How to “drill” a square hole that is not open in the back?

[Chris Sherwood]

I’m sure there is a better way to describe my situation. I need to cut a square opening about 3”x3” into a piece of pine. This piece is backed against a PT post. So no chance to use a jig saw. I made the first one by starting with a series of drill bits around the perimeter, then used a chisel. It worked but wasn’t fast.
I’ve seen ads for “roto” tools or something like that to cut drywall. Is there a different tool, or some other technique, that I should consider?

In case you’re interested, this is to install door stops for stable doors. Definitely a honey-do item.

[John K Jordan]

I’m sure there is a better way to describe my situation. I need to cut a square opening about 3”x3” into a piece of pine. This piece is backed against a PT post. So no chance to use a jig saw. I made the first one by starting with a series of drill bits around the perimeter, then used a chisel. It worked but wasn’t fast.
I’ve seen ads for “roto” tools or something like that to cut drywall. Is there a different tool, or some other technique, that I should consider?

In case you’re interested, this is to install door stops for stable doors. Definitely a honey-do item.

Can you pry, cut, or otherwise remove the pine piece from the PT post, make your holes in it (or a new piece of wood) then reattach?

A rotozip took works well for drywall and I've used mine to cut 1" thick wood, but I don't think it would work as well for a deep hole. But I don't see where you say how deep the hole needs to be.

A multitool can do decent plunge cuts with the right blade. I've used my Fein multimaster on a variety of materials, solid wood, plywood, composites, plastics. But again, I didn't have to cut very deep.

JKJ

[Paul F Franklin]

If it's not real deep, a router with a template would quickly hog out most of the waste. Then you'd have to square up the corners. Makes a bit of a mess.

[Chris Sherwood]

The hole is the depth of a 2x4 (1 1/2 inches).
I can’t pull off the board first because it is tongue and groove. Would a multi-tool work for this? I’ve never used one.
I don’t think I can easily use a router because there are so many inconsistencies in the area I need to cut ( near an edge and a “window” opening.

[Bill Dufour]

That hole is too big to drill with a rotary broach which can give you a square or hex hole easy enough with the correct bit.
Bil lD

[Frederick Skelly]

The hole is the depth of a 2x4 (1 1/2 inches).
I can’t pull off the board first because it is tongue and groove. Would a multi-tool work for this? I’ve never used one.
I don’t think I can easily use a router because there are so many inconsistencies in the area I need to cut ( near an edge and a “window” opening.

Im brainstorming. I dont know if either of these will work for you, but wanted to give you ideas:
* Would a smaller trim-type router work in this area? I searched for "very small electric routers" and this came up LINK
* Another idea - though man, it's crude - was to use a die grinder with rasp bits to hog out the waste and then trim it up with chisels. Makita makes one for $100. LINK Amazon sells rotary rasp bit sets for $10. Harbor Freight sells one ("long shaft die grinder") for $50 and the rasp set for $8. But like I said, this is very brute force and crude.

Good luck!

[Phil Mueller]

How many do you have to do? The drill and chisel may be faster than figuring out what other tool to use. If you’re looking for fast, how about a 3” plumbers hole saw?

[ray grundhoefer]

What about a 3 " forstner bit or self feeding bit like plumbers & electricians use. Would still have to clean out the corners but the center would take less than a minute.

[Chris Sherwood]

Appreciate the replies.
A larger bit doesn’t help that much because ultimately I still have the entire perimeter to chisel. Getting the center wood out isn’t the problem.
I could try my router but I think best case I may only be able to use it for parts of the perimeter.
I may just continue with the drills and chisel and a) envision myself building a barn in yon older times (uhhhhh except for my electric drill...) and b) use this as an opportunity to practice on my chisel sharpening skills.

[Phillip Mitchell]

You are basically just making a 3x3x1 1/2 deep mortise. I would continue with drilling and chopping and find some Zen in the task or make a mortising template for a plunge router if you have one. You would still need to chisel corners, but it could be a little faster overall and less chisel work depending on what size router bit you use. You’d have to screw / clamp the template to the jamb/whatever is it you’re mortising...kind of like you would do if doing mortises for regular door strikes / deadbolts, hardware, etc. It will be louder and dustier, but it could be faster and would give you a consistent mortise depth a bit easier.

How many do you have to do? That would help inform my approach.

[Jim Becker]

Remove waste initially with a drill and depth stop. Make a template that you can use with a bearing guided router bit to clean the edges...it can be stuck down with the painter's tape and CA glue method to the board you need to mortise in. Clean the corners with a sharp chisel.

[Chris Sherwood]

I’ve completed one, three more.
Depth isn’t necessary because the section I’m removing isn’t attached at the back. I’m removing a section of a board that is attached at other ends of the board.

[Curt Harms]

I have a Grizzly trim router. The fixed base with a 1/2" straight bit is 1 1/2" from the edge of the bit to the edge of the base. Don't know about other small routers. If you do much with woodworking/DIY, a small router is handy, as is a multi-tool. The only way I know to get a square corner involves a chisel or multi-tool.

[Ron Selzer]

multi tool with a plunge blade, a self feed plumbers bit to hog out the middle first would speed things up, however need a good slow drill to power it

[Brian W Evans]

I like the multi-tool idea. I don't use mine much but, when I need it, I really need it. Nice thing to have around.

I might remove most of the material before using the multitool. I like the hole saw idea for this.

Of course, by the time you get to the store and buy these things, you might be done drilling and chiseling. You'd also be $200 richer if you did it by hand.