In the near future I will be stupid and cut some vents into the e30's hood. I need a tool to cut hood sheet metal cleanly and in straight lines. I don't have air available, and I'm not taking the hood someplace else, because this is my DIY car project, so I have to DIM(yself).
Suggestions?
jigsaw with a metal blade?
I'd probably go with an angle grinder with a cutoff wheel, jigsaws like to catch the metal on me. Tape and a sharpie to show where to cut.
The only reciprocating tool that consistently works for me is a sawzall. Although they can be used for surprisingly fine work when wielded with skill.
Jigsaw will do it.
Right angle grinder with a cutoff wheel.
It is quite possible to do it with tin snips, if you are man enough!
I would recommend the angle grinder as well. I have one from Harbor Freight that works quite well.
In fact, I am probably going to use it to cut vents in the hood of my Miata whenever I get it running.
Plasma cutter? 
Jigsaw with a super-fine tooth blade is what I'd use. Don't do any turns and go slowly and it shouldn't grab for you. Make corner entrances with a step-bit so you don't twist and hog up the corners.
A little trick that Mercury Charlie taught me... If you're trashing the cutout piece and want to keep the rest of the panel nicer, put some dimples in the cutout about 1" inside the cut line. I just use an old punch or carefully use a ball peen hammer. Not much, just enough to move the metal. This will put a tiny pull on the steel and as you cut it will prevent the blade from binding as the metal warms up around the blade.
I've done the angle grinder route too, but I'm just no good at it. One good grab and I put a huge gouge in it.
thanks....I have a jigsaw and a steady hand, so will give that a go first. Also will try the angle grinder.
Luckily I still have the original hood (dented in in front) to practice/test on, before I mess with the good one 
I use a skill saw with a carbide blade..Go slow and it works the best.It won't warp the hood and it makes very straight lines.
Hand nibbler, this is pretty much what it was designed for. A saw will just distort the metal.
Shawn
Electric shears. They use these to cut the holes for sunroofs. Perfect cuts. Bosch makes a killer one.
This style http://www.harborfreight.com/18-gauge-sheet-metal-shear-92148.html?utm_medium=cse&utm_source=googlebase-pla&hft_adv=40010&mr:trackingCode=26730F9E-782A-E011-B31E-001B2163195C&mr:referralID=NA&origin=pla&mr:adType=pla&gclid=CLaXqam8-q0CFbMAQAod4H11wA
Dremmel, much smaller/thinner wheel and better control than an angle grinder. I did this exact thing on the hood of our XR4 when I put a vent in to help control underhood temps. I reccomend taping with painter's tape on both sides where the cut will be to help prevent paint chipping. Also, cut from INSIDE so if your cutting tool binds or skips you don't take a chunk of paint out the hood. Also, make sure to clean up the cut edge and either paint or seal so you don't start rusting...
I like the Dremel idea, I always have better luck with grinding wheels than saw teeth. You could also try this thing:
I have used it on lots of stuff and I love it. It oscillates instead of spins, and that makes it less "grabby" You can punch a hole downward with it, and then move in a straight line. (Use the semi-circle metal saw blade of course, sanding a vent would take forever!)
I don't like Dremels for cutting any more than about an inch. If you do try that, wear eye protection for the flying shards of disintegrating wheel.
Keith wrote: I don't like Dremels for cutting any more than about an inch. If you do try that, wear eye protection for the flying shards of disintegrating wheel.
I'd probably go with a face shield. Dremel cutting wheels are the perfect combination of rotational speed and flimsiness to really mess up your day.
Make sure you buy the 1/16" cutting disc for the grinder. I see too many people who use a grinding stone to try and cut sheet metal.
Keith wrote: I don't like Dremels for cutting any more than about an inch. If you do try that, wear eye protection for the flying shards of disintegrating wheel.
Plus +1 zillion. I have had too many Dremel blades disintegrate when I was doing stuff in my dorm room back in the day.
DrBoost wrote: Electric shears. They use these to cut the holes for sunroofs. Perfect cuts. Bosch makes a killer one. This style http://www.harborfreight.com/18-gauge-sheet-metal-shear-92148.html?utm_medium=cse&utm_source=googlebase-pla&hft_adv=40010&mr:trackingCode=26730F9E-782A-E011-B31E-001B2163195C&mr:referralID=NA&origin=pla&mr:adType=pla&gclid=CLaXqam8-q0CFbMAQAod4H11wA
Yep.
Similar to the hand nibbler theory but electric powered.
We used these to cut sunroof holes all the time at the shop I used to work at.
For all those who don't like the dremel, how close are you putting your face? I mean sure I break discs all the time, but they're lightweight and it's not like even at 20k rpm they do any damage if you're wearing appropriate clothing for metal cutting. Sure you can get hurt if you're cutting in shorts and a t-shirt without gloves and no safety goggles...
when i was making a scale hood impreza rs style I used a cut off wheel to cut out the louvres
You only have to take one light shard in the eyeball to regret the Dremel. Even disregarding the shrapnel aspect, changing discs frequently gets old fast. On an scale model car, they're perfect. On real sheetmetal, it's the wrong tool.
When I installed these:
In my 7 I used an angle grinder with cut off wheel for the straights and a dremel with flex wand and cutting wheel for the curves.
m
xflowgolf wrote:DrBoost wrote: Electric shears. They use these to cut the holes for sunroofs. Perfect cuts. Bosch makes a killer one. This style http://www.harborfreight.com/18-gauge-sheet-metal-shear-92148.html?utm_medium=cse&utm_source=googlebase-pla&hft_adv=40010&mr:trackingCode=26730F9E-782A-E011-B31E-001B2163195C&mr:referralID=NA&origin=pla&mr:adType=pla&gclid=CLaXqam8-q0CFbMAQAod4H11wAYep. Similar to the hand nibbler theory but electric powered. We used these to cut sunroof holes all the time at the shop I used to work at.
No sparks, no shavings left behind, no mess, no sharp edges, no worries.
For a nice straight line, I'll cast another vote for this guy:
DrBoost wrote: Electric shears. They use these to cut the holes for sunroofs. Perfect cuts. Bosch makes a killer one. This style http://www.harborfreight.com/18-gauge-sheet-metal-shear-92148.html?utm_medium=cse&utm_source=googlebase-pla&hft_adv=40010&mr:trackingCode=26730F9E-782A-E011-B31E-001B2163195C&mr:referralID=NA&origin=pla&mr:adType=pla&gclid=CLaXqam8-q0CFbMAQAod4H11wA
Can you use those on say a Yugo hatch to lighten it (removing material from the inside)?
93EXCivic wrote:DrBoost wrote: Electric shears. They use these to cut the holes for sunroofs. Perfect cuts. Bosch makes a killer one. This style http://www.harborfreight.com/18-gauge-sheet-metal-shear-92148.html?utm_medium=cse&utm_source=googlebase-pla&hft_adv=40010&mr:trackingCode=26730F9E-782A-E011-B31E-001B2163195C&mr:referralID=NA&origin=pla&mr:adType=pla&gclid=CLaXqam8-q0CFbMAQAod4H11wACan you use those on say a Yugo hatch to lighten it (removing material from the inside)?
Yup. The only thing that's an issue is when you have three layers of metal in a sammich.
You'll need to log in to post.
