You've seen them. The anti-chrome. The blatant air blockers used for streamlining on the salt and stone guards on the back roads. It's a simple piece of sheetmetal with the right arrangement of ventilation for the purpose at hand, function over, but not without, style. For example.... Upon starting this project, I asked for inspiration here on the HAMB and got plenty: http://www.jalopyjournal.com/forum/showthread.php?t=540856&showall=1 Here is how I did mine, with a few pointers and lessons learned. First, the tools. There are all manner of sheetmetal punch tools out there. I considered louvers, but lack access to a louver press and it wasn't quite the look I wanted. I looked at expensive hole punch and die tools from the big race cars suppliers and tool makers. Mittler Brothers is probably the best known of these, but they are pricey.They come in two basic types, the aviation hole which has an angular flare of about 35 degrees and the automotive hole that has a round radius on the flare. Their combination punch and flare tools run around $100 per size, $325 for the three I needed here. I kept up the search and found a lower cost alternative through that big auction site and a small supply house in Cali by the name of Pacific Customs. They have dimple dies for about $30 each, $80 for the three I needed. Score! (almost, the 1" size is on back order, so I bummed one from 54BOMB, thx Brett!) Keep in mind that flares from different manufacturers may not match. I can see a slight difference in the borrowed die. Now i just needed to punch the holes... I went back to one of my earliest lessons and recalled the knock out punches used by electricians and also available in standard sizes for general fab. Greenlee is one of the best known. Just pay attention and don't get the electrician sizes. Check the Greenlee or McMaster-Carr catalogs for specifics. I got one on Ebay ,and two more from Eastwood, for a total of $90, all in I spent half of the cost of the expensive sets. Last note on the holes, Stay away from hole saws because the edge will be jagged enough to create tearing when you press the flange. Now the how-to in pictures. Start with a design. I used a heavy poster board to pattern the insert with scissors, clecos and tape, then transfered the shape to my PC sketch pad to play with different arrangements. The ideas were numerous and some were not so good, so this is the final design. Remember to consider air flow. I found that many expanded metals or screen door mesh of various designs had only about 40% air gap, so I used that as a guide in my plan, aiming to have about the same open space. I probably fell short, but will have lots of air from below, so it should work. After settling on a design, you will need to transfer this to your sheet metal. Scale drawings and lots of measuring are key to good results. Sheet aluminum usually has a plastic film to protect from scratches. You can mark on this with a Sharpie marker or soft lead pencil and it is somewhat eraseable for adjustments. Leave an extra 3/16" around the perimeter for final trim later. Mark the centerline now for reference of all other lines and for the bend down the center. In the end, I settled on three sizes, 1", 1.5" and 2", for my design. I ordered up the punches and dies and anxiously awaited the brown van. When they came in, I made a couple dozen test holes to learn how to get the best results. The punches have a pilot bolt and require a close fitting hole to ensure accurate alignment of the cutter on your intended placement. I used an Irwin Uni-bit to enlarge 1/8" pilot holes after marking them with a punch. With all the pilot holes enlarged to the right size, grab a ratchet or turn your air tools way down and punch some holes! IMPORTANT: Place the cutter on the front side with the cup on the rear so that the cup doesn't mark the front surface. Now you might have noticed that my insert has a bend down the center. This is where I ran over to a friend's to use his sheetmetal brake. Before pulling the paper mock-up off the car, I measured the angle of the bend with an adjustable angle gauge and took that with me to make the bend. The sheet I used is .040" aluminum, so you can do this at home with careful use of a board to clamp and bend the line on a table edge, if you need this bend. Once I had the bend completed, I moved over to the press and started flanging the holes. Here is one of the dies from Pacific customs. This is actually the hardest part of the whole job. Alignment of the dies is critical. In this picture, I have stacked another die on the one in use as a press block to spread the load from the ram across the tools. Misalignment here can cause a mark around the outside of the flange. You might see a couple in my work here. Note that I am working with the part face down and have the male die sitting on the press so that the female die is pushed down onto it. My plan to fix the risk of marking the part when misaligned is to bore a hole through the dies for a clamping bolt in the same manner used on the punches. This is employed by other makers with great success. Take note of the roller bearings used on the bolts to prevent twisting of the dies. (I will place a nut of the right size under the top of my welding table and draw the dies down to the table.) The 1" die loaned to me used the through bolt arrangement. This picture is nearly the completed job. It looks fuzzy due to the previously mentioned plastic film. Note the four small holes on the sides for the Dzus fasteners. These are done just like the big holes using the Uni-bit for the hole and a small die found at most race suppliers for abot $15-$30. After some additional trimming, I installed the Dzus buttons in the insert and laid it into the grille shell for final fit and installation of the Dzus tabs. Remember to rotate the tabs so that the slot in the button is parallel with the panel edge. This looks nicer and lets you check at a glance that the fasteners are locked. Clamp the tabs to the back of the insert and mark the edge for trimming the tab, then trim it about 1/8" long. Lay the insert with tabs attached into the grill shell and tack weld the tabs in place. (The Dzus fasteners will run about $5 per set, so I had maybe $20 here.) There is a great Dzus install article here: http://www.s-sengineering.com/install/default.html Grind back anything that will interfere with the fit of the grille insert. Once you've installed the Dzus fasteners, clip the insert in and do your FINAL final trim. This is where really good shears come in handy. I used a set from Harbor Freight, but I never use them on hard metals so they stay sharp. I touched up a few spots with a file and grinding disc. Try to leave a 1/16"-1/8" gap around the edges so that vibration of the insert won't harm paint on the grille shell. Now you can peel the plastic off and admire your work! I spent about $30 on enough aluminum to do this 3 times (you did see my boo-boos, right?). I spent about $170 on tools for punching and flaring the holes, and about $20 for the Dzus fasteners. All in, less than $220 bucks for a nice grille insert that I can make over for $10 or make up one with fewer holes for race day, reserving this one for the heat of the streets. A couple of lessons learned: 70 year old grille shells are NOT symetrical. Each side is unique. Hard as you might try, you will scratch the aluminum through the plastic. The obsessive will polish the whole thing to a fancy mirror finish. An old press will never push straight down. Practice. Don't press too hard. See previous lesson. It's only metal. We can make another one and that's still fun! You can do this without a press or brake by improvising a couple of tricks on your bench, so don't be afraid to try your hand at making some holes. You'll find all kinds of uses after that!
Thanks guys. My pals thought the pics looked OK until they saw it in person and it really blew them away. It's hard to photograph and do it justice. That is a byproduct of the angle of the pattern I used. I wanted to impart motion in the lines, so I swept them up and back. It was inspired by the V under the Chevy bowtie on a '56 Chevy horn button. The angle is close enough that I am planning to put an emblem in that spot, including the V shape spears.
This is one of the best written posts I have come across on the board. Your photos and descriptions complement each other perfectly. Your grille came out great, and with your new skill for punched holes, I'll bet they show up in more places on your ride.
I have to mention this as I suspect it could be a problem. These grille designs look nice, and you did a real good job of making it. The problem I see is that you have severely restricted - reduced the surface area of airflow through the rad. In a hot climate like down south say in Texas I believe you would be in overheating territory on a 100 plus degree summer day in slow moving traffic. Heck even when driving. Early model cars have small rads already without blocking a large percentage of the airflow. I don't think getting any air from below (wherever below is) will help.
You are correct that it is much less than before, but it's also proven as you can see in the lead photos of cars using them. One factor that is often underestimated is the frontal pressure when going down the road. You can also baffle the sides and top of the radiator to make as much air as possible go through the core. In any case, I can easily unlatch the dzus fasteners and try another design!
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