Making an ABS upper grille cover, with compound curves
 

Here is how-to for making a template for an upper grille that has compound curves (curves in two directions), and some notes on working with ABS sheet material for the actual cover.

The info here is general, but some points are particular to the 2005-2007 Ford Focus.

I selected ABS sheet plastic for the cover, leaving the gloss side out. These sheets commonly come textured on the "finish" side and blemished on the glossy side. So it goes ... the blemishes are slight, and I intend to paint it later anyway. My ABS material is 3/32" thick. That's thin enough to work into place, and still thick enough for countersinking for flathead screws. I got mine from Tap Plastics, which will cut small orders to size.

1. The Focus grille has a deep recess, which I had filled with closed-cell sheet foam material for my previous, temporary grille block. (It had served both as an air block and support a covering made from a heavy duty construction garbage bag material, so wind wouldn't dish it it.) The sheet foam was wired in place. I left it there to both help support the thin ABS material of the new cover and to help support my template material while inking it.
http://ecomodder.com/forum/member-fo...cell-sheet.jpg

2. The grille is awkward to work with for two reasons. One is a combination of its balance and two long plastic legs that stick out from the upper backside. The other is the compound curves. My first attempt at making a template (for sawing the ABS material) failed because I the curves kept me from inking the template uniformly, completely, and without shifting. Here a means for taping the template down that was very secure and worked:
http://ecomodder.com/forum/member-fo...l-securely.jpg

My first (failed) template is in the background.

3. I had sharp folds in the template material so I could ink one side at a time. I used ink-stamp ink, which is thick and didn't diffuse into the thin poster material I used. I put it on heavy, using a thick edge of a scrap of paper towel, folded over several times. The ink wiped off of the grille easily with another paper towel. Then I could put the inked template half back down on its side and do the other side.
http://ecomodder.com/forum/member-fo...over-inked.jpg

4. Here is the finished ABS cover. I used 18 stainless #6 flathead screws, for a square head screw driver. I had planned on using half that many, but needed to hold down bulges along the edges. I tried heating the ABS with a paint removal gun, to make permanent compound curves, but I stopped when I could see that I was going to end up with an uniform, dimpled cover.
http://ecomodder.com/forum/member-fo...arter-view.jpg
http://ecomodder.com/forum/member-fo...front-view.jpg

5. Here it is on the car. The curves are smooth but don't appear that way in the photo because clouds are reflected. (Car needs a bath!)
http://ecomodder.com/forum/member-fo...ille-block.jpg

6. Here are my previous grille blocks, when first installed. This worked great for over half a year, until ravens worked it over. They picked out all the pipe insulation, leaving me only one piece of it. Days later they pecked holes in the garbage bag (they love digging for food in any garbage bag they spot - guess I was lucky mine lasted so long).
http://ecomodder.com/forum/member-fo...lastic-bag.jpg

Last word -- The grille cover itself isn't unique, but I thought the template making technique would be useful for others. Also, a trick for working with those long legs on the back of grille is to use two boards on the sawhorses (as shown), so the legs can be down the split, out of the way.

like it. good write-up.

Looks great! Do you plan to paint it white? Would love to see what a focus would look like with no upper grill...

White is the plan, sometime when I have time to get a brush out. I want to be sure it is protected from UV. That may not be a problem though, since black ABS is supposed to be OK for that. But I don't know how well stabilized it is. I recently primed and painted some rusty spots in my spare tire well and behind the rear bumper, so I have the paint on hand.

Note in the second to last photo that I have added some white foam weatherstripping in the gap below the lip of the hood. The gap was over 1/4", with airflow passing directly into the engine bay. With this gap filling, the upper grille block and an eventual more permanent (than before) air block for most of the lower grille, I am trying to reduce warm-up time. That is key for getting to low idle RPMs quickly, for maximized mileage when pulse and gliding on short trips around town.

I attempted the foam strip to seal the hood but used too thin of foam tape and only sealed up the headlights lol. The gap is huge and definitely need to be dealt with...

Can't wait to see results if/when you paint it, I wish that mine was a good color, the gold Ford used is so ugly and touch up paint is hard to find locally on the part store shelves.

I used 1/2" foam, so there is a bit of squish for a good seal.

If you look at the parking lot photo, note that the top edge of the cover is not uniform. I noted it was high on the starboard side after mounting it (combination of cutting boo-boo and mounting misalignment), but decided not to fix it due to a time limitation. If I make a version 2 I will raise the port side by an equal amount. That will help airflow bypass the gap. I will take a side view of the grille area sometime soon, so you can see the relationship in a more 3-D-ish shot.

I like it! the black with the screws around the edges looks aftermarket! You can check out my similar grille delete (seriously, it looks like there was never a grille!) here> http://ecomodder.com/forum/showthrea...d-32703-3.html

Very well done, HM'95.

Great stuff, Focus-Ak! The template technique is very cool.

The HDPE (root barrier) roll plastic that I used on Slambo's upper grille block ( https://youtu.be/RVzra5e4rpc ) buckled from the heat of the summer sun. Hopefully the ABS plastic that you used will be more resistant!

I want to rework mine before the cold weather sets in. The plan is to wrap it with a composite fabric, possibly a Kelvar weave.

http://i5.photobucket.com/albums/y16...ps8kdeujnt.jpg

Another method I used was offcuts of black HIPS ( high impact polystyrene) about 1mm thick, laid it on the inside of the grill and heated it with a heat gun until it sank slightly into the honey comb. Then a couple of dabs of impact adhesive and it stayed there.
You could also use any other thermoplastic that'll soften with heat. :) I got an extra 20 miles per tank iirc, got my first 400 mile tank on the 1.6 petrol using that grill.