Clamp

A printable C-clamp, or a two-plate clamp whose V-jaw is cut for a named pipe.

A clamp is a frame, a screw and a jaw. What decides whether a printed one is any use is not the shape — it is two things almost nobody gets right by eye: which direction the layers run, and what diameter the jaw was cut for.

Two styles. A C-clamp reaches round the work with a single screw, and is described by its *reach* (how far in from the edge it can bite) and its *opening* (the thickest thing it takes). A two-plate clamp pulls two bars together with two screws — this is the one that mounts a holder onto a tube, a rail, a bed frame or a table edge. It has two screws rather than one because a single screw lets the plates pivot around it.

Name the pipe; do not type a diameter. This is the part worth reading twice. A trade size is not a measurement: 3/4in PVC pipe is 26.7 mm across, 3/4in EMT conduit is 23.4 mm and 3/4in copper tube is 22.2 mm — three different pipes wearing one name, 4.4 mm apart. Set the jaw to V-groove and pick the stock under Cut for, and the groove depth is derived from the published outside diameter for that exact series. Type a diameter only for something the list does not cover.

Why a 90° vee, and why only its depth matters. A 90° vee cradles *every* diameter on two lines of contact — that is what a V-block is for — so one groove suits a whole range of pipe. The single way to get it wrong is to cut it too shallow: below about 0.35 × the diameter the tube stops touching the faces and rides on the two mouth *edges* instead, which crushes soft tube and slips on hard. The V-groove row says which of the two you have, and shows both figures when the groove is short.

Print the frame flat. The clamp is emitted lying down, and that is deliberate: a printed clamp fails by the frame springing open and the layers peeling apart at the throat. Layer adhesion is the weakest direction in an FDM part, so the frame has to be printed with its plane parallel to the bed — then the load that opens the throat runs *within* each layer instead of across the bond between them. Do not stand it up to save plate space. The screws are separate bodies and stand upright, which is their own strong direction.

No hardware needed — or use a bolt if you would rather. By default the thread is printed and the frame is tapped to match, so the whole clamp comes off the plate and screws together with nothing bought. The screw sizes offered are all *coarse*, because a printed thread is laid down in layers and a fine pitch asks for a flank finer than the layers that build it. Tick Use a real bolt to get a clearance hole and a nut trap instead — that is only offered for sizes the fastener tables cover (M8 and below); above that the setting is ignored and the panel says so rather than building a nut trap from a guessed hex width.

Watch the span-vs-thickness row. Frame thickness is the one number that decides whether the clamp holds, and the row names the span that is doing the bending — the *reach* on a C-clamp, which is a cantilever, and the *screw span* on a two-plate clamp, which is a beam between its two screws. Past about 5× that span it gives before the screw does anything useful, and the row turns orange and then red. That is a rule of thumb and is labelled as one: the frame is a curved beam, and a clamping-force figure is not something this can honestly give you without a printed part to check it against.

What it does not do. There is no swivel pad on the screw tip — a real C-clamp has one so the pad meets the work flat, and printed that is a second captive part. The screw hole runs horizontally in the print orientation, which is the accepted compromise for a one-piece printed clamp and is why the printed thread is given more engagement than a steel one would need. Run Print check over the result before you commit a lot of filament to it.

1. Open the Generate panel from the left sidebar and choose Clamp (under Clamps).
2. The frame and its screw drop in as separate printable bodies. The parameters open in the Properties panel.
3. Pick C-clamp to reach round the work, or Two-plate clamp to grip a tube or a rail.
4. Set the opening — the widest thing it has to take — and, on a C-clamp, the reach.
5. For round stock set the jaw to V-groove, then NAME the pipe under Cut for rather than typing a diameter.
6. Check the Reach vs thickness row, then print the frame lying flat and the screw standing up.