Another vote for hogging waste with a drill, follow up with a router and template, clean up with a chisel.
Another vote for hogging waste with a drill, follow up with a router and template, clean up with a chisel.
"A hen is only an egg's way of making another egg".
– Samuel Butler
How about using a 3" diameter hole saw on your drill? That would define a middle section easier to chisel.Then spade bits to start clearing the middle. It would leave some easier corners to chisel. A three inch forstner bit would be hard to control with a drill, but maybe? That would give a nice clean hole, with only the corners to chisel.
Last edited by Stan Calow; 07-12-2020 at 12:50 PM.
Dynamite ,crowbar and a sledge hammer. In that order.
Last edited by Mike Kees; 07-12-2020 at 7:24 PM.
"All that is necessary for the triumph of evil is that good men do nothing."
“If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals.”
The vibrating multitool is nice for making straight plunge cuts without any setup effort -- if you already have one. Mine sat idle for a long time until I discovered how versatile and efficient it is. Now it gets a lot of use.
If you don't already have one, and don't want to spring for one, I guess drilling and chiseling out the corners is the best approach.
If I had a lot of them to do I might make a template and use the router, then chisel out the corners. That said, for two or three I'd probably just chop them out with a very sharp chisel.
The oscillating multi tools are only about $20 at Harborfreight. Worth it even if you never use it again.
A jigsaw or Sawzall may help.
A jigsaw or Sawzall may help.You will need to shorten the blade and go slow.
Tom, there is a post that butts up to the board I need to cut. So no clearance for a jig saw or sawzall blade.
I borrowed a multi tool from a friend and will try it out this weekend.
The world’s smallest CNC?!?
There is a very fine line between “hobby” and “mental illness.” - Dave Barry
Another vote for oscillating multi-tool. I have a couple of them, one for home and one for work, and a variety of blades. Scribe your line, cut just inside the line with the multi-tool, and then finish it up by carefully paring to the line with a very sharp chisel. If you don't need a perfect hole, the multi-tool may be enough all by itself.
Jon Endres
Killing Trees Since 1983
Chris
Multi tools are very handy for "niche" applications, and this may be one, BUT,,, they do dull rather quickly, so you will need additional blades, AND, they tend to wander. You would be very wise to make a 3"x3" template to control the tool blade angle and alignment.
I have used them to cut holes similar to what you are doing when I had to replace some of the 1" thick barnboard and batten siding. Mine were for 4x4 soffet supports. needed to cut through the barnboard, but not the insulation board and sheathing.
I only had a 1/2 dozen to do, and it took about 10 minutes each. ( I was working on a roof with 9/12 pitch.)
"The first thing you need to know, will likely be the last thing you learn." (Unknown)
The correct answer is the multi-tool with plunge cutter. No doubt. With minor chisel cleanup.