TheSamba.com :: View topic - How To Detail Sand Body Panels, Edges, Corners, Etc.

Tue Aug 20, 2013 5:42 pm

I posted this on another forum I frequent, 67-72chevytrucks.com, hope it's ok to post since the truck in the pictures isn't a VW, but the sanding process works the same way.

I'm in the middle of doing the bodywork on a truck at work and thought I'd document the process of detail sanding around the various panel shapes, flanges, and stamped details. You can have the flat panels laser straight but if the other areas aren't detailed then the the bodywork still needs work!

This is the panel I'm working on. Has a raised area around the fender openings that wraps back around the sides and top, corners that have flanges that meet up almost against the raised stampings. The front bed corner wraps around and has a flat area stamped in it so I'll show how to keep the edges of the flat area crisp. It's already been metalworked, and the rough bodywork is done and has three coats of Slick Sand. Slick Sand is perfect for this since it builds thick enough that you have material to work with to get everything straight.

I started by making a sanding block that fits the shape of the panel that needs shaping. Remember that bodywork is about shaping first, not smoothing. Smoothing comes after the panel is shaped properly. This was all done with 80 grit to shape the panels flat, then I use 180 to smooth everything enough for the next step of paint prep. Using a guide coat is a must when doing this to show exactly where and how much you're sanding.

This block is just a paint paddle cut in half and glued together, then the edges were trued up and one corner was rounded to match the shape of the spot I was sanding. I wrapped it with a layer of tape for bit of padding. If you use paint paddles, make sure they are square and flat, many are bowed in the middle and aren't fit for getting your panels flat!

This is the area that was sanded with the homemade block, round on one side against the raised stamping, and squared edges on the left side against the flange.

You can see where I sanded against the flange all the way down, even in the area at the bottom where that section of the panel is flat. I'll blend the flat area into the sanded area against the flange later. This way the flat area and the sanded area against the flange are on the exact same level.

Once the area beside the flange was sanded flat, I re-guidecoated it.

Next I sanded the flat area at the bottom using a long/skinny Durablock with rounded edges. I wrapped the sandpaper around the edges and let the edge of the block define the lower edge of the raised stamping. This way the edge of the stamping has an even radius down it's length, and the edge is dead straight as well. Notice the sanding scratches are in a "X" pattern- don't sand parallel with the edge of the stamping or you'll cut a second groove on the outside of the block into the flat area!

You can see that the area I sanded first with the homemade block is still shaded with guidecoat, indicating that the flat area isn't level with the area against the flange yet. Keep sanding until you start cutting into the guidecoat to make both areas level with each other. You can also see how I used a couple layers of masking tape to protect the edge of the flange from being damaged by sanding against it.

Guidecoat against flange is starting to sand off, both area are level.

Underside of raised stamping has been cut evenly across. I like to cut into these type areas enough until you start to hit bare metal. Primer usually builds up thicker in concave areas so this way the primer isn't thick enough to crack later.

Tue Aug 20, 2013 5:43 pm

Next I block sanded the flange on the bed corner. I used tape again on the raise stamping to protect it from being marred by the sanding block.

You can see that the edge of the block cut an even radius into the corner of the flange against the bed corner panel.

Once the flange was sanded flat, I re-guidecoated the flange and masked out the flat part and 1/2 of the radius in the corner.

The masking tape protects the already flat flange, and blocking the corner panel into the flange cuts the other half of the corner radius flat and straight.

You end up with a perfectly flat flange, a corner radius that is straight and even top to bottom, and the corner panel blends perfectly into the radius/flange.

Tue Aug 20, 2013 5:43 pm

The corner panel had a slight flat stamped area in the middle of it. It's easy to lose these details if you don't use guidecoat and block these areas specifically. I started by blocking the flat area by itself, watching the guidecoat until I knew it was flat top to bottom. I wasn't worried about the edges being uneven, that's for the next step.

Next I re-guidecoated the center flat spot, and started blocking the right side, taking care to evenly block up against the flat area- again using a "X" blocking patter 45 degrees to the edge of the flat spot. Watch the guidecoat to see when the edge against the flat spot become straight.

And repeated on the left side.

Once both rounded sides were done, I shot more guidecoat on the sides and re-blocked the center flat area with 180 grit to double check for straight edges. Using 180 slows the cut of the block so you can slowly work up to getting the edges dead even. The edges of the flat area are now dead straight.

Tue Aug 20, 2013 5:44 pm

To get the edges of the raised stamping detail sanded, I first had to block the flat panel.

Once the flat panel was blocked out and shot with more guidecoat, I masked the edges of the surrounding panels (also masking 1/2 of the radius that's already been cut earlier) and used a long/skinny durablock to evenly round the edges of the stamped panel. Using guidecoat shows how far the radius is extending into the flat panel- this way you can get radius even along it's length.

That leaves the corners of the raise panel to sand. I trimmed down a section of a paint paddle to fit the shape of the corner, and also sanded the edge of the sanding block to match the radius of the corner. I used masking tape to protect the areas that were already cut flat around the corner.

The top edge of the corner can be sanded by hand, using the fat part of your thumb tip and 180 grit. Using 180 grit cuts slower so you can more precisely cut the shape you want.

Tue Aug 20, 2013 5:44 pm

The curved areas around the fender mounts can't be blocked like the flat edges. You'll have to do this with the fat part of your thumb, going slow and using guidecoat to show exactly where you're sanding and how far into the flat area you're shaping the radius of the edge.

Once all of the edge have been sanded smooth, shoot guidecoat over the entire flat area and block off the guidecoat with 180 grit. This will show how evenly the radius of the edges extend into the flat area.

Tue Aug 20, 2013 5:45 pm

At this point I had everything sanded with 80 grit. I started the process over using 180 grit to prep the primer for a round of PPG K93 tinted surfacer. With the K93 shot, you can really see the effect of detail sanding the panels. All of the edges are crisp, straight, and the edges all have the same radius. The corner panel's flat center is well defined and is very noticable. Paint will make the details stand out even better.

Wed Aug 21, 2013 9:40 am

Thank you for taking the time to post this. I keep learning because of people like you. Awesome work.

Wed Aug 21, 2013 6:03 pm

This is just perfect timing because i'll be blocking my fasty soon!

Thank you for the awesome info!

Thu Dec 19, 2013 10:35 am

supersuk wrote: This is just perfect timing because i'll be blocking my fasty soon!

Thank you for the awesome info!

That is good info.
MORE PICS!!!!

Thu Dec 19, 2013 10:56 am

Glad the post was a help! Here is how it looks after spraying the paint.

Sun Dec 22, 2013 10:34 pm

awesome :D

Tue Dec 24, 2013 4:24 pm

WOW! Lookin' great! Thanks fer sharing.
Please tell us what you do to preserve the spot-weld detail.

Tue Dec 24, 2013 4:48 pm

57BLITZ wrote: WOW! Lookin' great! Thanks fer sharing.
Please tell us what you do to preserve the spot-weld detail.

Thanks! I actually recreated some of the "spot welds" with a 1/2" carbide burr on a straight shaft grinder. Some of the spot welds were very pronounced, and some were so shallow that they disappeared completely after spraying/blocking the Slick Sand. I used the grinder to make them all match.

I posted a little more about that towards the end of the build thread here:

http://67-72chevytrucks.com/vboard/showthread.php?t=509519

Tue Dec 24, 2013 6:57 pm

All those details really add up!!! It's AMAZING what you did to that truck!
Again . . . nice work and thanks for sharing!

Tue Dec 24, 2013 7:31 pm

http://solutions.3m.com/wps/portal/3M/en_US/Marine...28R3361Cbl dont use paint as guidecoat use this
fabricator john

Tue Dec 24, 2013 7:51 pm

fabricator john wrote: http://solutions.3m.com/wps/portal/3M/en_US/Marine...28R3361Cbl dont use paint as guidecoat use this
fabricator john

I do use dry guide coat for certain applications, but I like paint better when the surface hasn't been sanded yet. Dry guide coat works better after the surface has been sanded, it gets down in the sanding scratches better. We use it on clear coat after blocking with 1000 grit to flatten the orange peel, before sanding with 2000 grit. It doesn't clog 2000 grit like paint can.