making tapered tubing [Archive]

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rustyclockwork

02-07-2004, 12:28 PM

Wray Schelin

02-07-2004, 01:20 PM

Hi Jason,

What will be the end use of the tapered tube? How thick does the brass need to be? What temper does the brass need to be?
Can the tapered tube be made from two pieces?

You'll need to answer these questions before any worthwhile advice to help you solve the problem can be offered.:D

Wray

r.w.dewar

02-07-2004, 01:23 PM

How long will these tubes be?
Bob.

r.w.dewar

02-07-2004, 01:31 PM

Oh, yah, reread the post, 10 inches long. Maybe a tapered mandrel could be used. Either press the mandrel into the tubing or use it to form the brass around. Depending on how many you need to make and what gauge a wooden mandrel would work. Also, it all depends on how many you need to make.
Bob.

rustyclockwork

02-07-2004, 04:20 PM

Hello all,

The tubes will be for a victorian rocket-propelled aeroplane toy in 54mm scale (you had to ask :-) It's for the fuselage, I've tried looking for this particular shape with metal funnels, kitchen utensils, etc. with no luck.

Whatever gauge of brass and alloy will be best suited for hand rolling this stuff. I'm assuming the brass they use on musical instruments would be typical.

I thought about casting the tube in two halves, but that's a lot of pewter.

I'll be making about 50 to 100 per year. The custom metal spinning place I talked to wanted almost $500 to make the metal spinning tooling, then $90 for each brass part made... not good, the toys will be (hopefully) under $400 each.

Once my cnc machine comes in (later this month) I could make my own tooling, but I figured it wouldn't be much of a deal to hand roll the fuselage, that part being the only fabricated piece, the rest are cast parts being soldered on.

anyone have any suggestions?

Jason

bcarlson

02-07-2004, 05:32 PM

Actually Jason, I've been wondering about this type of thing myself. I don't have an application for it, but I read about 'swaged' tubing a while back on a bike made by Salinas Boys (http://www.salinasboys.com/). On the frame they tapered the tubing over about a foot length. I don't know the diameter's but this looks to be what you want to do. Maybe you can contact Cole, he's a pretty approchable guy. You can find his contact info at the site above.

Ben

mr.c

02-07-2004, 05:59 PM

Jason: What you are trying to do is not that much different from cartridge forming. A brass cartridge is pushed into a die that forms the shape of the cartridge. I have a die that reforms a .223 cartridge into 221 Fireball which is a shorter cartridge. It doesn't require a lot of pressure. You do need to lubricate the brass before forming but just a little.
Basically what you need is a piece of steel bored with the taper that you need. Polish the inside of the bore. Put the brass tube into the tapered die and press. The tubing will get thicker at the little end.

Tony Sanchez

02-07-2004, 08:19 PM

Hello,

I've tried my best to find an quality used American-made slip roll that can do 3/4" minimum radius. Couldn't find anything, and I think I'm going to have to settle for a JET SR-118.

What I want to do, is to make tapered tubes about 10" long, and having a 3/4" opening on one end, and an 1-1/4" opening at the other end. Out of brass.

Everything I've found on the Internet about the JET SR-118 states that it's minimum radius is 3/4" ok, perfect... but since I've never used a slip roll before, can one make the machine do tapered rolls? I'm thinking that most have adjustments to do so... how much of a taper is the question.

Anyone have any ideas or suggestions?

thanks,

Jason

---Jason , Ron Covell uses radiator hose clamps to make tapered tubing for use on headers. One example is to split some 1 1/4" tubing overlap one end and start squeezing down the small end with clamps. The other is cut the appropriate size blank and roll it through a roll. Put the hose clamps on and continue squeezing it to the size needed.
---Tony.

rustyclockwork

02-07-2004, 09:55 PM

This is my kind of place to talk about metal.

Everyone, thank you for all the input... I think I'll try that last suggestion, I'll be able to hide the seam with an "underbelly" casting of a line of rivets (unless I'm really good with the fabrication :wink: )

Thanks again everyone,

Jason

Hemirambler

02-08-2004, 06:12 AM

Hi Jason,

I think I would revisit the spinning option. Spinning falls into that LOST ART and therefore becomes sorta mystical - but it is no more difficult than shrinking or stretching metal and we all know how easy that can be once we understand the basics.

$500 for a simple spinning buck is about as practical as a $3500 hammer.

And you don't need a CNC to make it!!! <grin>

Of course my perspective is sorta jaded as I make alot of my tools as a result of being disappointed by what SOME of the PRO's sell. Kinda like Wray's perspective on the whole Ewheel thing - and while I may too make mistakes on my stuff at least I am learning to make the next one better.

Given all this - I would DEFINITELY try spinning in your shoes - the tooling is easy to make -and the process is quite fast once your set up.

If you'd rather not - then I would try getting additional quotes - you might try the metalspinning groug on Yahoo - There are several PRO spinners there that can either guide your efforts OR possibly steer you towards what a fair piece part price would be.

AS high as the $500 tool appears - most places quote HIGH on tooling because most purchasers immediately amortize (sp?) that cost across a large number of parts - never stopping to think if it really is fair or inflated. While OTHER suppliers charge peanuts for tooling but MORE than make up for it with increased Piece Part costs. It's always something!!!!

Your mileage may vary

Jacin in Ohio

rustyclockwork

02-08-2004, 08:52 AM

Hi Jason,
I think I would revisit the spinning option. Spinning falls into that LOST ART and therefore becomes sorta mystical

I couldn't agree with you more, there was a page on the net a few years back about doing this sort of thing, and for some of my toys I do have a supplier of spun spheres (price is very good, about $35 each for a 6" sphere)

And you don't need a CNC to make it!!! <grin>

I know I know, I do own a restored 10" South Bend lathe, but it would be so simple to have my CNC cut it out. I don't have the taper adapter for the lathe (yet) and I don't like the idea of spinning "between centers" with a lathe dog and an offset tailstock, some may think it's perfectly safe, but I don't. (someone yell out "fraidy cat")

Of course my perspective is sorta jaded as I make alot of my tools as a result of being disappointed by what SOME of the PRO's sell. Kinda like Wray's perspective on the whole Ewheel thing - and while I may too make mistakes on my stuff at least I am learning to make the next one better.

That's the way to do it!

Given all this - I would DEFINITELY try spinning in your shoes - the tooling is easy to make -and the process is quite fast once your set up.

Well, I'm not sure how much of a diameter I would need for the brass to be spun over the metal buck. I wouldn't think it would have to be 20" The metal would stretch, but I only have so much clearance over the bed.

If you'd rather not - then I would try getting additional quotes - you might try the metalspinning groug on Yahoo - There are several PRO spinners there that can either guide your efforts OR possibly steer you towards what a fair piece part price would be.

I've got some groups I belong to at Yahoo, never thought of searching for a metal spinning group, thanks.

Bambi

02-08-2004, 01:11 PM

I've tried my best to find an quality used American-made slip roll that can do 3/4" minimum radius. Couldn't find anything, and I think I'm going to have to settle for a JET SR-118.

What I want to do, is to make tapered tubes about 10" long, and having a 3/4" opening on one end, and an 1-1/4" opening at the other end. Out of brass.

Everything I've found on the Internet about the JET SR-118 states that it's minimum radius is 3/4" ok, perfect... but since I've never used a slip roll before, can one make the machine do tapered rolls? I'm thinking that most have adjustments to do so... how much of a taper is the question.

A couple of problems that I see.
First, I am afraid that you would be out of luck with the Jet Slip Roller. Though it can do a 3/4" radius, with an 3/4" opening you would need a 3/8" radius.
What you would need here is a mini slip roll, you might have to fab one up. There are several places for plans for slip rolls, you will just have to down size one to fit your needs. Other than that you might check into Jewelry makers, they have many metalworking tools in miniature.
Second most tapered tubes are formed using rotary swaging machines and are quite expensive. I would think this would be out of the question.
You never mentioned the thickness of the material. I would only be guessing somethin like .030 22 ga.
Spinnining would be out of the question, everything has its limitations, you would be askin the process and materials to do somethin maybe impossible.
Someone mentioned hammer forming in two pieces. This is a viable option. With light brass one could make up tooling out of wood or aluminum and with a small hydraulic press, form the two halves and then solder them together. No need for a press brake.
I would try for the smaller Jewelers type roller even if I had to make one. Roll the piece.
Make up a tapered mandrel out of aluminum and install the mandrel inside the brass tube. Make up 3 collars out of aluminum that slide over the brass tube. These collars should match the taper and should also be slit thru, so they will loosen or tighten as needed. Some generic hose clamps over the collars should be enough to pull things together, then just solder away with an soldering iron. Remember the aluminum will act as a heat sink. So choosing an iron, might be an issue.

Good Luck
Bambi

thefabman

02-08-2004, 01:33 PM

I have not done any metal spinning, and i do see it as a lost art. I am very interested in it and have plans to make a spinning lathe. It seems to me from what i understand of it that you can make wooden dies to form the metal around and then just cut out the small end.

Scott

rustyclockwork

02-08-2004, 01:56 PM

Bambi, thanks for the info on the mini rollers...

Scott, here is a link on how to go about spinning metal. We should invite this guy over to our group.

http://www.coe.ufrj.br/~acmq/spinning/

Thanks everyone,

Jason

Peter Miles

02-08-2004, 02:07 PM

I know absolutely knothing about making tapered tubing.

However, some of the suggestions above made me think about some of the Pexto (now Roper Whitney) forming stakes.

Look at the #925 Blowhorn Stake on the following link:
http://roperwhitney.com/misc/2-26.cfm

The taper on that long horn is similar to what you're talking about but I don't know if it would be useful for your application or not.

The picture below shows an old one that I've cleaned up recently. The stake is 27" long overall.

http://www.metalmeet.com/photopost/data/3233/99Pexto_925_-_Cleaned_Up_-_Cropped.JPG?6538

thefabman

02-08-2004, 04:13 PM

I was thinking......scarry i know..........since you are working in brass i was thinking you might be able to buy 3/4" brass tube. Then turn a copy of the tapper you want to lenght and polish it. Will some annealling of the brass and some lubricant you could probably press the piece into the tube and expand it to the tapper. Don't know if it will work but it might be something to try.
Not too much time to invest on something that might work for your application.

Scott

Hemirambler

02-10-2004, 09:48 AM

Well, I'm not sure how much of a diameter I would need for the brass to be spun over the metal buck. I wouldn't think it would have to be 20" The metal would stretch, but I only have so much clearance over the bed.

Hey Rustyclockwork, I don't think we are yet on the same page. As I recall your specs were something like 1-1/2" od tapering down to 3/4" od over about 10" long????

So given this I would attempt this on my lathe by 1 of 2 approaches - first being lazy i would try FREE SPINNING it - no buck - this would require slightly heavier wall but I see no reason why it wouldn't work. I would START out with 1-1/2 " TUBING . I would then turn a blank that would fit INSIDE of your tubing so I could clamp down HARD on the tube while this blank supports it (prevents collapsing). I would then spin spin away - anneal only if necessary. Think of it as "rotary swaging" - well sorta :lol:

The other approach would be much the same EXCEPT I would make the internal support the FULL LENGTH and tapered like we first talked about. I would make the tapered buck on your 10" lateh by adjusting the compound to the desired taper. Sure it will take a couple of "steps" since you're limited in travel but you will still find it easy enough to do. Just polish it up a little when done and wha-lah!!!! you're in business. The supported method will allow you to use thinner material as the buck will take your loads.

The part will grow longer as you taper it so that might be the biggest hurdle in guesstimating the proper length to start out with.

Another approach might be to hydro form it. I saw a guy making bike exhausts this way. You can easily get some crazy shapes and use a old power steering pump for the fluid - just be careful to make sure there's no AIR in there!!! This DOESN'T suggest you can't get asymetrical shapes by spinning (you can) it really depends on how complicated your shape might be - asymetrical versus symetrical versus complexity. This might be more novel than practical for your quantities, but might be worth looking into for some "one off" prototype work.

Just thinking out loud again,

Jacin in Ohio

rustyvolvo122

02-29-2004, 08:16 PM

You could just start with flat brass sheet and work in into a cone around a mandrel. At 50-100 per year, this could get old and time consuming. There is a formula for laying out a cone onto a piece of metal, and then coming up with a perfect cone. Unfortunatly I no have access to that book. I used it to make a pewter base for a sculpture one time. Maybe I can find a sample somewhere. Then you could silver solder the seam, file it down and buff, and it would be practically seamless.
-Gil

Hawk

03-01-2004, 08:00 AM

Jason, :D go to this URL, then click on ( Home shop software)
then click on and down load ( CONE.ZIP ) then follow the instructions. Fill in all details using decimals only. This will tell you what angles and radius to cut the sides and ends of your pattern. I would think that you could roll over a wood dowel and solder the overlap without specal tools. :) Also Jason and eveyone else, this site has a lot of good programs for the DIYS type. :?
George Hawkins
http://www.geocities.com/mklotz.geo/#shop

Gene_Olson

03-01-2004, 10:08 AM