Wednesday, 30 April 2008 10:00

Beating the Clock: Bare Metal Prep for a Chopper

Written by Rich Evans

Going through my photo gallery the other day, I came across a project that I’m surprised I have not written about yet. It was such an interesting project, I should have gone into detail about it a long time ago.

    The project involved three main players, the client which was Giovanni Wheels, Von Dutch Choppers were the builders, and custom body and paint work by Huntington Beach Bodyworks. This interesting little alliance of ours, coupled with how well the final project was received by the SEMA crowd, made this one of my more memorable projects.
    Oh, yes, by the way, the job came with one huge condition—a 72-hour deadline! The bike had to be at SEMA in three days. That’s seriously pushing it for even the simplest of paint jobs. Once I saw the bike, I knew I wouldn’t be getting much sleep for the next three days.

   The concept was to make a chopper version of the new Mercedes SLR—complete with all its tricky shapes and angles. The project was further complicated with steel grill accents incorporated into the design of the gas tank itself. The tank had to pivot on its top mounting point to show off a gauge cluster configuration under the tank.
    In addition to all that, the frame itself was customized. All of these parts were brought to me in raw metal form to be picked up 72 hours later with a show stopping finish. This bike was going to be on display next to Lamborghinis, Ferraris, and Bentleys. So the paint job obviously had to be pristine.
    I had to use nearly everything I’ve learned and picked up over the years for prepping bare metal to get this bike ready. First of all, the welding needed to be completed before I could even begin the prep work. A lot of the tank, in particular, had been spot welded, but not completed. So I started by breaking out the TIG welder and finished welding all the seams, then ground them down. This needed to be done first or the duraglass would sink in the cracks. With deadline imminent, I didn’t have the time to continuously add and sand duraglass.
    To prep the metal, I used a brillo pad disc for excess weld material and to generally clean up the welded areas. I blew off all dust and residue and feathered the edges with a DA sander, 150, and 320 grit sand paper to give the polyprimer something to bite on to.
    Use a red Scotch-Brite pad for any areas the DA couldn’t reach. Do not leave any excess weld material, dust, or residue or you can pretty much count on the paint lifting and having adhesion problems.
    With all the welds finished and ground down flush with the contours of the tank, I began the process of filling the high and low areas with duraglass. I wasn’t quite ready to tackle the grill areas, because these were going to take some extra attention and some different tricks. I also didn’t want my duraglass pouring into the grill areas and making a mess in there.

    This is something most non-professionals tend to overlook when applying their duraglass. On a normal collision job, it is usually not such a big deal, but when you’re doing a custom job, you have to do a little planning ahead. Duraglass hardens very fast and takes a lot of work to sand down again, so having to clean up a messy application of duraglass can be time consuming and costly.
    Before mixing the duraglass, I taped off the grill areas to keep the duraglass from seeping in there. To cut down on sanding time, one technique I employed was to use a straight razor to  shave away at the duraglass to kind of sculpt it into a rough shape of what I wanted.
    This needs to be done at just the right time. The duraglass can’t be still wet and if it hardens it’s too late. You have to apply it, giving it a moment to harden into a gummy consistency that’s not quite hard yet.
    Start shaving away at the areas that are really high, because this will save you sanding time after it has hardened. The tank was blocked down with 36 and then 80 grit sandpaper using various blocks. I then peeled the tape and began applying filler to the grill areas. It was obvious that this was going to be a little tricky, because of all the fins and the tiny workspace of the grill.

    Rich Tip: One trick is to put my duraglass mixture into a zip-lock baggy and then cut one corner off and squeeze the duraglass through it and onto the surface of the grill—exactly like decorating a cake.
    The next challenge was to sand these areas. I couldn’t use my finger, because this would leave rounded areas in the corners of the grills. I used paint sticks as my blocks and ended up getting perfect corners all around. I also taped around the grills before all of this so I wouldn’t mess up the smoothed out duraglass already finished around the tank. The other parts of the bike were much simpler and had all received the same treatment. Everything was now ready for polyprimer.

    For the frame and fenders, I sprayed some epoxy primer sealer, followed with some PCL Polyprimer. It’s important not to use the epoxy primers as filler, because it is only going to make a mess and ultimately create more problems. So don’t build-up. I used three coats of Polyprimer. Allow 30 minutes to an hour of dry time, depending on the temperature and humidity. Polyprimer is meant to be a high fill primer which is exactly what I needed—especially for the tank. The tank itself took about one quart of PCL polyprimer.

Rich Tip: When doing any sanding for prep work, always use a black guide coat to see your high and low spots.
    Choose a nice long block suitable for your project and work from 80 grit to 150, finishing off with 400 wet. For sanding filler always start with 36 grit and apply more black guide coats each time before progressing to finer grits.
    By now the pieces have been blocked down with 80 grit and then skim-coated with a black guide coat to determine the high and low spots of the polyprimer. Next, we blocked with 150 grit sand paper and sprayed another quick black guide coat. Finally, all the repaired areas were wet sanded with 400 grit wet sandpaper. I also went back a few times to apply more polyprimer where it was nearly completely sanded away.
    Finally on the last night, I hung everything in the booth and gave it three nice wet coats of House of Kolor Orion Silver, followed by three very smooth coats of clear. Every coat needed to lay down as smoothly as possible to limit orange peel because there was going to be absolutely no time for color sanding.
    In true dramatic form, we made our deadline. The bike was a show stopper and SEMA was a blast for the whole crew. For more detail on this project, it has been completely documented in our collection of instructional DVDs, available at www.huntingtonbeachbodyworks.com.
    Hopefully this information will spur your imagination when customizing a bike. And I’ll be back next month with something new to show you guys and gals. For now, go out and conquer your own projects. Remember to always have fun and good luck.

Rich Evans, owner of Huntington Beach Bodyworks in Southern California, is an award-winning painter and fabricator. Currently he is offering workshops at his facility so he can share his special techniques to other industry professionals. For more information about Evans, visit www.huntingtonbeachbodyworks.com.