Print in place: a moving model straight off the printer

How it works

Typical examples are a chain, an articulated dragon, a hinge, gears on pins or a screw in a nut. Everything is printed at once on the bed and after you take it off, the parts move. Technically it is ordinary FDM printing, only the model is designed so that a small clearance remains between the parts.

The biggest advantage is that there is no assembly. The downside is that the print is more sensitive to accuracy and the model is not so easy to repair when one joint seizes.

Clearance and limits

The gap between moving parts has to be big enough that the layers do not fuse, but not so big that the part rattles. With a 0.4 mm nozzle 0.3 to 0.5 mm per side is most often used. Less than 0.2 mm almost certainly means the parts will join. This is related to tolerances.

• Overhangs. There must be no large overhangs above the gap, otherwise the underside sags and fills the gap.
• Supports. Supports cannot get into the gaps, so print in place models have shapes that do not need them.
• First layer. It is printed on the bed, where elephant foot can narrow the gap. A well designed model therefore has a chamfer at the bottom.

What to do when ordering

If the author designed a model as print in place, we print it as it is. We do not change the clearance in it, it is part of the model. If you download it from a source, check which nozzle and layer height it was designed for. We print with a 0.4 mm nozzle and 0.2 mm layers, so designs with a 0.3 to 0.5 mm clearance should work well.

Do not scale such a model up or down, the clearance would change with it. After printing you may need to work the joints loose gently by hand. If one will not come free, write to us and send a photo. We also check every batch with a photo before dispatch.

For model designers

If you are designing a model, try it as a single piece first and only then order a bigger batch. With a larger number of pieces make sure they fit on a bed that is 246 × 246 mm. It is a good idea to use a proven clearance and not agonise over whether a tenth less would do.