# How to cut a large square hole in 2x8.



## arthur5005 (Jun 5, 2012)

I'm a bit new to wood working, so greetings first of all! 

I have a project where I'd like to cut a large square hole into my 2x8s. The hole is supposed to fit a 4x4 going straight through the board. I need to repeat this a number of times. 

I tried my hand at cutting this myself with my drill for the initial holes and cutting along some lines I drew with my jigsaw. The results were pretty 'meh'. I found my jigsaw in some places had not cut straight down, meaning the cuts were tapered, so I was revisiting the square with my jigsaw a number of times before I got my 4x4 through. By the time I got the 4x4 to fit, the hole was pretty loose.

Is there a good mortising technique or machine someone can recommend to cut square hole this size in a consistent manner? I was thinking of using a mortising machine, but the drill bits seems a little small for my project, and could be pretty time consuming. 

Mind you, I'll take precise and consistent over getting it done 'fast' for this part of the project.

Thanks!!


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## michelevit (Apr 30, 2012)

I'd use a hand held router with a brass bushing. Create a template with 1/4 inch luane or mdf and clamp it to the wood. Route away. The template will ensure repeatable precise cuts.


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## Fred Hargis (Apr 28, 2012)

You didn't mention what tools are available, but my approach _might_ be make a template and use a plunge router with a bushing. Such a cut would still leave you with rounded corners in the hole, which would need to be squared up....should not be too hard on 2X stock. Or, you could round the corners of the 4x4's over to match the radius of the bit you used.


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## cabinetman (Jul 5, 2007)

I would use a dedicated mortiser, or one of the better drill press mortising attachments. 








 







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## SeniorSitizen (May 2, 2012)

Check the blade for square to the base plate of your saber saw and buy a new quality 6 tooth blade. A dull blade causing one to apply too much pressure can result in what you are seeing. If chipping out at the cut line is a concern cut from the bottom side that won't be visible. If that isn't possible masking tape applied to the visible side often helps with chip out.


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## Dominick (May 2, 2011)

Do you have a chainsaw? How accurate does it need to be? Plunge cut it with a chainsaw.
If you need accuracy then do what's been said.


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## jschaben (Apr 1, 2010)

arthur5005 said:


> I'm a bit new to wood working, so greetings first of all!
> 
> I have a project where I'd like to cut a large square hole into my 2x8s. The hole is supposed to fit a 4x4 going straight through the board. I need to repeat this a number of times.
> 
> ...


Looks like you have plenty of input so far. My personal choice would be a router with a 1/2" plunge bit. Use a 1/4" roundover on the 4x4. 
That said, another option would be a multitool. Would be a lot of cutting for one of those though. :smile:


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## DaveTTC (May 25, 2012)

cabinetman said:


> I would use a dedicated mortiser, or one of the better drill press mortising attachments.
> 
> 
> 
> ...


Definitely agree a mortise attachment for drill press is an option. 

Personally, for speed and efficiency, I would stick with the jig saw unless it is an internal application where absolute tight fit is imperative. 

Mentioned in an earlier post was need for 'sharp blades'

When cutting through thicker boards where a square edges cut is desired, I always cut towards myself to control which way the blade wonders. You will find that by watching the angle the blade is entering the timber you can compensate pressure on the saw to keep a square edge. 

That being said you may find that by setting up a jig you can do it just as quick with a router. I would consider a jig if extreme accuracy was desired or if I had to repeat the action more than 10 times

Dave The Turning Cowboy


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## DaveTTC (May 25, 2012)

This is an example of a job I did back in 1993/94 using the jig saw technique described above. The material there was 11 x 2 from memory.

Dave The Turning Cowboy


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## jharris (Jan 8, 2011)

Or you could plunge cut the majority of the mortise with a CS and finish with the jigsaw.

I had a Skil jigsaw and found that it had a tendency to cut off 90° but if I slowed the rate of cut I could get closer to a 90° cut.

Notice I said "closer".

I finally got fed up with the Skil (it takes alot of Skil to overcome the poor quality of these tools) and bought a Dewalt that I like very much.

Based on opinions I've read here, if your considering a new jig saw look at Bosch as well.

If you have alot of these mortises to cut but like me can't find room in the budget for a mortising machine use the template/plunge routing method and round over your tenons using a router table with a stop block attached to the fence.

Just my 2¢ (worth about a penny in this economy).

Good luck with your project. Please keep us posted on your results.

Jeff


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## arthur5005 (Jun 5, 2012)

So much great advice. You guys rock, I'm going to give the plunge routing method a go, and compare that to another go at it with the jigsaw and the recommended blade! I really want to get this part right.


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## DaveTTC (May 25, 2012)

arthur5005 said:


> So much great advice. You guys rock, I'm going to give the plunge routing method a go, and compare that to another go at it with the jigsaw and the recommended blade! I really want to get this part right.


Be sure to let is know how it went and what worked for you

Dave The Turning Cowboy


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## Fred Hargis (Apr 28, 2012)

If you try the router trick, be sure to remove most of the waste before your route it out...just makes life a little easier. You'll also need a really long bit, if you don't have one long enough you could cut 1/2 of it with the template, then flip the piece and flush trim it from the other side. Good luck with whatever appraoch you choose.


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## Steve Neul (Sep 2, 2011)

I think I would cut the holes out with a jig saw, cutting about a 1/8" inside the line. Then true the hole up with a router with a templet. Thats a hard cut cutting 1 1/2" with a router.


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## cabinetman (Jul 5, 2007)

In assessing what tool to use to make the opening, the OP hasn't made clear how square the corners must be. Off the shelf 4x4's could have sharp edges or slightly eased edges. 

His use of just a jig saw and continued dressing of the opening sounds like the corners could be square (how sharp we don't know...yet). So, getting back to the tool and the method, unless the mortise has corners eased to fit a similarly shaped tenon, I wouldn't use a router. No router bit would leave a sharp corner. 

If there will be more than one or two, I still suggest a hollow chisel mortiser of some type. An outline, or a guide jig could be configured to mortise a perfect pattern. I think this method would be the least aggravating.









 







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## woodnthings (Jan 24, 2009)

*depending on the corner needed...*

For a sharp corner the jigsaw will work.
For a small radius corner, just predrill the corners with a 1/2" or 3/8" drill so the holes are within the desired lines and then use a jig saw to remove the waste.
A hollow chisel mortiser is not a "common" piece of woodworking machinery for most home woodshops. It took me 50 years before I got one at $380.00 or so. Drill press attachments are under $100.00, so that's a more economical approach. 
A good blade for a jigsaw that is already in the shop will be the cheapest way to go....about $5.00 for the package. 
If the jig saw is not performing to the quality needed it may be time to upgrade to a Bosch, or other high quality saw, I donno?  bill

BTW a hand mortising chisel used with a jig saw could also be used to clean up the sides and corners....


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## jschaben (Apr 1, 2010)

Maybe use a combination of the router and jigsaw to keep from breaking the bank. Route a groove, say 1/2" wide by 1/2 or 3/4 deep using the template. Cut out the opening with a jigsaw, just need to keep the kerf inside the width of the groove. Follow that up with a flush trim or pattern pattern bit to clean up the cut. Inside corners can be squared up any number of ways but, my personal preference is for eased edges so I would just round over the 4x4. 1/4" roundover would match the corners left by a 1/2" router bit.:smile:

I haven't got a mortiser but it seems like a hard way to go on this one. Wouldn't a 1/2" mortise chisel take about 30 cuts to get around a hole that size??


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## cabinetman (Jul 5, 2007)

jschaben said:


> I haven't got a mortiser but it seems like a hard way to go on this one. Wouldn't a 1/2" mortise chisel take about 30 cuts to get around a hole that size??



You can get a ¾" chisel and bit attachment for a DP.










 







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## SeniorSitizen (May 2, 2012)

We must be completely out of something to do or find it real entertaining batting around all the possibilities of how to do this when we have not the foggiest idea if this is outdoors on a deck with pressure treated wood where the deck boards are fastened down or inside a million dollar house.

A true craftsman knows how to cover rough work so attach a cove molding around the rough too big loose hole and get on with the show.:laughing:


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