Velocity stacks

[ironman]

Hi all, 
Im thinking about making my own little series of different hight velocity stacks for my racing engine (v8). 
Injection bodies allows 2.5" stacks. 
I managed to find a local guy that can supply me (almost unlimited) with 2.5" 6060 straight aluminium tubes at a very low cost.

So, the question is, how do i make make nice stacks in an easy way? 
I have seen some vids where they run the tube on a lathe and using some kind of tool to shape the end. Also seems that some uses a press to form the end of the tube. 



Any ideas or help is very welcome. I hope i can make lets say 3 sets of stacks with different hights, without spending a fortune. 

[PixMan]

Those appear to have been made via mandrel and die method. If the 6060 aluminum is T4 and dead soft, you could create dies and try your hand at spinning, though I'm rather ignorant about how you would hold onto the tubes. Perhaps make a plug for inside so you can put the tubes in some contour turned (harder) aluminum pie jaws?

[ironman]

(01-27-2015, 09:14 AM)PixMan Wrote: Those appear to have been made via mandrel and die method. If the 6060 aluminum is T4 and dead soft, you could create dies and try your hand at spinning, though I'm rather ignorant about how you would hold onto the tubes. Perhaps make a plug for inside so you can put the tubes in some contour turned (harder) aluminum pie jaws?

Im getting a sample on thursday, so i'll have a closer look to it then.
Here are the specs on the tubes:
AIRCOM 6060, DIN AIMg5i 0,5, Werkstoff nr 3.3206, ASTM B 241  A96063 T5 , UNI 3569 - 9006/1

[ironman]

Found a video of "how to make a velocity stack". Im going to try this, but not sure im able to make exact copies.

[PixMan]

That's metal spinning and done at a MUCH higher speed than I would ever suggest.

You can get more repeatable shapes by spinning to a form. Unsupported like that works, but it's very much freehand and not likely to make two the same.

Also, that fellow is using a common solid tool. A mounted ball bearing works fantastic.

[arvidj]

(01-28-2015, 03:09 AM)ironman Wrote: Found a video of "how to make a velocity stack". Im going to try this, but not sure im able to make exact copies.

After watching your video this one popped up. I suspect this was not his first attempt at a velocity stack.





I wonder if 90% of the shape could be done against a form, with the lip reversal being the only 'free hand' required. 

[Mayhem]

Hmmm - loose fitting gloves and rotating metal parts. I see blood in his future and possible the nickname "stumpy".

I don't think repeatability would be all that difficult using the technique the first video shows, as it could all be done off the dials. He actually compares the one he made with one he prepared earlier and it looked the same. The second video I think would be much more difficult to replicate without the skill level demonstrated. Interesting process.

[ironman]

Got a free sample today..delivered on my doorstep, what a great service.
This wasnt bad at all! Its 2mm thick, seamless walls. Maybe a little bit on the heavy side because they are 2mm, but still...
Its powdercoated on the outside, and have thin layer of epoxy coating on the inside - but both will be easy to remove. Im going over to a friend with a much bigger lathe later and see if we can do some magic to it.