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Tools & jigs
Prusa MK4 filament runout guide with PTFE fitting
A guide arm that bolts to the top of the Prusa MK4 or MK3.9 frame and routes filament from the spool holder into the Nextruder through a short length of PTFE tube, smoothing the path and stopping the strand from dragging across the frame. The bracket fits the 30 mm extrusion with an M3 T-nut slot on 20 mm spacing, rises 60 mm above the frame and ends in a hole threaded for a PC4-M6 pneumatic fitting; a 4.2 mm bore accepts 4 mm OD PTFE for 1.75 mm filament. Print it upright in PETG with 4 perimeters and a small support under the arm. Open the ready-made model free, resize it on your phone or computer, then download a print-ready STL, 3MF or G-code sliced for your printer, free.Opening the ready-made model and downloading it as STL or 3MF are free, no card; AI changes use credits, from Maker at $7.99 a month.No printer? We print this part and ship it to your door. See its priceUpdated
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Adjust
Change its numbers in the viewer for free, or ask the AI in the chat: wall thickness, hole size, the thing it clips onto. AI changes use 2 credits per request (1 for a quick edit, 3 for a redesign), paid with a plan from Maker at $7.99 a month.3Print
Download a watertight STL or 3MF free, with your numbers and hand edits, or G-code sliced for your printer at the same price. After an AI change the download is included in every plan (4 credits without one).
Dimensions of the ready-made model (editable)
| Parameter | Value |
|---|---|
| base length (X) | 40 mm |
| base width (Y) | 30 mm |
| base thickness | 5 mm |
| slot width (M3 clearance) | 3.4 mm |
| slot length for adjustment | 6 mm |
| arm thickness (extrusion depth in Y) | 4 mm |
| arm width (in the bending plane) | 10 mm |
| vertical rise | 60 mm |
| forward reach | 40 mm |
| boss diameter | 10 mm |
| boss height | 12 mm |
| through bore for filament | 4.2 mm |
| PC4-M6 fitting hole | 5.5 mm |
| counterbore depth for fitting thread | 6 |
Example prompt
Design a filament guide bracket with a 40 by 30 mm base 5 mm thick and two M3 slots 20 mm apart, a curved arm rising 60 mm and reaching 40 mm forward, ending in a 10 mm boss with a 5.5 mm hole for a PC4-M6 fitting and a 4.2 mm through bore, 4 mm arm thickness.
Fit notes
Community guides are tuned to one spool holder position. In SpeakCAD you describe where your spool sits, preview the arm in the browser, adjust the height or angle in the chat, and download the STL.
Questions people ask about a Prusa MK4 filament runout guide with PTFE fitting
A guide arm that bolts to the top of the Prusa MK4 or MK3.9 frame and routes filament from the spool holder into the Nextruder through a short length of PTFE tube, smoothing the path and stopping the strand from dragging across the frame. The bracket fits the 30 mm extrusion with an M3 T-nut slot on 20 mm spacing, rises 60 mm above the frame and ends in a hole threaded for a PC4-M6 pneumatic fitting; a 4.2 mm bore accepts 4 mm OD PTFE for 1.75 mm filament. Print it upright in PETG with 4 perimeters and a small support under the arm.
Click Open it free on this page and create a free account (no card): the ready-made model opens in your browser, on your phone or computer, nothing to install. Change its numbers in the viewer for free and download a watertight STL or 3MF free, or G-code sliced for your printer at the same price. An AI change in the chat uses 2 credits per request (3 for a redesign), and the download after it is included in every plan (4 credits without one). Start with Maker: 50 credits a month for $7.99, cancel anytime.
On this page: open the ready-made model free in a SpeakCAD account (no card), change any dimension in the viewer, then download the STL or 3MF free, or G-code sliced for your printer at the same price.
A shared STL is modelled for someone else's measurements. Here you open the ready-made model free, change it to your measurements in the viewer, then download a file sized for the part you actually own, free as STL or 3MF.
Yes. SpeakCAD slices the part on its servers with OrcaSlicer and your printer's official profile (380+ printers, including Bambu Lab, Prusa, Creality and Elegoo), and you download the G-code (a sliced .gcode.3mf for Bambu Lab printers). G-code sliced for your printer costs the same as the STL: included in every plan, free for a part you shaped by hand, 4 credits without a plan for a part with AI work in it. Pick your printer on the printers page to see its profile.
No. SpeakCAD runs in the browser on your phone or computer: the chat, the 3D engine and the live viewer load in the tab. The only file you download is the finished STL, 3MF or sliced G-code.
Print it your way
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