Dado Thickness?

[erik_f]

I know this could be figured out with some work on my part with some simple scrap...but I was interested in knowing other peoples way of getting a good dado joint. I seem to have a hard time finding a good balance between hammering the joints together once they have glue and them having to much play and not having solid contact on all 3 sides of the slot once everything is cut...is there a set number you guys are using after you measure your material? Just figured this would help me get a better idea of what others are doing as well as maybe get some new ideas out on the table for construction ideas.

Erik

[phil_o]

My preferred method is to cut the dado first, then I plane the board to fit snug.

[erik_f]

so am I being too lazy by not wanting to plane the board?

[benchmark]

Hi Eric

The method that works for me is not using the actual cutter size when setting the tool paths, I run a test groove with the cutter I intend to use and then measure the width of the groove.
I then measure my material before drawing the dado's, combined with the groove width I can get really snug fit.

Paul

[stickman]

Erik,

I mic out the thickness of the lumber and offset my dado 1/64th. That gives me 1/32 overall. That is how I do it. Seems like splitting hairs, but I feel that gives me a great dado joint in anything I do.

Jay

[erik_f]

.032" gives you a snug fit and still allows you to put glue in the joint without beating it with a hammer...I guess thats the number I'm really looking for...thanks for the input guys...any other ideas?

Erik

[jay]

Erik, I agree with Mr. Mack, mic it! In our shop we find sheet goods, even off the same lift, vary in thickness. One setting does not give us the best all around dado, it is a pain but every joint is nice and tight.

[mziegler]

Erik, how about a drum sander. That good for taking off a few thousandth and giving you a good finish too. That will work for sheet goods like mdf. Mark

[erik_f]

I usually measure the stock before I design what ever it is I'm designing. Most of the time though if I get it all from the same place and lot, I measure the mdf in a couple places to find the average...but always seem to get some slots good...some not so good...I just upgraded the x and y car to the alpha frame and added an extra y motor...so I'm hoping I will be able to get closer to "splitting hairs"...hoping to get to around +/- .005"

[mikejohn]

And don't do as I did.
Make some shelves that fitted the groove (dado) perfectly.
Then, before fitting, painted them, ends an all!!!
.........................Mike

[bleeth]

I'm not sure I would be willing to admit that one Mike.
A Dado for solid wood should always have a small clearance for wood movement and to allow enough adhesive to remain in the dado for adhesion. Clearance is less of an issue for plywood.
Perfectly sized dados can be sheer heck to get wider stock into as there is usually a bit of a cup to it by the time it gets from the finish sanding to the dado.

[mziegler]

Erik, if it's a part you run alot, you could put a variable in the part program for the dado width. That way you can change dado width to what ever the sheet goods measure on that day. Mark

[erik_f]

I'm using Rhino...and I called and asked them if there was any way to set up something like that...and they told me no...seems kind of odd that I wouldn't be able to do something like that in a cad program as good as Rhino.