[Adam Baker]

Im not really sure where to post this, Im hoping this is ok. I generally spend my time in the Bench Top forum, but didnt think this was a topic that would fit in there.

Ok, Im planning on machining an aluminum barrel for a 1/35 scale model for a friend of mine, for a German WW2 railway gun (Dora/Gustav). The real thing had rifling in the barrel, and the barrel is large enough that the rifling would be visible on the scale part. The interior diameter of the barrel will be about 22.85mm/.899 inches in diameter.

Im wanting to add rifling to the completed barrel, but Im not sure exactly how to pull it off, and looking for suggestions. Im assuming that what ever would be used would be something similar in design as a standard threading tap. I dont have a problem making something, if it comes down to it, Im just not sure what to use for the cutter, how to design it, and how to go about using it.

To actually cut the rifling, Im assuming I could just the same lathe that Im going to use to cut the interior and exterior, and just turn the lathe at a very low RPM and let the rifling cutter draw its way into the barrel.

Anyone have any tips or suggestions? The barrel will be turned using aluminum bar stock, so the metal wont be too hard, but Im sure I will still need something w/ some strength to it, so that it will cut the rifling w/o deforming.

[ger21]

I thought I read some info on rifling here last week? Try the google search

[jalessi]

http://www.firearmsid.com/Feature%20...anufacture.htm

[universalfab]

Adam thats a bad mover, your going to completely waste your time on making a barrel out of aluminum. You want a mild steel or stainless steel, now the question is will your machines machine either of those. Now for the rifeling, well first you'll need a rifling lathe, then you'll need tooling. All which are not cheap. You may be able to find a adaptation for you lathe to do rifeling, but that also is expensive. In my opinion unless you plan on manufacturing barrels then you should just bore yourself a piece of mild steel stock and have someone with a rifling machine. Or what you can do from the sound of it you have a 22mm gun that needs just a barrel, well your not going to want to shoot right out of aluminum because it will warp your barrel. So what you can do is a oversized bore on your aluminum barrel and buy a 22mm rifled sleeve for around $15.00 and press that baby in there. You'll also need a reemer.

Im not really sure where to post this, Im hoping this is ok. I generally spend my time in the Bench Top forum, but didnt think this was a topic that would fit in there.

Ok, Im planning on machining an aluminum barrel for a 1/35 scale model for a friend of mine, for a German WW2 railway gun (Dora/Gustav). The real thing had rifling in the barrel, and the barrel is large enough that the rifling would be visible on the scale part. The interior diameter of the barrel will be about 22.85mm/.899 inches in diameter.

Im wanting to add rifling to the completed barrel, but Im not sure exactly how to pull it off, and looking for suggestions. Im assuming that what ever would be used would be something similar in design as a standard threading tap. I dont have a problem making something, if it comes down to it, Im just not sure what to use for the cutter, how to design it, and how to go about using it.

To actually cut the rifling, Im assuming I could just the same lathe that Im going to use to cut the interior and exterior, and just turn the lathe at a very low RPM and let the rifling cutter draw its way into the barrel.

Anyone have any tips or suggestions? The barrel will be turned using aluminum bar stock, so the metal wont be too hard, but Im sure I will still need something w/ some strength to it, so that it will cut the rifling w/o deforming.

[bearwen]

Universalfab, It is a scale model aluminum is fine.

Adam as for rifling you will need to make a tool. If you look online you will find how rifling was done in the old days not to difficult to do especially in aluminum. What you do is make a tool that you pull through the barrel that slowly rotates as you pull it through the barrel. most barrels have a small rotation number example an M16 will have 6 to 9 revolutions per foot a 9mm will not even have 1 full rotation due to short barrel. I dont recall where it is (someones 9x20 lathe page) but I read that someone made a key cutting tool for cutting keyways in axles. What I would do is build something similar but would set it up to pull rather than push the cutting tool and then get a friend to help and design the the tool shaft to where one person pulls the cutter through the barrel very slow and the other slowly rotates the shaft that the cutter is connected to. It sounds complicated but if you look and find the key cutting tool and see how it works you will understand what I am saying and it would be pretty easy to do in aluminum especially since your only trying to get the look of rifiling and not actually rifiling a steel barrel for accurate shooting.

Good luck

[Adam Baker]

Sorry for the misunderstanding universal, Bear is correct, this is going to be for a 1/35 scale plastic model, so it wont be shooting anything, its purely for looks and to put a more accurate barrel on the model, so thankfully I wont have to worry about any of the issues involved w/ machining a real barrel.

Thanks for the info Bear. I hadnt planned on drilling the barrel all the way through, since its probably going to be between 18 & 24" long. Im not sure how I'd go about drilling & reaming it that long, as I dont think I have access to the tooling for it. I'd planned on only drilling about 6-8" into the barrel, long enough to give the impression of a through drilled barrel, and long enough to try getting it rifled, again to give the impression of a through barrel.

Thanks for the suggestion on looking at how it was done in the past, I'll definitely look into that, and I figured that it would have a very low rotation number on it. If I were to rifle the entire length, I wouldnt imagine it would have many rotations to it.

[Arquibaldo]

Adam:

Would you or your friend be willing to post pics of the finished model? It would be awesome! The Dora/Gustav was so huge that even a 1:35 scale model will be quite big...

Nelson

[bearwen]

Adam,
since you dont plan to drill the whole thing out then again look at the key cutter and do waht I posted earlier except use the key cutter to push into the barrel and rotate the barrel or the cutter just a little as you feed the cutter into the barrel should be simple enough and you dont have to cut the rifiling deep its just for looks. Here is the link to the keyway cutter http://homepage3.nifty.com/amigos/sl...ing_tool-e.htmnow Im not saying to build this but something similar and perhaps more simplified as it will probablly only be used this once should work for you and like I said if you have a lathe mount the barrel in the lathe and by HAND rotate the chuck as you feed the cutter into the barrel and you should come out with a reasonable rifiling look for your barrel. Also you might want to make a cutter with more than one cutting tip so you only have to feed it one time and be done as most rifiling in a barrel is more than one thread like a multi start acme screw.

You can do it and post pics we all want to see how it turns out.

[bearwen]

I just realized and reread your first post you do have a lathe so here is what I would do to be simple and quick. After you bore the barrel out to the specs you want make a 3 or 4 point cutting tool like a shaft just slightlly smaller than the barrels bore and then drill through this shaft at 90 degrees so you have 2 holes that go all the way through and are 90 out so you now have 4 holes 90 degrees out all the way around take some HSS stock such as the $3 set of HSS cutters HF sells there is a 1/4 inch round bar in the pack and cut it the round bar down so I have 2 bits that are just barrelly longer than the barrels inner diameter sharpen them like a lathe tool and incert them into the holes of the shaft now incert the shaft into the barrel and as soon as the cutters start into the barrel start feed the cutter and rotating the chuck since the barrel is locked in the chuck of the lathe. I am thinking you mount the cutting shaft in your tail stock drill and just turn the cranck on the tail stock to feed the cutter in. not sure if it will work you might have to adjust stuff and make a different tool. I dont think you will need to lock the cutting bits in to the shaft as they are bigger than the barrels inner diameter and the shaft is just smaller than the ID of the barrel so thay cant fall out once they are inside the barrel and rotaing the shaft wont effect them either now this wont be good for real rifiling do to wobble and depthe will be different along the length of the barrel but for a model will be fine.

[BillTodd]

If I were going to do this:

1) Use a screw cutting lathe with external gears
2) disconnect the spindle drive so the spindle is free to turn.

3) Arrange the screw cutting gears to give you the required pitch - i.e. the lead screw will have to turn many times for each spindle rotation - 6 revs per foot = 1/2 TPI so with a typical 8TPI lead-screw you'll need 16:1 between the spindle and the lead-screw.

4) Fix up a hand-wheel on the lead-screw. The spindle will be turned by the gears

5) fix-up a modified boring bar to cut the rifle profile that you want.

6) cut the splines one at a time turning the piece in the chuck to index the starts.

Bill

[M250cnc]

Use an reamer with the end ground flat as a broach.

You could probably hold the barrel in the chuck and use the saddle to push it through.

Just remember it must be able to rotate

Phil

[Adam Baker]

Thanks for hte help guys. I like bills suggestion the best, but unfortunately I dont have access to that sort of lathe.

I guess I'll focus on getting the external turning done, and hten experiment w/ different ways of trying to rifle the barrel w/ scrap stock. I had thought about trying to make something that would do all the rifling at once, but I think that might be too much work to try doing all the grooving at once.

[will gilmore]

what is the ID of the scale barrel? what is the twist rate?

if the ID is small and the twist rate is long you might not even be able to see the twist and you could just broach it straight.

[Adam Baker]

Inside diameter is going to be .900". Not sure what the twist rate is at this point. Im hoping to get some info from my friend, as well as find more pictures, and go from there.

[will gilmore]

.9" is big, you will need the twist to make it look right

[Adam Baker]

Yea, I figured it was large enough that I would have to put in at least some kind of twist. Im hoping to get some prints & info on the barrel this week. If so, I might possibly be able to get started on it on Thursday evening.

[will gilmore]

ok it's friday, lets see your progress...

[Adam Baker]

Unfortunately I still havent gotten the prints or info I need to get started. Was hoping to have it by now, but I never got it.

[Adam Baker]

Just thought I'd bump this, since some of you seem interested in the project.

I finally got the spec's for the barrel today. The completed barrel will be 26.277" long. Largest diameter is 2 inches at the very base, and it necks its way down to 1.181" at the muzzle. B/c of the size, its most likely going to be done as 2 pieces.

Ive attached a Solidworks drawing that I just made, to give you guys an idea of what the barrel will look like.

Right now the plan is to do this thing on a manual lathe. However, I might possibly be able to do this on a Mazak lathe, but Im not to 100% thats going to be possible. I'd much rather do it on the Mazak, as it would be quicker, and be a lot easier to do it, than it would be on a manual.

Now that I have spec's, Im hoping to try getting started on it Thursday evening when I teach again. Next week is spring break for hte college, so I wont be able to get anything done next week. So hopefully I'll be able to get some progress made this week.

Now a question for you guys, what do you suppose would be a fair price to charge for something like this? The guy who provided the plans is interested in a turned barrel, but I havent got the slightest idea what it would cost. If I do this manually, Im assuming bare minimum would be 3-4 hours of machine time, probably longer.

[will gilmore]

If you are using a CNC lathe you could probably do the rifling easily with that. Did you get the specs on the # of starts and twist of the rifling?

As for cost I think it's really what he is willing to pay and you are comfortable with. I dont think you can charge him what a machine shop would charge for 3-4 hours.