Leaving a long story for another day, suffice to say my roofer let me down in many ways. One of which was in the installation of two bathroom vent fittings that they'd failed to put the male end onto prior to mounting, and subsequently misaligned the hole in the vent to the hole in the roof.

My roof is a VERY low pitch (almost flat), so I'll have to slide back to there on my back in 60 years of mouse droppings, dust, rockwool and rusty nails. Yay.

I need to trim out some plywood without hurting the metal fixture. I was hoping to find a tool that is something like a Dremel, battery powered, and powerful enough to grind out some plywood in fairly short order.

I looked at HD and Lowes but didn't see anything obvious. I thought perhaps someone here would have some good ideas.

Thanks guys!

Roto-tool?

https://www.amazon.com/Makita-...d=1603643413&sr=8-14

quote:

trim out some plywood without hurting the metal fixture

I'd just put some strong tape inside on the metal (to protect from scratches) and use a thin blade jigsaw.

Geez, that's gonna be a serious PITA

If you don't have the knowledge to do it from the top, yourself, I'd consider hiring a new roofer to come over, pull the necessary shingles, fix the damn thing right, and replace the shingles. Done right: It'll have zero impact on the integrity of the roofing job.

(In my case I'd have to hire expensive, factory certified guys, because our roof is warrantied for fifty years.)

The only tool with which you could do it from underneath that comes immediately to mind is a RotoZip, but they're hella messy and you'll have to use a pre-cut template to control the cutting path.

Re: "Hella messy": I cannot imagine doing what you want to do, with the hole overhead, in cramped quarters, with a RotoZip or any other powered cutting tool.

I too thought of Roto-Zip, but they are not cordless.

Maybe an oscillating tool and some patience.

I would have to go with a jigsaw for that. It will be more controllable that a rotary tool. Be sure to mark the cut first.

If you have (or can borrow) a router:



https://www.homedepot.com/p/DI...it-DR44100/202585369

Something like a Rotary Rasp in a cordless drill be precise enough ?

For $20 you can get a mini router from harbor freight...not cordless though.

If you end up needing to use a corded Router or Dremel, and have a light bulb socket in your attic, you could buy one of the light-socket-to-plug adapters to shorten the run for your extension cord.

I have used a roto zip blade in my cordless drill.

Insert to desired depth in chuck.

The speed is much slower and allows you to better control the bit.

Draw your circle and have at it.

Oh, you can also then use a deburring tool in your drill to clean up the edges.

They also will cut albeit much slower...

Why do you need to cut anything? That vent looks like the kind that you just point the duct towards it but not actually connect to the duct work.

I've used dremel cutoff wheels in a cordless drill and they work fine.....if cordless is needed that is the way to go. I bought a dremel cutoff diamond blade wheel.....it was almost $30 if I remember, but that little wheel is a monster in the way it cuts.

What ensigmatic said, do it from above, or hire someone to do so. I'm a production manager for an exteriors company, and my crews do quite a few roofs every year, FWIW. Not just taking a wild guess - it's what I'd do on my own home.

I've used a jigsaw to cut things like that, no big deal.

I’d use a hole saw on a cordless drill. A short piece of wood across the hole screwed in place across the other side of the hole is wanted. To guide the hole saw via its arbor pilot bit.

After repair, sue the idiot who did this to recover your costs....

quote:

Originally posted by M1Garandy:
I too thought of Roto-Zip, but they are not cordless.

They used too make cordless models, surely they still do.
If not, other companies do.

Take your pick...
https://www.google.com/search?...B8_XtAa3n5LQBg42:603

They make a bit for wood. It will chew up that plywood with little effort.
They also have a hole attachment.