Frame bracing means adding stiffness to a 3D printer’s frame (diagonal struts, top braces or tie rods between the uprights, or panels bolted across an open face) so it flexes less when the print head changes direction. Less flex means smaller vibrations, and those vibrations are what print as ghosting or ringing next to edges. Before you add anything, do the free part: square the frame, tighten every frame bolt and put the printer on a surface that does not wobble. Klipper’s documentation lists an insufficiently rigid frame, loose or springy belts, misaligned parts and heavy moving mass as the usual causes of ringing, and says to fix those first.
Bracing helps most on tall, open-frame printers with a single upright pair; a closed box frame gains far less. This guide covers how to tell whether the frame is the problem, how to square it, what each type of brace does, and how to check that it worked. It deals with hardware only; slicer settings and firmware fixes for ringing are in our ringing and ghosting guide. Sources are Klipper, Voron and Prusa documentation, linked at the end.
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Stiffening a frame in order of cost
- Put the printer on a firm surface that does not move when you push it.
- Tighten all frame bolts, the PSU, the screen and anything else bolted to the frame.
- Check the frame is square: measure the diagonals and correct them.
- Print a ringing test and keep it as your baseline.
- Add bracing where the frame is weakest, usually the top of the uprights on a bed-slinger.
- Print the same test again and compare. If you use input shaping, re-measure the resonances.
Is the frame causing your ghosting?
A frame that flexes is only one of several things that ring. Rule out the others, because bracing will not fix them: loose or over-springy belts, a loose hotend or fan duct, play in wheels or bearings, and a wobbly table. Then look at the frame itself.
| What you see or feel | Frame-related cause | Fix |
|---|---|---|
| Printer rocks or the table moves during fast moves | Surface or feet, not the frame | Firm table, feet in the right place, moderate padding |
| Tops of the uprights sway when you tap them | Tall uprights fixed only at the base | Top braces or tie rods from the uprights to the base |
| Frame diagonals differ, gantry tighter at one end | Frame out of square | Loosen, square and retighten (procedure below) |
| Rattle or buzz at certain speeds | Loose PSU, screen, panels or frame bolts | Tighten everything attached to the frame |
| Ringing with a very low frequency on an accelerometer or test tower | Low overall stiffness or heavy moving mass | Stiffen the frame or lighten the moving parts before tuning further |
| Ghosting stays the same after bracing | The vibration is in belts, toolhead or bed, not the frame | Mechanical checks and input shaping (links below) |
The frequency is a useful clue if you measure it. Klipper’s resonance guide says that when ringing frequencies are below about 20–25 Hz, it may be worth stiffening the printer or reducing the moving mass before going further with input shaping, because a low-frequency shaper limits speed.
Printer placement: table, feet and padding
A braced frame on a flimsy table still shakes, because the table becomes part of the system. Prusa’s vibration guides say the surface should be steady and firm and should not wobble while printing or when pushed by hand. They suggest a hardwood table, or a concrete tile under the printer to keep vibration from reaching the desk.
- Feet: on the MK3S, Prusa places the rubber feet 2–3 cm from the ends of the frame extrusions. Feet in the wrong place let the frame rock.
- Padding: moderate padding such as a folded towel damps noise. Prusa notes that soft padding alone is not optimal, because a printer on something too soft can wobble. Our guide to vibration dampers covers the trade-off.
- Location: a corner of a solid bench or a wall-mounted shelf moves less than the middle of a light desk or a shelving unit on castors.
Tighten and square the frame
Prusa’s vibration checklist is a good model for any printer: go round everything bolted to the frame, not just the frame joints. It lists the heatbed screws (tightened in order: centre first, then the four edges, then the corners), the PSU screws and the LCD assembly, alongside pulleys and belts that must not rub.
Squaring is the step most people skip. Voron’s build documentation assembles the frame on a granite countertop or a similarly flat surface and checks squareness by measuring the diagonals, which should differ by less than 2 mm. That tolerance is for Voron frames; use it as a reference point for other extrusion frames.
- Loosen, don’t remove. Slacken the frame joints on the face you are squaring just enough that the extrusions can shift.
- Set the printer on a flat surface so the base is not twisted while you work.
- Measure both diagonals of the face corner to corner with a tape or long rule. On a bed-slinger, also check each upright against the base with an engineer’s square, front to back and side to side.
- Push along the longer diagonal until the two measurements match.
- Tighten the joints in a cross pattern, checking the diagonals again as you go, because tightening one corner can pull the frame back.
- Re-check the motion. Move the gantry by hand through its full travel. If it now runs freely where it used to bind, the frame was part of the problem; see our guide to mechanical binding for the axes themselves.
Types of frame bracing and what each does
Every brace works the same way: it turns a rectangle, which can shear into a parallelogram, into triangles, which cannot. The closer the brace gets to the corner that moves most, and the stiffer its material and its fixings, the more it helps.
| Brace type | Where it goes | Best for | Watch out for |
|---|---|---|---|
| Top braces / tie rods | From the top of each upright down to the rear or front of the base | Bed-slingers with a single pair of tall uprights | Must not pull the uprights out of square; set lengths with the frame squared |
| Corner gussets and angle brackets | Inside the corners of an extrusion frame | Joints that twist or loosen | Small; they stiffen joints more than they stop a tall frame swaying |
| Diagonal struts | Across a face of the frame | Open box frames that can shear | Can block access or the moving gantry |
| Panels | Bolted across the sides, back or bottom | Box and CoreXY frames | Heavy panels add mass; plastic panels add little stiffness |
| Enclosure as structure | Printer frame fixed into a rigid enclosure | Printers that need an enclosure anyway | Ventilation, heat and fire safety come first |
Panels matter more than they look. Voron’s documentation notes that extrusions joined with blind joints can rotate, and that the panel corners and skirts added later in the build prevent it. On a box frame, bolting on the panels properly is bracing. If you build an enclosure around an open printer, see our DIY enclosure guide for materials and fire safety.
Printed or metal braces?
Printed brackets are cheap and fit well, but any plastic is far less stiff than aluminium or steel, so a printed brace is only as good as its shape and its bolts. They work for gussets and for mounts that hold a metal rod or extrusion. For top braces on a tall frame, metal rods or extrusion lengths do most of the work; the printed parts just connect them. If you print brace parts, print them solid enough not to flex at the bolt holes and do not overtighten into plastic.
Check that bracing worked
Print the same ringing test before and after, at the same speed and acceleration, and compare the echoes beside the edges. If you run input shaping, Klipper says frame rigidity add-ons, tighter belts or a new toolhead change the resonant frequencies, so measure again after bracing. Our input shaping guide covers the measurement with an accelerometer.
Common frame bracing mistakes
- Bracing a frame that is out of square. The brace locks the error in and the gantry binds at one end. Square first.
- Tightening tie rods unevenly. Rods set to different lengths pull the uprights sideways. Adjust them with the square on the upright.
- Ignoring the table. The stiffest frame still rings on a wobbly desk.
- Expecting bracing to fix belts or the toolhead. If the echo is the same after bracing, the vibration is elsewhere. Work through the ringing diagnosis.
- Adding mass instead of stiffness. Heavy plates on moving parts lower the resonant frequency. Braces belong on the stationary frame.
Frequently asked questions
Does frame bracing reduce ghosting?
It reduces the part of ghosting that comes from the frame flexing, which is largest on tall, open-frame printers. It does nothing for loose belts, a wobbly toolhead or a shaky table. Compare a ringing test print before and after to see how much the frame was contributing.
Do I need bracing if I use input shaping?
Not always. Input shaping cancels vibrations in firmware, but Klipper recommends fixing mechanical causes such as a weak frame first, and suggests stiffening the printer when ringing frequencies are below about 20–25 Hz. A stiffer frame lets the shaper work with less smoothing.
How do I check if my 3D printer frame is square?
Measure the two diagonals of each face corner to corner; on a square frame they are equal. Voron’s documentation accepts less than 2 mm difference for its frames. On a bed-slinger, also hold an engineer’s square against each upright and the base.
Where should I put my 3D printer to reduce vibration?
On a firm, steady surface that does not wobble when you push it, such as a hardwood table. Prusa suggests a concrete tile under the printer to stop vibration reaching the desk, and moderate padding rather than very soft material.
