Ports and fittings

A port is a node that opens to the outside. It has a bore — the through-hole into the channel — and a fitting geometry on top, which is whatever your tubing or syringe needs to mate with.

Make a node into a port by selecting it and setting Node type → Port in the inspector.

Start from the catalogue

The Catalogue fitting row cuts a socket sized for a specific real part. Pick one and every dimension fills in; all of them stay editable afterwards.

Fitting	Accepts	Bore
Norm-Ject Luer slip	The male cone of a Luer-slip syringe, or any male-luer adapter	1.6 mm
Norm-Ject Luer lock	The same cone plus a threaded collar	1.6 mm
PVC tubing socket · 1/8“	A cut end of 0.125“ ID × 0.188“ OD PVC tubing, pushed straight in	1.6 mm

The tubing socket is the one to reach for if you want to go straight from chip to tubing with no adapter. The socket is 4.70 mm against a 4.76 mm tube, so the PVC compresses about 0.06 mm and grips. Warm the tube if it will not start.

Note

The tubing socket’s bore is 1.6 mm, not the tubing’s 3.18 mm ID. A 3 mm hole meeting a 0.8 mm channel is a pocket that traps bubbles and blurs a concentration step. The socket floor becomes a shoulder the tube butts against instead.

A port stops claiming to be a catalogue part the moment you edit its geometry away from one. The match is computed from the dimensions, not from a stored id. A chip that claimed a catalogue part while carrying hand-tuned geometry would be a lie in the one place you are trusting the app to be literal.

The four port types

Underneath the catalogue, every port is one of four types.

Syringe

A plain cylindrical barrel socket for a blunt needle or a length of tubing. Default bore 1.2 mm.

Field	Default
Barrel diameter	1.6 mm
Barrel depth	6 mm
Boss height	2 mm

The simplest thing that works, and the easiest to print.

Luer slip

The friction-fit 6 % taper — the most common microfluidic interface there is. Default bore 1.6 mm.

Field	Default
Taper diameter (large end)	4.27 mm
Taper diameter (small end)	3.925 mm
Taper length	7.5 mm
Boss height	3 mm

4.27 mm is the ISO 594 / ISO 80369-7 reference-plane diameter of the male cone.

Caution

The type default pairs 4.27 / 3.925 over 7.5 mm, which is arithmetically a 4.6 % taper rather than 6 %. The catalogue Norm-Ject fitting derives its small end instead — 4.27 − 0.06 × 7.5 = 3.82 — so the socket is exactly 6 % over its whole engagement.

The difference matters: a taper that is nominally 6 % but arithmetically 4.6 % seals on a line contact rather than a cone, which is precisely the failure a printed port is prone to. Prefer the catalogue fitting unless you have a reason not to.

Luer lock

The same taper plus a threaded collar so a Luer-lock fitting screws down and stays. Default bore 1.6 mm. Use it whenever the line is pressurised or will run unattended.

Field	Type default	Catalogue default
Thread major diameter	7.6 mm	7.7 mm
Thread pitch	1.27 mm	4.7 mm
Collar depth	5 mm	5.5 mm

The pitch difference is not a typo. A real Luer-lock is a two-start form, and the generator lays a single-start helix — so the lead is what governs whether a real collar winds on at the right rate. 4.7 mm of lead is roughly the half-turn engagement the real fitting has. A fine 1.27 mm pitch would need four full turns where the real part engages in about half of one.

Every luer-lock port raises thread-support as an info: the thread is a helical rib whose underside is unsupported at every turn. Print the chip flat.

Custom

Free entry. Outer diameter, depth, boss height, and whatever bore you want.

Use it for anything the other three do not cover — a barbed fitting, a ferrule, an O-ring seat you will finish by hand.

Bore, footprint and clearance

Two different diameters, and confusing them causes a specific failure.

• The bore is the hole into the channel. Typically 1.2–1.6 mm.
• The footprint is how much of the chip face the fitting occupies. A luer boss is about 4.3 mm across.

Edge clearance is measured against the footprint, because that is the part that runs out of material at the chip edge. A port whose bore clears the edge by plenty can still have a boss hanging over it. See channel-near-boundary.

Why you must test-fit

Every catalogue fitting carries a caveat, and they all say a version of the same thing: a resin print shrinks a little as it cures.

How much depends on your resin, your exposure, your post-cure schedule and the ambient temperature. It is usually small — tenths of a percent — and on a 6 % taper over 7.5 mm that is enough to move where the cone seats.

The advice is the same in every case:

1. Print one port on a test coupon, not a whole chip.
2. Wash and post-cure it exactly as you will the real part.
3. Try the actual fitting.
4. Adjust by 0.05 mm at a time and repeat.

Once you know the offset for your resin it stays good until you change resin. See A first test-print protocol.

What the geometry does and does not guarantee

• The 6 % taper follows nominal ISO 80369-7 geometry. It is not a certified connector and it is not tested for the safety properties that standard exists to guarantee. Do not use a printed port in anything clinical.
• The luer-lock collar is a single-start approximation of a two-start ISO thread, with the pitch set to the real fitting’s lead. It screws on. It is not the ISO form.
• The tubing socket is an interference fit, and interference fits are the most resin-dependent geometry here.

Next

• Tubing, fittings, and connecting to a syringe pump — what to buy and how to plumb it.
• Mixing chambers — the other kind of special node.