Noob problem on boolean merge

I’ve just started learning blender and am merging a few shapes together (e.g: to from a hand) rather than “joining” them because this gets rid of unneeded vertices inside the model. To build a kind of a hand, I have a box shape with three cylinder “fingers” emerging from it. Merging each finger with the box one at a time worked for the first two fingers. The remaining one however, seems to cut itself away from the hand, more like what I would expect for “difference” boolean.

I have played with this a few times, changing order of which object I select first, trying to flip the finger (invert its geometry)… even actually using “difference” doesn’t seem to bind the objects into a single mesh like I am wanting.

Does anyone know what might be causing this problem and how to fix it?

Hope you can help me fix this, it’s got me stumped (my first ever post here too :wink: )

P.S: Anyone know where I can FTP the blender file in case people want to look at it for themselves?


The type of boolean you need to use is ‘union’ although you would most probably get a better result by manual joining the parts together.

I recomend not to use Boleans for organic things.

little Hand Tutorial created in the last 3 minutes…

Scale a Cube and use the Loop Cut until it looks like this:

Select the upper 3 Faces:

Hit the E Key to Extrude and select individual Faces.
do this Twice till it looks like this:

Select this Edge:

And move it outwards like this:

Extrude the Face above and Rotate it a litle inwards, do it again to form the Thumb.

Add the Subsurf Modifier

Use Setsmooth

With a litle tweaking and Extruding you end up with a simple hand like this in under 3 Minutes.

hope this helps.

With all the boolean merging, the vertices got kind of complicated, perhaps one got dropped somewhere. Selecting an object and then going itno EDIT mode (with none of its points selected) to perform SELECT >> NON-MANIFOLD identified a point in the main hand (this is bad - it means that somehow that point does not think it’s closed… kind of like a leak).
So, selecting ALL points in the hand in EDIT mode (A key) I then chose MESH >> NORMALS >> RECALCULATE OUTSIDE which fixed the leak.

The two objects would now perform boolean operations sanely.

I knew about Union versus join… wanted union because join keeps al the interior vertices intact and I wanted just the external shell. Am mollding a hand for chartacter creation and animation.

Thanks for the pics… I’ll look into them, as the way I’ve made hands it pretty time consuming.