I think a dado blade on the tablesaw is the best way to make grooves and dados.
I used to consider blade changes a hassle, and planned my work to avoid extra changeovers. Then I timed a blade change from rip blade to a full 3/4" dado stack. It took about a minute.

My tablesaw has a bigger table top than my router table, so I tend to use the dado blade quite often.
Plus, a dado blade has shims to get the fit just right. Even undersized router bits for plywood don't fit every sheet of plywood.

 

I totally agree with pintodeluxe. But, to answer your question: Measure and mark where you want the dados on a piece of scrap 1×2 that is as long as your work piece is wide.
Lay the 1 X 2 perpendicular to the fence and close to the bit. Adjust the fence to meet one of your marks. Make your first dado. Then reverse the work and do the same again.

 

Thanks guys - seems like using a router is not so much measuring as it is trial and error

Guess I have to swallow the pill and go for the TS dado. Haven't used that yet either, so another new thing for me this weekend

 

It's not that hard.
Get a sample pc the same size as you are going to use.
Measure from the fence what you need. Make a small (1" into the board) cut, pull the board out and measure it. Draw a line on your table where your fence is, move the fence the appropriate amount, run your test pc again going a little farther this time, remeasure repeat until you get it right.
Run all your pcs then repeat for the next grove the same way.

When ever your going to do anything that needs to be precise, you need to make a sample cut first, even if your using the dado on your table saw.

 

I would most likely use the router handheld with a guide rail to cut those. Measure the distance from the edge of the bit to the side of the router base plate and clamp the guide that far from the location you want the dado and run the the router along the guide to make the cut. Or several people have posted exact width dado jigs that will do the same thing over and over for different size dados.

 

i have also ripped a board on my table saw that is equal to the distance the dado is offest from the board edge, and just used that to position the router tables' fence.

For instance if I wanted my dado 1" from the edge of my board, I would rip a 1" wide strip, lay it against the fence and push it up to the blade until a single piece of paper fit there with moderate resistance. Seems to work.

-Brian

 

great idea about ripping a piece of wood - thanks all - response are all much appreciated

 

Draw the dado on the end of the board and use that to line up the bit. It is not that hard.

 

Bondo for the win! At least that's how I do it so it must be right.

 

Thanks guys - seems like using a router is not so much measuring as it is trial and error

Well I have never found it so. But, then, I am using a Woodpecker router lift. One of the great features of their router lifts (and their router plates BTW) are rules on both sides of the bit inscribed on the plate with the 0 point at the center of the router bit.

A little quick math that involves the diameter of the router bit and the desired offset of the dado and I set the fence on my router table to these rules dead nuts every time to make dadoes. This is not a failure of the tool - this is a failure with your equipment surrounding the tool.

Not that the Woodpecker stuff is the be all and end all. I frequently have requirements for dadoes past the end of the rules that Woodpecker provided. But, with a little effort and knowing that their 0 point is accurate, I can always measure from the 0 point to whatever I need.

 

what about using hand held router and dado router jig, instead of table ? i would imagine, time saved from the jig is better than whatever can be done on router table or table saw. maybe.

 

Thanks everyone for the advice - it's greatly appreciated.

I tried doing a hand held today - I set the board on fire Now I know I'm doing it wrong.

Me and my router don't seem to be getting along very well.

 

Fire and power tools aren't a good combo. If its a struggle to make a cut, then make shallower passes or use another bit. Shrapnel from a failed router bit can cause serious injury.

 

Yeah, you want to set your depth per pass such that you can keep the board moving continuously without hearing the motor strain/bog, and without leaving burn marks on the wood. Straining the motor is bad for the tool and the bit. Going so slow you burn the wood is bad for the bit an the wood.

-Brian

 

Thanks all - I've been setting the bit to 1/4" is that too deep? Go to 1/8? Maybe the router is just too old?

 

What kind of bit(profile, carbide or old steel one) what wood, what speed on the router? All important questions to determine how much you can take in a pass and how fast you can feed.

 

My router seems to only have 1 speed - fast

The bit is a straight bit - not sure of the material as it came with the router and both are pretty old, wood = 3/4" ply (I'm still going through my scrap to build jigs and tables and stuff).

Thanks for the response

 

I would suspect the bit is the culprit. Probably not carbide and probably dull. Get yourself some carbide bits.

 

...or at least some sharp HSS bits. Plywood is also harder on the bit, as the alternating layers have glue between them. Most articles you read about routing say to take 1/8" per pass.

If you want to get really fancy, I suppose you could act like a machinist and calculate the speeds and feeds for your router/bit combination. At that point, you could figure out the horsepower required to make a cut of a given depth at those speeds. Compare that to the HP of your router, and you can figure out the max depth per cut.

Or just start at 1/8" and arrive at the same answer as above through trial and error.

-Brian

 

Thanks guys - new bits it is - I've been thinking about buying some new ones and waiting for some inexpensive sets to go on sale.

bbasiaga - calculating the speed - not gonna happen - but your 2nd option - right up my alley LOL

Going to move towards the 1/8" and see how that goes next.

 

I was working on a couple of project that required some router work. Seemed like my router was doing what your described, and not working very well. It was a pretty old router. I replaced it with a newer router with more HP and a new bit.

What a difference. Slices like butter now. How old is your router and what horsepower. I actually wound up buying 2 "new to me" routers at a pawn shop but they are newer routers. About 1/2 of new price.