aligning holes for through the roof mast

[flyinbubba]

Does anyone have a suggestion for exactly aligning the hole in the eve with the hole in the roof deck for a 2 inch service mast. I start with a 2 and 1/2 inch hole in the eve, since I can obviously pinpoint exactly where it needs to be. Then I use a long bit and attempt to drill a locator hole in the roof deck by drilling up through the hole in the eve and attempting to hold the drill plumb. This rarely works very well. I almost always have to enlarge the hole in the roof in order to get the mast plumb. It's not a big deal since the flashing will cover the hole, but if there is a way to get it exact each and every time I'd sure like to know how to do it. Thanks.

 

[WorkSafe]

A plumb bob?

 

[muskrat]

Put your level on the barrel of a .22 and fire off a round. Dont use a shotgun as the flashing won't cover.

 

[Hendrix]

I always used a 18" pilot bit with my hole saw. You just have to get it fairly streight.

 

[Dennis Alwon]

You have some play with the boot on the roof so the holes doesn't have to be perfect but a plumb bob or laser works well. I usually just eyeball it.

 

[kwired]

It has been a while but I remember someone posting a picture of a piece of pipe with a hole saw welded to the end of it and some kind of drill adaptor welded to the other end.

Looked like it would work great but never tried it.

 

[Dennis Alwon]

I believe that was Ken but the picture is not available in that thread anymore. Maybe he will repost it.

 

[Jim W in Tampa]

Put your level on the barrel of a .22 and fire off a round. Dont use a shotgun as the flashing won't cover.

Sounds like a winner. I been useing my chain saw.

Seriousl just start with small bit

 

[hurk27]

I always used a 18" pilot bit with my hole saw. You just have to get it fairly straight.

This is what I also do, and have done for years, after using a standing up straight Iwire (plumb bob):grin: or level to mark the center of the hole, using the long pilot bit to mark the center of the hole on the roof side, then just follow the hole back down or drill from underneath if you don't like burning up hole saws on roofing material.


Sorry Bob just had to do it.:grin:

 

[480sparky]

Piece of cake.

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[K8MHZ]

It has been a while but I remember someone posting a picture of a piece of pipe with a hole saw welded to the end of it and some kind of drill adaptor welded to the other end.

Looked like it would work great but never tried it.

We call them bell bits and they do work great! You drill up from the bottom and with a long enough bit sometimes you don't need a ladder.

I have never seen them for sale, just home brew.