3D app like autocad that will let you put holes in a design

I do a lot of mechanical designs and have a so so app called Emachine shop but sometimes it screws up when i export to an STL file and it does not come out right on here. Autocad Delux will not let you cut holes in stuff LOL and apparently neither does 123D design. Would appreciate some help.

Try Meshmixer http://www.123dapp.com/meshmixer

Not sure if this is an efficient way for you but could you try using boolean in Blender? Create a cylinder and intersect it with your object, then just do a boolean.

AutoCAD doesn't have a Boolean?

Mine does, which works for solids, surfaces (it's "Trim" for surfaces), and polygon meshes.

MB

Turns out that some of it is the object. It was created in Emachine shop which is easy to use but buggy. Once a problem object is created you can't add any holes or in some cases solid parts to it.

I occasionally have similar problems with TurboCAD. There are several workarounds.

The simplest is to save the file, exit and re-load.
Sometimes, the object is considered too complex and you have to Explode it to a collection of simpler pieces before doing what you want.
Least simplest (but still pretty easy) would be to perform a 3D Slice on the object. If doing that allows adding a hole, then you could 3D Add the two pieces back into one before continuing.

The actual names of the equivalent functions in other software will most likely be different, but the techniques may work for you.

Jeff