# Repeated half lap using a router table



## jcmilam (Apr 14, 2009)

I'm just getting back into woodworking and have a new router and router table. I'm building a stand for cub scout adventure belt loops.

Horizontal pieces will be about 3/8 inch thick and will be held by a center support piece going vertical. I want to dado or half-lap just that vertical piece so the 3/8 think horizontals sit flush. There will be 5 horizontal pieces.

Roughly similar to the photo attached, but nicer.

I don't have a very accurate table saw and no dado set for it, so I want to use the router table. I'm struggling to find something online that will work, to do this evenly several times without a ton of setup or measuring.

Advice greatly appreciated. Thanks!


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## Quillman (Aug 16, 2010)

I would not do this on the router table.
Everything will tearout without edge back up.
At least you can do some back-clamping with hand routing.
Moreover, I know of nothing in routing that doesn't require careful
measuring & setup. It's the nature of Routerdom.
Get some right angled fixtures and verify them to be 90°.
Clamp them to the work and rout the space x 1/2 thickness.
If you use the x-piece to space the guides, you can use a flush trimmer to rout the space.
The nuance of the rout may take an afternoon or more.
Use scrap. Nuthin's easy or fast if done well.
But the extremely talented will get the hang of it quickly.
Not me, took all day to figure the nuance.


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## Cherryville Chuck (Sep 28, 2010)

Much like what Pat says. Your best bet is probably to put the crosspieces on one at a time and scribe where they cross. Then clamp a board against the scribe line and use a bearing guided mortising bit which will ride against the board. That could give you a pretty good fit.


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## furboo (Oct 12, 2015)

Great advice, Jeremy. You might also try a shallow cut, rather than the full depth on the first pass.

Very nice idea for a project.


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## old55 (Aug 11, 2013)

Welcome with your first post Jeremy.


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## DesertRatTom (Jul 3, 2012)

Start by making an exact width dado jig. Pretty simple to make if you look it up on YouTube.

Assuming you're using pre cut material, you'll line up 6 pieces. Find the center of the length. and then center a cross piece on that and mark the width. You'll use this marked piece to guide the dado jig to cut the center groove in all the rest of the pieces at one time. Clamp all six pieces together carefully and using an accurate square, align the jig 90 to the six pieces. Add a sacrifical piece to each side of the bundle to prevent chip out. Set the bit to cut to an appropriate dept, probably no more than 1/3rd the thickness of the work pieces.

Clamp everything up carefully while checking that everything is square and aligned. Clamp the jig in place and adjust it to exact width of the work pieces.

Make passes with a Mortising bit with a bearing.

Remove one piece from the pack which will become your vertical center piece. Position the remaining fice cross pieces on the center stick, moving them until you have the spacing you want. Mark their position, then set up the exact fit router jig (already pre-set for width. You will want to put in some mdf on each side of the center stick to present tearout, but also to add width to attach the jig. I would consider setting up an outrigger pair of sticks near the ends of the jig for added stabillity. Clamp down, rout the groove (2-3 passes) about 1/3rd the thickness of the piece.
I notice the 5 sticks stand proud a little bit, thus you won't cut to half the thickness.

Unclamp the jig, but not the workpiece, reposition to your marks, clamp, cut. and repeat for the remaining cross pieces.

If you've done this right, you will have a tight fitting, flat bottomed grove you can glue up, then use a decorative tie.

Another method using a pull saw, chisel and rabbit plane

Mark pretty much as discussed but also mark your desired depth as well. Being careful, use the pull saw across the workpiece and cut to just shy of the depth mark. I'd use an engineer's square to guide the saw. Cut carefully to the depth mark. Cut both edges of the groove (probably 10-12 pulls each cut), then make a number of cuts in between. Use a chisel to roughly clean out the cut, then a rabbit plane to flatten the bottom. I'd use a much wider piece of material to cut grooves, then rip the five cross pieces from that. The cross pieces only have one groove, the other, center piece has five grooves, but one is centered so you can cut it with the rest. 
If this is being made of pine, I'd consider taking a good, 5 foot long 1x5.5, cutting it in half and gluing it into a panel wide enough to cut 6 pieces from. If you have the plane, a decent pull saw and sharp chisels, I'd probably just do it by hand. You'll also need a marking gauge to have a uniform depth mark. the pine will be easy to work with and you can generally find a decent 5 ft length of 3/4 pine. 

You could also use a router plane to flatten the bottom, if you have one. It will give you greater accuracy on the depth of the groove.

OK, that's my take.


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## Everend (Mar 15, 2013)

can you cut the half laps before cutting each piece to size? So if you are starting with a 1x6, cut the half laps before ripping the board down to final width. This way you can cut the half lap on several pieces at the same time and the wider workpiece will be more stable. If you have a miter guage or crosscut sled, score the edges of the half laps there, then clean up the waist between your table saw cuts with the router. Depending on your setup, you may have an easier time setting up support blocks on your table saw so you get the clean edge there.


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## DesertRatTom (Jul 3, 2012)

Everend said:


> can you cut the half laps before cutting each piece to size? So if you are starting with a 1x6, cut the half laps before ripping the board down to final width. This way you can cut the half lap on several pieces at the same time and the wider workpiece will be more stable. If you have a miter guage or crosscut sled, score the edges of the half laps there, then clean up the waist between your table saw cuts with the router. Depending on your setup, you may have an easier time setting up support blocks on your table saw so you get the clean edge there.


You can do that, yes. But make sure the board is quite flat, particularly no twist.

You said your table saw wasn't great, but if you have a blade that cuts a flat bottom to the groove, you could do this on a sled. Carefully mark the correct width of the cuts, then "sneak up" on the full width of the groove making repeated passes. If the bottom isn't flat, you could go over it with a rabbit plane or sandpaper attached to the narrow edge of a wood block--although sandpaper is likely to round over the edges a bit. which likely won't matter much if the bottom is really flat.

Theoretically, you could do the sneak up method on a sliding miter with the depth stop set to give you the correct depth. You will need a cross cut blade with flat top teeth, or cut with an ordinary blade a little shallow and clean up with a rabbit plane or router. You might get away with flattening with a very sharp chisel, but it's unlikely to produce a flat bottom. If the bottom isn't perfectly flat on every groove, the five cross pieces won't line up straight so they'll appear cattywampus.

A router plane would be a great solution for the cleanout because it will produce a bottom that is consistently flat and parallel to the top surface on every piece, and they are fun to use. Makes you feel like a serious woodworker :wink:


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## Knothead47 (Feb 10, 2010)

Never thought of using the router for a half lap. Me? I mark where the cut will be, run it through the TS, cutting the outsides first. Then, I repeat the passes on the TS. I either move the wood back and forth or use a wood chisel to clean it up.
Note: This is all done very carefully.


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## jcmilam (Apr 14, 2009)

*Thanks!*

OP here, thanks all. Lots to think about. I'll reread everything later today and decide which way I want to try. If I decide to use the router handheld with a wood piece clamped on top and lined up with where I need to rout (as described in the first few replies) this would be the correct type/size bit, correct?

(I can't post a url)

Freud 50-116 Top Bearing Flush Trim Router Bit, 3/4" Diameter by 1" Carbide Cutting Length 1/2" Shank

Amazon: Freud-50-116-Bearing-Diameter-Carbide


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## DesertRatTom (Jul 3, 2012)

Knothead47 said:


> ...This is all done very carefully.


Amen to that. In fact, that's why I popped for the Veritas router plane. It is a joy to use. Precise and consistent depth, perfectly flat bottom every time. Great for inlays too.


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## OPG3 (Jan 9, 2011)

Jeremy, Welcome to the Router Forums and Happy New Year!

I find myself needing to do cuts like this frequently, but unlike the previous posters - I use my SCMS (Sliding Compound Miter Saw). If you have one or have easy access to one... Start with scraps and set the depth stop as needed to remove half of the thickness, several adjacent passes and you've accomplished the required width. Set-up some stop and start marks or whatever method you like. As an example if you need 20 - of these with a 2" wide x 1/4" deep slot 9" from one end, set-up a stop at 9" and 11" from your blade. Make all 20- cuts, then tackle the others like that. If you concentrate on what you're doing, it should go pretty fast. In my shop, we do this kind of thing very often.

Otis Guillebeau from Auburn, Georgia


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## Everend (Mar 15, 2013)

OPG3 said:


> I use my SCMS (Sliding Compound Miter Saw). If you have one or have easy access to one...


Otis, I got a new Dewalt SCMS this year, only the top end saw had the depth stop to it. The one I got was on sale for about half the price of the full price top end one. It would have been a good feature but not worth $400 more.


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## Everend (Mar 15, 2013)

jcmilam said:


> OP here, thanks all. Lots to think about. I'll reread everything later today and decide which way I want to try. If I decide to use the router handheld with a wood piece clamped on top and lined up with where I need to rout (as described in the first few replies) this would be the correct type/size bit, correct?
> 
> (I can't post a url)
> 
> ...



I don't think I would use a 3/4" bit for this, rather use a smaller bit and make more passes. If you do use that large of a bit then hog the center of the half lap out first then work toward each edge of the lap. This way the bit is cutting only the edge, when cutting the edge. If you start with the edge cut and that large of a bit you're removing too much wood at one time to get a perfect edge. - can someone else chime in here, I'm not explaining that very well.


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## DesertRatTom (Jul 3, 2012)

If you use any kind of saw, make sure you get one with at least some teeth ground flat on top so the groove bottom is flat. Definitely will need to experiment with scrap to get the right gap.

@Evernend If using a long bit to make a shallow cut your guide bearing will be pretty high and more prone to tipping,which would mess up the appearence of the groove. I would use a fairly short flat bottom bit, like a hinge mortising bit, so the bearing is supported very close to the cut. In looking at the original picture, I noticed that the cross pieces are proud of the center stick, so I don't think the cut would be deeper than 1/4 inch, which on a 3/4 piece of stock would give you about 1/4 inch proud. Thinner stock would be proportional in thickness. Half inch stock could probably be done in a single, unhurried pass. Not sure you can get a hinge mortise stock in a half inch shank, but its short length would easily be adequate for this kind of a cut, and you can get it at immediately at the Home Depot's Freud display. 

Man,this string sure demonstrates that there are many ways to do most things in woodworking. Cool discussion.


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## woodknots (Mar 7, 2012)

Just want to bring everyone back to the original question - the OP ONLY wants to dado the vertical piece and the horizontal pieces are only 3/8" thick and wants them to be flush with the front face of the vertical piece.

I think this is a job for a table saw, and can be done without a dado set (as the OP doesn't have one) although it will take a bit longer. The cross pieces look like they are symmetrical - the top cross piece is the same distance from the end as the bottom cross piece, the next two are the same and then there is the middle one.

I would use a miter gauge with a stop to define one shoulder of the dado, and another stop block against the fence to define the other shoulder, then hog out between the stop blocks.
Flip the vertical piece end for end and dado the bottom - no measurement required.

Adjust the two stop blocks to define the next two dados, top and bottom - same procedure.

Final adjustment for the middle dado.


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## tomp913 (Mar 7, 2014)

If you're looking for a quick and easy way to do this, and not looking to make this a production item, make a quick fixture as shown in the photos. You'll need a hinge mortising bit as mentioned previously (Lowes or HD would have them, 1/2" dia cut x 1/4" shank.

Take a piece of scrap 1/2" plywood long enough to provide clamping on either side of the cutout.

Lay out the width of the center strip on the ply, depth of the cutout should be width of the center strip plus about 2". Make sure the side lines are 90° to the edge of the plywood.

Roughly cut out the recess, staying INSIDE the lines. Tack small strips along the pencil lines, turn the plywood over and use a bottom bearing bit running on the wood strips to true up the cutout.

Remove the small strips and add a short piece at the open end on either side of the cutout - these will act as "stops" on the edge of your center strip.

Layout the edges of the recess on the center strip.

Clamp the fixture on the center strip with the inside edges on the pencil lines and the bottom stop against the edge.

Use the hinge mortising bit to remove the material in the center strip between the edges of the fixture. You'll have to decide how many cuts are needed to get to the finished depth.

Recommendation - to prevent chip out along the edges of the cutout, I would remove a narrow strip along each edge (there should be enough clearance at the inside edge of the cutout for you to start the router and then feed into the center strip) but feed RIGHT to LEFT (climb cut). This will reduce the chance of wood splintering out - the light cut/minimal material removal should prevent any problems for climb cutting.

I use the fixture shown for cleaning up and squaring rough cutouts in 2X material - the fixture works very well, and took me about 10 minutes to make - mostly finding the little bits to make it. It doesn't have the stops as I just line it up with the layout lines on my parts, and you could do the same, but the little strips tacked across the ends will assure that your recess is square to the part.


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## Everend (Mar 15, 2013)

I guess I was confused by the half-lap lap title, I thought that means cutting a dado on both pieces with each piece being half the depth necessary so the faces would be flush. I also thought the OP wanted to use a router table to cut the dados, not a hand held with a template. 
So if we are going hand held with a template and are making many of these but only cutting dados in the vertical piece, then I would make a template like Tom suggested and use a bushing instead of a pattern bit. Then it doesn't matter what the diameter of the bit is because the bushing is going to keep it strait. If making just one I probably wouldn't bother with a template like this but for making more than three of these trees then I'd make this template first. This diagram is made of 3/4" plywood top and 3/8" plywood cleats and has 1-1/8" channels between 7/8" fingers. Adjust these measurements depending on the width and spacing of your horizontals and the difference between your bit and bushing. Make sure the cleats on the bottom are the same thickness as your workpiece. Clamp (or screw) the template to the table then slide your workpiece in to the stops. Clamp the workpiece to the template or put blocks in around the work piece and clamp those. Then have at it with the router and bushing. After making the template you could probably turn out one vertical every five minutes or less.

To make the template, use a table saw to cut the channels on the top (so your lines are strait). Then glue on the cleats/stops on the bottom. Make the long cleat wider than the channels you cut so it holds the workpiece in from the end of the channels. The first time you cut with the router it will transfer the fingers to the cleat so no need to worry about those.
Blue=top, Green=bottom


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## woodknots (Mar 7, 2012)

@Everend - you weren't confused - the title did actually say "half-lap" and in the post, the OP said dado or half-lap just the vertical piece. His option to use the router table was because he said his table saw wasn't accurate and he doesn't have a dado set.


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## jcmilam (Apr 14, 2009)

OP here, thanks all. Sorry for any confusion with the title.

I decided to try the table saw. It's a 1954 Craftsman that is a family heirloom, I'm not planning to replace it but it's a little iffy on really accurate cuts. Anyway, I used two stop blocks on the miter gauge and that worked well. A little adjustment on depth and width and I should be good...for 1 dado.

Now I'm trying to wrap my brain around doing at least two more on the same piece of wood. If it was one pass with a dado set I'd put some kind of runner to move each dado onto to do the next one, but I'm unclear what to do now to move the piece down a set amount but still able to slide left-right enough to make another cut, at least 2 more times.

Thanks!


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## thomas1389 (Jan 4, 2012)

DesertRatTom said:


> Amen to that. In fact, that's why I popped for the Veritas router plane. It is a joy to use. Precise and consistent depth, perfectly flat bottom every time. Great for inlays too.


Nice!!


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