Leigh jig-Inlaid dovetail tutorial - Woodworking Talk - Woodworkers Forum
Old 03-19-2011, 07:53 PM Thread Starter
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Leigh jig-Inlaid dovetail tutorial

Well, I didn't get it finished, but I got a good start on it. So if you are interested in this thread, you will have to wait until tomorrow for its conclusion.
I have a Leigh dovetail jig, specifically, the D4R Pro and I love it. The joinery that it accomplishes is wonderful and I really enjoy using it. This thread isn't about whether or not the Leigh jig compares to hand cut dove tails and I'm not even going to go down that road. We've been there and done that. This thread is about satisfying the requests of some of the members of WWT who have asked how this particular joint is done on the Leigh dove tail jig. So, here we go....

The first step, is an easy one. You need to determine the thickness of your inlay. For this particular box, I am using a maple body with a walnut inlay, but you can use whatever you want. I have decided to make the inlay 1/8" thick.

Shims are required for this project and the shims are required to be a little thicker than the thickness of your inlay. In fact, the formula for the shim is the thickness of the shim X 1.15. The reason for the larger shim, is to compensate for the 8 degree dovetail cutter. I didn't want to have to deal with multiplying 1/8" by 1.15 so I used my digital calipers, and converted 1/8" to millimeters and then multiplied that.

Excuse my messy writing, but as you can see, 1/8" is equal to 3.24mm. When multiplied by 1.15, that is equal to 3.726 or 3.73mm.

I then set up the table saw to cut some shims from some scrap walnut.

From that point, I was able to rip shims that were equal to the thickness that I needed. The shims are needed for the setup of the jig. When doing normal dove tail joints on the jig, the shims are not needed.

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Old 03-19-2011, 08:08 PM Thread Starter
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tutorial cont'

From this point, after the shims are made, I prepared my stock for the box. Cutting the lengths and the widths and making sure that the pieces were the correct thickness and that the end cuts were square. For this particular box, I am going with a 1/2" thickness.

The inlay material, walnut in this case, is required to be thicker than the body of the box, by the thickness of the inlay. I chose to have an 1/8" inlay, so for this box, the thickness of the inlay material must be 1/8" + 1/2"=5/8". I milled some walnut to the needed thickness and cut it to the same width as the box sides.

I now have all of my pieces cut to length. The ends have been checked for square and the thickness have all been double checked. I have given all of these pieces a light sanding, just to remove any small imperfections. You may notice, that the pieces of walnut are different sizes. This is not particularily important, as long as the width matches the width of the box. Length of the inlay material is not a factor at this point.

The pieces are now marked to indicate which pieces will be the tail boards and which will be the pin boards. The markings that you see on these pieces are markings that are suggested by the manufacturer of the jig and I stick to them to make reference to the manual a little easier when I screw up. It is important to remember, that for this particular application, (through dove tails) the markings must be facing out during all routing. You cannot reverse a piece at any point. The markings must been facing you. I can't stress this enough. Not paying attention to this will result in designer fire wood.

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Old 03-19-2011, 08:25 PM Thread Starter
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It is now time to set the distance of the dove tails. The jig is placed in the pins mode and a tail board is placed in the jig. The outer half fingers are spaced approximately 1/8" in from the edge of the board and the fingers for the middle of the board are centered to give it some symetry.

Each outer half pin, is then spaced 1 shim width away from it's current spacing. The easiest way to do this, is to slide a spare finger up against the outer fingers current position, and tighten it down. You can then use a shim and space the outer fingers, sliding the spare finger out of the way once proper spacing is acheived. In this photo, we can see that I haven't slid the spare fingers out of the way yet.

For every full width tail or pin, the fingers on the jig must be spaced 2 shim widths apart. You can see here, that the spare fingers are still in place. For ease of set up, I drew a center line on the tail board to aid me in spacing.

The scale on the jig is then set to the <1" setting. All tails are routed in this setting. It allows for the dove tail bit to pass completely through the stock and cut the tail properly. For those that have a Leigh jig, you may notice that I have already rotated the finger board and it is now in the tails mode of routing.

Here, we can see that the finger board has been rotated into the tails mode and the set up of the fingers for this stage is complete. We can also see that the spare fingers that I used to space the end fingers have been moved out of the way and at this time, are only used to support the router during routing.

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Old 03-19-2011, 08:43 PM Thread Starter
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A line is drawn on the tail board at a distance equal to the thickness of the inlay material (5/8") from the end of the board. At this point, we want to set up the router. An 8 degree dove tail cutter is placed in the router and the bit is set to cut at the center of the previously drawn line.

If you are using the VRS attachment for the jig, do yourself a huge favour and check that the highest point on the VRS is level with the fingers of the jig. It only takes seconds to verify and it will save you a lot of frustration. I have made it a habit to do this before each cut. The VRS (vacuum router support) is a great attachment which help support the router and also sucks up about 90% of the chips, but if it isn't square to the fingers, it can cause uneven routing and sloppy and crooked joints.

From there, you want to find yourself a handsome devil, to do the routing for you. I managed to find this strapping young man.

Rout all of the tail boards and put them aside. Remember that all of the markings that you placed on the boards earlier must be facing out during routing. If you did things correctly, you should have something that looks like this.

It's time to remove the dove tail cutter and install the straight bit into the router. Do I need to say it? I think I should anyway. UNPLUG the router before changing the bit. Don't try to be a hero and think that it wont happen to you. All it takes is a slip of the finger and the power is on with that bit spinning in your fingers. For the 5.2 seconds that it takes to unplug your router, is it worth losing a finger or two.
Here we can see the straight cutter installed in the router.

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Old 03-19-2011, 09:02 PM Thread Starter
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I'm not going to get into the details of how the jig is set up to rout the pins. The fine tuning of this process takes a little bit of trial and error and it is specific to the router that you are using. If you have a Leigh jig, you are familiar with the process and already have the measurements recorded in your manual.
I am going to simplify this by saying to flip the finger assembly to the pin routing position and set the scale for the settings of your router.
Set the straight bit to cut a depth equal to the thickness of the box walls. In this case, 1/2" and rout the pins out of your inlay material.

You can see what the pins look like in this photo. There is a small amount of tear out in this shot, but I'm not too concerned about it.

Test the fit of the joint, and if you are happy with it, apply a liberal amount of glue and glue the joint together, making sure that the joint is square. Sorry about the glare on this photo but the sun was shining in through the window of my shop and I was enjoying it too much to close the blinds.

Wipe off all of the excess glue and allow the joint to fully cure. This is very important. You'll know why later.

I then set up my table saw to cut a strip equal to the thickness of the inlay material. 5/8". You may notice that I am using my miter gauge and my fence. Note that I have a stop block set behind the blade. The stock is butted up against this block and then the miter gauge follows through for the cut. It is important that the stock is never in contact with the stop block/fence and the miter gauge at the same time while cutting. This is a recipe for disaster and will most certainly cause kickback. The stock must clear the stop block before it ever contacts the blade. Do a dry run to make sure that this is the situation.

Once the previously glued joints are dry, run them through this set up to shave off the excess walnut. There should be an extra 1/8" of walnut left above the maple. Sorry guys that I didn't get a picture of this. I'll try to get one tomorrow. Basically, you want to cut off the length of walnut at the 5/8" mark.

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Old 03-19-2011, 09:12 PM Thread Starter
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At this point in time, you want to rotate the finger board to the tail routing position and return the jig's fingers back to their original settings, before you spaced everything with the shims. Remove the straight cutter and reinstall the 8 degree dove tail cutter. Set the depth of cut to equal the thickness of the box walls. In this case 1/2". With the fingers back in their original positions, rerout the tails.

It's important to be patient here. A little bit of extra time in double and triple checking measurements will provide you with a much nicer outcome. If you routed correctly, you will have something like this.

If you rushed things and didn't wait for glue to fully cure, all in the name of completing this tutorial, you will end up with something like this.

It was at this point, that I thought it best to call it quits for the day. Tomorrow, I'm hoping to repair the damage and carry on with the box and the tutorial. Hope you're enjoying it so far guys.
Until tomorrow.
Ken

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Old 03-19-2011, 09:23 PM
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Excellent tutorial, thanks for taking the time to do it. I look forward to the rest of it.
--Matt
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Old 03-20-2011, 12:59 AM
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Kembo

Those are great looking inlayed dovetails I had often wondered how they were done. I don't think I could justify the \$499.00 price for the jig, I think I would rather spend it on a power tool instead.
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Old 03-20-2011, 03:22 AM
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Originally Posted by Bob Willing View Post
Kembo

Those are great looking inlayed dovetails I had often wondered how they were done. I don't think I could justify the \$499.00 price for the jig, I think I would rather spend it on a power tool instead.
Bob, you might think about it like getting an older unisaw and then buying a nice sliding table for it. The saw's usefulness is enhanced by the accessory, just as the router with a dovetail jig, or router table with lift ... that can easily exceed the cost of the router itself.

I'm with you on the costs of some of the jigs, and I find other ways to do somethings, make my own, use different joinery accents... Cool result though, don't you think?

Kenbo, great job and good looking joints! I almost lost faith in you when I saw the chip/ tear out from not letting the glue dry. Can't fault you though for posting up the pic and giving others the warning not to rush things. This coming from a man that seems to have the patience of a Saint with all your scroll saw work, as well as other recent work.
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Old 03-20-2011, 09:34 AM Thread Starter
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Quote:
I almost lost faith in you when I saw the chip/ tear out from not letting the glue dry. Can't fault you though for posting up the pic and giving others the warning not to rush things.

This one is almost laughable. Once the tear out happened, I quit. Not from being angry or frustrated, but at that point, I knew that my mind wouldn't be on the work and that creates a dangerous situation for me. I came inside and thought about how that could have happened and I sat in my living room, running through the process of what I did, using my fingers as the joints and mimicing what I'd done earlier. That's when it hit me. I only put the glue on the walnut and never applied any glue to the maple which left whole sections of the inlay without any adhesive. What the heck was I thinking? If you look at the photo, you can see glue where the tail is, but no glue residue on the shoulder of the joint. I wont make that mistake any time soon I tell ya.

Quote:
I don't think I could justify the \$499.00 price for the jig, I think I would rather spend it on a power tool instead.
Believe you me, I had a hard time with the price too. At the time though, there wasn't a tool that I wanted, and I had a gift card for \$175 (I think) and some money that was given to me for my birthday. I had been wanted one for a while, and when you have someone else pay for 1/2, it's not so bad. I really enjoy working with it though and even if the entire price had come out of my pocket, I would have no regrets. I love this jig. I've been working with it on and off since I got it last summer and I still haven't done everything that it is capable of doing. The setup is easy and after a small learning curve, you're in business. Speaking of which, I'm off to the shop now to hopefully finish this tutorial and the walls of my project.
Thanks for the kind words guys.
Ken

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Old 03-20-2011, 12:39 PM
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Hurry up Kenbo, we're getting anxious. Put a fan on that glue!
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Old 03-20-2011, 07:53 PM Thread Starter
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Inlaid dove tails cont'

Well, let's see, where were we? Oh, I know. When we last spoke I was busy showing you guys how NOT to do things by using poor glueing technique and impatience to blow a joint apart.
I was awake until almost 1:30 this morning and then I got up at 7:15 to continue this project. Headed out to the shop and cut off all of the dove tails that were done yesterday. I then repeated the whole process and remade all of the inlays that I ruined. Plenty of glue used this time I tell ya. To make sure that no impatience was to be had, I went out with a friend of mine for coffee and 3 hours later, I returned to the shop.

I had mentioned yesterday, that when you trim the walnut inlay material, there would be a 1/8" overhang. I didn't have a photo of this, but through the magic of screwing up and having to redo things, I was able to get a photo of it. This overhang is important because without it, the continuous line of inlay around the dove tails will be broken making it look incomplete.

At this point in time, we are ready to rout our pin boards. We have successfully routed our tail boards, complete with our inlay material firmly glued in place. We have rotated our finger board assembly to the pins position, and have set the scale to the readings that you have recorded in your manual from other testing. Unlike doing regular through dove tails, where the depth of the bit is set to the thickness of the box walls, when using inlays, we must set the bit depth to the thickness of the inlay material. The straight bit is used for this and you can see here that I have drawn a line on the pin board for reference and I am also double checking that the inlay thickness matches this line and the router bit depth.

Routing the pins is the next step and it is important to take your time here. We don't want any blow outs. Step routing is the way to go here, taking small passes the avoid large amounts of material removal. Make a light pass across the front and then you can rout completely through one side and take a light pass on the back side of the pin board. This will ensure a crisp edge, even is there is a little chip out. From this point, you can continue to take light passes until all of the material is removed. Check for fit, and if you are happy with it, rout all of your pins, remembering that your symbols that you previously marked on the boards must be facing outward.

You can see a few rough edges here on the pins, but that is nothing that a light sanding wont cure. Remember not to sand too much at this point as we don't want to change the shape or size of the pins.

With a light sanding done for all parts, you should have your 2 pin boards and your 2 tail boards, complete with inlays, ready for final assembly.

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Old 03-20-2011, 08:07 PM Thread Starter
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From this point, we are home free. I like to do a dry fit run without actually driving the boards home. Everything here looks like it will line up just fine. Even though we checked our pin fit earlier, it is always possible that a small router slip or too much sanding has altered the pins. Do yourself a huge favour and just check it one more time.

We see here, the first stage of the glue up. Nothing spectacular. It's just like putting together any other dove tail box at this point in time. I did, however, want to point out 2 of my best friends in the shop. They are pictured here. One is the box of Q-tips and the other is wax paper. A dampened Q-tips is awesome for cleaning up little squeeze out sections of glue on a project like this. I use them constantly. The wax paper is also great for when you don't want to get glue all over your bench, or for that matter, if you don't want to glue your project to the bench.

The joints on this project didn't turn out as tight as I would have liked, but overall, I am happy with the look of them. You can see small little gaps here in the joinery, but when everything is said and done, these will not be noticed by anyone other than me. (and probably you now that I have pointed them out) You can also see here how the squeeze out was cleaned up by the Q-tips. The wood is a little wet, but we still have our final sanding to do.

Once everything is glued together and dry, (I stress the dry part here because of earlier events) you will find that there is a small, 1/8" ridge that is left on the inside of the box.

With the aide of a sharp chisel, you should be able to remove this strip fairly easily. You may leave it if you wish, but I prefer to remove it.

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Old 03-20-2011, 08:18 PM Thread Starter
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We can see here that the small strip has been removed and although it still needs a little sanding to clean it up a bit, you can see how removing it, leaves a pattern on the inside corners, that I find is very pleasing.

Well, that's it. All that remains now is to do some final sanding on the interior and exterior of the box and your are done.

Of course, for this box, I plan to have a surface lid and bottom attached. That is just what I chose for this project. You can choose whatever method you want for the lid and base. Whether you choose dados, rabbets or surface mount, is up to you.
I hope you have enjoyed this tutorial. I had fun making it. This box is far from finished for me. I will hopefully be finishing it next weekend and you all can see how it turned out in the project showcase. Thanks for looking in on the tutorial and all I can say is, if you have a Leigh dove tail jig and haven't tried this joint, give it a go. If you want the technical instructions, you can download them for free at the Leigh Industries website.

Ken

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Old 03-21-2011, 10:24 AM
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Thanks for the great tutorial, Ken. Nice looking project, as usual.
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Old 03-21-2011, 09:18 PM
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Awesome. Cant wait to do it.

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Old 03-28-2011, 11:41 PM
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That looks very nice. A little above my skills. Just bought me a Leigh 24 super jig. Did my first dovetail this weekend. Great tool.
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Old 03-29-2011, 12:58 AM
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That is amazing thanks for sharing.
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Old 03-29-2011, 01:34 AM
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Got a Leigh jig years ago, did several drawers for a project and then haven't touched it since. Seeing this makes me want to blow the dust off it and make some boxes. Thanks for the inspiration.

That bowl was perfect right up until that last cut...
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Old 03-29-2011, 08:32 AM Thread Starter
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Glad you enjoyed it guys. Thanks for the kind words.

Swede, don't think that this is above your skill level. It is no different than routing normal through dovetails. It just takes a little measuring and a little patience. Give it a try. I think you'll be pleasantly surprised.

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