Dadoes, rabbets, grooves for cabinet making

[bob]

I am an AutoCad user and fairly new to CNC. I'm planning kitchen cabinets and am trying to find out how I would draw dadoes, rabbets etc. in AutoCad or any other CAD program(dxf). I've hear that some people draw a straight line to indicate a groove but somehow that doesn't make sense to me. Can anyone help? Thanks!

Bob

[nschlee]

Bob,

Take a look at CabinetPartsPro, easy way to create boxes, has a post & exports a dxf file you can tweek in ACAD if needed.
http://www.cabinetpartspro.com/
Ryan, the author works for SB.

[rnels]

Bob,

It doesn't seem to make sense in the CAD world. But if you look at the machining options in the CAM part of CNC one of them is machine along vector (line). If you are using a 3/4 inch end mill for instance and you position your straight line vector in the middle of your dado and then tell the CNC to machine along this vector at a depth of .5 you will get a dado or groove of 3/4 wide by .5 deep. Hope that makes sense.

[wooden_innovations]

I cut dados and rabbets using the area clear function. I draw the dados and rabbets 0.2" past the part so the bit will not leave rounded edges from the bit.

The reddish lines are the dados on this file.

(This was done in AutoCAD)

Rodney


5105

[bob]

Thanks everyone!

[andre]

Bob
Just draw a rectangle and place it where you need it and do an area clear.
You will want to make some test dados first to get the right width. You will find taht all sheet goods differ in thickness, and that the area clear can leave a dado slightly smaller or bigger than you instructed it to cut, depending on the tool path.

[ryan_slaback]

Bob,
A couple other things to mention. Make sure you measure your material. 3/4" material is never .750" In my experience plywood runs small, melamine is oversized and mdf is close. Also your mileage may be different than mine, but my machine cuts about .010 undersize when climb milling (I guess due to bit flex). I always cut dados and rabbets (via area clear) by conventional cutting.

[Gary Campbell]

Bob..
We use an oversize rectangle to area clear. I usually start with .800" dado box centered .350" from the end. you may have adjust a few thousandths one way or the other for actual thickness of material. The downside of this is it adds a 3rd pass as we use a 3/8 bit, but it seems most bits are under the advertised size anyway.
Gary

[brucehiggins]

Along the lines of this thread: I bought a used shopbot and it will arrive in a week. My first project is going to be to build some shop cabinets using 1/2" and 3/4" birch ply. There will be lots of dadoes for modular shelves and drawers. Can someone recommend a good bit or bits for cutting and dadoing birch ply? Thanks.

[Gary Campbell]

Bruce..
We use a mortise compression with a .200" upshear for dadoes and 1 pass profile. 3/8" & 1/4" are the most common.
Gary

[andre]

Alot of times I use just a good old regular .25 straight amana bit. On MDf it works great with no tearing, I get a real nice clean cut. On some veneers like baltic birch, I will go to a down cut spiral for a clean cut.
Gary, I thought that Compression bits really only work if you are cutting through in one pass. Up cut bits only give you tear out.

[Gary Campbell]

Andre...
True.. but, mortise compression bits are made with a short up spiral on the bottom (.2) so that you can dado 1/4" with a downshear edge against the veneer. We are using 1 pass on the O.S. profile. I have had very good luck with the Centurion Mort. Comp.'s (I beat Jack J. to that!)

[andre]

I will have to pick one of those up
Thanks for the info Gary

[brucehiggins]

Gary, where do you get the Centurion bits? I didn't find their website.
Any recommendations on feed rate and rpm's if I use a 1/4" mortise compression bit with the 3.5 hp router?
Thanks for your help.

[Gary Campbell]

Bruce...
Try this: http://www.centuriontools.com/ and dont miss the small page #'s at the top right.
Gary

[gene]

Bruce
I run mine at 3/8 deep 13000 and 5.5 ips in birch plywood. I am using a spindle but i dont see that it would make a difference with a 3.5 hp router

[Gary Campbell]

Bruce..
We are usually in the 2-4 ips range with a 3/8 bit. 2+ for solids and 4+/- for plywood. 11/12,000 for wood, 12/15,000 for plywood. Just about the same as Gene.
Gary