Agent☣Orange
12-23-2011, 03:29 PM
DIY bumper cutting:
Materials: Dremmel with large cutoff wheels, metal spike, marker, level, goggles ( whole face protection or ski mask recommended).
To be specific, the bumper cover is the plastic part that will be cut. The actual bumper is the aluminum bar hidden by the cover.
I've done two different versions: short and long but the process is the same. Crawl beneath the rear of the car and study the area to be cut. You can see the actual aluminum bumper hidden by the bumper cover along with four plastic braces that attach the bumper cover to the aluminum bumper. The actual bumper is the reference part to use for the cutting line. Do not simply measure from the floor to the bumper because the car or floor may be uneven and so will your cut.
Decide how high up and how wide you want to cut the bumper. Ideally for me, it was to cut it all the way up to the bottom of the aluminum bumper. Any higher and the aluminum bumper would be exposed and may ruin the project. The width for this particular project was determined by the space between the center two of the four plastic bumper cover braces.
Application note: Putting the rear of the car on stands or ramps makes this project much easier. Your cutting lines will be based upon the aluminum bumper to the bumper cover, not the bumper cover to the ground.
Here is a view from below. There is the bumper and the four braces:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4382.jpg
Since I decided to cut the bumper cover as high up as possible without exposing the actual bumper, I use a metal spike and hold it against the bumper to push holes evenly along the bumper cover:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4383.jpg
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4381.jpg
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4384.jpg
For the long version (detailed later) I made about six punctures ensuring that that I got either end of the bumper. This is important because standing behind the car, I don't know where the aluminum bumper ends on each side. By spiking a hole at the each end, I now have a reference for my down cuts. For the short version, I used the two center bumper cover braces as my guide. I left them in place and my vertical cuts would be in between the two.
The horizontal cut line is easy; it's just a matter of connecting the dots (puncture holes). I used a plumb-bob to assist me with the vertical lines but most of it was a good eye and freehand. Using a marker, draw the lines for the final cuts. Don't worry about the ink as it can be cleaned up easily later.
This is the important part: check and re-check and then re-check your lines. Decide if you want rounded corners or straight. I chose rounded corners in the same diameter is my Dremmel sanding cylinder to make my finishing work easier. Also, rubber trim such as door edge guard works with soft, rounded curves but not with right angles.
Don your eye protection and preferably a face shield or ski mask because your face is going to be assaulted with molten plastic. Cut along your lines slowly and carefully. There will be globs of molten plastic that gathers in places so stop, let them cool and then break them off and continue cutting.
Application note: If you think you are unsteady with a cutting or sanding tool, mask off the entire area with thick paper to prevent scratches from a runaway device.
Do not worry if you deviate from a straight line! Cut inside your marked lines so that you can fine tune your cuts later with a sander. Even after that, you're going to cover the edge with trim so relax and keep cutting. It's going to look ugly for a while and you'll be tense.
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4390.jpg
Okay, now the bumper is cut, it's time to clean up the cut line. Using a sanding cylinder on medium speed, gently even up your cut ensuring that you get inside the edge as there are hidden plastic gobs that will prevent the final trim to go on evenly.
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4399.jpg
Appication note: Take it easy with the sander, removing small bits at a time. Sand a little and step back to check for eveness. You can easily remove material but you can never get it back.
So that's it for the short version:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4453.jpg
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/NBbumpercut-1.jpg
The long version:
The long version involves cutting the bumper cover almost from end to end and allows the greatest airflow. It does away with all four support brackets underneath leaving the bumper cover a little floppy. It can be made rigid again by applying 3M double sided tape or pads between the aluminum bumper cover and the actual bumper so this is not really an issue.
This particular Miata started with the short cut but later modified for the long cut. The same procedure from before applies here except this one is just longer. Just to reitterate one important tip though, make sure to puncture holes on either end of the aluminum bumper through the cover in order to guide you better.
It is up to you whether to round the ends or do a straight vertical cut. Since the Miata is is rounded everywhere, I think the long version should be rounded as well.
First I start on one side and freehanded a marker line that gave me the most appealing design. It took me several times with a chalk pencil to settle on the design would work best and I kept crawling back underneath the car to make sure my cut wouldn't interfere with anything.
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut9.jpg
Then I cut the piece out:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut11.jpg
and used it as a reference for the other side:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut5.jpg
similar to this but just flipping it over and taping it to the uncut part of the bumper to mark my line:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut7.jpg
Once the cutting was done, I cleaned up the edges as before:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut14.jpg
got out the roll of trim (good thing I got a roll!) and finished the job:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut22.jpg
and this project is done!:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/BlackNBrearbumpercutwide.jpg
Materials: Dremmel with large cutoff wheels, metal spike, marker, level, goggles ( whole face protection or ski mask recommended).
To be specific, the bumper cover is the plastic part that will be cut. The actual bumper is the aluminum bar hidden by the cover.
I've done two different versions: short and long but the process is the same. Crawl beneath the rear of the car and study the area to be cut. You can see the actual aluminum bumper hidden by the bumper cover along with four plastic braces that attach the bumper cover to the aluminum bumper. The actual bumper is the reference part to use for the cutting line. Do not simply measure from the floor to the bumper because the car or floor may be uneven and so will your cut.
Decide how high up and how wide you want to cut the bumper. Ideally for me, it was to cut it all the way up to the bottom of the aluminum bumper. Any higher and the aluminum bumper would be exposed and may ruin the project. The width for this particular project was determined by the space between the center two of the four plastic bumper cover braces.
Application note: Putting the rear of the car on stands or ramps makes this project much easier. Your cutting lines will be based upon the aluminum bumper to the bumper cover, not the bumper cover to the ground.
Here is a view from below. There is the bumper and the four braces:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4382.jpg
Since I decided to cut the bumper cover as high up as possible without exposing the actual bumper, I use a metal spike and hold it against the bumper to push holes evenly along the bumper cover:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4383.jpg
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4381.jpg
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4384.jpg
For the long version (detailed later) I made about six punctures ensuring that that I got either end of the bumper. This is important because standing behind the car, I don't know where the aluminum bumper ends on each side. By spiking a hole at the each end, I now have a reference for my down cuts. For the short version, I used the two center bumper cover braces as my guide. I left them in place and my vertical cuts would be in between the two.
The horizontal cut line is easy; it's just a matter of connecting the dots (puncture holes). I used a plumb-bob to assist me with the vertical lines but most of it was a good eye and freehand. Using a marker, draw the lines for the final cuts. Don't worry about the ink as it can be cleaned up easily later.
This is the important part: check and re-check and then re-check your lines. Decide if you want rounded corners or straight. I chose rounded corners in the same diameter is my Dremmel sanding cylinder to make my finishing work easier. Also, rubber trim such as door edge guard works with soft, rounded curves but not with right angles.
Don your eye protection and preferably a face shield or ski mask because your face is going to be assaulted with molten plastic. Cut along your lines slowly and carefully. There will be globs of molten plastic that gathers in places so stop, let them cool and then break them off and continue cutting.
Application note: If you think you are unsteady with a cutting or sanding tool, mask off the entire area with thick paper to prevent scratches from a runaway device.
Do not worry if you deviate from a straight line! Cut inside your marked lines so that you can fine tune your cuts later with a sander. Even after that, you're going to cover the edge with trim so relax and keep cutting. It's going to look ugly for a while and you'll be tense.
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4390.jpg
Okay, now the bumper is cut, it's time to clean up the cut line. Using a sanding cylinder on medium speed, gently even up your cut ensuring that you get inside the edge as there are hidden plastic gobs that will prevent the final trim to go on evenly.
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4399.jpg
Appication note: Take it easy with the sander, removing small bits at a time. Sand a little and step back to check for eveness. You can easily remove material but you can never get it back.
So that's it for the short version:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/IMG_4453.jpg
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/NBbumpercut-1.jpg
The long version:
The long version involves cutting the bumper cover almost from end to end and allows the greatest airflow. It does away with all four support brackets underneath leaving the bumper cover a little floppy. It can be made rigid again by applying 3M double sided tape or pads between the aluminum bumper cover and the actual bumper so this is not really an issue.
This particular Miata started with the short cut but later modified for the long cut. The same procedure from before applies here except this one is just longer. Just to reitterate one important tip though, make sure to puncture holes on either end of the aluminum bumper through the cover in order to guide you better.
It is up to you whether to round the ends or do a straight vertical cut. Since the Miata is is rounded everywhere, I think the long version should be rounded as well.
First I start on one side and freehanded a marker line that gave me the most appealing design. It took me several times with a chalk pencil to settle on the design would work best and I kept crawling back underneath the car to make sure my cut wouldn't interfere with anything.
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut9.jpg
Then I cut the piece out:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut11.jpg
and used it as a reference for the other side:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut5.jpg
similar to this but just flipping it over and taping it to the uncut part of the bumper to mark my line:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut7.jpg
Once the cutting was done, I cleaned up the edges as before:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut14.jpg
got out the roll of trim (good thing I got a roll!) and finished the job:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/2Extendingbumpercut22.jpg
and this project is done!:
http://i1194.photobucket.com/albums/aa375/YellowYata/Miata%20NB%20bumper%20cutting/BlackNBrearbumpercutwide.jpg