Friday, April 12, 2013

Making a tank, pt 4

Now with the two halves trimmed and shaped correctly, we smoothed out the crown where the two meet up, to make a nice weld joint.
We made a filler strip to go underneath the seam-  this serves two purposes:  first, it absorbs heat, which is very important when welding aluminum sheet.  Second, it distributes the stress when you weld it to each half from the underside, so that your seam down the center doesn't have to absorb all the stress and vibration.

strip tacked to one half, then the tacks were ground down so that the second half could mate up flush with the this one-  you don't want a gap down the center to fill in.

Welding the top seam

Done-  in retrospect, we should have taken the few hours to metal finish all the shrinker marks on each half, because now it will take TWICE as long to finish them without disturbing the weld.  It may just need to be ground down flush, we are not sure yet.....

A little more shrinking to add some curve to the lower tank edge, along the main "bulge" on each side.

BAM!  We also took a few minutes to add the nice detail of a tank badge recess, by using a metal hammer form and just pounding it in with a plastic mallet, no wizardry involved!

On the bike-  you can see the shrinker marks more clearly here, not a big deal, just will take a lot of filing and wet sanding, because we intend to go for a mirror finish on these pieces.

Starting the tunnel.......

Monday, April 8, 2013

Making a tank, pt 3, shell finished.

Trimmed to fit around the heads, now to make the tunnel and floor.....

Making a Tank, pt 2

back to the wheel to concave the tank around the bulge, sort of the signature Bultaco Sherpa shape

Danny making a buck to hammer the top edge of each side around, he then used a router to round the edges

side clamped to the buck, beating wildly.  It worked, somewhat...

but needs more annealing


now more hammering at the top edge on the beater bag

Now to use the shrinker on the top edge to bring the fronts of each half in towards the backbone
now we have the right shape up top- and you can see how the shrinker brought the fronts in, and overlapped them. 

Now to trim each half down the top centerline
yup, we're getting somewhere now



yesssssss  a mirror image of the old tank!
more soon

Sunday, April 7, 2013

Making a tank pt 1

Started getting this tank banged out today.  It's getting there....   Since I amposting from the phone i will have to caption everything in one paragraph- something like: annealed the aluminum, quenched it (didnt work well on 5052), so we redid it and air cooled it, pounded the rough shape, got tired and had Danny take over, re-annealed, pounded, english wheeled, annealed, wheeled, trimmed, and now we have two rough sides!