Guidelines for bending cutouts

I’ve seen 2D designs that have cuts or ‘wedges’ cut on the perimeter so that a bend can be made in the resulting cut piece. Are there guidelines or best practices that can be used to calculate or design ‘bendable’ regions?

They are there to make it easier to bend and form the part. As a lot of people don’t have a large metal bender. On thicker metal you can bend it then weld it up ( like a bumper kit) also makes it easier to ship a flat piece.

Yeah, I’m one of those who don’t have a large (or even small) metal bender :wink:

I should have been clearer in my question, I’m wondering if there are any equations or rules of thumb that would provide guidance on how much to cutout for a given metal thickness.

I really don’t know if there is a size cut chart or rule. I have seen everything from a thin cut line (on thin metal) to a thicker cut line (on thicker metal). I would guess the cut line would be about the same as the thickness as the metal to be able to bend it at a 90* bend.

Ah yes, good point! Thanks!

On my 45 xp cutting 14 gage I just cut straight lines.My kerf is .049 and that bent nicely.

About 14gauge and thinner, you can just cut a straight single line like Heath said. Thicker than that, you’d want to calculate what they call a K factor for where the material will fold back onto itself on the inside of the bend. You can Youtube some pretty good explanations.

The little notches at the edges of the bend line are for when the metal distorts and basically bulges outward when it’s bent. I like them because they double as a guide line to line up the upper die on my press brake.

But honestly, anything that is thick enough to require a K factor calculation or notches for the edge distortion is going to be too thick to bend in a vise by hand anyways unless you’re leaving a sliver of material left to bend as a guide. Then you’d weld the two pieces together.


Not sure about Fusion360, be Autodesk Inventor has a sheet metal utility that might help. You can build you box or shape of choice and unfold it into 2 dimensions. It also helps with bend order.

Fusion has a sheet metal utility that will unfold 3D into the flat version. It uses K factors to determine how to size the sheet based on the resulting bend radius.


There are many bending tools here you can choose from to do that