How to cut perfect holes in sheetmetal???, need vents on rear trunk lid.... Options

[Eric_Shea]

Jig saw and tape it off before you cut.

[GWN7]

What size hole do you need? I can make 'em perfect in: .45, 9mm, .38, .270, .22, ......  

--------------------
Shannon Gomes

LMAO

(IMG:style_emoticons/default/beerchug.gif)

[TimT]

Mike, you could have the louvers made as "innies" that way you get the vent and keep the lines. also they would be kinda stealth vents.. You can buy stamped louvers from places like Coleman, then weld them in and metal finish the area.


or drill the proper radius hole in the corners, then use your trusty cut off wheel.

[SpecialK]

Kind of shocked no one mentioned a plasma cutter and template ("plasma cutter" is on my Christmas List, but I think the boss is thinking more "new refrigerator"). That'd definitely be the quickest way. And by using a template you could ensure that both holes are identical, or at the very least, damn close. (IMG:style_emoticons/default/blowtorch.gif)

[914werke]

(IMG:style_emoticons/default/smilie_pokal.gif)

many years ago on racebikes by a brilliant gent named John Brittain

He will be missed (IMG:style_emoticons/default/sad.gif) ( and it wasnt that long ago)

[Jeroen]

There's quite a bit of surface tension on it. If you cut the holes it's gone...
After you've cut the perfect openings, you'd have to at least curve the edges to keep any rigidity

Get a f/g hood.
Slightly easier to cut
Lot easier to fix f-ups
Easy to add reinforcements if needed

What's them holes for???

cheers,

Jeroen

[tat2dphreak]

holes in sheet metal + perfect = plasma cutter!! they rock!

one of these days I'm going to steal my dad's cutter for good, and tell him the shady guy in the trailer down the way musta done it!

[airsix]

Mike, a tool I used too punch holes through thick guage stainless sheet, works like this:

Drill pilot hole.
Special tool has die cutter that bolts through pilot hole.
Tool is fastened to both sides of the work.
As you tighten bolt it draws cutting blade through your metal into the receiving die part of the tool.
Only takes a minute or two to punch any size hole you want. Perfect hole every time.

I would inquire at an electric supply house for a K.O. punch ( knock out )
or a " slug buster ". (IMG:style_emoticons/default/smash.gif)

May be a rentable tool.

KT

Trekkor is the only one posting here with a clue (sorry guys). You should be able to find a tool like he describes at a radio shop that caters to mobile 2-way business FM, HAM, or CB radio. People use them to cut a perfect circle for mounting antennas. I've seen them in sizes from 3/8" to 1". They are designed to cut through auto-body guage steel (12-16ga.). I assume you'd want to use said tool to cut radiused corners for your rectangular cut-outs (as in your illustration)? Should work well for that. IMHO this would be the cheapest and only practical way to cut a perfect hole without warping, edge-deforming, or otherwise screwing up the cut.

-Ben M.

[Chris914n6]

Mike, a tool I used too punch holes through thick guage stainless sheet, works like this:

Drill pilot hole.
Special tool has die cutter that bolts through pilot hole.
Tool is fastened to both sides of the work.
As you tighten bolt it draws cutting blade through your metal into the receiving die part of the tool.
Only takes a minute or two to punch any size hole you want. Perfect hole every time.

I would inquire at an electric supply house for a K.O. punch ( knock out )
or a " slug buster ". (IMG:style_emoticons/default/smash.gif)

I...errr, my dad... has a bunch of these 'chassis punches' for making electrical boxes. Up to 2.5" if you want to borrow one.

Don't know why you'd want to cut holes there for but as an indea you might want to think about welding edges on for reinforcement. Grind it clean and the initial cut quality won't matter as much. Or as said before fiberglass, it's easy to fix. (IMG:style_emoticons/default/wink.gif)

[SpecialK]

Mike, a tool I used too punch holes through thick guage stainless sheet, works like this:

Drill pilot hole.
Special tool has die cutter that bolts through pilot hole.
Tool is fastened to both sides of the work.
As you tighten bolt it draws cutting blade through your metal into the receiving die part of the tool.
Only takes a minute or two to punch any size hole you want. Perfect hole every time.

I would inquire at an electric supply house for a K.O. punch ( knock out )
or a " slug buster ". (IMG:style_emoticons/default/smash.gif)

May be a rentable tool.

KT

Trekkor is the only one posting here with a clue (sorry guys). You should be able to find a tool like he describes at a radio shop that caters to mobile 2-way business FM, HAM, or CB radio. People use them to cut a perfect circle for mounting antennas. I've seen them in sizes from 3/8" to 1". They are designed to cut through auto-body guage steel (12-16ga.). I assume you'd want to use said tool to cut radiused corners for your rectangular cut-outs (as in your illustration)? Should work well for that. IMHO this would be the cheapest and only practical way to cut a perfect hole without warping, edge-deforming, or otherwise screwing up the cut.

-Ben M.

Sorry Airsix, but I totally disagree! (IMG:style_emoticons/default/bootyshake.gif) We use hole saws on every access opening we cut, and there is zero deformation of the material, even in the real thin skins. Hole saws are WAY cheaper that a KO cutter of the same size (a 1/2" radius would IMO look too boxy with the size of holes it appears he's making), with just as clean of a finished hole. Besides, once he cuts out the sides, he'll have to go back with a file (rotary or hand) to smooth out the transistion area anyway. That said, I still think that a template made out of 1/8" hardboard and plasma cutter would be the quickest and easiest way to go.

My 2.5 cents

[airsix]

Here you go.

2\" KO punch on ebay

.Or even better - here they are in any size you want.


-Ben M. (IMG:style_emoticons/default/smile.gif)

[F4i]

(IMG:style_emoticons/default/smilie_pokal.gif)

many years ago on racebikes by a brilliant gent named John Brittain

He will be missed (IMG:style_emoticons/default/sad.gif) ( and it wasnt that long ago)

(IMG:style_emoticons/default/agree.gif) Way ahead of his time.

[bondo]

I don't think that's what brad meant when he said 914s were going to go the way of the 356 (IMG:style_emoticons/default/lol2.gif)

[airsix]

Sorry Airsix, but I totally disagree!  :bootyshake:  We use hole saws on every access opening we cut, and there is zero deformation of the material, even in the real thin skins. Hole saws are WAY cheaper that a KO cutter of the same size (a 1/2" radius would IMO look too boxy with the size of holes it appears he's making), with just as clean of a finished hole.  Besides, once he cuts out the sides, he'll have to go back with a file (rotary or hand) to smooth out the transistion area anyway.  That said, I still think that a template made out of 1/8" hardboard and plasma cutter would be the quickest and easiest way to go.

My 2.5 cents

I just know, having used both ko punches and hole-saws, that if Mike dropped his lid off at my house and said "please cut out these rectangles with radiused corners" I would not dare do it with a hole-saw. I've NEVER seen a hole-saw make as clean or accurately located hole as a ko-punch. In this application accurate location of the hole is really important IMHO. I'm interested in your comment about using a plasma cutter and a template - I've never used a plasma cutter. Maybe that's the way to go.

If I had to do it myself using the tools I have and know, I'd stip the lid, mark it with dykem, scratch-awl precise layout lines, use a compas to locate the center of the corner radii, center-punch and drill pilot holes, enlarge holes to size for ko-punch draw-bolt, ko-punch the corner holes, and then nibble inside the layout lines connecting corners. At that point you'd have perfect corners and rough sides. I'd then use a belt sander with ceramic belts to true up the sides of the rectangles (nibbled cuts between the radiused corners) removing matterial until you touch your layout lines. The important point here is just kissing that layout line. I say belt-sander because that will help you keep the line straight, and only a ceramic belt will hold up to the job (I recommend 3M Cubitron) At that point you should have a perfect rectangle with radiused corners and you've done zero filing or hand-sanding. Now all you've got to do is dress the edges which shouldn't take long at all.

-Ben M.

[Trekkor]

(IMG:style_emoticons/default/agree.gif)

Even better! (IMG:style_emoticons/default/clap56.gif)

KT

[Mueller]

opps, I forgot to mention, it's a 'glass lid..


just kidding (IMG:style_emoticons/default/smile.gif)

I thought about the Greenlee punches Trekkor mentioned, but it seems that with such thin sheetmetal, they might tweak it.....I guess I can try it on a damaged donor lid first (IMG:style_emoticons/default/smash.gif)

[Andyrew]

Whats it for?

[SpecialK]

Well airsix, I guess we'll have to "agree to disagree" on this one. (IMG:style_emoticons/default/beerchug.gif)

The hole saws we use are this type (note the "major aerospace corporation" reference in the discreption. I work at the military aircraft division of the same corporation in St. Louis- see Avatar for clue).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...3834474077&rd=1

These aren't the hardware store type hole saws you'd use around the house. They're made specifically for metal, and cut it like butter (titanium in my case), leaving an exceptionally clean hole. We're in total agreement on using scribe lines as opposed to other marking methods; when the shiny line disappears, you're there. As for the belt sander, I've never thought about using that tool for grinding metal. I suppose with the right belt, it'd work like a champ. I'm a fan of the rotary file, I guess because I use them alot. We use hand files (bastard) to finish the opening because of the close tolerances required between skins and the access doors (which incidentally is how I got nicknamed "Special K" by a friend/co-worker. I'm way to anal about how the assembly turns out...pretty sure he didn't mean it as a complement though (IMG:style_emoticons/default/sawzall-smiley.gif), whatever works for you "is" the best method.

Oh, and by the way, that's a GREAT DEAL on those ebay hole saws so far. If anyone on this board buys them, contact me about the special arbor you'll need to use them.


Kevin

[Scott Carlberg]

Whats it for?

(IMG:style_emoticons/default/agree.gif) er, I mean, good question... (IMG:style_emoticons/default/clap56.gif)


ventilation for the VR6 perhaps???

[neo914-6]

Mike,
Lot's of good suggestions. On the reality rod builder shows, I've seen the fabricators use hole saws and scroll saws and then clean the edge up to the drawn shape with grinding wheels. These are $100k rods with new metal bodies...
Felix