Hey all,
I'm currently working on making the buck for my custom gas tank. I keep going in between 16 gauge steel and ?? gauge aluminum. Question is, I cant find what thickness of aluminum I should be comparing the steel too.
Anyone have any ideas?
I think you're approaching the issue from the wrong direction.
Aluminum tanks are not as strong or 'durable' as a steel tank.
They dent extremely easily and are known to crack from vibration and stress risers in the construction.
Try to decide what gauge you need by how much formability and rigidity you need and the construction methods available to you as well as your welding ability.
That's my idea. ;D
Im looking at weight.
Its going to be "capped" with carbon fiber. It wont need to look pretty, just need to hold gas.
Define "capped".
I'm a bit busy at the moment but I can figure it out for you this weekend.
Quote from: MrIncredible on April 07, 2009, 12:38:23 PM
Define "capped".
I'm a bit busy at the moment but I can figure it out for you this weekend.
Foam will be added to the exterior then sanded to shape and have a vacuum bagged layer of carbon fiber as the exterior of the tank.
Quote from: TiAvenger on April 07, 2009, 12:42:33 PM
Foam will be added to the exterior then sanded to shape and have a vacuum bagged layer of carbon fiber as the exterior of the tank.
Then make a rectangle out of 1/8" and be done with it. [roll] ;D
Quote from: ducpainter on April 07, 2009, 12:44:17 PM
Then make a rectangle out of 1/8" and be done with it. [roll] ;D
That was the original plan, but I need a minimum of 750 cubic inches (about 3.25 gallons) and to be able to get that and keep the profile I want would be near impossible
Quote from: ducpainter on April 07, 2009, 12:32:56 PM
I think you're approaching the issue from the wrong direction.
Aluminum tanks are not as strong or 'durable' as a steel tank.
They dent extremely easily and are known to crack from vibration and stress risers in the construction.
Try to decide what gauge you need by how much formability and rigidity you need and the construction methods available to you as well as your welding ability.
That's my idea. ;D
Most important sentence highlited.
Vacuum-bagging an aluminum tank may be a problem.
I would expect that it would crush it quite effectively, unless you support it internally somehow.
Even a modest vacuum of 10 psi adds up to large forces very quickly.
Quote from: ducpainter on April 07, 2009, 12:44:17 PM
Then make a rectangle out of 1/8" and be done with it. [roll] ;D
He's got a point.
Quote from: Speeddog on April 07, 2009, 12:50:47 PM
Most important sentence highlited.
He's got a point.
They were all important until he added it didn't have to look like anything.
...and it's on my head. ;)
Quote from: TiAvenger on April 07, 2009, 12:48:03 PM
That was the original plan, but I need a minimum of 750 cubic inches (about 3.25 gallons) and to be able to get that and keep the profile I want would be near impossible
You can modify the shape. I'd still use 1/8" and brace it internally if you're going to try and squash it before it ever holds fuel.
Quote from: Speeddog on April 07, 2009, 12:50:47 PM
Most important sentence highlited.
Vacuum-bagging an aluminum tank may be a problem.
I would expect that it would crush it quite effectively, unless you support it internally somehow.
Even a modest vacuum of 10 psi adds up to large forces very quickly.
He's got a point.
I had planned to put vertical cross members for anti slosh/ structural integrity.
Quote from: Speeddog on April 07, 2009, 12:50:47 PM
Vacuum-bagging an aluminum tank may be a problem.
I would expect that it would crush it quite effectively, unless you support it internally somehow.
Even a modest vacuum of 10 psi adds up to large forces very quickly.
He's got a point.
Fill tank with 2 part polyurethane foam and then when finished wash it out with some acetone it will dissolve the foam. That`s common practice.
Quote from: ducpainter on April 07, 2009, 12:59:51 PM
They were all important until he added it didn't have to look like anything.
...and it's on my head. ;)You can modify the shape. I'd still use 1/8" and brace it internally if you're going to try and squash it before it ever holds fuel.
You mean I shouldn't try and bag it full of gas? [laugh]
While I have your attention, I assume por 15 should be used to back up my welds internally?
Quote from: TiAvenger on April 07, 2009, 01:03:48 PM
You mean I shouldn't try and bag it full of gas? [laugh]
While I have your attention, I assume por 15 should be used to back up my welds internally?
It's not a bad idea.
I'd assume that all the ethanol would create some corrosion in an aluminum tank...i may be wrong.
Just follow the directions like it was a steel tank.
Quote from: ducpainter on April 07, 2009, 01:16:26 PM
It's not a bad idea.
I'd assume that all the ethanol would create some corrosion in an aluminum tank...i may be wrong.
Just follow the directions like it was a steel tank.
doing the rough math.... 6061 is .0975 lbs per inch
3 or .0122 per inch
2 (1/8th inch)
The Al would be around 9 lbs alone :o
Glue together blue styrofoam blocks to rough shape.
Finish shaping to your heart's desire.
Lay carbon.
Aircraft Spruce probably has fuel-resistant epoxy.
See what they say.
Tell them about the next step:
Dissolve blue foam with acetone.
Seal tank with POR.
Check for leaks.
Paint/clearcoat or whatever.
Run it.
No FHE with this method, but it's what I'd do.
Aluminum and carbon in intimate contact will suffer galvanic corrosion if there's any water.
Quote from: Speeddog on April 07, 2009, 02:36:55 PM
Glue together blue styrofoam blocks to rough shape.
Finish shaping to your heart's desire.
Lay carbon.
Aircraft Spruce probably has fuel-resistant epoxy.
See what they say.
Tell them about the next step:
Dissolve blue foam with acetone.
Seal tank with POR.
Check for leaks.
Paint/clearcoat or whatever.
Run it.
No FHE with this method, but it's what I'd do.
Aluminum and carbon in intimate contact will suffer galvanic corrosion if there's any water.
sounds like the best option to me
i know many "carbon fiber" parts are actually a carbon fiber/kevlar or Fiber glass with a carbonfiber outer layer
inspiration:
http://www.bayarearidersforum.com/forums/showthread.php?t=145975&highlight=carbon+fiber+gas+tank (http://www.bayarearidersforum.com/forums/showthread.php?t=145975&highlight=carbon+fiber+gas+tank)
QuoteI'm currently working on making the buck for my custom gas tank.
Sounds like a worthy project. I have a friend of a friend who makes aluminum tanks starting with flat sheets. I'll see if I can get some feedback from him. Also see if I can get his opinion on just the carbon fiber over foam technique with no metal.
I made a venturi type vacuum pump for a long abandoned project using plans and parts I got from an internet woodworking site. It pulled good vacuum although I never got as far as using it for anything useful.
I've made aluminum, steel, copper, stainless and carbonfiber fuel tanks so far. I also admittedly have more metal shaping tools/machinery than probably almost everyone combined on the DMF.
As for making an aluminum tank and then sealing it and then making a carbonfiber tank overlay on top of that? Way too much work in terms of hours, potential for leaks, weight (enormous) and long-term I think you'd gain nothing. If you had to ever fix it --- forget it --- it hits the dumpster.
If you are doing a one-off tank, just carve what you want from foam and pull molds with flanges. Fastest method to get what you want with internal baffles. If you are lazy, you can do it without a mold and just overlay the foam and dissolve later. (not as nice internally) note: somewhere I posted on this forum a BARF thread of someone who has all steps in making of a carbonfiber fuel tank for a SV650 -- definitely a worthwhile read.
My preferance for tanks? Steel (long term it's worth the effort and strength). Aluminum (quick / easier to shape but easily damaged). Carbonfiber (fast construction for a newbie but not necessarily the lightest given a one-off layup) Stainless -- it's a nightmare to shape/stretch/shrink but welds beautifully. Copper -- incredible looking but tough to shape as the material thickness needs to be thick to offset its inherent "soft" nature.
With any "metal" fuel tank, you have to have welding skills to make happen properly. If you aren't a good welder -- find someone who is.
POR15 is just an insurance policy to add incase you miss a small pinhole leak somewhere as part of welding/layup and "pressure testing". It isn't a "cure" for bad construction.
Metal thickness for tanks?
- aluminum: .060/.063 for top/sides at minimum. I'd stay away from .050 as it will get too thin real quickly when being formed/shaped. If the tank bottom as a backbone mount (ala Harley) -- then I'd recommend .080 minimum for the bottom / mounting system. TIG welding is ok but possibly cracks in the future due to HAZ (heat affected zones) and metallurgy changes thereof. O/A gas welding is best for tanks but very few people do anymore. (I will only do aluminum tanks via O/A) If fuel injected bike, remember you need to create a thicker flange for the fuel pump assembly to clamp into without disforming everything.
- steel: .040 minimum for lightweight. .050 is pretty common. TIG welding is fine. Ditto for the fuel pump flange ala above.
note: if carbonfiber tank, just get aluminum machined for the fuel pump mounting flange and bond into the tank itself. I wouldn't recommend a fuel pump / carbonfiber mounting system as something worth trying for someone who hasn't done carbonfiber layup before.
Thanks for the info.
I think I might be going the pure cf route. I had not realized the weight issue with the Al/CF cap
Im reading through the barf thread now
as for welding A/O is how I learned so should I decide to make a metal tank, that is good news
I will probably make several attempts at this [laugh] My best friend (who does sheet metal and composite work for the army) was supposed to be helping me, but ships out to Iraq on Sunday. If all else fails (me) he is going to help me when he gets back.
Quote from: MrFry - Cycles on April 07, 2009, 03:37:49 PM
inspiration:
http://www.bayarearidersforum.com/forums/showthread.php?t=145975&highlight=carbon+fiber+gas+tank (http://www.bayarearidersforum.com/forums/showthread.php?t=145975&highlight=carbon+fiber+gas+tank)
Fantastic thread. [bow_down]
Quote from: Speeddog on April 07, 2009, 08:56:01 PM
Fantastic thread. [bow_down]
Just finished it.
Looks like I may be doing a composite tank [laugh]
QuoteI also admittedly have more metal shaping tools/machinery than probably almost everyone combined on the DMF.
Sheeesh. I think you are underestimating us or overestimating yourself or a combination of all of the above ;D
TiAvenger, I'm working through the BARF thread and it is great. Once concern they mention with a carbon fiber tank is what happens when you crash. I think even adding Kevlar isn't a complete solution but no FHE.
Quote from: Langanobob on April 08, 2009, 03:05:31 AM
Sheeesh. I think you are underestimating us or overestimating yourself or a combination of all of the above ;D
TiAvenger, I'm working through the BARF thread and it is great. Once concern they mention with a carbon fiber tank is what happens when you crash. I think even adding Kevlar isn't a complete solution but no FHE.
I'm not to concerned with that. The tank will only be as wide as my frame, so it would take a violent high side for it to come into contact. Plus since I will be making a full mold, I will probably just make two tanks from the start.
I pick up my foam Friday, to start the plug. ;D
QuoteI pick up my foam Friday, to start the plug. Grin
Excellent. Amazing amount of information in the last day or so and just thinking about teh interweb. Without it we'd be on our own and always be re-inventing the wheel, or the tank.
Next question, do I have to put the fuel pump inside the tank?
Quote from: TiAvenger on April 08, 2009, 12:49:51 PM
Next question, do I have to put the fuel pump inside the tank?
what year / engine displacement / fuel injected or carb'd? You have differing options.
For fuel injected bikes that I've custom built over the years, I've always used an internal fuel pump (factory Ducati setup or 5.0l Mustang assembly through the gascap opening itself). note: the pump itself gets hot due to constant circulation and the fuel itself helps keep it cooler strangely enough. With high pressure fuel pumps you will need a feed and return line plus electrical routing and vent hoses. If you go do a high pressure external fuel pump -- make sure it has adequate ventilation to keep from overheating.
For carb'd custom Ducati-powered bike's that I've built, I always use either a 3.5psi external electric or vacuum fuel pump. (although technically if the fuel pickup location is higher than the carbs, you can go gravity feed also) I've used self-regulated pumps here and thus only one fuel line from the tank is required.
Quote from: MotoCreations on April 08, 2009, 01:17:15 PM
what year / engine displacement / fuel injected or carb'd? You have differing options.
For fuel injected bikes that I've custom built over the years, I've always used an internal fuel pump (factory Ducati setup or 5.0l Mustang assembly through the gascap opening itself). note: the pump itself gets hot due to constant circulation and the fuel itself helps keep it cooler strangely enough. With high pressure fuel pumps you will need a feed and return line plus electrical routing and vent hoses. If you go do a high pressure external fuel pump -- make sure it has adequate ventilation to keep from overheating.
For carb'd custom Ducati-powered bike's that I've built, I always use either a 3.5psi external electric or vacuum fuel pump. (although technically if the fuel pickup location is higher than the carbs, you can go gravity feed also) I've used self-regulated pumps here and thus only one fuel line from the tank is required.
2002 SS 750ie motor, will eventually be replaced with a 800
Actually you used a very hard metal, my suggestion is you used you aluminum.
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