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Building a gas tank

  • Thread starter Thread starter n1elkyfan
  • Start date Start date
OOOh someone's been reading up then :-D good info there spyug but a little more complicated than it needs to be

My way is to make a 2 peice buck (top & base) slightly undersized as you said, there's many materials you can use for this foam is only one, timber is another for example

The next step depends on what the buck is made from, foam will need covering, i'd use sheet wax in this case & polish any imperfections from the mold, with smooth well polished & waxed timber it is possible to make the mold directly off that, if the buck has undercuts (the laminators enemy lol) the mold may need to be in more than 2 peices the worst ive done is 7 :shock:

Presuming you can get a good top & bottom half from your molds joining the base of your new tank into the top half wont be a problem

hope this helps & good luck with it n1elkyfan :-D
 
I think It will be in at least two part because I was thinking of using the lower part of the other side, The one oppisite of the petcock, for housing the electronics to try and clean up the bike a little bit. And this would be harder if I used the method were I dissolved the foam, and I would like to build at least two tank one I can beat on to see how strong it is.
 
Tone,
I'm interested in your mould making. Can you give some more detail. I'm sure lots of us would benefit from some more info.

I'm thinking you will finish you buck to mirror smoothness then paint with release agent then a gel coat followed by lightweight cloth backed up by mat and reinforcements of cardboard or light wood. Would that be close? How do you prep the mould prior to making the part.

As far as the actual part what would you recommend for layup ?

You mention undercuts as the bain of the fabricator anything else to guard against?

I've always found that you can never have too much info so if you and anyone else would care to share it would be appreciated.

Cheers,
Spyug.
 
n1elkyfan said:
I've been thinking of building a gas tank for my gs and was wondering If I should make it out of fiberglass, which would be easyer, or making it out of steel, which I'm thinking could be safer. My questions are has anybody on here ever built there own gas tank or have anybody had experiance with a fiberglass gas tank.
Click to expand...

Here's exactly what you're looking for. This fellow even went so far as to make one for an SV650...Out of carbon fiber... A feat I would have considered unlikely for a home made job.

Read all about it here:
http://www.bayarearidersforum.com/forums/showthread.php?threadid=145975

2766775-pa010014b.jpg
 
Read that whole thread, that is the standard that your work should be judged by. The last page of the thread shows an easy way to do the whole thing using a male mold. Try it, let us know how it works.
 
I'm in the middle of reading that thread right now. He makes it look easy. I don't know if I will use carbonfiber but I'm definitly going to be using kevlar for reinforcment.
 
Amazing thead. all the information you will need. Notice that they also touch on my lost foam method.

Now ( despite my misgivings) I'm starting to think carbon fiber tank. I can lessen the weight and increase the capacity. How about a 10 gallon "Iron butt" tank:-D

Good thread guys.

Cheers,
Spyug.
 
Ok I just read the whole thread and my brains now mush from info overload. Definitly will have to revisit several times but looks like I will have to go get some foam to start designing the new gastank. I hate when an Idea sticks on you and you can't get rid of it untill you finally decied to do it.
 
Try a couple of smaller projects first. I know many of the concepts of the layup process. I have to say though, that I learn something that makes my next project better each time. I would like to do a fiberglass tank. I need a bit more practice though. To me the thing that matters most is that it is safe and professional looking. Nothing looks worse that an amateurish job. I recently made a tail section for my bike and a lot of the work that I am doing to make it look right has to do with my choice of layup methods. I didn't vacuum bag, I didn't make a female mold. Now I'm doing a lot of surface prep. I figured since it wasn't a production part, I'd save a couple of steps. I'm starting to doubt if I really saved anything. This is like anyhting practice practice practice. The cool thing is that fiberglass is relatively cheap. If it doesen't turn out right you can start over.
 
The information in the Barf thread is excellent and there is a lot of valuable insights into the different methods of producing f/glass pieces.

The big things about moulded versus using the lost foam method for making a tank is that with moulded, there is little if any outer skin finishing and it gives the opportunity to work inside the tank prior to joining the parts. The lost foam method would be quicker overall but there would be much more outer skin prep and ,of course, little access to the inside of the tank.

I think the lost foam would be best suited to a painted finish rather than the carbon fiber finish as layup of the c/f over a completed mail form would be fairly difficult. Still doable but hard to keep in place during setup.

In the Barf thread making a plug from the tank is an extra step that isn't really necessary if the tank itself is preped and used as such. In looking it all over for a custom tank, I think I would make a plug or buck out of rigid foam, cover with packing tape and make the moulds using that form as per his instructions.

The moulds would not be mirror smooth as they come off due to the edges on the tape creating little ridges but these should sand out easily and with some rubbing out with polishing compound should provide a smooth surface.

Despite the good results, I don't think I would start out with a carbon fiber project as that is really tough stuff to work with. It is tough to cut and hard to keep the warp and weave lined up in the layup process, especially on compound curves.

I'm thinking of having a go making a tank for my Tracker, kind of a tear drop or peanut shape with slab sides like those on some of the Mule trackers or the tracker built by Mert Lawmill. It will be easy enough to do using the lost foam method so I might try that first. Winter is long enough that I might have a try at the moulded type as well.

Interesting thread guys.

Cheers,
Spyug.
 
In answer to some of spyug's questions

The plug should be made to the standard of finish you want the mold to be, rough plug = rough mold & its far more difficult to polish a mold than to prep a pattern properly, time spent here is time well spent, sometimes the plug is even sprayed with 2pac paint & lightly flatted back to give a smooth surface (dont try it with anything other than 2 pac)

The info in the thread on the carbon tank is very good but i was taught never to use auto filler on a plug unless it was to be sprayed as above & even then only the smallest smear, the reason for this is it can sink (even if dried for a week) due to the heat caused by the chemical reaction of the resin going off

lay up needs depend on the job & what its used for but as a general rule 2 or 4 layers of either 400w or 600w mat with core mat in high stress area's is enough, the finish from the gelcoat usually means lightweight mat or tissue is not needed for most jobs

As for the use of release agents ...... again depending on the job i use solid wax mostly but sometimes liquid wax or a pva release agent, with a liquid release agent you can get lines in the mold or job from where it dries, not too much of a problem but it does mean more polishing

will post again later when i've recovered from all that typing :-D
 
Billy Ricks said:
Carbon fiber would be my choice. This guy makes it look reasonably easy.
http://www.mci.i12.com/carbon/index.htm
http://www.mci.i12.com/carbon/petrol_tank.htm
Click to expand...

I found that guy's site a few years ago. He is a good resource too. He improvises with a lot of everyday stuff. For instance, when he vacuum bags his parts, he just uses black garbage bags. He also has a writeup where he made a battery tray by using an ice cream container for a mold. He makes it pretty clear that you don't have to spend a ton of money to do composites. On that note, what others have said about CF is true. It can be really hard to work with. It is also getting very expensive. The military is using a lot of it and for a while it was in short supply to the general public. I think its safe to say that most beginning composite projects won't win any beauty awards. It really is advisable to start out with fiberglass. Its cheaper and for what most people want a composite part for, it is just as good as CF. If your at the level where the difference between the weight of CF and fiberglass will make or break you, then you probably aren't reading this thread anyway.

One other note, when you jump in to make an actual tank, use epoxy resin and not polyester resin. Polyester was used for making tanks in the old days. It is not compatible with the alcohol that is used in our gasoline today. The alcohol will attack the polyester and delaminate it. There is much discussion on this issue in the airplane community. They've been using fiberglass tanks for quite a while and a lot of people are finding that they have to rebuild or replace their older tanks. If you have any doubts call the company that you are getting the resin from. They can lead you in the right direction.
 
I was actually thinking of using vinly ester resign because on the fibreglast.com website they say its actually better then epoxy and polyester in corrosion resistance.

Vinyl ester resin is often described as a cross between polyester and epoxy. This is oversimplified, but it does help convey its qualities. Vinyl ester falls between polyester
and epoxy on price, most physical properties and handling qualities. However, vinyl ester does exceed both polyester and epoxy in corrosion resistance, temperature
resistance, and elongation (toughness.) We offer a pre-promoted version which needs to be mixed with 1.25% MEKP to begin the cure reaction. This material has a limited shelf-life of 3 months, so order as needed for your projects. It is compatible
with all our fabrics, pigments , and fillers. It is also suitable for construction of most fuel tanks. However, we recommend the customer test for compatibility before the tank is put into service.
Click to expand...
 
n1elkyfan said:
I was actually thinking of using vinly ester resign because on the fibreglast.com website they say its actually better then epoxy and polyester in corrosion resistance.
Click to expand...

You really should contact them and get a precise answer. The specific issue is compatability with the alcohol (Ethanol) that is present in todays gasolines. They say at the end of the paragraph that you posted that a you should test for compatability before using it. Yikes. I think if they can't give you a straight answer, call West System and talk to them. Fiberglast has reasonable prices, but I have found West Sytem to be generally more knowledgable on issues like this. They also have a much broader selection of stuff. I know for myself, I'd hate to do a a lot of work only to find out that I used the wrong product and that I relied on a somewhat non-commital response from the OEM about its uses. Just my .02. As a friend of mine used to say, "most people don't have the time to do it right, but they have the time to do it twice".
 
Vinyl ester resin seems to fall in between polyester resins and epoxies. This reference rates their properties less than epoxies: http://en.wikipedia.org/wiki/Vinyl_ester

I think the easiest and likely safest resin would be an epoxy as these are what are used in the gas tank sealer kits. West System has been recommended but I think there may be lesser cost alternatives from other manufacturers. I've used product from Industrial Formulations (Cold Cure) and Evercoat which were about 1/3 or more less costly than West. They work just as well.

Check around with the local fiberglass supply, autobody supply or marine repair guys. You might find something a bit more reasonible cost wise.

Keep us posted as to how you proceed.

Cheers,
Andy.
 
Last edited:
Two words....West System. Their technical expertise is un-paralleled.
 
just my 2 cents. although it seems well understood that ployester resin is no good.
I use the stuff to make artificial rock climbing holds for my indoor wall, and I can vouch that it is not good for much else. It is extremely brittle as far as resins go, rather sensitive to air conditions when it sets, and yes, it will react with petrolium products.


by the way, for anyone still thinking about using aluminum or steel for a tank, one thing to keep in mind.
As some of you may or may not be aware, metals change their properties with temperature. with some types of aluminum, heating with a low temperature flame can make them butter soft, even after they have cooled down to room temperature. Also, as you beat on them, they will harden up again. The same goes with steel.


Every alloy is different. And so I will offer this service

If anyone is thinking of using any metal to make a tank, PM me, and I will get you the material data that you need to make it easy. From stress and strain data, to heat treating to alloying element content, I can get it all for you. just let me know what you are thinking of using.

Good luck to all
Kevin
 
BentRod said:
just my 2 cents. although it seems well understood that ployester resin is no good.
I use the stuff to make artificial rock climbing holds for my indoor wall, and I can vouch that it is not good for much else. It is extremely brittle as far as resins go, rather sensitive to air conditions when it sets, and yes, it will react with petrolium products.


by the way, for anyone still thinking about using aluminum or steel for a tank, one thing to keep in mind.
As some of you may or may not be aware, metals change their properties with temperature. with some types of aluminum, heating with a low temperature flame can make them butter soft, even after they have cooled down to room temperature. Also, as you beat on them, they will harden up again. The same goes with steel.


Every alloy is different. And so I will offer this service

If anyone is thinking of using any metal to make a tank, PM me, and I will get you the material data that you need to make it easy. From stress and strain data, to heat treating to alloying element content, I can get it all for you. just let me know what you are thinking of using.

Good luck to all
Kevin
Click to expand...
Im thinking of attempting a cafe ducktail seat and pan from either steel or alu...will be my first attempt at something of this involvement, so i may need some info from ya whence i get the stuff together...
 
no problem

Just make sure you get the alloy number for the metal that you choose.
ie, 6061 T6 Al, or 420 grade steel and such. I can't do a whole lot with out knowing at least the alloy series.
 
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