Rock Guard From Fabric and Foam

April, 2013

Watchful eyes protect from road debris

I try to keep these blog posts organized in the order they happened, but sometimes that means I'm writing about things I worked on months or years before. Please bear with any fogginess on the details.

I don't remember my exact steps for making this rock guard, so this isn't big on details. Besides, a full narration of my two steps forward, one step  back technique on this could get tedious. So I'll make it a summary of what our rock guard looks like now, what went into some of the decisions, and what aspects of it work well for us.

 Rocks happen, even to trailers that are mostly sheltered by their tow vehicles. Our '71 Tradewind caught a rock on the streetside curved front window the first time we towed her home. Replacing a curved window for a 40 year old trailer is another story that we will eventually write and put up here. But this entry is about one way to protect windows so that won't happen again.

Why fabric? Why not something hard, like lexan or metal?

Zig-zag stitching holds appliqued canvas design on mesh.

Textiles are kind of my schtick, so that's often the first place I'll turn when looking for a solution to a problem. Bart's the mechanical engineer and his first solutions often involve metal. In this case, Bart was elsewhere occupied with details like new axles and making the electrical system safe for driving (yes, we started this three years before we finished it). He had suggestions, but I had the time to put into it. Fabric won by default.

I picked Sunbrella because it is nearly impervious to sun damage. I picked this particular tan because it was as close as I could get to gray/silver on the cheap fabric source I was using online. (It might have been newtoto, or another.) I picked the open weave because I knew we'd be leaving this up on the trailer in all kinds of weather and I wanted it to drain moisture more than canvas does. I picked the blue for the applique because I liked it and it had good contrast.

Are those devil eyes?

An Eye of Horus

They're from Ancient Egypt, the Eyes of Horus. I have no idea what their significance might be. I wanted eyes and I chose these, in part as a nod to my archaeologist daughter whose childhood ambition (or one of them) was to discover Cleopatra's tomb.

I knew if I was going to go through the trouble and trauma of sewing something I was this unsure how to do, I wanted something I liked to look at at the end. the front of the trailer was begging for eyes. I did a google image search for "eyes" with a vague notion that Betty Boop cartoon eyes might provide the right vintage touch. These came up in that search.

The applique is done with WonderUnder and the image was blown up onto several sheets of letter size paper because that's the only printer I have. You can see the zig zag edge stitching in the picture above.

Yeah, it's catchy and all, but how does it work?

Metal eyelets are set into Sunbrella bias tape border

The guard is two layers thick. On the backside are openings where foam can be slid in between, providing a rock proof defense. The slit is near the center of the pocket so the foam has to be bent to be put in and it can't work its way out while we are underway. The foam is cut from thick, closed cell interlocking floor tiles. They have the strength and density to withstand road debris and the stiffness to hold the fabric tight.

We only put the foam in the area that covers the two side curved windows. First, that is the area most likely to be hit while on the road. Second, those are far more difficult and expensive to replace than the plain, flat center window. And third, the center has  the lacing, which makes it much more difficult to put foam there. More on the lacing later.

The edge is finished with Sunbrella bias tape, wide enough to have space  for the twist studs outside the foam.

What holds it on?

West Marine twist studs hold the cover on

 We chose West Marine twist stud canvas fasteners. We tried the ones with a single screw on the back side, but those sheared off too easily. We went with drilling two holes for each fastener and getting more security. We found that if we stayed along the rivet line we were sure to be outside the glass while staying inside the frame border. We squirted a bit of Trempro (Vulkem, ppolyurethane sealant) into each hole before inserting the screw. After the first couple of holes, it stopped being quite so nerve wracking.

Since the parts in the frame had to go into a specific location, always between rivets, we installed those first, before putting the corresponding eyelets in the cloth of the cover. We held the guard over the window and marked the location of the top twist studs. After marking a few, I put the metal eyelets for the studs into those places. With those in place and clipped to their twist studs, we lined the rock guard edge with the edge of the window frame and marked a few more eyelet locations. It was a multiple step process to get all the eyelets located and installed, but it insured that the spacing on the fabric matched the spacing on the window.

What's with the bodice on the front?

Lacing through grommets provides adjustability.

 If the Eyes of Horus are the eyes of the trailer, the "bodice" lacing makes the bridge of the nose. That's why it is tapered to be wider at the bottom than the top.

The other reason for the lacing is that there isn't any other way that I can see to have a full width fabric rock cover without some way to adjust the width. These pictures show it a bit baggy because I had to loosen it when putting it on again for these pictures, in order to get it to reach all the twist studs. I had been perfectly adjusted on the road before we got here. Foam stiffens, materials change with warmth and cold. The foam that we used can take a set when it's been off the trailer for a bit.

The adjustment area needn't be bright blue lacing reminiscent of a Renaissance bodice. That's happens to appeal to me, so I did it. It could be done with velcro, or with straps and buckles. I have also seen success with doing fabric covers for each side window separately. That leaves a much smaller covered area and can be done without size adjustment allowances.

This rock guard has traveled thousands of miles without a glitch. It sure beats the camping mats held on with gaffer tape and rope that acted as a placeholder while we figured out the right solutions for this project. And it makes the trailer easy to spot in a sea of silver at a rally.

.