BMW R90/6 Cafe

trek97 said:
Yeah Im having a lot of trouble wrapping my head around...

This....
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and then This....
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Seems to me at some point it should've ended up in the recycle pile. ;D

How are you annealing this. It looks thick enough that it would just crack.

Haha Are you talking about the tuck shrinking around the edges or the recess up the middle?

It’s .080” aluminum which is pretty standard for fenders. .063” is also commonly used, depends on how the parts will be mounted.

I anneal using the standard acetylene-soot method. It’s a very simple procedure that a lot of people try to make sound impressive.
 
irk miller said:
Only certain aluminums, like 5054 need to be annealed to form. Thickness isn't necessarily an issue. But, an easy way to anneal it is to take an acetylene torch and coat it black, the follow up with O/A and heat it until the soot is burned off. Then it's annealed.

IMO annealing of the material is based on several factors. The alloy, the amount of shape that you’re going to put into the panel, the tools your using, and the material thickness. Annealing makes the aluminum much easier to work, which will come in handy if your putting in a lot of shape or working thick material. However if you’re just wheeling minimal shape, like a roof skin, you may want to leave the material un-annealed to help you from over stretching. Some alloys will be easier to form than others without issue, but it more depends on what you’re making.
 
ncologerojr said:
IMO annealing of the material is based on several factors. The alloy, the amount of shape that you’re going to put into the panel, the tools your using, and the material thickness. Annealing makes the aluminum much easier to work, which will come in handy if your putting in a lot of shape or working thick material. However if you’re just wheeling minimal shape, like a roof skin, you may want to leave the material un-annealed to help you from over stretching. Some alloys will be easier to form than others without issue, but it more depends on what you’re making.
Sorry, I was referring to his "it would just crack" comment. Harder alloys like 5054 can't really be formed at all without cracking unless you anneal them. Of course, technique and tooling should be adapted for the specific task.
 
Both the tuck shrinking and them middle. Its just amazing to me.

I must have some hard aluminum (street sign sheet) cause if I tried that w the stuff I have here. It would crack unless annealed.
 
I dont understand how you could get rid of that tuck shrinking and make it come out so nice and smooth.

Seems those wrinkles would have to go somewhere. Not just disappear. lol
 
irk miller said:
Sorry, I was referring to his "it would just crack" comment. Harder alloys like 5054 can't really be formed at all without cracking unless you anneal them. Of course, technique and tooling should be adapted for the specific task.

Oh gotcha. Yep, right on.
 
trek97 said:
I dont understand how you could get rid of that tuck shrinking and make it come out so nice and smooth.

Seems those wrinkles would have to go somewhere. Not just disappear. lol

I see what you’re getting at now. Basically any imperfection that is not a fold can be planished out. In other words, if you place it against a smooth surface, like a dolly, and beat on it the wrinkle will mush down and form a uniform surface. The consequence of this is that at some point you will begin stretching (thinning) the material as you planish. So a good rule of thumb to achieve a nice surface finish is to always over-shrink whenever shrinking is needed. In this case I used deeper tucks and shrunk the edges more than required so I could then afford to go back and planish out the leftover imperfections.

Make sense?

As far as the process for the center recess by hand, those are the kind of tricks that take time to learn.
 
ncologerojr said:
For anyone following along, I said that I would further explain the paint vs. polish decision when making your own tins and why it’s not easy to change at this stage. I began typing a response explaining material selection, shaping methods/approach, the metal finishing process, and how the final finish impacts these decisions. As you can imagine, it started getting loonnggg...

If anyone is really interested in the metal shaping process post up and let me know. I truly don’t mind typing it all up, but if no one is really into it will probably just be boring and you won’t get thru it lol.

I think a lot of members would be interested in the process. You are an amazing craftsman!
 
CrabsAndCylinders said:
I like the side panel, as long as you can massage it to fit the tube in front of it better.

Paint might make the seat match the tank better but I love all the naked aluminum, I don't think I would paint it.
+ 1 for no paint, because it's too sweet to cover up your skills

Sent from my SM-A530F using Tapatalk
 
ncologerojr said:
For anyone following along, I said that I would further explain the paint vs. polish decision when making your own tins and why it’s not easy to change at this stage. I began typing a response explaining material selection, shaping methods/approach, the metal finishing process, and how the final finish impacts these decisions. As you can imagine, it started getting loonnggg...

If anyone is really interested in the metal shaping process post up and let me know. I truly don’t mind typing it all up, but if no one is really into it will probably just be boring and you won’t get thru it lol.

If you're kind enough to take the time, I'm sure many people like myself would love the chance to get an appreciation for the process.

It's awesome the internet allows us to follow/share the snapshots progress of projects like these across the world -but seeing a lump of material get turned into a masterpiece, for a novice, it can be easy to fool oneself into thinking it's that easy - without seeing all the planning, experience, knowledge & failures and takes to get to that point.
 
I am certainly happy to know that there are some people out there who may find this interesting. Because of all the comments regarding final finish (paint vs. polish) I am going to mostly focus on that aspect. I am always happy to talk metal, so if anyone has any questions don’t hesitate to ask. ***I want to stress that this is entirely my opinion only*** Some may disagree, or approach things differently, and that is perfectly fine.

Project Planning & Material Selection

When making your own tins there are several factors to take into account when selecting your material. Importance of weight, potential abuse (vibrations/impacts), structural integrity (etc. rear fender with passenger seat) are all obvious factors. For example; if you are building a rigid chopper with a solid mounted v-twin, thin aluminum tanks and fenders are probably not the best choice. Proper mounting, varied material weights, welding techniques, and overall build techniques also play a big role, but we won’t get into that right now. Another factor which can be very important, but may not seem so obvious is final finish. Especially when working with a customer. In order to explain why final finish plays a role in material selection, and why switching finishes mid-project is a big deal, I first need to talk a little about the shaping and metal finishing process.

So what is metal-shaping? When metalshaping you are using various techniques to shrink or stretch the material in different areas to put the desired shape into the panel. When stretching the material you are increasing surface area, but decreasing thickness. When shrinking it is the opposite. A good way to think of it is if you were to take a flat sheet of steel and bend up the four sides to form a box, you could bend the sides back and have a relatively flat sheet again. It is pretty much the same as it started. In contrast, if you were to take the same sheet of steel, place it on a sand bag and begin pounding the center until if formed a bowl shape, you could not flatten it back out. It is not the same sheet anymore. By pounding on it you’ve stretched the center of the sheet and increased the surface area, at the expense of thinning material in that area. Make sense?

There are many different tools and techniques to shape metal. Some shrinking, some stretching. I am not really going to get into tools and processes here, but for this topic it’s important to note the consequences of your approach to shaping. Some techniques will move material fast, but leave a harsh, inconsistent surface. Think about a ball peen hammer striking a sheet over a sandbag. Other processes will move material more slowly, but leave a nice, even surface. Think about an english wheel with nice polished dies. The techniques and tools you use will generally be dictated by the shape you’re making. For example; a very tight-radius panel may not fit into an english wheel, and will need to be shaped entirely with hand tools like hammers and dollies.

The last last stage of shaping a panel is referred to as “metal finishing”. This is where you deal with the imperfections left behind by whatever techniques you used to shape your panel. Essentially, you are bringing up any low spots, and bringing down any high spots. Just like in your initial shaping, the panel design will determine what approach you take with this process. Maybe you can run your panel through the english wheel with very low pressure to smooth it out. Or, you may be using a polished slapper and dollies to make a consistent surface. Often you will coat the panel with a die, and skim it with a straight file or sanding block to reveal the high and low areas. There is a lot to cover in this process alone, and you can continue the metal finishing process until your panel looks like chrome. It is tedious and time consuming. What is important to note for this topic, is that you will generally be further thinning the material as you go through this process.

How perfect does a panel surface need to be? This is a topic that a lot of people with a little knowledge have a lot of opinions about. The truth is, it depends. Obviously if its polished aluminum panel, it needs to be pretty perfect. If it’s going to paint, does it need to be flawless? No, it certainly doesn’t need to be. You can create a panel that can be painted without any body-filler, and some people like to boast about that. But, let’s think about what that means to the metalshaper and the customer. One option is to metal-finish the panel to a level where 1/16” or less filler is used in the lowest spots. (For motorcycle tanks and small parts it’s generally 1/16” or less, but on large panels it’s not uncommon for top quality shops to go up to 3/16”). From a technical standpoint this is perfectly fine, faster, and less labor cost to your customer. On the other hand, you can spend hours creating a perfect surface, have zero filler, and your panel will look exactly the same as the panel with a little filler. If you’re making panels for yourself, or have a customer who wants to pay for flawless panels, perfect. But, is it good business to create a flawless panel to go off to paint?

Now, using the above knowledge we can circle back to the the beginning topic of material selection, and how it relates final finish. Let’s look at the two common aluminum thickness used in shaping, .063” and .080”. Let’s say that I am going to be shaping an aluminum fuel tank which will have a lot of shape. If it will have a final polished finish I am going to consider some factors; thinning in spots during shaping, continued thinning during metal finishing, and even more thinning during the polishing process. So for a polished tank I am going to use the .080” material, which will be more difficult to work, but after all of the finishing/sanding/polishing will still be strong. In contrast if the tank will be painted, I will use the .063” and metal-finish to a surface where an acceptable amount of filler can be used. In the end both tanks will be practically equal thickness, and the customer can be charged appropriately for the product they recieve. This is also why I charge less for tank ready for paint vs. a polished tank.
 
As a follow up:

Here is a polished tank during the metal-finishing process, and after a quick polish.
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Here is an aluminum tail metal-finished to be painted, and the final result.
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The BMW tank was planned to be painted and shaped from .063” aluminum using mostly hammers and dollies. It is metal-finished to be painted. The polish on it was done without any sanding, and just used to help me better see the panel’s shape. To polish it, I would have to cut out the tunnel to continue the metal-finishing, and then the polishing process could make it thinner in spots than I am comfortable with.
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The fairing, seat and fenders are all made from .080” aluminum because of the extra abuse they will take during riding. They could all be polished.
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Bootsey said:
If you're kind enough to take the time, I'm sure many people like myself would love the chance to get an appreciation for the process.

It's awesome the internet allows us to follow/share the snapshots progress of projects like these across the world -but seeing a lump of material get turned into a masterpiece, for a novice, it can be easy to fool oneself into thinking it's that easy - without seeing all the planning, experience, knowledge & failures and takes to get to that point.
CrabsAndCylinders said:
I think a lot of members would be interested in the process. You are an amazing craftsman!

Thanks guys, I hope my post answers some questions. I’m happy to expand on anything, just ask.
 
Here’s another pic set showing some of the process used to create the rear engine cover.

The flange is made from .090” material, and the skin is .080”. The corner shape was created by shrinking the material in those areas. There was no stretching or thinning of the skin material.
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If you look close you can see that the top of the engine is slightly rounded. To match the engine profile the top panel required just a little stretching down the center.

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Next, everything was tig welded. Whenever a seem is welded you’re going to experience some distortion and shrinking as the weld bead cools. There are different techniques to minimize the effects of welding, but you’re always going to have some work after if you’re looking for a perfect surface. As usual I planished the welds to stretch the material back to its surface area before welding. The flange complicated things a little, making it difficult to planish out the weld as well as I’d like. Unfortunately I didn’t take pictures at this stage.

In the following pic you can see the cover during metal finishing. It was completely coated with blue machinist dye, and then skimmed with a straight body file to reveal the surface imperfections. They look deep in the pics, but the majority of the low spots were only a few thousandths deep and early brought up using a slapper and dolly. Once the surface was even I used a da sander with 220 grit to remove the file marks.

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Once the metal finishing was completed the part was placed in a blast cabinet. Using low pressure I applied a light texture to the mater in to match the engine casings. A quick hit with a buffing wheel, and it should match the engine casing pretty well. I gave it a quick wipe with some cleaner which left some streaks. So the surface looks a little off in the pics, but it’s just the cleaner streaks that almost looks like shadows.

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Thanks for posting.

I've just recently been getting into metal shaping, as I'm doing some rust repair on old VW's. Definitely not as precise as scratch built fuel tanks and the lot, but good to think about nonetheless.
 
advCo said:
Thanks for posting.

I've just recently been getting into metal shaping, as I'm doing some rust repair on old VW's. Definitely not as precise as scratch built fuel tanks and the lot, but good to think about nonetheless.

Awesome! My first metal shaping project was rust repair and floor pans on my mk1 gti.
 
ncologerojr said:
Awesome! My first metal shaping project was rust repair and floor pans on my mk1 gti.

Ahh man, thats one car that I will own someday. I'm working on a 1970 Westfalia Camper right now, and I have a 1970 Karmann Ghia chassis with a '68 donor body that I'm going to build into a baja.
 
I have been watching a diesel rabbit that an old guy just parked that is in great shape. Dont know if he will come off it though.
 
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