How to cut a "pretty" hole in steel siding.

[green.bubbly]

As I have been building my house, one thing kept eating at me. Cutting holes in my exterior walls for vents. The idea of cutting holes in my nice steel siding has kept me up a few nights. It kept stressing me out.

Well today, I tackled my nemesis. I needed to run two vents for my bathroom exhaust fans. First thing I did was get a scrap piece of metal and started experimenting with my RotoZip. I picked up some metal cutting bits and a circle cutter. No good! Bit would not really cut without a lot of fighting.

I found a grout bit and played around with that. It actually cut better than the metal cutting bit. The bit is basically a round rasp. Still had trouble cutting a nice circle even with the circle cutter. It would wander and the circle cutter would pop out of the guide hole.

Then I decided to cut a circle template out of wood. Inserted the grout bit so that the smooth part of the shank was sticking out just enough to follow the wood circle. I secured the wood template to the steel with two screws.

The first hole took me all morning and into the afternoon to get the procedure down. The second vent took all of 30 minutes.

Hopefully the pics below help explain things better.

 

[4StarCstms]

Good advice - thanks for sharing

 

[cyamaha2007]

Did you try a hole saw ive heard they work ok?

 

[green.bubbly]

Did you try a hole saw ive heard they work ok?

I fought with a hole saw on the purlins of my garage. I am not sure how a 4 or 6 inch hole saw would work on PBR sheets with the humps.

 

[cyamaha2007]

i figured so ill have to use this as a excuse to buy a roto zip. ive had a use for one but now i have a sloution with one thanks. And this very problem has been bothering me for a few weeks. I have no idea how some people do this with a pair of tin snips. Is your entire building metal siding and roof?

 

[green.bubbly]

i figured so ill have to use this as a excuse to buy a roto zip. ive had a use for one but now i have a sloution with one thanks. And this very problem has been bothering me for a few weeks. I have no idea how some people do this with a pair of tin snips. Is your entire building metal siding and roof?

Yeah, I did a lot of Google searching and I never really came across any good methods of cutting large holes other than tin snips.

Yes, my entire house is metal. My sig has a link to my build.

 

[Possum]

http://www.grainger.com/Grainger/MA...ng Tools-_-1ELH8&ci_src=14110944&ci_sku=1ELH8

 

[Slick6]

I've cut several holes in steel siding with holesaws. I'm not trying to put you down but those two holes would have taken all of two minutes. One thing you can do with hole saws is drill a 1/4" pilot hole in the center, then place a 1/4" rod in your hole saw arbor to keep it aligned and use the hole saw. Keep the holesaw perfectly perpendicular to the siding. So if you are cutting a hole where there is a ridge and a "low spot", cut into the ridge until it reaches the low spot and continue cutting. You don't want to use a lot of pressure on the drill, let the bit do it's job slowly otherwise your drill might try to throw you around.

 

[socapots]

http://www.grainger.com/Grainger/MA...ng Tools-_-1ELH8&ci_src=14110944&ci_sku=1ELH8

probably wouldnt work so good with non flat surfaces..
as in the humps in the siding..
Cool tool none the less.

 

[6768rogues]

I have used a hole saw (metal cutting blade) and a die grinder with a 3 inch cutting wheel. The die grinder works well for larger holes. I cut inside the line then trim it to perfection.

 

[green.bubbly]

http://www.grainger.com/Grainger/MA...ng Tools-_-1ELH8&ci_src=14110944&ci_sku=1ELH8

I had looked at those but I do not see where it would cut anything other than flat steel. My siding is like the PBR sheets with humps/valleys.

I've cut several holes in steel siding with holesaws. I'm not trying to put you down but those two holes would have taken all of two minutes. One thing you can do with hole saws is drill a 1/4" pilot hole in the center, then place a 1/4" rod in your hole saw arbor to keep it aligned and use the hole saw. Keep the holesaw perfectly perpendicular to the siding. So if you are cutting a hole where there is a ridge and a "low spot", cut into the ridge until it reaches the low spot and continue cutting. You don't want to use a lot of pressure on the drill, let the bit do it's job slowly otherwise your drill might try to throw you around.

I used a hole saw on one of my purlins. It was terrible. It would walk and wobble and break the bit. I ended up replacing the bit with a screwdriver shaft and that made it better but I was still not comfortable trying it on PBR sheet metal with the humps.

Guess it was the fear factor. I searched and searched for a video of somebody using a hole saw but could not find one so I figured that would not be a good option.

 

[nehog]

I cut my larger diameter holes in the metal siding with a Dremel and a cutoff blade. Takes me about 3 minutes to cut the holes. Just did the vent for my new heater the other day. Basically I draw a circle the right size then cut around that circle.

 

[Nighttrain]

Green.B I think you are like me in over thinking our builds. In the long run you cut a nice round hole but then you covered it up with the vent cover and can't see it anyways! I will probably use your idea though if I put in a heater/vent in my shop.

 

[jdub63]

Looks like a good solution for the larger holes. thanks for sharing.

jdub

 

[Milton Shaw]

Heating and AC suppliers have Malco circle cutter model HC -1 That cuts from 2 to 12 inch holes using a side cutting drill bit in a bearing guide unit. They are about $50 and well worth the money if you have over one or two holes to cut. Get and extra bit and they will cut a lot of holes before you have to replace it. Works much better than the RotoZip circle guide and bit set.

 

[Provincial]

I cut holes through my ribbed steel siding by marking the finished hole size using a compass with a pencil on one leg. Then I used a 1-1/2" hole saw to make a starter hole. I used Wiss Aviation Snips to cut the hole to size. Spiral out leaving 1/4" of material inside the line. Make your final cut to the line and it will not warp, since all the distortion goes into the thin waste strip. The edges will be slightly rough, but the trim from your penetration piece covers that.

The purlins on my steel building were tempered steel and very hard. The plumber borrowed a knockout punch from an electrician after dulling his hole saw, and it barely punched a 2" hole at maximum hydraulic pressure - the punch normally will punch a 4 1/2" hole. I discovered that I could drill holes for 1/2" and 3/4" conduit with a Harbor Freight step drill. I thought I would eat them up quickly, even though I was using Thread Cutting Oil to lube them, but one bit has lasted for the whole project! I use a Milwaukee 1/2" drill to run it, and keep it slow with the variable speed trigger. I find that the HF step drill doesn't drill the pilot hole well, so I start with at least a 3/16" regular drill.

To make a hole for a 3" PVC vent pipe I laid out the 4 1/2" circle, then laid out an octogon whose sides touched the circle. I drilled 3/16" holes at the points of the octogon and connected them with a cutoff wheel on a 4 1/2" grinder, leaving an octogon hole with radiused corners.

I did similar work on an older steel building that didn't have hardened steel for the purlins and girts. On that building I used a Harbor Freight air nibbler and it ate the steel like butter! These girts broke the cutter within a few inches. I would have used the nibbler to cut the holes in the siding, but I had broken the bit on the girts!

 

[mgilde13]

For smaller (3" and under) holes in sheet metal nothing works better than a chassis punch. Clean cut and no distortion of the panel.

 

[rockchucker]

I use a Carbide Grit Hole Saw to get through the Metal. Then switch Hole Saws to a Wood Hole Saw and finish up through the Wood. The "Bi-Metal" Hole Saws really **** for cutting through thin Metal. Once one tooth goes through the material the saw will bind really bad or rip apart the material if you are lucky. This is why I use a Grit based Saw on thin metal. Slow RPM and just let the Saw do the work of course.




The Carbide Grit and the Masonry Hole Saws are really good for cutting through Stucco and other really hard Concrete based House Coverings.


Masonry...

http://www.amazon.com/dp/B0043FJQZS/?tag=atomicindus08-20

 

[Possum]

I will do great on the smaller ribs. I can attest to this. Probably not the large ribs. I avoided them in my application.

probably wouldnt work so good with non flat surfaces..
as in the humps in the siding..
Cool tool none the less.

 

[Gary S]

Why not a chain saw?

 

[Dustball]

I'd whip out my plasma cutter for that.