# Cutting a Dado 2-5/8" from the Bottom



## scott lindsay (Jun 22, 2010)

I need a little help. I have watched several videos on cutting dadoes. I have seen some really nice jigs but none of them are meant for close to the bottom. I made a jig that is meant to set on the centerline and then lift up so the router will cut along the center of the bit. However, like most plywood today, especially Baltic Birch, it is not 3/4" but more 18mm. I have my two pieces cut at 18-1/2" so they need to be identical or my shelf will be a little offset. Any suggestions to a good jig or how to cut these so they line up and fit? I thought about pattern bits but the 2.25" is a short distance for a jig. I thought about screwing a 2.25" piece of wood to my sides and then just filling in the holes. Since the holes will be on the inside, no one will know or see them. Any thoughts? Am I on the right track?


----------



## Steve Neul (Sep 2, 2011)

For that it's a lot easier to do on a table saw with a dado blade. It could also be done on a router table however usually the top of a router table is small and large parts become cumbersome. Another option is harbor freight sells a straight edge that would clamp to the part to freehand route the dado. 24 In. Clamp Edge and Saw Guide.


----------



## Tetis (Oct 17, 2020)

good day! I want to ask not on the subject! In what program did you develop the design and drawing of your project? Thanks in advance!


----------



## Rebelwork (Jan 15, 2012)

.....


----------



## TomCT2 (May 16, 2014)

Rockler (and perhaps others) have a really slick set up:





also, many router bit makers offer "undersized" bits - intended for 'not really that thick' plywood.





Freud 4 Piece Undersized Plywood Bit Set (1/2" Shank) (89-650) Perma-SHIELD Coating Red - Bearing Flush Trim Router Bits - Amazon.com


Freud 4 Piece Undersized Plywood Bit Set (1/2" Shank) (89-650) Perma-SHIELD Coating Red - Bearing Flush Trim Router Bits - Amazon.com



www.amazon.com





which often work, but not always - which is the slick part of the Rockler jig. both edges of the plate will run in the guide grooves, the plate is "split" so the router bit can be (slightly) off-center - with the result you can make any width dado you need with exact repetition without changing the set up - run it on one edge, flip it run the second edge - the off-set plate nibbles just a fraction, to the exact width you want.

obviously you need a straight bit that is less than the desired width . . .


----------



## scott lindsay (Jun 22, 2010)

Steve Neul said:


> For that it's a lot easier to do on a table saw with a dado blade. It could also be done on a router table however usually the top of a router table is small and large parts become cumbersome. Another option is harbor freight sells a straight edge that would clamp to the part to freehand route the dado. 24 In. Clamp Edge and Saw Guide.


Steve, I thought about the tablesaw buy since I do not have a cross cut sled yet I fond it not wise to try and guide it through the saw. I have done that before and have had the cut not be completely square. I would do the router table idea also if I had one. Of course with a router table you have the same issue with a long piece possibly not going through square.


----------



## scott lindsay (Jun 22, 2010)

Tetis said:


> good day! I want to ask not on the subject! In what program did you develop the design and drawing of your project? Thanks in advance!


Tetis, I did not come up with the design. This was a project I saw on Woodsmith Shop TV show. I like the show but they have all the neat shop jigs to make the project.


----------



## scott lindsay (Jun 22, 2010)

Rebelwork said:


> .....
> 
> View attachment 426232


Rebelwork, basically, I made this jig and have a straight edge. However as stated before, my plywood is 18mm thick and there is router bit I have can make it in one pass. I need to use a pattern bit or take the straight edge and try to adjust it for a second pass. I like the (2) different jigs made on You Tube from the Wood Magazine people but that 2.25" is causing a design issue.


----------



## scott lindsay (Jun 22, 2010)

I like this jig but requires a pattern bit. At the moment I do not have a pattern bit (yes I can buy one) however with a pattern bit, how deep can I cut? I am using 18mm (roughly 3/4") and would like to go about 3/8"inch deep. Well, I guess it is time to experiment on a scrap piece of plywood.


----------



## scott lindsay (Jun 22, 2010)

TomCT2 said:


> Rockler (and perhaps others) have a really slick set up:
> 
> 
> 
> ...


TomCT2, I did buy a set of undersized plywood bits. I have not tried them yet. I was going to experiment with them this weekend. My jig I made is the same as the image you attached. Right now, if my home made jig works then I rather use that than spend money on a jig that should not cost so much. It may be a nice tool but I think it is a little over priced and paying for the name Rockler is not worth it at the moment. I like Woodpecker tools and them making anodized aluminum tools is smart but why over priced for me. Let me experiment over the week and hopefully one of these jigs online and the bits I have will work.


----------



## Rebelwork (Jan 15, 2012)

scott lindsay said:


> Rebelwork, basically, I made this jig and have a straight edge. However as stated before, my plywood is 18mm thick and there is router bit I have can make it in one pass. I need to use a pattern bit or take the straight edge and try to adjust it for a second pass. I like the (2) different jigs made on You Tube from the Wood Magazine people but that 2.25" is causing a design issue.


This is done using the router base. Nothing special to buy...

Make two or more passes. I don't see the issue..


----------



## woodnthings (Jan 24, 2009)

scott lindsay said:


> Steve, I thought about the tablesaw buy since* I do not have a cross cut sled yet I fond it not wise to try and guide it through the saw*. I have done that before and have had the cut not be completely square. I would do the router table idea also if I had one. Of course with a router table you have the same issue with a long piece possibly not going through square.


Typically, you do NOT use the crosscut sled for dados because it will remove 3/4" from the sled! I always use the fence which is quite long and has lots of length to register the workpiece against. Lacking a good tablesaw and good fence, I would use a router, with a straight bit in the reduced diameter for 3/4" plywood and a long straight edged clamp as shown in several posts above. There is really no better way to make dados in large panels and especially in from one end a good distance, but I have done it this way very successfully because I have a very wide tablesaw support for them.


----------



## Steve Neul (Sep 2, 2011)

scott lindsay said:


> Steve, I thought about the tablesaw buy since I do not have a cross cut sled yet I fond it not wise to try and guide it through the saw. I have done that before and have had the cut not be completely square. I would do the router table idea also if I had one. Of course with a router table you have the same issue with a long piece possibly not going through square.


It isn't difficult to do on a table saw, you just set the fence at 2 5/8" and run the panels against the fence. Of course with plywood the blade needs to be sharp and it wouldn't hurt to wax the top of the saw. We used to make melamine cabinets and had to dado the parts so glue would stick. We used a table saw for everything.


----------



## allpurpose (Mar 24, 2016)

I used my old aluminum slotted top saw for dado's with no problems. It was like pushing a car uphill on a gravel road with a rope, but it cut nice, straight dado's every time. It sounds a bit like your saws fence is too short, but just clamp a longer sacrificial fence to it and glide along the side of it instead..


----------



## B Coll (Nov 2, 2019)

scott lindsay said:


> I need a little help. I have watched several videos on cutting dadoes. I have seen some really nice jigs but none of them are meant for close to the bottom. I made a jig that is meant to set on the centerline and then lift up so the router will cut along the center of the bit. However, like most plywood today, especially Baltic Birch, it is not 3/4" but more 18mm. I have my two pieces cut at 18-1/2" so they need to be identical or my shelf will be a little offset. Any suggestions to a good jig or how to cut these so they line up and fit? I thought about pattern bits but the 2.25" is a short distance for a jig. I thought about screwing a 2.25" piece of wood to my sides and then just filling in the holes. Since the holes will be on the inside, no one will know or see them. Any thoughts? Am I on the right track?
> 
> 
> 
> ...


I have a few easy jigs that I use, some are a one and done. For this I would make a sled similar to one that would be made for a circular saw. Get a piece of 1/4" plywood, mdf, whatever. Glue another strip of it, 2" or so wide, does not really matter. What is important is that the strip is glued on perfectly straight. Take you router and put in whatever bit you plan on using 23/32" cab plywood straight bit. Now, using the strip as the fence, run the router along the fence cutting off the excess plywood. That edge is now exactly where the router will cut every time. Simply clam it to your work piece and cut being careful to keep the router against the fence.


----------



## gj13us (Apr 19, 2016)

Maybe someone can explain the problem because I'm not really understanding it. Why not clamp a straight edge and cut the dado with your router? Then carefully measure and line it up on the second piece and do the same thing.


----------



## Wingedwheel (May 17, 2021)

I like to use the straight edge clamp, routervand also bar clamps to hold the two parts to be dadoed together. That way the cut goes across both pieces on the same set up. That generally insures both pieces are the same.


----------



## kwoodhands (May 1, 2020)

scott lindsay said:


> I need a little help. I have watched several videos on cutting dadoes. I have seen some really nice jigs but none of them are meant for close to the bottom. I made a jig that is meant to set on the centerline and then lift up so the router will cut along the center of the bit. However, like most plywood today, especially Baltic Birch, it is not 3/4" but more 18mm. I have my two pieces cut at 18-1/2" so they need to be identical or my shelf will be a little offset. Any suggestions to a good jig or how to cut these so they line up and fit? I thought about pattern bits but the 2.25" is a short distance for a jig. I thought about screwing a 2.25" piece of wood to my sides and then just filling in the holes. Since the holes will be on the inside, no one will know or see them. Any thoughts? Am I on the right track?
> 
> 
> 
> ...


You do not need a jig. If you have a decent fence for your router that will do. If you do not have a fence , clamp a straight edge and install a bushing in the base. or just run the router base along the straight edge.


----------

