Help with curved profile

[Tapp1300 (John)]

Hi, All!

New to the group and still figuring things out–slowly.

I want to duplicate a missing corner piece from an old headboard. It’s basically a quarter circle with outside diameter of 5" and inside diameter of 3" with radiused edges and a 1"inch x 1/4" flat on top.

I sort have the outline done and know what the profile should look like. On the Round Modeling toolpath I don’t see any way to specify the radius of that rounding unless somehow restricting the height is supposed to do that. Even if I figure that out, the ends do not need to be rounded, but square.

If someone could walk me through some of that, I should be able to apply it to other projects in the future.

Thanks, all, in advance!

John

[WillAdams (William Adams (Carbide 3D))]

Probably you would want to model the entire arc in two sections, then have intermediate geometry to flatten the middle with an Equals operation.

Alternately, is using a Roundover tool an option?

Using unsupported tooling in Carbide Create: Roundover / Cove / Radius bits

These are usually used in routers for decorative effects in wood: https://www.whitesiderouterbits.com/products/1570 but they are potentially useful for joinery: They are also useful for rounding off parts to allow rotary motion as for a hinged lid. Unfortunately, Carbide Create does not support this endmill geometry — but using the new support for previewing a V endmill when used in a No Offset Contour toolpath, it should be possible to preview them w/ confidence by stacking a series o…

(and that suggests using a succession of V tooling to approximate this)

If you have trouble, upload the file and someone will walk through this with you.

[Tod1d (Tod (with 1 'd'))]

To model this you want to extend the vectors outside of the intended bounds, and make the width of each section 1". The angle & height will determine the radius. Angle 90° and height 0.5" will make the radius 0.5"

You really don’t need to model the flat center section as that can be achieved with 2D
The only portions that need to be cut with 3D are the rounded shapes.
3D toolpaths calculate with the center of the cutter on the boundary, so you’ll want boundaries offset by the radius of the ball mill. I’ll use a 1/8" ball, so offsets are 1/16"

I designed the part, stock & model 0.8125 height, your 0.750 plus the radius of the ball mill so I can cut the 1/16" below the bottom edge of the part to get the tool tangent at the bottom.
Add 0.0625" base to the model components.
So I machine around the center section down to 0.25"
Then machine the rounds with a 3D path
I also created dummy paths to trim the outside

[Tapp1300 (John)]

Thanks! I was able to do a pretty good job with a bandsaw and a router. Just knowing that the CNC is capable of doing it perfectly makes me wish I had done it that way.

[Tapp1300 (John)]

Thanks so much! When I get a chance I’ll go back and read through this slowly a few times and see if I can understand it. Not sure I get how to 2D model on top of a 3D, but I’ll work with it for a while, maybe something will click…

[Tod1d (Tod (with 1 'd'))]

Here’s the part… https://drive.google.com/file/d/1mYtzb1s_TlI3yi8Tbvu5kC4NVomU0Zzd/view?usp=sharing

[Redlander (Tim Jones)]

@Tod1d

Thanks for the tutorial. Not said but it seems the last operation for the 2D tool path for the 1” wide x .25” flat top (Ogee) cut used a square end mill correct? At least the simulation indicates that based on the 90 deg inside corner.

[Tod1d (Tod (with 1 'd'))]

Yes. This will give you a sharper corner at the top of the radii. I used a really big, unrealistic, end mill just to remove more material for the simulation.