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Plea for help - mortise in 4x4

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Forum topic by rmh09 posted 05-01-2018 07:39 PM 1948 views 0 times favorited 32 replies Add to Favorites Watch
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rmh09

22 posts in 2834 days


05-01-2018 07:39 PM

Topic tags/keywords: workbench joinery mortise

I am attempting to build a fairly basic work bench. The top is glu-lam 5 1/4” thick x 6.5’ long by 22” wide (heavy). For the base I wanted to try thru tenons using 4×4’s. This is a long sad tale full of opportunity to learn from many iterations. I will spare you most of them. I first used a drill press with a 1/2” auger bit to hog out the mortise. There was too much clean up left and the moritise looked unusable unless I wanted to spend hours cleaning it up with chisels. I then went to two holes with the bit and then used a jig saw. Again, not usuable. Then, I went to two holes, jig saw out the waste and THEN use a long straight router bit = 2 1/2”, (flipping the leg to get the 3 1/2” depth). I made a jig for the router using a bushing to keep it within bounds. Nothing seems to get me to a decent mortise. Even after using an ocsillating spindle sander to smooth out the sides, the mortise is down right ugly! I could attach the legs and stretchers with metal brackets but I want to try to figure out if a good square mortise (maybe with rounded corners) is possible. Any help would greatly be appreciated. Thanks!!

-- Randy


32 replies so far

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CRAIGCLICK

117 posts in 218 days


#1 posted 05-01-2018 07:54 PM

I, too suck at mortises..but practice helps a lot. Using scrap soft pine and then moving your way up to harder woods, spend a lot of time on your chisel work and it will pay off.

Use a good straight piece of wood as a guide (place it at the edge of the mortise once you drill it out and use it as a guide for your chisel when paring down the sides and corners….that helped me a lot.

Your other alternative is to find a used mortising machine. I purchased one (a Jet JBM-5) from a fellow Lumberjocks member for 150 bucks and it is TOTALLY worth the money in time saved.

Of course, given the time, I’d rather do them by hand…it helps me “connect” to the project…but when you need to do something right now, the mortising machine certainly is a godsend.

-- Somewhere between raising hell and amazing grace.

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AlaskaGuy

4506 posts in 2454 days


#2 posted 05-01-2018 09:14 PM

Do you have a band saw? Cut a saddle in the post and glue a block in place.

-- Alaskan's for Global warming!

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rmh09

22 posts in 2834 days


#3 posted 05-01-2018 09:36 PM

Thanks AlaskaGuy! I may have to do it your way. The 4×4 is just too thick at 3 1/2” for to get straight sides any other way.

-- Randy

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AlaskaGuy

4506 posts in 2454 days


#4 posted 05-01-2018 10:03 PM



Thanks AlaskaGuy! I may have to do it your way. The 4×4 is just too thick at 3 1/2” for to get straight sides any other way.

- rmh09

I guess you know the first thing you should do is make sure all 4 of your post/leg are square. Start at the jointer and square them up. It will save you grief later when you assemble everything.

-- Alaskan's for Global warming!

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TheFridge

10311 posts in 1631 days


#5 posted 05-01-2018 10:27 PM

It won’t take hours to clean it out with chisels. Unless you have a mortiser or use a router you’ll have to clean it out by hand anyway. The inside of the mortise may be serviceable off the bandsaw but you’ll still need to clean it out with chisels.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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Rayne

1057 posts in 1685 days


#6 posted 05-01-2018 11:05 PM



Thanks AlaskaGuy! I may have to do it your way. The 4×4 is just too thick at 3 1/2” for to get straight sides any other way.

- rmh09

Another way is to take 2 – 2×4’s and cut the appropriate dado’s in each side and glue it together as one.

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AlaskaGuy

4506 posts in 2454 days


#7 posted 05-01-2018 11:11 PM


Thanks AlaskaGuy! I may have to do it your way. The 4×4 is just too thick at 3 1/2” for to get straight sides any other way.

- rmh09

Another way is to take 2 – 2×4 s and cut the appropriate dado s in each side and glue it together as one.

- Rayne

You can also build up the leg using 3 pieces of wood, omitting the area were you want the mortise.

-- Alaskan's for Global warming!

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BFamous

166 posts in 266 days


#8 posted 05-02-2018 01:05 AM

One thing to note, the inside of your mortises don’t need to be pretty…
Personally, I prefer to use a good sharp chisel after hogging out the meat. If the chisel isn’t razor sharp, you’ll be crushing g the wood fibers instead of cutting them. I like to use a chisel the width of the narrowest side of my mortise, it means I can clean up at least two of the sides of the mortise in one pass from each side of the board. The only thing you need to be certain of is that you mortise sides are square to each other and either square or parallel to the side of the board – you don’t want your mortises to be crooked. And that’s easy enough to do using a marking gauge, but you want to ensure you’re right on those marks

Also remember, practice makes (closer to) perfect.

-- Brian Famous :: Charlotte, NC :: http://www.FamousArtisan.com

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rmh09

22 posts in 2834 days


#9 posted 05-02-2018 02:06 AM

This is some very good advice. I don’t think I would have as much of a problem with the mortise if it was normal sized (1 or 1 1/2” thick). This is HD pine 4×4, the mortise measures 2” x3”. Soft wood that “should” be easy to tame, just not by me. Every one that have attempted has been very wonky. Not straight, wavy, and rough on the inside. I will try another method. I really appreciate your help!

-- Randy

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TheFridge

10311 posts in 1631 days


#10 posted 05-02-2018 02:09 AM

I use a 2”x2”x2” square of ebony to register my chisels at 90deg. Not so much anymore but this method worked on my 2-3/4” benchtop.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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Holbs

1959 posts in 2174 days


#11 posted 05-02-2018 04:16 AM

why not go bridal joint? I am currently slogging through 4”x6” for legs & stretchers for my joinery bench.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

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MrWolfe

93 posts in 268 days


#12 posted 05-02-2018 04:25 AM

Rayne’s suggestion works well. You can cut the waste out of each half of the mortise on a table saw with a dado set if you have one. Its easy enough to clamp or tape the two halves of the leg together side by side and run them through your saw on a sacrificial fence attached to your miter gauge. This will make the dados on the two halves exactly the same dimension. Make a plug out of scrap 2×4 that is the size of the tenon and wrap it with packaging tape. You can then glue the two halves of the leg together around the plug/tenon and get really tight alignment. The packaging tape will not stick to the glue and you can knock the plug out with a mallet after the glue sets.
Hope that helps.

A good set of mortise chisels would be great too.

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jimintx

832 posts in 1729 days


#13 posted 05-02-2018 05:12 AM

This video from Paul Sellers helped me understand the best use of chisels for making a mortise. I recommend it.

https://www.youtube.com/watch?v=q_NXq7_TILA

-- Jim, Houston, TX

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MikeB_UK

150 posts in 1180 days


#14 posted 05-02-2018 08:32 AM

I did my first mortises on for my bench as well.
Clean up with chisels seems like it will take an age but gets faster as you get the hang of it..

First one took about 3 hours
Last one took 20 Minutes

Clean up half from one side and half from the other, so you only need to get 1 3/4” square at any one time.

-- If I say I'll fix something around the house I will, there is no use nagging about it every 6 months.

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chrisirving

121 posts in 576 days


#15 posted 05-02-2018 12:08 PM

I did Maloof joints because I wanted the legs to be flush with the sides for a leg vise…and they look good ;). They were fairly easy to cut and fit

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