# Jaws

The jaws bolt to the two carriers on the rail and are yours to adapt. The product repository has three designs,
all in [Gripper jaws attachment](https://github.com/Source-Robotics/MSG-compliant-AI-stepper-gripper/tree/main/STEP%20files/Gripper%20jaws%20attachment);
each file is one jaw, mirrored in the slicer for the other side, except the solid jaw, which has a mirrored file.

| Design | File | Use |
|---|---|---|
| PETG body with a glued-on TPU pad | `MSG_JAW_TPU_GLUE` | the recommended jaw: the soft pad deforms around the object and holds it better |
| Solid jaw | `MSG_solid_jaw`, `MSG_solid_jaw_mirror` | one part, quick to print |
| Hollow jaw | `MSG_JAW_HOLLOW` | lighter, and suited to multi-colour prints |

![The jaw body, with the mounting holes for the carrier](https://docs.source-robotics.com/MSG-gripper-docs/1.2/assets/gripper_jaws.webp){ width="520" }

## The TPU jaw

![The TPU jaw: a PETG body (black) and a TPU pad (yellow)](https://docs.source-robotics.com/MSG-gripper-docs/1.2/assets/tpujaws.webp){ width="700" }

Print the body in PETG with your usual settings and the pad in TPU with 16 % infill, no top or bottom layers and
two walls, for the softest pad. Then glue the pad to the body with ordinary super glue, in the orientation the
pictures show: a pad glued the wrong way round leaves the jaws facing the wrong direction.

<div class="grid" markdown>
![Apply super glue](https://docs.source-robotics.com/MSG-gripper-docs/1.2/assets/jaw_glue.webp){ width="300" }
![Press the pad on](https://docs.source-robotics.com/MSG-gripper-docs/1.2/assets/jaw_assembly.webp){ width="300" }
![Check the orientation](https://docs.source-robotics.com/MSG-gripper-docs/1.2/assets/jaw_orientation.webp){ width="300" }
</div>

## Sponge pads

A strip of 1 mm sponge tape (30 mm wide, in the BOM) on the gripping face of any jaw improves the hold on hard
and smooth objects a great deal. Cut it to length, peel the backing and press it on.

## Your own jaws

Keep the carrier's hole pattern from one of the designs and shape the rest for your objects. Long jaws
multiply the lever arm on the carriers: keep them short and stiff, and remember that the grip force is set at the
jaw faces, not at the rail.

!!! warning "Custom jaws on a PAR6"
    On a PAR6, custom jaws must keep the size of the original jaws: no longer, no wider and no thicker. The
    PAR6 software works with the gripper's original dimensions (its collision model of the tool and the tool
    centre point), so a larger jaw reaches where the robot does not expect it.

## Calibrate after changing the jaws

The gripper calibration finds the end stops with the jaws fitted; jaws that meet earlier or later than the old
ones change where 255 is. Calibrate again after a change, which happens at the next power-up anyway.