Guide for making STLs that are easy to integrate

The Assembler can load and scale any STL or OBJ file, but some things make it easier.

Scale and Orientation

Scale should me in mm.

The part should be oriented with Z up and Y axis forward. That is, as if the arm is straight along the Y axis, so elbow, wrist, knuckle, and finger joints should be in a straight line. This makes it easiest to align and scale the parts to the actual arm position for previewing and rendering.

The object should have origin at the relevant control point. The origin is the [0,0,0] coordinate.

• Gauntlet: origin in center of wrist joint
• Palm: origin in center of wrist joint
• Thumb and Finger Proximal: origin in center of knuckle
• Thumb and Finger Distal: origin in center of joint between proximal and distal

Measurements

The key measurements for the parts should be documented. These are:

Gauntlet:

• width at outside of wrist end of gauntlet (to fit inside palm)

Palm:

• Length from center of wrist joint to center of knuckle joint
• width at inside of wrist hinge (to fit gauntlet)
• width at outside of knuckles (to match other hand)
• spacing between finger knuckles (center to center)

Proximals:

• distance from center of knuckle to center of joint

Distals:

• distance from center of joint to tip

Printing orientation

For all parts, please provided the information needed to put the part into position for printing. This allows Handomatic to orient and pack parts for printing, so the users don't have to know how to do so.

The information required is:

• rotation for printing. For example, if a part should be rotated upside down, or tilted 5 degrees, to be level to the print bed.
• translation for printing, so that it's flat on the print bed. For example, if it needs to be raised 7mm. This allows Handomatic to render the part for printing and to combine parts into printable plates.

The easiest way to get the translation and rotation from preview location to printing location will depend on your CAD software.

Other parts

If there are additional parts, such as snap pins, they should be provided as separate files so that they can be positioned separately for previewing and for printing. For those parts, please place the origin at the center bottom of the part, and document:

• How many to print
• Where they fit in relation to the other parts (so that they can be previewed jn place)

Future

When we add this capability to Handomatic, joint holes should be removed from parts, so that they can be replaced in software after scaling and translation.