Long Tail Cone Fabrication

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PyroJoe
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Long Tail Cone Fabrication

Post by PyroJoe » Tue Feb 26, 2008 7:42 pm

I haven't found a construction thread for the fabrication of long tail cones. How are they typically formed? I can roll the larger cones and often use a hammer/anvil for touch up areas.

The thin long cones are more of a problem, as they cannot be hammered from the inside.

I remember Larry has a special tool for cones.

Does anyone else have tips or tricks for fabricating them?

metiz
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Post by metiz » Tue Feb 26, 2008 8:02 pm

I 2nd this.
Quantify the world.

larry cottrill
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Post by larry cottrill » Wed Feb 27, 2008 2:30 pm

My rig is only "special" in that it is very simple, rugged and usable. The mandrels are nothing but pre-threaded steel pipe -- the largest one permanently mounted, and a couple smaller diameter "attachments" which thread on with pipe reducers. None of these pieces are all that long, and I'd have to make longer attachments to do really long cones. I'd also have to brace the thing somehow so the downward force on the mandrel wouldn't pull the thing over on top of me. But, for the small stuff I do, it works really well. Even did the stainless cones for my last Lady Anne with it, and they were practically perfect. The small mallet and good work gloves are other necessary parts of the "kit".

The first time I tried this, I expected to have to mess with the cone for hours to get it right. Instead, I had a usable cone in about 15 minutes -- what a surprise! I just got a board and software for my PC to let me convert analog camcorder video into digital files and do basic editing, etc. One of the things I ought to do is a basic "cone forming" video, showing how a simple pipe mandrel like this is used to make cones.

L Cottrill
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The Cottrill Cone Mandrel, originally a stand built by my friend the late Fred Lock for our amateur telescopes. The metal pail is entirely filled with concrete! Photo Copyright 2006 Larry Cottrill
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Mike Everman
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Post by Mike Everman » Thu Feb 28, 2008 3:18 pm

Mike
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PyroJoe
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Post by PyroJoe » Thu Feb 28, 2008 3:44 pm

Slip rolling appears to be the prevailing method. Will need to extend my current setup. Reinforcing the mid section of the roll pipe.

GRIM
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Post by GRIM » Thu Feb 28, 2008 6:43 pm

For any cones more than about 12” long I usually make them in several pieces and weld them together

This sounds horrendous; The truth is it depends how you go about it, my oval locky tailpipe and cone was made from 14 separate hand formed pieces and did not take as long as you would imagine ,

Accurate templates are the key ,
The excellent cone designer program, (here on the forum ) and the print shop are the solution here , just stick them down on the sheet steel and cut them out,

Solid bar is much better than tube for using as the internal, “mandrel” it doesn’t absorb the blow from the mallet the same as tube does , try old half shafts from the car wreckers ,

Another essential item is a 3ft length of old railroad track , its just perfect for forming and generally persuading steel sheet to go where you want it to,

OH, AND HOSE CLAMPS , THE WORM DRIVE TYPE, These are your friends , use them to clamp your kinda oval and flat sided cones together then just gently work the metal over the mandrel with a mallet , tack weld, clamp, more mallet work etc,

My 2 cents

PyroJoe
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Post by PyroJoe » Thu Feb 28, 2008 7:16 pm

Often if the cone has a long slow taper I will use a C-clamp to shut that last little bit. I usually go with several healthy tacks from the middle outward.

If the taper is large this method only leads to cussing fits, as the clamp will be sliding down the taper.
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larry cottrill
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Post by larry cottrill » Fri Feb 29, 2008 1:00 pm

Joe, I really like your white-on-black artwork. Man, I wish I could get hold of a couple of those left-hand threaded C-clamps ;-)

Yes, the stainless worm-screw hose clamps are one of the best tools for cones when it's time to tack weld. They're stainless (at least they are if you get good ones), so you can weld pretty close up to them. As mentioned with the C-clamps, if your cone is too "blunt" they also will slip off at just the wrong moment.

Purists will quibble, but I have thought of designing an "easy build" Lady where you would hand-form the cones and just leave the edge zones flat (by that, I mean the areas along the long seams that you can't curve without hammering), for a sort of "pear shape" section throughout the whole engine. If you did the whole thing that way, you'd probably have performance very close to the true circular form (the cross-sectional areas would be practically the same). This technique would give you very quick prototyping, and possibly a sort of "artsy" appearance to the finished product. Ha.

L Cottrill

PyroJoe
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Post by PyroJoe » Fri Feb 29, 2008 2:05 pm

Those left hand thread C-clamps are usually found between the left handed screwdrivers and adjustable metric crescent wrenches. on the same shelf as the muffler bearing extrators. Ha.

Sorry bout that, have an odd sense of humor.

Pear shape, will give it a try in a few tail sections. Thanks.

This one by Rossco often comes to mind, when thinking about ease of construction:

http://www.pulse-jets.com/phpbb2/viewto ... c&start=45

Al Belli
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metric adjustable wrench

Post by Al Belli » Fri Feb 29, 2008 3:57 pm

Hi,

Here is a scan of My metric adjustable wrench.

Al Belli
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PyroJoe
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Post by PyroJoe » Fri Feb 29, 2008 4:52 pm

DELETED

leo
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Re: metric adjustable wrench

Post by leo » Fri Feb 29, 2008 11:22 pm

Al Belli wrote: Here is a scan of My metric adjustable wrench.
Now we only have to get a imperial adjustable wrench, and then we always have a tool that fits. Uhhhhh.

Mark
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adjustable wrench

Post by Mark » Sat Mar 01, 2008 12:00 am

Although you probably can't see the numbers too well, the two largest wrenches are flipped so you can see the English side and the small one turned so you can read the metric side. I got them as a free gift for ordering from Harbor Frieght or Grizzly, (China). I should say the wrenches have a most pleasing patina to the metal, whatever it is. You can't really see/appreciate it though in the scan.
I still recall my big metal lathe instructions, "Do not enjoy beer while operating lathe." You got to love it. ha

Here's a few other designs. The battery powered one sounds cushy.
http://zo-d.com/stuff/
http://www.handytoolguide.com/2006/07/b ... .html#more
http://www.elwindesigns.com/images/Tree ... Wrench.JPG
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Presentation is Everything

Mark
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adjustible measurement cruncher

Post by Mark » Sat Mar 01, 2008 9:06 pm

Here's an old, thin tool I find handy; it converts kg/lb, C/F, cm/in, and liters to gallons by pressing the orange or blue arrows, which for some reason I find myself doing often out of curiousity. Other than the basics, I don't use/know what the other buttons do. ha
http://www.voidware.com/calcs/hp32sii.htm
I even have one of these, what a long time ago.
http://www.voidware.com/calcs/hp35.htm
I gave this old one I had to my brother, he wanted it for some reason. Nostalgia I guess.
http://www.voidware.com/calcs/hp25.htm
And I remember in high school chemistry using one of these. Oh!
http://www.voidware.com/calcs/sliderules.htm
Presentation is Everything

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