Reaming a tube

[refinery mike]

Just a question, you are talking about a paint ball gun aren't you. Because if you are talking about a 16 mm air gun, like a quackenbush or the like you should reconsider the material for the barrel. a plain old piece of steel pipe is likely to get you killed. consider just how powerful this thing is going to be, If you are talking an actual weapon i would suggest you get some serious input into making the barrel.

[Nebse]

The honed tubing would be the way to go, but a 25mm bore gun is probably way overkill...

I am from europe, and as such, i lack the vast amount of tooling suppliers that i can see are in the states. I am currently getting most of my tooling from the german ebay site.

The airgun i am building is a quackenbush-style gun, and should be as powerfull, is my calculations are correct. i would use the mild steel tubing either on its own at reduced pressures or as a sleeve, OR use hydraulic tubing as a final barrel. Hydraulic tubing is probably way harder than mild steel thou, and as such i choose mild steel as a start. Or maybe i am wrong, and it is possible to ream a hydraulic tube?

edit; picture added

[Richard_W]

Have you considered starting with solid stock and gun drilling it to size?


Richard W.

[Nebse]

I have actually not considered that, no, as i think it would be pretty darn difficult. If that is not the case, then i miqht, but i have a normal lathe without a high pressure coolant pump, and no suitable drill either, and as this is a hobby project, it would probably get pretty expensive...

[Richard_W]

I have actually not considered that, no, as i think it would be pretty darn difficult. is that is not the case, then i miqht, but i have a normal lathe without a high pressure coolant pump, and no suitable drill either, and as this is a hobby project, it would probably get pretty expensive...

There was a guy whose name I don't remember did an article on it. He used a China built lathe as I recall and was doing this in his garage. ( I think his lathe was something like 13 X 40 "Taking" brand?) He just added a high volume coolant pump and explained how he did it pretty well. Could be someone else can fill in the blanks in my memory?

Richard W.

[Harold_V]

There was a guy whose name I don't remember did an article on it. He used a China built lathe as I recall and was doing this in his garage. ( I think his lathe was something like 13 X 40 "Taking" brand?) He just added a high volume coolant pump and explained how he did it pretty well. Could be someone else can fill in the blanks in my memory?

Richard W.

Here you go!

http://www.chaski.org/homemachinist/vie ... 10&t=90457

Harold

[Nebse]

as fascinating as deep drilling is, it is a bit much to get into, for a couple of barrels...

So, being the novice i am, would i dull a hss reamer in a piece of hydraulic tubing (ST 37.4) or should i rather get a carbide reamer? And what are your thoughts of adjustable reamers?

I am open to suggestions, but it has to be feasible to do, being a novice like me... thanks (:

[mechanicalmagic]

Here in the US, there is nothing magic about hydraulic tubing. The alloy is often just mild steel. The internal & external finish and dimensions are controlled better than cheaper tubing. Some is Stainless Steel, which can be more difficult to machine.
For your machining operations, you need to know what alloy is available. If you are using scrap yard metal, it's almost impossible for us to tell you all the pitfalls.

But I can suggest one thing to reject immediately. Adjustable reamers with loose cutting leaves are not suitable for this task. Tip adjustable reamers will dull before you complete the bore.

Do you have a link to properties of your "ST 37.4" hydraulic tubing? A search here looks like it's a dimensional spec, not an alloy.

Dave J.

[ken572]

Do you have a link to properties of your "ST 37.4" hydraulic tubing? A search here looks like it's a dimensional spec, not an alloy.
Dave J.

I found this for you guy's to look at.

Parker - Steel Tube St. 37.4 .pdf

(68.7 KiB) Downloaded 303 times

Full Catalog 4300 is here. (Very Large)
http://mdmetric.com/4300/4300cat06.pdf

Ken.

[mechanicalmagic]

I'm sure nebse has been all over the Quackenbush site, but I found it very informative.
http://www.quackenbushairguns.com/steel_for_airguns.htm

BTW, the majority of the steels listed on Q'bush site would be compatable with a HSS reamer, although proper speed/feed and cutting lube is needed.

Please remind me, what is the expected caliber??

Dave J.

[hammermill]

i was just going to post the quackenbush site for he excellent tutorial/discussion on steels,battels and processes

http://www.quackenbushairguns.com/Airgun_barrels.htm

one can learn a wealth of info in these pages.

[Nebse]

The desired caliber is 16/18mm, allthou i could go somewhat lower. (i have a 22mm hole in the block, so 22x2 or 22x3 tubing fits nicely)

I am building the rifle and on a trial and error basis, not saying that i am building a deathtrap, but hammer weight, spring tension, sidelever system pull ratio and so on are hard to get right when modelling.

Deep drilling is off the table for now, and as such, the choice is pretty much between what the local tractor etc mechanic can supply (unspecified mild steel alloy) and the 37.4 hydraulic tubing

searching for 37.4 i come up with the grade 1.0255. st37.4 seems to be a german name for that specific composition. I am a bit confused with the grades, as i am generally getting my material in germany, using their own numbers and grade systems compared to danish retailers. On top of that i do a lot of my searching on american sites, which doesnt really help on the transperancy.

I think i will go for the 37.4 tubing, does anybody have experience with the alloy, and if, could you help me with feed and rpm's`?

Thanks in advance, and thanks for all the help so far!