139 – Exact-Width Dado Jig

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In the Weekend Wall Shelf episode, I showed you how to use a parallel jig to create dados. But the jig was originally created for making coves at the tablesaw. So here’s a special jig made specifically for the purpose of creating dados with your router. The best part is, you can get exact-width dados EVERY TIME!

This jig was developed and demonstrated in the current Guild Build as part of the Wall-Hanging Cabinet series (it was originally inspired by this Wood Magazine Jig). This video is a little sample of what Guild members are enjoying every week during the build season. If you are interested in joining the Guild, learn more here.

This jig can be made to any size for any bit/guide bushing combination. Just remember that once you use a particular bit/bushing combo with the jig, you are stuck with it. Using a different combination will defeat the purpose of the jig. I used a 5/8″ guide bushing and a 1/2″ router bit.

Don’t forget to download the PDF and SketchUp drawing for the Exact Width Dado Jig!

Jig Modifications

I requested ideas modifications to the jig, and a couple Guild members were quick to off suggestions. If you have a modification, upload it to our SketchUp Library and share the link in the comments below.
Denny’s Suggestion
Robert’s Suggestion (SketchUp File)

Resources

Jig Hardware Kit JIG IT(R) Hardware Kit
This is a nice multi-pack of jig-building parts. Assorted T-bolts, knobs, and inserts for customizing your own jigs and fixtures for your shop. Very handy to have around.

JIG IT(R) Hardware Kit

Category: Techniques

Comments

  1. OfficeSpaceWoodworking February 10, 2011

    Thank you thank you thank you for finally explaining the outro music! Haha and on a more applicable note, that was a wonderfully detailed explanation of how to construct and use the dado jig; much better than any previous attempt I’ve seen.

    • Denis Allan August 1, 2014

      Great video on making this jig. If you make your end pieces wider, the working area would be further away from the knob. I think I would invert the bolts so that the are pointing up and use a speed cam to lock everything in place once it’s set.

  2. TomB February 10, 2011

    Can Robert do a segment on how me made that sketch up file….pretty cool! no offense Woot Whisper

  3. I have been thinking about buying the Infinity Precision Router Jig which with all the extras is around $100 I think. After viewing your video, I am going to try yours instead. Thanks – saved me some money!

  4. Tony Z February 11, 2011

    I like the jig, but I’m puzzled as to why you wouldn’t just use a pattern bit. That way you could forget about the rabbet on the jig and collar on the router. I’m sure I’m missing something.

    •  

      The primary reason is wear and tear. Any jig that I have used repeatedly with a flush trim bit eventually starts to show wear, either from a stopped bearing, accidental contact from angling the router, or blades that aren’t quite perfectly aligned with the bearing. On this jig, we should get the same results 10 years from now as we do today, since its the stationary guide bushing that’s actually guiding the router. My hope is this jig will last a good long time.

      • Ben February 16, 2011

        I had the same question. I guess the biggest downside would be marrying the jig to the router bit. If this jig is supposed to last 10 years, then the bit has to last 10 years too, without sharpening! If a jig that used a flush-trim bit was subject to wear and tear, could you not just re-true it with a pass against the fence on a router table?

        •  

          Yeah that would work. But keep in mind with my jig, you could just buy another 1/2 router bit. Buy from the same manufacturer and you can be pretty confident everything will be perfect. Either way, do whatever sounds right for you. Both systems are great.

      • Randy K June 7, 2011

        Hey Marc,
        I’m new to your website (very entertaining). The dado jig I use has a plywood base, the 1X runners glued to the top of that, and I have both star knobs facing up. So on mine the router sits inside the runners (as opposed to on top). Works great for me.
        I use a simular setup for a rip fence for my circular saw, (except you’re using only one side)
        Keep up the great videos
        Randy

  5. I saw this used in the guild build, and it is great. It is on my short list of things to build.

  6. Mark H February 11, 2011

    Just got to say Love the outro music and the jig is great too…..thanks for all the cool things you do.

  7. Hey Marc, great video as always! Loving the HD! As for a modified verson, check out this one…
    http://www.newwoodworker.com/autodadojigpln.html

    •  

      Thanks my friend! And I actually considered making the jig like the NewWoodworker version, but the thing that bugs me about it is that it references from the router base. So if your bit is not perfectly centered with reference to the base, you could end up getting inconsistent results. Also, if you have multiple router models, you won’t be able to use them with the jig. The jig is essentially married to the router. All that said, its certainly a simpler jig to construct!

  8. You describe Horatio “El Saxofonista” as being “the Venezuelan Kenny G, only cooler”.

    _Everyone_ is cooler than Kenny G.

  9. Tom Collins February 11, 2011

    Great video Marc! I love the jig and will be making it. One addition I am considering is an adjustable fence to index off the top or bottom of the panel. This way you can quickly and accurately move the jig between right and left sides of a cabinet and get the dados aligned perfectly. You were very specific that the screws should not be installed till after the glue is dry. Why is this? Thanks for a great podcast and website!

    •  

      Try it and you’ll find out. :) Actually its because the screws will have a tendency to move the fence slightly as you drive them home. And when you’re trying to hit dead on 90, this is bad. So I just avoid it and then add screws later for extra reinforcement.

  10. Love the grand intro-duction of the outro-music. The dado jig is such a clever shop item and relatively easy to build once the process is understood. Your videos are a blessing to the home shop hobbyist. Thank you for your time and hard work.

  11. James Stenhouse February 12, 2011

    Why not make your main/long fence wider(4 1/2″) instead, allowing room for the router base and then bring the handles to the top face? Seems that may solve a few issues and make a more stable base to keep the jig square. With no need to access the bottom you could put a fence on the fence and lock it against the bench.

    James
    ps Now i’ll have to Sketch this up just to see

  12. James Stenhouse February 12, 2011

    Having trouble posting a different version of this jig. It can be found in the Google 3d warehouse under JamesnotJim at:

    http://sketchup.google.com/3dw.....revstart=0

  13. David February 12, 2011

    You were hand planing to the soothing sounds of one of the greatest Jets victories of all time! That made this a truly marvelous video it was Scrumtrulescent. Awesome Jig!

  14. A really useful jig. Another great post, especially for us that live in Europe where dado blades are illegal to sell. Ive used a similar router jig for years, but I think I will be upgrading to this one soon.

    You can never have to many jigs.

  15. Great video. Thanks, Mark.

    I’ve seen several incarnations of this jig and yet, while watching your video, I managed to pick up a couple of tips I’d not seen before – namely, flush-trimming with the table saw and rebating/rabbetting the edges for the guide bush/router cutter offset.

    Have you considered adding an adjustable stop to limit the length of your grooves or dadoes? It could make things easier than having to squint for a pencil line.

    How about using those new Bench Cookies from Rockler – the ones with the Risers? They would probably allow you to use this jig OVER your workbench in most circumstances.

    Thanks again. :-)

  16. Dan Drabek (http://deleted) February 15, 2011

    Simple, cheap and effective. My kind of tool.

    DD

  17. Friend thank you very much for your words, I learned from you the woodwork and I have my workshop today. The structural work helps me relax from the crazy world of art. I made that song for your show of gratitude to everything you do for us. from my country Venezuela the biggest hug.

  18. Will March 6, 2011

    Hey Marc, another great video. I love the series.

    When I watched you drilling the holes and sinking the screws at the 7:35 mark in the video, I realized that there are lots of screws and related tools and techniques I’m unfamiliar with. I was wondering if you might do a video on the different types of screws out there, and when and how to use them. For instance, what was it you used to drill the pilot hole there, and what screws did you use and why. And more generally, what to use where. For instance, just looking at the Highpoint brand of screws, there are the Confirmat screws, the XT washer head screws, the trim-head screws, etc. When would you use those different screws? I’d really appreciate your perspective here.

    •  

      Hey Will. I don’t use screws often so when I do, I can honestly say I don’t put a whole lot of thought into it. I primarily stock two different screw types, general square drive wood screws and pan-head screws (the type used in pocket holes). Most of my screws are purchased from McFeely’s and they have an excellent “Screw Portal” that will lay out your options quite nicely. Try it out: http://www.mcfeelys.com/shop/screwportal

      Their cabinet-making page should clear up some questions too, especially concerning confirmat screws which are usually used for particle board and MDF. http://www.mcfeelys.com/shop/sp-cabinetmakng

  19. Hi there.

    I am new here and allready enjoy in Your site. I am in a middle of a shelf project and i need something just like your Dado jig. I am going to start with it tomorow morning. Only what i dont have is this specialy router bit. I saw that there is some wider gold colored part above the knives on the router bit. What is its name and where can I buy it in Europe?

    P.S.
    Sound of wood shaving with hand planer is better than the TV sound ;)

    Thanks in advance,
    Stipe Marasovic, Croatia, Sinj

  20. Lori March 9, 2011

    Very cool jig Marc. What a less problamatic way to do dados!!! Thanks for the video, great detail!!!

  21. CJ March 14, 2011

    awesome jig…just finished up mine this weekend for a greene and greene bookshelf, and it worked perfectly

    thanks for posting

  22. Silas March 18, 2011

    Thanks for putting that one to bed about the outro lyric. It has been bothering me since day 1.!

  23. Marc, thanks for the “exact-width-dado-jig” design. I build one with the nuts up. I posted it on Lumberjocks and I was incouraged by other LJ’s to post it here, because you asked for ideas and modifications. Soe here you go. http://lumberjocks.com/projects/46827

    Pabull

  24. Marie April 3, 2011

    Hi, this is just to test my gravatar. I just opened an account, haven’t a clue now to use; at least not yet. Happy woodworking.

  25. kimball (http://yahoo) April 20, 2011

    Hi,
    First I would like to thank you fro this wonderful little gadget. As soon as I finished watching the video, I ran out to the garage and built myself one. Then I thought about the knobs getting in the way problem. I solved that for myself by simply using 4 bench cookies and 2 F clamps. It woked out just fine.
    I only have one further recomendation; make sure your router comes to a complete stop before lifting it free.

    Kimball

  26. Sternberg April 24, 2011

    I would make the stationary fence, 6″ or more wide, to make it easier to clamp to your work piece.
    I also usually put a sacrificial aluminum piece on things that I want to be the cut line. That can then be changed, to accomodate different router bits/bushing combos, and allow you to make repairs to your jig.
    The aluminum cuts as well as most hardwoods.

  27. Anthony June 15, 2011

    I like this! Thanks Marc.
    I wonder what to do about repeat-ability though. Say you are building a book case in which the shelves sit in dados on the sides. Those dados would have to match exactly on the two separate sides.

    •  

      Well you can do a few things. If you make the jig long enough, you can do both sides at once. Or you can simply mark the pieces accurately. Alternatively, create a story stick that you can reference the jig from.

  28. Anthony June 16, 2011

    Thanks Marc! Hope Nicole is doing OK.

  29. dave g June 26, 2011

    I made this jig for a project and I found it to be very easy to use. I got a lot of use and it was super accurate. I made mine so I could dado 48″. Thanks for the pics and the free plans.

  30. David July 5, 2011

    What size template guide are you using on your festool router for this? 17 mm flange guide?

  31. Keving July 16, 2011

    Is this the guide bushing adapter that you used with the Festool 1400? With a 5/8″ guide bushing?

    http://www.festoolusa.com/prod.....93566.html

  32. Dear Mark, I understand you were looking for modifications to your exact width dado jig to mount the setting knobs on top. I have done just this with my jig which is made of a laminate with two bristol levers to lock it down. I have made the side fences wider and recessed the bolts to achieve this. i do have photos of the jig but am not sure how to upload them to you. All the best, good woodworking. Alan.

  33. Mike Corwin August 21, 2011

    Hey Marc – Sorry for the newbie question…in the video you were making a stopped dado, but I was wondering if there is any problem doing a through dado with this jig given the fact that the beginning of the workpiece butts up against the short fence of the dado jig. Thanks very much!

  34. Matthew November 16, 2011

    Hi Marc

    Awesome jig, and very clear and thorough explanation of its construction and use. I’m going to build one this weekend. I’ll probably setup for use with a 20mm guide bushing and a 1/2″ bit – so the offset will be greater, which means I’ll have to make a narrower rabbet and/or use thicker edge banding, in order for the bit to contact the lip when flush trimming – right?

    When I’m done, there may not be a more southern jig than this – I’m in NZ!

  35. Rick December 2, 2011

    Love the jig design, I made one earlier this year, however yours
    seems to not only be better, but last longer. How would you go about making do mortise type of dato? I am currently on a project that will
    need such for legs into the bottom side of shadow box. I am using Black Walnut and do not have enough extra for mistakes.

    •  

      Well for mortises, I would just rely on the router’s edge guide. I find that to be the simplest solution. You could build a specific jig for the task, but if you get good at using the edge guide, you can apply that skill to just about every project.

  36. Rick December 2, 2011

    Marc

    I was not completely clear, mortise was not a good term here. I
    believe a hidden dado, a start and stop points where the the dado
    cut is the exact size of the piece that will be inserted into the cut.
    Thus the end result would look like a mortise. After doing some critical
    thinking, at age of 65 any thinking can be critical, this really may not be feasible, as you may have to have 2 sets for every size required.

    Also, I have watched most of your videos and have found them quite good and extremely helpful, especially the tools set ups.

    •  

      Oh so just a stopped dado? For that, I would just mark a line and stop the router before getting to that line. I would then use a chisel to do the final squaring off of the stopped end. I suppose you could also just clamp a stop to the jig or even rig up and adjustable stop for repeated cuts. But I don’t know if this particular design would accommodate something like that.

  37. Rick December 9, 2011

    Marc

    I have started to build the template jig, like you did except that I
    used Roberts modification of T stripes and made the long strips 5″.
    The it dawned on me to add two parallel T tracks on the outside
    of the long sides. Then add two T track clamps on each parallel
    track. The clamps hold in place a piece of wood at the top and
    bottom ends. Now just add to these two blocks with screws a
    smaller block the size of the cut. Just set the new blocks to the
    size when you set the cut size. Hope to finish constructing the
    jig Monday, then test it. How do I send photo of the jig if it does
    what it should do?

  38. Big Jim January 14, 2012

    I enjoy to watch Width Dado Jig. What 1/2″ router bit talking about 1/2″ shank bit or 1/2″ straight cutting bit? thanks………..Big Jim

  39. found this on a video by the woodworker’s journal that was quite good:

    T-Square

    Make yourself at least one T-square. Simply glue and screw two straight-and-true scraps together in a T-shape. One piece, called the crossbar or the head, butts against the edge of the workpiece, and the other, called the fence or the guide or the blade, extends at a right angle across the workpiece surface.

    The big advantage of the T-square is that it saves setup time. Instead of having to mark the full length of the dado, usually a single tick-mark is sufficient. So long as the fence is perpendicular to the crossbar, you can be assured that the dado will be square to the edge.

    Dual-Fence Jig

    The dual-fence jig enables you to rout custom-width dadoes (within limits). It is ideal for cutting dadoes perfectly sized for the particular plywood you are using. Since routers vary in base size from brand-to-brand and model-to-model, you build the jig to work with a particular router and a particular bit.

    When the fences are collapsed, the router’s base just fits between them, and the cut width equals the bit’s diameter. As the fences are spread, the router’s path widens, and so does the cut.

    Construction is straightforward. Cut the parts to the dimensions on the drawing. The width of the fence base is the sum of the fence width plus the router base’s radius. Glue the fences to the bases as shown.

    Attached the fixed fence to the crossbars, making sure it’s at right angles to both crossbars.

    After routing the slots in the movable fence, butt its base against that of the fixed fence and trace the slots onto the crossbars. Mark the centerpoint for the fence?s machine screw ?stud? at the end of the slot that?s farthest from the fixed fence. Then drill a 3/4″-dia. counterbore about 5/16″ deep. Bore a 1/4″ hole in the center of the counterbore, and countersink the hole on the underside of the crossbar. Install the screws, then the movable fence.

    Finally, trim the bases using the bit you?ll always use with the router. I recommend a 3/8″ bit, since that?ll allow you to rout dadoes for 1/2″ plywood and thicker stock as well. Jam the movable fence tight against the fixed one, so the bases contact edge-to-edge. Adjust the router and bit for a cut just a hair deeper than the thickness of the bases. Clamp the jig onto scrap stock to support the cut. Set the router between the fences and cut from end to end.

  40. I think if you make the 1/4 base adjustable you would have one that can accommodate any bushing and bit.

  41. Lito March 13, 2012

    Marc,

    First, thank you so much for posting this jig, I really like this handy jig and it works great. I took the challenge of getting rid of the knobs so that I can put it flat to the work piece and not overhanging. I use a flange nut and allen bolt . Here’s the link:
    http://www.routerforums.com/ji.....-busy.html

    Lito
    Round Lake Beach, IL

  42. Paul Tucci March 19, 2012

    Marc…..great video and very informative. I just completed a project that required a dado and it wasn’t as tight as I would have liked it. I’m going to make your Exact Width Dado Jig, but need some guidance on the router bit and bushing. I been looking through my woodworking catalogs and now I’m completely confused on the bit/bushing. Do I need a straight bit, trim bit, planner bit, dado cleaning bit, etc? I was looking for a 1/2″ bit with a 5/8″ bushing but came up empty. Can you please make a recommendation for me ( I don’t care what manufacturer you use), a part number would be GREAT.

    • Lito March 19, 2012

      I use 1/2 straight bit (diablo from home depot) and 5/8 bushing, but you can use any size straight bit you like and bushing that fit just right to your selected bit. What ever bushing/bit combination you use will be dedicated to your exact dado. Mine is here on this link:
      http://www.routerforums.com/ji.....-busy.html

  43. Jim June 25, 2012

    Marc,
    I really like the Dado Router Jig that you have made and demonstrated. I plan to make one. Will be very useful.

    Question: Looking at your router table fence I wondered which model of fence and router lift you are using? Also, have you done any “comparison” tests of the various router fences and lifts on the market. Mine is home made and not as precise and fast to set up as I would like. I realize this is “off-target” but your reply would be appreciated.

    Thanks.

  44. Brandon December 24, 2012

    This looks like a simple but effective design. I think the blank at the fixed end, plus a t-slot underneath would allow you to reverse the knob system so it can be used on a flat surface. The wider end board would be needed to allow proper clearence of the router base. It would be really great to create a method of interchanging two face strips for each bit and guide. Not sure how to accomplish that just yet.

  45. Eric December 30, 2012

    One comment. Love this jig, and made a similar one using a guide bushing on my router’s baseplate. The problem I had was that every new project required me to setup the bushing exactly center with the bit such that the bit is alway cutting flush to the rabbet on the jig. I must have been a hair off just one time, and caused the rabbet on the jig’s guide rail to become a hair smaller. I then found that the dados came out too tight! i was like, “ok man! what the heck!” I modified the jig to use a mortising bit with a guide bearing. Therefore there is no rabbet on the jig anymore and it eliminates this problem. Simply use the flush bearing router bit to take off the rabbet when it starts to make dados that are too tight. I bought a 1/2 by 3/4″ long mortise bit with the bearing on the shank side (bottom?) . The only issue is that this setup won’t make dado less than 1/2″.

  46. Russ Prechtl January 9, 2013

    I made my jig with a wider movable arm (about six inches wide) and longer side pieces with bolt slots. This allows the bolts and wing nuts to be mounted on the top with enough room for the router base to pass. Since the bolts and nuts are on top, now I can work on top of the bench without having to cantilever the work over the side. It’s much more stable!

  47. Wayne January 29, 2013

    I need make some dados at a 85 degree angle. Do you think this jig could be modified to do that? I was thinking I could add a shim to the fence to askew the angle.

    thanks

    Wayne

    •  

      sure. As long as you have the angle set on the rail just right, it should work. But keep in mind you’ll probably have to make a dedicated jig just for this task. If you try to use an existing jig at an angle, the jig will not line up properly with your line since the bit is tilting away from the inside edge of the rail.

      • Wayne January 29, 2013

        Marc,

        I am confused or I was not clear in my initial comment. My dado will be at 90 degrees to the face of the workpiece. The issue I am having is that I need cut the dado (at 85 or 15 degrees depending on how you look at it) across the face of the workpiece. That is why I thought I could make a shim for the edge of this jig to make it sit at angle a crossed the face.

        Thank for the quick reply and the amazing support you give all of us budding woodworkers.

        Wayne

        •  

          Oh well in that case, absolutely, yes. I thought you wanted to have the dado at an angle with reference to the face, not with reference to the edge. So yes, you can absolutely use this jig at an angle. Either create an angled shim or simply draw your lines and match the jig with the line and clamp it down.

    • Scott April 3, 2013

      Make two wedges the full width or length of your work piece.
      These wedges should also be large enough to accommodate your jig.
      Clamp your wedges on either end or side so that they create the angle you need for your dado.
      Place your jig on your workpiece against your wedges which will cause your jig to be at the angle you need.
      Align the jig to your mark and your set to cut your dado.

      :-)

  48. Brian April 24, 2013

    Hey, I’m planning on making this jig, but don’t have any guide bushings on hand. Rather than buying one, is there any reason I couldn’t use a flush trim bit and just skip the final step to set the collar size?

  49. Hi,
    Your Jig cross atlantic ocean and finished in France.
    I decided to make it, very usefull, simple to make and to use it. Accuracy is good.
    I think I’ll do few project and maybe bring some more convenient modification like a adjustable end stop to control the router range.
    Thanks

  50. Greg February 23, 2014

    Marc-
    Do you use this for rabbets as well?

  51. DJ July 22, 2014

    Marc,

    I know this is an old video, but it’s still very useful! Thanks for posting it. I am mid-project in building one of these for myself and wanted to add my modification to the list. I should have read the comments first as I like some of the other suggestions also and could have just used one of those.

    In stead of using the T-bolts and knobs, since I didn’t have a ready source for them and wanted to be able to adjust from the top. I purchased t-slot nuts and a 1/4 hex nut that matched. For the slots, I made them narrow on the top side and wider on the bottom. Enough for the T-nut to fit in the bottom slot but not go through the top part. Then I counter sunk a hole for the hex bolt with washer, so that I can tighten it from the top using a 1/4 inch hex wrench. Maybe even using a T- handle hex wrench. So these don’t stick out either on top or on bottom.

    Thanks for the concept.

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