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xs650 > > Custom Work: Chop, Bob, Cafe and Flattracker - Streettracker > > Cafe Racer > > How to build a fiberglass cafe gas tank ethanol proof


How to build a fiberglass cafe gas tank ethanol proof
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dpmphoto
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Joined: Apr 18, 2007
Posts: 485
Location: syracuse NY

PostPosted: December 15, 2009, 2:48 am    Post subject: How to build a fiberglass cafe gas tank ethanol proof

I thought it would be a good idea to start a new post seeing as how its been awhile and I probably lost you guys. Basically I made a plug which will be used to make female molds out of tooling gel,which then can be used to make the actual gel coated parts of the gas tank. Below is a picture of the raw material I started with and the almost finished plug that will be used to make the mold. My posts aren't rally in the right order but I'll work on that,I don't wanna lose anyone cause I think this is the best way to build seats and tanks that can be reproduced relatively cheap. More tomorrow


resin.jpg
 Description:
You don't really need any special type of foam to make your plug. as long as you brush a coat of west systems epoxy over it you can apply basically any product such as bondo without worrying about the foam melting
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primed.jpg
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After many hours of shaping sanding this is the plug I have built out of that scummy styrofoam,I actually did wash it off before proceeding
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primed.jpg


raw sheet.jpg
 Description:
This was blowing around my buddies yard,it was used as insulation and I managed to salvage 5 or 6 2ft by14inches high by 2 inch thick pieces.you can buy a whole sheet about 8ft long 2ft wide and 2 inches thick either pink or blue at home depot for 14 buck
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raw sheet.jpg

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dpmphoto
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Joined: Apr 18, 2007
Posts: 485
Location: syracuse NY

PostPosted: December 16, 2009, 9:15 pm    Post subject: Re: How to build a fiberglass cafe gas tank ethanol proof

Ok I'm back and gonna go through how I got to the plug stage before getting into the chemistry or one of the ways to avoid having your tank eaten by gas. In the last post I showed that crappy piece of foam it's actually better to get a new piece any kind will do.The easier to carve and work with the better and cost is a big factor too.Your better off just buying an 8ft long by 2ft wide and 2 inch thick piece from home depot $14 and it should be enough to make a couple tank plugs and a seat or two. Stay away from the craft store or you"ll spend big bucks, I have also had good luck with the spray foam insulation.
Ok take your foam and glue it together with wood glue,glue gun,construction adhesive or whatever you have laying around make sure your glued pieces are long,tall,and wide enough for your carving obviously.While that dries cut out two patterns of your tank one for each side I used a piece of luan. make sure you cut and sand them at the same time so there a perfect match.

Once the styrofoam is dry place a pattern on each side of the foam,you need to carefully measure, align, and mark the foam so each pattern is exactly across from the other, otherwise your blank wont be even. Once your patterns are in place its time to cut the foam which can be a real pain without the right tool.I guess u can get by using a hacksaw blade or a big knife but it wont be that neat.I have found the neater and cleaner u cut things, even if there just preliminary cuts the better things turn out. What we need now is a giant hot wire foam cutter,they can cost about thirty bucks for a small one and I have never seen one 2ft long so were gonna have to make one.Total cost will be about 3 dollars if you own a battery charger. I'll post constructing the hotwire foam cutter tommorow along with some other pics



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dpmphoto
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Joined: Apr 18, 2007
Posts: 485
Location: syracuse NY

PostPosted: December 17, 2009, 5:01 pm    Post subject: Re: How to build a fiberglass cafe gas tank ethanol proof

Here's a pic of my hot wire cutter,it's rather simple to make.I just cut a giant u shape out of a piece of luan attached a guitar tuning peg to each end and threaded the wire through each one. Then take your battery charger and hook one alligator clip to each post wait about 5 minutes and your good to cut. try not to breathe in the smoke obviously,but there shouldn't be too much. This cutter works great and cost about 3 bucks. almost forgot the wire is called NIcrome and you can get it at any good hobby shop. I have seen guys using 4 foot long cutters to do body work on cars.It comes in very handy for making seats also


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dpmphoto
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Joined: Apr 18, 2007
Posts: 485
Location: syracuse NY

PostPosted: December 17, 2009, 5:28 pm    Post subject: Re: How to build a fiberglass cafe gas tank ethanol proof

After you have cut out your profile,u can take the plywood off and start shaping,I found that 60 or 80 grit sandpaper works well for shaping,also kitchen knives. I stopped a lot and just stared at the tank this is the hardest part and does take a little skill to get things even on both sides. don't forget that you have to cut out the tunnel for the frame.It also helps to get a thick sharpie for drawing on your piece. Remember you can use these methods to build a cafe,dirt track or custom seat or seat pan. Don't be afraid to use whatever type of styrofoam u want the cheaper the better. Again the foam insulation thats available at any builder supply house(blue or pink 2 inch thick) is cheap and u can get a lot for 14 bucks. I have never used the floral foam cause it is pricey, I used regular styrofoam because it was blowing across my friends yard (Free) and u can see in the other post that the almost finished plug is fine.

Tomorrow I will talk about ethanol and gas tanks.I will also address the myths that u cant use styrofoam or other common foams to make fiberglass molds for cafe seats or tanks. .I will also add some links on the ethanol problem which has been a big problem not only for motorcycle tanks,but the marine industry and the home boat builder seeing as how they use fiberglass for boat fuel tanks which are built right into the frame of the boat in many cases.



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gordonscott
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PostPosted: December 17, 2009, 6:47 pm    Post subject: Re: How to build a fiberglass cafe gas tank ethanol proof

very Cool post and that tank has great lines, VERY sharp Wink
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dpmphoto
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Joined: Apr 18, 2007
Posts: 485
Location: syracuse NY

PostPosted: December 18, 2009, 6:20 pm    Post subject: Re: How to build a fiberglass cafe gas tank ethanol proof

THANKS GORDON! I want to get some more information together before I go into the science of the ethanol problem so for now I thought I would post a few more pics and talk about the next steps. After your done with your plug you need to seal it with the west epoxy,follow the directions on the container and brush a coat on the styrofoam. Epoxy will get very hot if applied thick and could melt the foam so apply about an 1/8 layer. Once the plug is hard u can lightly sand any bumps or imperfections and start applying your Bondo. I used a gallon of bondo on my plug and its less than a 1/4 thick (i sanded about 95% of it off) but that is the way it goes at least for me. Sand,apply,sand,apply,sand,apply you get the picture if you have ever worked with it before and I'm not very good at spreading it.I should mention that I used several different grades of sandpaper and finally got down to an 800 wet sand before finishing up. The plug has to be smooth and the lines must be perfect because this is going to be your mold whatever blemishes are on the plug will be transferred to the mold which in turn will be transfered to your new part.I don't know about you but I"m not gonna spend money on a new part that says you'll have to remove imperfections before painting and I've seen that disclaimer on some seats people are selling . Your plug is smooth and perfect now it's time to lay down some paint.I start by spraying a few light coats of filler primer i think it's dupli color, wet sanding in between coats. The filler primer fills in any tiny scratches or pin holes in the primer. After that u need to lay down a couple of coats of an epoxy primer. I guess u could use something else but I think this works better when applying mold release and partall film. Next steps are purchasing the items to actually make the mold.Next Time I show you what items you need to get and the cheapest places to get them online.If you don't want to make your own plug u can always borrow your best friends seat or tank and copy that and that where will pick up things later.
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dpmphoto
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Joined: Apr 18, 2007
Posts: 485
Location: syracuse NY

PostPosted: December 18, 2009, 6:33 pm    Post subject: Re: How to build a fiberglass cafe gas tank ethanol proof

Just a few more photos


rough.jpg
 Description:
This photo shows how well sandpaper works on styrofoam for shaping,nice even smooth pieces removed
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rough.jpg


bottom.jpg
 Description:
Before u get to far into shaping make sure the bottom is right.Some use wood for the bottom half of the plug that way they can change them out so the tank will fit different bikes such as the honda cb series very popular bike for building cafe's
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bottom.jpg


after hot wire.jpg
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This photo shows how great the hot wire works nice and even saves you work down the road
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after hot wire.jpg

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