New Method of Rifling

[Hubb]

I was thinking about PVC rifling and a thought occurred to me. Everyone knows that PVC becomes flexible when heated, right? Well, I was thinking that maybe a length of pipe can be heated enough to become pliable, then the entire pipe twisted to form rifling.

Whatcha think?

Here's what I think.....
If this can be done, it would form even rifling throughout the entire length of the pipe. It would also allow the projectile (since most of them are some sort of food) to flow smoothly down the bore rather than have to be cut with grooves, which would probably translate into a better spin. And don't forget about the simplicity of the process. It would be much faster than our current standard method and produce better results.

Now, obviously, the biggest flaw is heating the entire pipe up at a consistent level.

I'm sure there should be plenty of other positive and negative thoughts on this, but, right now, I've been awake for 34 hours and I'm kinda tired. If there are some intelligent (<<keyword), I'll give it a try. If anyone else wants to tackle it before I do, though, please feel free.

[twizi]

wait u want to heat a entire peice of pvc u could accidentaly crip the ends even a little, accuracy would be the last thing your worring about.shrapnel how would u twist it if its soft and mauble.with out flanting or crimp the ends?

good idea tho

[john bunsenburner]

I think it is easyer to inster a piece of pipe with a positive form of the rifeling on it into the heated and expanded pipe, once said pipe cools the rifeling will be engraved and the mold should be able to come out with a bit of turnining.

[twizi]

yeah i think that a better idea

[Hubb]

Molding the pipe around another positive grooved one would probably easier initially, but how do you plan on removing the positive grooved pipe? How about even making the positive groove pipe?

As far as the integrity goes, well I'm sure it looses some integrity, but I wouldn't think it would be enough to create shrapnel. Besides, if that is of a concern, it can simply be sleeved to add durability.

As far as how would I go about doing this without crimping the ends? Well, I have thought about several different methods to do this (in other words, crimping the ends is not an issue for this project). I'm not going to get into a discussion about it right now. I just want to know your guys thoughts on twist barrel rifling.

[jrrdw]

Unless you have a "pipe twisting jig" to keep it uniformly straight, you would come out with uneven twist amount from end to end, or bent pipe. That's what I imagine happening.

[far_cry]

Unless you have a "pipe twisting jig" to keep it uniformly straight, you would come out with uneven twist amount from end to end, or bent pipe. That's what I imagine happening.

thank you .you said what i was think.

and did you mean ,first we rifle the barrel with straight lines, then we heat and twist ?

[Moonbogg]

I have an idea for a simple fixture that corqscrews the pipe as you push it along, and blades on the fixture can be adjusted to stick out more and more. You can gently tap the pipe through the fixture taking deeper and deeper cuts each time.

[Hubb]

I'm was just wanting to discuss if this method of rifling (if done right and all that good stuff) would work better than cut groove rifling. That's all. I think it will but I'm only one person with only one thought. I was looking for the positives and negatives of this.

I figured that once we either shot the idea down, or figured it would work out a lot better*, we could go into more detail on how it can be done.

*by "work a lot better" I'm talking about perfect rifling to spin the projectile with no ill effects.

Edited by jrrdw.

[psycix]

Risky. Besides being twisted uneven (when a certain area is twisted, it may be weaker, becoming the only part that twists). I would worry about the ammo jamming into some sort of wrinkle or bump. Catastrophic fail results.
To make sure this pipe stays as it should be, a rod or pipe should be inserted (ID of pipe = OD of rod) and the pipe should be sleeved in a metal pipe. The pipe should be sleeved on both sides during the whole process to avoid wrinkles.

It is a bad idea, but I give it a tiny tiny tiny tiny tiny chance to work.

[jimmy101]

I would think that it is possible to heat the tube and twist it but actually getting it to work well enough in your garage is pretty unlikely. Plus, it is unclear exactly how much of a ridge you would form.

The pipe could be fed through a fairly short oven at a slow speed. Don't heat the ends of the pipe, use the unheated ends to attach to the twisting apparatus. After the pipe is twisted just cut off the untwisted ends.

Control the power to the heater and the feed rate through the oven so that the only place where the pipe is hot enough to be twisted is right when it exists the oven.

Like I said, certainly could be done but probably not in your typical home shop. There are a number of industrial processes that do this exact type of thing. The machine that forms the spiral fluorescent light bulbs probably works something like this. A straight piece of glass tubing is fed through a short (very hot) oven and at the exit point it is bent around a mandrel.

In addition, heating PVC (or ABS) to just the right temperature is pretty tricky. I would think there are a number of easier ways to rifle a plastic barrel. Heck there are at least a couple threads discussing ways to do it that nobody has ever actually tried.

Personally, I would just go with a thin piece of sheet PVC (perhaps 1/8" thick by 1/2" wide) twisted and glued into the barrel. (hey, it's has at least of chance of working and it would be a heck of a lot easier than heating a long piece of pipe to just the right temperature. )

[Technician1002]

When heated, PVC pipe resembles a garden hose. Twisting it while soft doesn't generate anything resembling rifling.

You could make nice bends and twists however. Is this for a spudgun or an art project.

[iknowmy3tables]

heres my suggestion when you manage to evenly heat the pipe insert a rod a few mms smaller than the pipe's ID then twist the pipe with the rod in it. and to finish cut off the parts were you atached your twisting implements. also assuming you can muzzle load the projectile I doubt it would result in a violently shattering barrel

[kozak6]

It might also work to use a heated nail or something similar in a more traditional process to rifle a barrel. Perhaps a soldering iron could be disassembled and rebuilt for this purpose.

[Hubb]

Okay, to clear up the "how", here is what I was thinking.

Insert a metal rod into the pipe. The rod (or pipe, whatever) should be nearly equal to the inside diameter as the PVC. It should also leave a little bit of PVC overhang on both sides. Wires connect to the rod and a current is passed through it.

Now, this rod serves two purposes at the moment. (1) It heats the pipe at a constant rate, which is a rate that can also be controlled fairly easily if need be, and (2) it will allow the PVC to maintain it's internal diameter during the entire process.

With the ends left to not heat, a hole is drilled through them and a thinner rod is placed through it (both ends). One end of the PVC is held still, while the other end is twisted. This position is held, the current is removed, and the pipe is allowed to cool.

I'm sure there are some flaws with that, but it's just off the top of my head.
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As far as how it will work, I would think that it would be very similar to a hex rifled barrel and instead of the projectile actually having grooves cut into it, it would take the form of the barrel and be forced to spin, but in a smooth flow, just like it would in a smooth bore.