

It's late and I may not have answered all of your questions, but then, again, most consider their particular system a bit of a trade secret, and I'm having to guess at a bit.

Doc.

[XEMON]

As always DocsMachine you're super thorough.

For the PPS tubing, it's off the shelf ... And they do sell it by the foot, but it's $$$. and no, you can't buy it elsewhere as the manufacturer only sell bulk to pro/super large quantities

[flyweightnate]

To add to what Doc said...

Roller burnishing is a great finish operation, as it can very accurately cold size a bit that's close, until it becomes exact. Many honing machines also have in-process gauging.

When you're running thousands of a thing, the machine will typically also have a probe that measures each part in process, and correct the tooling offsets based on, say, the average size of the last few parts. The first few might be bad, but the machine gets into spec quickly. Volume helps!

The old OTP barrels were clever, in that the bore sizer was very short. The short collar is not only cheaper to have several of, but also much easier to machine accurately. The shorter it is, the more rigid; the more rigid, the more accurately it can be cut. So then, a .690 back bore (that might be as big a .695) isn't a big deal, since the little collar is so precise.

[Siress]

lol - you posted while I was juggling kids to knock out the post below. I'm amused that we both lead with the roller burnishing comments. Really highlights the importance of it.

[Siress]

Roller burnishing cannot be stressed enough here... That's the 'one trick' or whatever that would throw most people off when tackling the kind of surface quality we're after for a paintball barrel at depth/diameter ratios greater than 5-10. A 14" barrel for instance has a ratio of 20.6. This is the only reason that 2 piece barrels are even attractive from a mfg perspective - as adding the mating threads on both parts is more complicated, but a lot more shops are capable of producing those features.

Here's my own MFG SWAG for high quality 2-piece barrels produced in quantities of 1 to 1000 barrels. It would be more sophisticated if contracting a quantity of ~10,000 or more, but I don't think a savvy businessman would take that bet on a high-end paintball barrel. Steps here are individual operations:

1. Order 6-10ft lengths of 1-1/8" x 5/8" aluminum tubing... nothing special.
2. Gang cut to rough length +1/8" to +1/4" of final length. Typically done by stacking them on a band saw and spot welding one end of the tubes together to maintain relative axial location during cutting. Banding and rollers support the bunching and limit any sag along the length.
3. Get the new guy to deburr the rough parts at the sander.
4. Using a custom expanding drum to grab the ID, the rough part is turned to have smooth OD and 1 perpendicular end face - creating a datum reference frame for the next operation.
5. The part is then fixed in a collet chuck using the datum reference frame just created. The male threads should be cut first: lip, shoulder, and threads. If making a barrel front, cut down the OD to a smaller rough OD and add whatever through features are desired (e.g. porting). The ID can then be drilled out using typical means (e.g. carbide spade drill) and finished by reaming and roller burnishing (with the same tool if you can afford it.)
6. The part is then fixed to a custom fixture using the male thread shoulder and end face for location, with threads providing fixation for clockwise cutting forces. The entire exterior surface can then be turned as needed; milling may require additional fixation such as an end face clamp. The last step would be the addition of the female threads if making a barrel back.
7. Thread caps onto each end and tumble polish the exterior features.
8. Remove the caps, clean/degrease, and send for annodizing.
9. Inspect final part
10. Apply markings/labels and package for sale.

Drilling from solid arguably gives the best and straightest bore, but really, it's the kind of thing that only precision metrology can even discern.

Why do you think starting from billet can produce a straighter bore than starting from tubing? From my perspective, they can each have the same end result if done using best practices. The billet will require a lot of extra time, tools, and material so it's far more efficient to start from tubing. I suspect you're going to say that any inherit curvature from the tubing will end up affecting the end part, but at the scale you mention I suspect that condition is analogous to stress relaxation experienced when starting from billet - regardless of annealing.

[Drcemento]

As always M.Carter delivers on the overnight express.Thank you all so much for taking the time to walk through the process. Good coffee reading instead of flipping aimlessly through Instagram or getting depressed reading the news.

I've been keeping an eye out for a decent lathe on the craigslist etc. for a bit now and want to include the ability to, while maybe not make barrels from scratch, at least tinker with the abundance of existing ones to retrofit and update my growing pile of old markers that are frustratingly being left behind by the aftermarket barrel world

[jeramiej]

Great info here, as always.

[alpha_q_up]

Why do you think starting from billet can produce a straighter bore than starting from tubing?

From my experience the qc of raw tubing(not just aluminum) that comes out of a lot of mills put out is pretty laughable(bowing, pitting, od & id not concentric), for whatever reason it seems like mills just pretend like they're doing a good job with qc

[Seajay]

Just like my local lumber yard... you want straight? HA

[Siress]

and just like lumber, it doesn't really matter if you know how to handle it.

[alpha_q_up]

Siress I was curious about why billet vs tubing would make a straighter bore, the only thing I can think that might affect something in anyway is of raw tubing vs billet drilled, grain structure coming into play possibly.

I suppose when manufacturing, it comes down to what are the capabilities of the company/machinist that manufactures said barrel(s) . The company I work for specializes in seamless precision tubing and we use both raw tubing and billetes to for jobs. At times it's nice to just get the tubing in(saves my ass from having to gundrill it) chop it on the saw and go, but there are times where you can see the little things in the finish product that normal people would turn a blind eye to, it can drive us up the wall.