Your Active Print Setup

7 min readUpdated Aug 2026

A hole modelled at 5.00 mm does not print at 5.00 mm. On a typical 0.4 mm machine it comes out around a tenth small, and a 5 mm pin comes out a tenth large, which is why the pin you designed to slide needs a mallet. Your active setup is the app's answer to that: a printer, a nozzle, a quality preset and a material, chosen at the far right of the editor header, feeding real measured numbers into every formula in the document.

With no printer yet, the workbench is one button. Every number the rest of the app reads starts from what you add here.

Reading the chip

The pill shows, left to right: a coloured glyph for how well calibrated this combination is, the printer's name, a nozzle glyph with its diameter, a layers glyph with the layer height, and a coloured badge for the material. With nothing set up it reads No printer.

The glyph colour is the part to read first. Green means this exact combination is fully calibrated. Orange means the numbers are being carried over from a related setup. Red means you are on market-standard defaults, either because nothing is calibrated or because there is no printer at all.

Click the chip and four columns open: Printer, Nozzle, Quality, Material, each with an add action that opens the matching wizard in a new tab. The list reloads every time you open it, so a printer you added in another tab is there immediately. Before anything exists you get No printer set up yet and an invitation to Set up a printer.

The eleven numbers

Whichever setup is active resolves to eleven constants, and they are usable in any numeric field in the app, typed in upper case like FIT_SLIDE, with autocomplete alongside pi. This is the table worth keeping.

The calibration constants

Constant	Unit	Market default	What it is
`HOLE_COMP`	mm	0.05	How much a hole prints undersized, per side
`PIN_COMP`	mm	0.05	How much a solid pin prints oversized, per side
`ROUND_COMP`	mm	0.02	Extra gap a curved wall needs over a flat one, per side
`FIT_FRICTION`	mm	0.10	Locating fit: goes in and stays, separates by hand
`FIT_SLIDE`	mm	0.20	Free moving fit: rotates or slides without binding
`FIT_PRESS`	mm	−0.05	Interference fit: forced in, permanent. Negative on purpose
`MIN_WALL`	mm	0.80	Thinnest vertical wall that prints solid
`MIN_GAP`	mm	0.40	Smallest slot that stays open instead of fusing
`MIN_DETAIL`	mm	0.40	Smallest pin or relief feature that survives printing
`MAX_OVERHANG_ANGLE`	deg	45	Steepest unsupported overhang, measured from vertical
`MAX_BRIDGE_SPAN`	mm	10	Longest unsupported horizontal span that prints clean

Every clearance value is per side. A hole is a diameter, so a hole takes twice the constant.

Designing against them

The first three are bias terms: they describe how your printer shifts a wall, in whichever direction it shifts it. The three fits are gaps by intent: how much room a joint needs to behave the way you want.

That gives you a pattern you can use everywhere. A hole that has to come out at its modelled size is 5 + 2 * HOLE_COMP. A hole for a 5 mm pin that has to slide is 5 + 2 * HOLE_COMP + 2 * FIT_SLIDE. Swap FIT_SLIDE for FIT_FRICTION and the same joint grips; swap it for FIT_PRESS, which is negative, and the hole comes out under nominal and the pin has to be forced in.

Written that way, the part re-fits itself when the calibration changes. Type 5.4 instead and it fits your printer today and nobody else's, for ever.

The limits work the same way as floors and ceilings rather than corrections. A rib at MIN_WALL * 3 is three printable beads wide on whatever machine opens the file. A vent slot narrower than MIN_GAP fuses shut and prints as a solid face, which is the failure that looks like a slicer bug and is not.

MAX_OVERHANG_ANGLE is measured from vertical, following the same convention as the overhang view: 0° is a vertical wall and 90° is a flat roof, so 45° is the classic limit and a larger number means a better machine. MAX_BRIDGE_SPAN is the span you can cross with nothing underneath, which is what decides whether a hole in a wall needs a teardrop top or not.

What the chip changes and what it does not

Selections made in the chip last for the session and are never saved. They snap back to your stored active set when the editor mounts and every time you open another file. That makes the chip the right place to ask "what would this look like on the other printer" and the wrong place to set your default. The stored choice lives on the workbench dashboard, at /workbench, which is behind a sign-in: signed out you land on the sign-in screen and come back to the dashboard afterwards.

Changing the setup rebuilds the document, because the constants are part of the expression scope. If nothing about the resolved numbers changed, nothing rebuilds.

Expect the difference to be invisible. These are sub-millimetre corrections; the part will not visibly move. What changes is whether the printed pin goes in.

What ships in a download

Calibration is applied when geometry leaves the app. A store download bakes the downloader's own calibration into the mesh, not the author's, so a model that reads FIT_SLIDE arrives already sized for the machine that will print it. A visitor with nothing set up gets the market defaults from the table above.

The file preview panel shows this as Calibration used, described as Values from your active print setup are baked into downloads., listing only the constants the document actually reads. A store listing tells a visitor with no printer the same thing from the other side: The clearances and limits this model reads from your printer. Showing market defaults — connect a printer to personalize.

This is the argument for writing formulas rather than numbers. A part built from constants is a part that fits on somebody else's printer without either of you doing anything.

When it fails

There is no chip in the smart object editor. An object has no print set of its own; it inherits the setup of whatever document it is placed in. The constants still resolve in expressions while you author.

The values cannot be typed in. There is no panel anywhere for editing a calibration constant by hand, and nothing is stored per browser. The numbers come from a calibration run against a real printed coupon, or they are the market defaults. Calibrating Your Printer is the only way to move them.

The glyph is red and you own three printers. Red is about calibration, not about ownership: the setup exists but nothing has been measured for it, so you are on defaults.

Your setup reverted. You changed it in the chip rather than on the dashboard, and then opened another file.