# Create a substration with a gap on the subtracted one

Hi, i wanna make stands for my resin vat, however i want to make a little gap to make easy to insert the « foots » on the vat. How can i make this ?

Hi! Are you looking to create a small tolerance gap between the two bodies? In this case, just create a copy of the purple body, scale it up by a few percent, then subtract it. The result will be a tiny (0.1-0.2 mm) gap between the two bodies which will make it easier to assemble them after manufacturing.

using scaling for this task has many problems:

• the direction of the scaling is tied to the current xyz axes. at least i couldn’t find a way to rotate the direction, i need to rotate my body instead.
• can’t set the size of the gap properly. i figured out that i can play with the distance between a given point on my body and the origin of scaling and the percentage value to get the desired result. like i can move my gizmo 100mm away from an edge and set the value to 0.99 to get a 1mm gap. but only at that point.
• scaling distorts the surface because of the percentage value so the gap is not consistent. in theory i can move my gizmo very far away (100 000mm) and set the difference to a very small number (0.99999) but what’s the lowest number i can use? the ui shows hundredths by default.

two years passed, is there a better tool for this job by any chance?

Hi @gex,

The pivot point of the scale can be adjusted to faces and edges where it will automatically align to the snapped elements, there is no need to rotate the body. However, it is indeed not the most accurate solution.

With the recent release of the history-based beta, offsetting the faces with a given distance will allow you to set a clearance with a defined gap.

The pivot point of the scale can be adjusted to faces and edges where it will automatically align to the snapped elements, there is no need to rotate the body. However, it is indeed not the most accurate solution.

sorry i haven’t checked this. i used a very far point to reduce the size difference and there was nothing to snap to.

With the recent release of the history-based beta, offsetting the faces with a given distance will allow you to set a clearance with a defined gap.

i tried this many times in stable but did not in beta. it works as i expected!

Gif with offset face in action

I select all mating surfaces on dovetails and use Offset Face to add gaps to make sure they’re mateable on a 3D print. Having the history to be able to change the gap widths easily will be useful, especially after named parameters are added.

With the recent release of the history-based beta, offsetting the faces with a given distance will allow you to set a clearance with a defined gap.

what are the limitations of this tool? i tried to use it on more complex bodies and it doesn’t work all the time, especially on merged and/or intersected bodies.

here is a simplified example:
first body is union of a cylinder and a spline swept around it. i get an error. second one is just a swept body. now this shape was easy to replace with something else but in my original project i couldn’t come up with a solution like this.

offset-face-example.shapr (12.4 KB)

There are no limitations set, but offsetting the faces could end up in non-manifold bodies if the geometry is complex or has some tiny details.

In your example, the shape on the left has a small remaining face from the cylinder. Please select that face too and the Offset Face tool will work fine.