need advice for half lap joints - Woodworking Talk - Woodworkers Forum
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post #1 of 25 Old 08-06-2013, 04:34 PM Thread Starter
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need advice for half lap joints

I am planning to build a gate for the side of my house out of western red cedar. i know the best method is M&T but I don't have and don't want to buy the tools to do it. I am going to use half lap joints. Since some of the pieces are 2x6 about 5 ft long and I have to cut dados at the ends I figured a router would be better than doing it on the table saw.
I was going to use some a simple clamp on edge guide like this and just use the edge of router base.

http://www.amazon.com/gp/product/B002NZZE7O/ref=s9_simh_gw_p60_d0_i2?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=035J2JG2A4GHWW3X83RH&pf_rd_t=101&pf_rd_p=1389517282&pf_rd_i=507846
Besides gluing the joints I was going to put dowels through them or screws from the back side. I think screws might be stronger since they would be pulling the two pieces together. Any suggestions on design, tools, methods would be appreciated.

Last edited by jnbrown; 08-06-2013 at 04:36 PM.
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post #2 of 25 Old 08-06-2013, 04:58 PM
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I would use the table saw for dados myself and just sneak up on them much quicker and easier imo, but if you have a router and a table saw you got all you need to make m and t joints. Those are the two tools I use and have made hundreds of m and t joints.

As far as screws or dowels go I like to use dowels because o tend to shy away from mechanical fasteners, but screws would work just as well I would think.
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post #3 of 25 Old 08-06-2013, 06:07 PM
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What you are planning with half laps is a rabbet on each piece that's matched.
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You could do this with a router, without buying a guide. You can make one yourself. It's a basic design like a "T" square, and intended for a handheld circular saw, but can also be used with a router.
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post #4 of 25 Old 08-06-2013, 06:43 PM
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Here you go ,

a scarf joint / lap joint for every occasion

http://www.google.co.nz/search?q=scarf+joint&rlz=1W1GGNI_enNZ484&source=ln ms&tbm=isch&sa=X&ei=cHsBUpiXGc7HkQWAtYCIAQ&ved=0CA cQ_AUoAQ&biw=1360&bih=629

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post #5 of 25 Old 08-06-2013, 07:33 PM
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half laps are quite strong, however ...

If all the "pickets" are vertical you should really have a diagonal brace. Why? Because the weight is all hanging on the joint itself, rather than a structural member like the diagonal. Triangles make everything stable, rectangles collapse under load. Think cardboard box with all the flaps folded in. Now fold the flaps out and overlap them.... much stronger.

Here's some gates with diagonal braces:
http://search.yahoo.com/search?ei=ut...r%20gate&type=



As to how to make the half laps there are several ways.
1. A circular saw making 1/2 material thickness kerfs 1/2" apart and chisel away the material down to the kerf bottom.
2. a radial arm saw used in the same manner.
A table saw with a dado set or again make a number of kerfs.
3. A bandsaw can saw the thick material in one pass for the face of the laps.
4. A handsaw will do the same, but more work.
5. A router came be used to make wider kerfs/dados but you need a way to support the router base off the work...usually 2 pieces of equal thickness along either side. More chiseling or planing with a rabbet plane.

Finally don't bother, just butt the pieces and use a good diagonal or plywood on one side if that will be OK...I donno? It may not work for you application.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 08-06-2013 at 07:46 PM.
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post #6 of 25 Old 08-06-2013, 10:49 PM
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Table saw for your tenons, drill, Forstner bit & chisel for mortises. Go for it man! Much stronger...
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post #7 of 25 Old 08-06-2013, 10:52 PM
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Quote:
Originally Posted by jnbrown View Post
I am planning to build a gate for the side of my house out of western red cedar. i know the best method is M&T but I don't have and don't want to buy the tools to do it. I am going to use half lap joints. Since some of the pieces are 2x6 about 5 ft long and I have to cut dados at the ends I figured a router would be better than doing it on the table saw.
I was going to use some a simple clamp on edge guide like this and just use the edge of router base.

Amazon.com: E. Emerson Tool Co. C24 24-Inch All-In-One Contractor Straight Edge Clamping Tool Guide: Home Improvement

Besides gluing the joints I was going to put dowels through them or screws from the back side. I think screws might be stronger since they would be pulling the two pieces together. Any suggestions on design, tools, methods would be appreciated.
Hi - I don't blame you for not wanting to handle 5ft 2x6 for crosscutting on a table saw. I know my saw hasn't got enough table to do it comfortably.
I don't think that guide clamp is going to help you though. The job is going to entail removing the stock that is supporting the router. Sort of like sawing off the tree branch you're sitting on.
I sketched up a little jig that should work for you. Just a few 2x4 scraps. the lighter parts are the jig. Just two side supports, an end stop and a back stop. The end stop would go right against the end of the workpiece and the back stop would be 5" (width of half lap) plus the radius of the router base minus the radius of the bit away from the end stop. If your router base has a straight edge on it you could use that dimension to the center of the collet instead of the radius of the router base.
Good Luck
Attached Files
File Type: skp half lap jig.skp (47.1 KB, 437 views)

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post #8 of 25 Old 08-07-2013, 01:28 AM Thread Starter
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Quote:
Originally Posted by jschaben View Post
Hi - I don't blame you for not wanting to handle 5ft 2x6 for crosscutting on a table saw. I know my saw hasn't got enough table to do it comfortably.
I don't think that guide clamp is going to help you though. The job is going to entail removing the stock that is supporting the router. Sort of like sawing off the tree branch you're sitting on.
I sketched up a little jig that should work for you. Just a few 2x4 scraps. the lighter parts are the jig. Just two side supports, an end stop and a back stop. The end stop would go right against the end of the workpiece and the back stop would be 5" (width of half lap) plus the radius of the router base minus the radius of the bit away from the end stop. If your router base has a straight edge on it you could use that dimension to the center of the collet instead of the radius of the router base.
Good Luck
I did think about that and I could could just use some pieces of the 2x6 stock clamped next to the piece I am working on to support the router base. Thanks for sketching the jig. I would think the jig would have to drop down where the lap is otherwise the router bit will cut right through it anyway unless I am missing something? I like the idea of the guide clamp because I don't have to make a jig and I can adjust it on the fly. I will also be doing some lap joints in the middle as well as the ends. I know a lot you like to make your own jigs and that's great. This isn't really a hobby for me I just need to get these built and if that means spending a few bucks for tools instead spending time building jigs I am ok with that. Buying these gates pre made would cost me $1700.
Hopefully I will get some enjoyment from building them.
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post #9 of 25 Old 08-07-2013, 06:11 AM
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Your first post you said...

Quote:
Originally Posted by jnbrown View Post
I am planning to build a gate for the side of my house out of western red cedar. i know the best method is M&T but I don't have and don't want to buy the tools to do it.
And later you said...

Quote:
Originally Posted by jnbrown View Post
I like the idea of the guide clamp because I don't have to make a jig and I can adjust it on the fly. I will also be doing some lap joints in the middle as well as the ends. I know a lot you like to make your own jigs and that's great. This isn't really a hobby for me I just need to get these built and if that means spending a few bucks for tools instead spending time building jigs I am ok with that. Buying these gates pre made would cost me $1700.
Hopefully I will get some enjoyment from building them.
It's great to get some advice for a onetime project. Maybe woodworking might become a hobby and we will see you in the future.






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post #10 of 25 Old 08-07-2013, 06:58 AM
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One of the few things radial arm saws are good for.....fence and gate parts.With some quick tuning,most are capable of accuracy enough for outside work.Slap a cheapo dado head on a 10" and have at it.

Not having the above.....and still considering accuracy requirements....probably would just do the roughing cuts with a circ saw,parts/ends clamped down to bench and clean them with a rabbit plane.Not that a router "wouldn't do it"....its just the way a router cuts vs a saw blade.It would be hard on a router.

But as mentioned above...mortices are just a,few drilled holes and chisel clean-ups away.They've been done that way for a mighty long time.Heck,I've done PLENTY,using brace and bits back as a young-in.Its a great way of teaching kids(brace vs power tools).

Those who say it cannot be done shouldn't interrupt the people doing it.
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post #11 of 25 Old 08-07-2013, 02:33 PM Thread Starter
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First thanks for all the great feedback.
I should clarify a few things.
I am not totally new to woodworking. I have a table saw, router (Crappy old Craftsman), drill and a sliding miter saw (on loan).
I did extensive research into M&T joints and spoke with friend who does a lot of woodworking.
For joining 2x6 my understanding is the mortises should be pretty deep, at least 3".
A lot of benchtop mortise machines won't even go that deep and a drill press is required.
I didn't want to go buy a drill press because of the size and weight.
I suppose I could try learning to do it by hand with the drill and chisel method.
So what I meant is i don't want to spend money on a big heavy expensive mortiser.
The half lap appeals to me because I have used it before with success and I am confident I can do it accurately and I think it will be strong enough even though not as strong as M&T. I have built joints with dowels but don't feel they would be strong enough.
I discovered a set of chisels at my mother in laws garage that her late husband used for woodworking so I might borrow those and play around to convince myself that I can or can't do M&T by hand. Since Cedar is a relatively soft wood that might make it easier. Then there is cutting the tenons which I understand can done by a hand saw, dado blade on the TS or router. At one point I bought a beadlock tool from Rockler and then returned it when I discovered it was impossible to drill straight holes with it, at least without a drill press.

Question about the rabbet plane, I don't think it work because it would cutting across the grain, not with it.

Last edited by jnbrown; 08-07-2013 at 02:45 PM.
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post #12 of 25 Old 08-07-2013, 03:23 PM
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Quote:
Originally Posted by jnbrown View Post
I did think about that and I could could just use some pieces of the 2x6 stock clamped next to the piece I am working on to support the router base. Thanks for sketching the jig. I would think the jig would have to drop down where the lap is otherwise the router bit will cut right through it anyway unless I am missing something? I like the idea of the guide clamp because I don't have to make a jig and I can adjust it on the fly. I will also be doing some lap joints in the middle as well as the ends. I know a lot you like to make your own jigs and that's great. This isn't really a hobby for me I just need to get these built and if that means spending a few bucks for tools instead spending time building jigs I am ok with that. Buying these gates pre made would cost me $1700.
Hopefully I will get some enjoyment from building them.
You're right, that jig I drew up will get some damage. Roughly 1/2 the bit diameter would be taken out on each side of the jig on the first half lap. That's why I had it drawn up with 2x4 lumber so the edges could accommodate some loss there.
The thing I see you running into is that router bases are typically 6-7" in diameter and your board is 5" wide. One other approach would be to remove the plastic sub base and substitute it with a larger piece of 1/2" plywood. The plywood would need a hole large enough for the bit to pass through and a couple of holes for attaching to the router. This would effectively give you an oversized base that you could use against the guide clamp and increase the amount of support area available.

John

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post #13 of 25 Old 08-09-2013, 12:08 PM Thread Starter
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So last night I experimented with making a mortise in a douglas fir 2x6.
The mortise size was 1/2"W x 4.5"L x 2"D
I started by drilling a series of 3/8 holes using a dowel jig.
Then I used a regular chisel that is about 1.5" wide along the sides.
What i found was that since I was going with the grain, there was a lot of tear out along the wall of the mortise. Could be because of the soft wood or my chisel wasn't sharp enough. I think the result might have been better if I just used a 1/2" mortise chisel without drilling the holes. One thing is for sure doing large deep mortises by hand isn't something I want to do. If I was going to do M&T I think a drill press with a mortising bit is the way to go. I still think the half lap is a viable way to go and will make some test joints.
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post #14 of 25 Old 08-09-2013, 10:21 PM
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Softwood's need a very sharp chisel to work effectively. I would spend some time sharpening the chisel and then trying again to see if it makes it easier. For what is worth, the mortise walls are important for strength, but they don't have to be pretty
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post #15 of 25 Old 08-09-2013, 10:40 PM
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I know the thread had kinda veered away from half laps, but while we're talking about mortises...
I use a bit of the same width as the mortise, for ex a 1/2" diameter Forstner bit for a 1/2" wide mortise. Just gotta be careful to always start dead on the center line & overlap the holes. Then just pare the mortise walls clean with a sharp chisel (you shouldn't even need to strike the chisel with a mallet) and square up your corners. Makes the whole deal pretty quick & clean.
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post #16 of 25 Old 08-09-2013, 10:46 PM
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use a guide strip for both

When drilling a series of holes in a straight line use a strip to butt the Forstner bit against. Use the same strip to keep your mortising and paring chisels vertical to the surface.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #17 of 25 Old 08-10-2013, 12:01 AM
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I learned to mortise on this job.

need advice for half lap joints-2013-07-12_16-20-51_115-smaller.jpg

need advice for half lap joints-2013-07-12_13-04-47_269smaller.jpg

What I learned first was to design the project to suit your tools.
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post #18 of 25 Old 08-10-2013, 01:34 AM Thread Starter
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Quote:
Originally Posted by BZawat View Post
I know the thread had kinda veered away from half laps, but while we're talking about mortises...
I use a bit of the same width as the mortise, for ex a 1/2" diameter Forstner bit for a 1/2" wide mortise. Just gotta be careful to always start dead on the center line & overlap the holes. Then just pare the mortise walls clean with a sharp chisel (you shouldn't even need to strike the chisel with a mallet) and square up your corners. Makes the whole deal pretty quick & clean.
That does sound easier, but my concern is unless I use a drill press (which I dont have) then drilling a hole 3" or more deep is going to be just about impossible to do it straight enough. Having a drill press would also make drilling about 9 holes per mortise faster and easier.
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post #19 of 25 Old 08-10-2013, 09:52 AM
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My experience cutting mortises in douglas fir is that it just plain sucks. Either the wood is wet, in which case is comes away in stringy chunks, or it's dry, in which case it shatters. Here's how I finally made it work on some fairly dry posts:

1) Mark the mortise well. If it's a through mortice, mark both sides.
2) Pre-drill. Use a drill press, bit brace, whatever.
3) do a rough cleanout with a medium sized chisel. The ones I were cutting were almost nine inches long by one inch wide, and I used a 3/4" chisel for the first round of cleaning out. Don't worry about getting the walls straight, just get the big chunks out. If it's a through mortise, go halfway from one side, then flip the piece over and work from the other side.
4) Clean up with the widest chisel you can fit. I used a 1" for the ends and a 1 1/2" for the sides. I tried to clean out from the outside to the center sloping up, meaning the board that was a perfect fit when it entered the board wouldn't fit at the center. Once I had the edges of the mortise clean and straight, I used the wide chisel to slow pare away the excess inside, working on a diagonal. I finally put a mark all the way around the edge with a pencil to make sure I wasn't going to cut the edge, and that let me speed things up a little.

If your final work will be in something other than douglas fir, I recommend trying it in that. You may find it's a lot easier.
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post #20 of 25 Old 08-10-2013, 11:50 AM
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Quote:
Originally Posted by jnbrown View Post
I am planning to build a gate for the side of my house out of western red cedar. i know the best method is M&T but I don't have and don't want to buy the tools to do it.
For rectangular stock joints, like a gate, a half lap IMO would be a stronger joint than a M&T. If done properly, there is better (and more of) gluing surfaces. It would likely be an easier joint for you to make.






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