Bob La Londe wrote:
"David Billington" wrote in message
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Bob La Londe wrote:
"chaniarts" wrote in message
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On 1/1/2012 9:34 AM, Bob La Londe wrote:
snip
perhaps switching to explosive forming would be easier/more fun?
Ooooh! Now that sounds fun.
Has anyone mentioned a wheeling machine (english wheel) yet? They do
seem to get mentioned in various boat hull related places.
See http://www.radford-yacht.com/wheel/wheel.html for one, maybe
larger than you need.
I have played around in my head with some variations of roller type
forming operations. They big problem is 5052 and 5086 work harden.
If you need to make multiple progressive passes to get the shape you
want (such as a hard chine) you would need to setup back to back
rollers each with a progressive angle from the last close enough so
that the flex of the metal never stops from one end of the process to
the other. Setting up a single set of rollers might be pretty doable,
and even economical if they can be repurposed from something you
already have, but building an array of them and setting them up to do
a job like this could be cumulatively as expensive as a large brake if
you can find one at salvage. For something like a round chine they
can do multiple passes because only the area being immediately worked
hardens. The next pass will be next to rather than on the previous pass.
Its an interesting problem.
I thought I recalled seeing making of the likes of chines in the centre
of a bonnet (US hood) with a wheeling machine in the book by Ron
Fournier but couldn't find it. I recall it involved tipping the lower
wheel over on one side by spacing it up on one side so the side edge
radius did the work but can't currently find the detail.
Other than that I might try a progressive approach with a former like a
boat prow and work your way from one side to the other then start at the
beginning again repeatedly until you have the chine shape. The former
possibly having the full shape but not used all at once to prevent to
much localised deformation of the work. The former could be pushed into
rubber, polyurethane, air maybe. I did something vaguely similar
recently to form some 300mm dishes with about a 250mm radius for a
lighting job in 5mm aluminium. I used a radiused former to push the
aluminium into the end of a pipe, I had some 5mm UHMWPE sheet between
the pipe end and the al to prevent marking. I was using a fly press so
was able to strike rapidly with measured blows and each item took about
5 minutes to form once I had done a practice piece. Forming just
required repeatedly working around the circular blank until it had an
even radius. I suspect a chine would be more work but could be tested
on a small scale to see if the technique was viable.