HOW TO: Make your own Knee Dent Tank


XS400 Junkie
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Saratoga Springs,NY
For those that asked for a DIY /HOW we go.
This is the way I do it...I dont own,or know how to TIG weld at this point in this is how I accomplish what I want.
I'm sure there are better...more professional...more exspensive...time consuming ways to do this...but this is how a self taught redneck does it!

I started with a tank I swapped for some pegs...thanks Volcomskater77!!

These are the basic tools required to get started:

and this was the tank as I got it

First I used my trusty grinder with a flap disc style attachment to remove the paint from the sides of the tank....use something like course sand paper grit.You dont need to remove anything but the paint,the more aggressive grinder discs can really remove too much metal if you're not careful!!


Next I lay out my initial pattern...for this tank I thought I would experiment with the whole side instead of just a partial style knee relief like I did last time.The process is the same either way..its personal preference how you do it.
For the layout I used 1/8" fine line tape from the body supply store

I like to step back and look at the overall shape of the tank,and create a design that works with the lines.Once I had the design I liked,I next took a piece of masking paper and laid it over the top of the design,and using the side of a pencil(or a crayon) I marked thru the paper to get a representation of the tape underneath for a template.


Then I used the scissors to cut out the shape on the inside of the marked lines on the paper.

Next....using a tape measure I measure for refernce on the first side,and transfer to the second side.

Then,taking the paper template,I attach to the second side and trim around the outside of the cutout with the fineline tape.Keeping exact to the edge of the template,while referencing side 1 a few times for accuracy.
Then I remove the paper.
Next comes the fun part....the hammer....I start in the center and work outward...kinda get a rhythm and it helps...tap,tap,tap....have to be a little aggressive at get the feel of it after a few swings...dont use a big will deliver more force than necessary.

Just keep working from center out...dont hammer right to the edge of the your way out towards it.Much of this is kind of 'feeling' your way along.When I get the shape fairly close,I use the flat side of the hammer to set the edges and get things looking somewhat uniform.Once side 1 is to my liking,I start side 2..the trick here is to observe what you are doing,and take some time to make the sides match.Its not a catastrophe if they aren't 100% the same..but the closer the better.



When I'm satisfied with the design...I touch up with a grinder once more..looking for high spots.Address any high spots with a little hammer work,try to get everything a smooth as is the filler work.
For filler work I went to the local body supply shop...mine is PPG shop...but most shops sell the same,or similar fillers.This is what I used.

The Rage filler is the first step...the icing is for later.
You'll also need some spreaders...harbor frieght had a box for very cheap...but you can just as easily get them at the auto body store to save a trip.Start by mixing up a portion according to the always portion control is up to you,and how much will be necessary,no need to be wasteful....especially when you see the materials cost!!!
Apply evenly and try to cover the entire area with the first coat.

Remember to do it as smooth as will require less elbow grease that way.
After about 1/2 hr set up time I used 80 grit paper and a flexible rubber block that takes 1/2 sheets of paper(body supply shop)..and work the high spots down.Use the respirator dust'll thank yourself later!!

Depending on the quality of the first coat,you may need to apply another coat or two of the Rage filler to get it mostly contoured.I also build the edges out with filler so I can get a crisp edge as a final product,as you can see in this pic.

After getting it where you are happy with it using the Rage filler,you can move on to the Icing.The Icing mixes to a consistency of hot toothpaste...its for fine filling and finish contouring.It wont hold a raised profile when its wants to sag and flow out smooth...which is its use your judgement here.


I use 180 grit paper to sand the works very well,and sands very easily.
In the contour you will be best served using your fingers,or the edge of your hand to get the contour the way you want it.Wherever there is a flat surface or a straight edge along the contour, I use the flat block to keep my lines as straight as possible.Avoid using your finger tips on the center of the relief,or on flat surfaces,because you will sand finger lines into the filler,which will show in the finish paint.....ask me how I learned that!!
After going over the rest of the tank looking for dents and filling sanding them you should end up with something similar to this.
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Once its sanded out,and you are happy that you dont see any little pin holes or divets in the surface,you should be ready to prime.Always look it over real will probably find little spots here and there that require a tiny bit of adjustment....the Icing mixes very easyin small portions..and dries very quick to be sanded use some patience here to get it right.
One trick I was taught was to close my eyes and rub the body work slowly with my hands and you will actually feel low/high spots.Your hands work better than your eyes in many cases when it comes to finding spots that need attention.
But now that you have it where you think you want is prep and prime.
I use some cleaner from the body supply shop...such as Prepsol or something similar...and then some Ammonia FREE glass cleaner.(Disregard the Lacquer thinner in the DO NOT want to use that on anything!)

After cleaning it down and getting yourself a prop to set the tank on..make sure you get rid of any dust in the immediate are ready to prime.
Now...I use a 2k urethane high build primer.
That being said...if you have exposed bare need an etching primer or a to metal primer.For a tank...I would just get a quality rattle can of etching primer from the body supply shop.Once you find a supply shop..try to stick with one line of product,or what they recommend,it saves screwy troubles later when finish painting.

Next note...if you are going to rattle can prime your work...use a quality product from a body supply shop.....and you will likely want to sand the entire surface with something more like 320 grit paper.I use the 2K Urethane high build...becuase it wet sands very easily and ,with a couple of decent coats,hides the 180 grit sand marks.
Heres what I use.

Mix it according to directions...4-1...and spray it thru an HVLP spray gun at about 25psi (using a 1.7 tip if you have it).....after a few coats this is what I ended up with.

This took me approximately 8-9 hrs from out of the box to in primer.
From here it will get wet sanded with a 400 grit paper...any touchups with the filler necessary( and re-primed etc,..) and it will be ready for prep and paint.
I'm going to go grab my sledge right now and go to town... Skippii style :thumbsup:

In all seriousness, fantastic write up. If I were going cafe this would definitely be a project to do. It doesn't appear to cost a lot in materials and the instructions are simple enough. Heck I may try it out on an extra tank I have laying around just for fun.
its more of a trial and error time investment.....the materials arent cheap...but theres more than enough to do several tanks etc,..
I do have 7-8 yrs of body shop experience/practice to draw its not as hard for me...but if you have a spare tank...give it a shot...and learn the skills along the way.....always ask questions if you need help.

maybe even get a cheap HVLP from harbor frieght...lowes ...home depot...and try the painting as well....see if you have a knack for uncle was kind enough to let me hang around the shop and help out for 3-4 years before he moved away.....most of this stuff is paying attention to what you're doing,seeing what you are you doing as you do it,and common sense adjustments as you go.I still learn things every time I do it.
Yeah ya do. lol
MAN! shes a lot nicer now that you gave 'ol bertha a facelift. I never thought it would look that good, nice job. ill be using this if i ever get a tank for scrap price or something. sorry about that rust. it rattled when i shook it. haha. maybe an electrolosis guide next? hint hint anyone?
I'm very impressed and greatful. I'm hankering for my next project. Your procedure is pretty much what I went through in reparing my RUSTO MOD tank.

The tank is the most significant styling detail to make a bike look right followed by the seat and then the wheels.
I agree Jim
Travis...the tech section could fill up pretyy quick with some of the skills on this site...lots of ingenuity in the members here.

Volcom....I think the loose rust is gone after the beating I gave this tank...electrolisys and tank sealer should .....seal it.... shall we say!!
Damn!! That is sweet! I have bodywork skills (college and technical school), but I still would have trouble beating on a tank! haha I am definitely gonna keep this in mind for a future cafe build!! Great write up man!