E: Engine Comet Mongrel

davidd

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Anything that does the job is good. I used the Beverly shear for most cutting and a small rotary ratchet shear for the small trimming jobs.

David
 

ClassicBiker

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If I understand what you are saying, that is pretty much what option 2 is... although I don't know what you mean by a caulking tool. I have enough Cerrobend to make a female die and also have a decent sized hydraulic press. I ordered up enough alloy for quite a number of attempts so hopefully one way or another I'll come up with something other than fodder for yard art.
A fellow I know actually used cement to make a female buck to form wheel arches for an MG. It sounds bizarre, but his work is absolutely amazing.


Even if you aren't a MG fan, this is worth a look.

https://www.mgexp.com/phorum/read.php?1,3513512

Actually, I'm a member on that forum as well. I have a '70 BGT, same name and avatar there.:)

100_1460cropped.jpg

Rather than hitting the metal directly with a hammer, you use an intermediary tool to transfer the blow. The name comes from boat builders. To caulk the seams of a boat by driving rope (hemp) in between the planks then coating with pitch (tar) to seal up the joints water tight. I'll post some picture of some tools I have.
Making soft tooling from Cerrobend would be good. Just have to account for material thickness if you use you buck as a core for making the die. How would you do that? Layer up tape or cloth and smooth out the ridges in the die afterwards?
Steven
 

Cyborg

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I get your "drift". I've done my share of caulking boat seams and still own the damn thing. 1947 Chris Craft U22. I bought a cheap set of drift/roll pin punches for the air hammer that I can modify for that purpose.... either using them with the air hammer or just a normal hammer.
Accounting for the material thickness will be a little tricky. Bouncing around a couple of ideas, but focusing on getting the panels for the oil tank and side cover formed with the bucks that I have. There is an outfit in the UK that uses Cerrobend for stamping out small batches of panels, but I'm assuming they make a panel the old fashioned way and then use that to form the dies.
 

Cyborg

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The first attempt was a dismal failure, except I learned that (for my skill level) I was trying to shape too large a radius and the amount of material that I was folding around the radius was way too wide. No way I could shrink the metal that much. Then tried putting a 1/4" radius on the flip side of the bucks and trimmed the panel so that there was about 1/2" extra to fold around the corner. Just have to figure out a simple way to put a bit of a convex curve on the outside of the panel so it looks a little better. I suppose hydroforming would work, but setup would consume a lot of time.
This was done with a basic body hammer. I ordered up some leather for the face of the home made (wood) slapper. When searching the net for images of slappers, it turns out that word has more than one meaning.
Side cover.jpg
Side cover 2.jpg
 

davidd

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You should be very pleased with this. It is about as fast as one can learn.

DSCN2768.jpg


"T" dolly, a Covell slapper and a Fournier slapper. I think the plastic hammers are fine as long as they are working well. I tend to have a lot of extra wood an metal hammers that I have picked up over the years so I can re shape them to what I need. Fournier, Covell and Tin Man still sell this stuff.

You also might experiment with the order you do the bends in. Sometimes starting at the tough part that needs a lot of shrinking will give you more space to shrink the extra metal into if you have not already folded the easy bends over. When doing the easy rolls with the slapper you should continue the shrinking as you leave or approach the corners where most of the shrinking is happening. You want to shrink your extra metal over the largest area possible. If you think of it like you need to put darts or pleats in the metal and hammer them flat (making the metal thicker), then you need room to make three or four small darts instead of on big one, which is probably what happened in the first try. You did the right thing by broadening the corners to shrink the metal over a larger area.

Also, you can put darts or tucks in aluminum with a tucking tool.

Tucking Tool.jpg

The tucking tool allows you to make uniform corrugations, which can be hammered down making the metal thicker. It is usually used on bigger panels. But, thinking about how many tucks it would take to shrink the area you are working on will help you not to bite off more than you can chew.

Nicely Done!

David
 

Cyborg

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Thanks David. The first one had me thinking this was a bad idea and wondering what I was going to do with the rest of the aluminum. Maybe a fish cleaning table for the boat.... I watched a video of a fellow using one of those tucking tools and it gave me the feeling that I should avoid any projects that require the use of one. I do need a few of those T shaped dollies in your photo.
 

vibrac

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I remember seeing a film fifty years ago at engineering college about explosive forming based on removable formers mounted on top of a 500cc motorcycle engine barrel petrol was introduced and a spark plug attached when all was set up one bang formed the deep draw shape. Another good idea I never saw again.
 

Cyborg

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I posted this picture before.... its a Ducati Shock rocker with a home made fork. Not sure why I chose this system other than I had the rocker already and it looks like an interesting setup. I had either forgotten or never noticed that Harris used a similar system years earlier (1984) than the Monster it came off. Does anyone out there know if Harris came up with this system or who did?

Fork and Rocker.jpg


Harris KZ750.jpg
 

Cyborg

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After reading about belt tension on Oldhaven's thread, I spent the day "fettling" the gearbox adjusting slots to allow for a little more slack. Thankfully they just needed some cleaning up to allow full travel. Almost finished the rearsets. Not sure what to think of them. They appear to function as intended, but look like they belong on that Gypsy caravan someone mentioned. The other side is even more garish, because it has to hold the master cylinder. The plates also hold the swingarm pivot shaft captive.
Rearsets shifter.jpg
 
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