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Brackets & mounts
Shimano Di2 junction box holder for 31.8 mm handlebar
The Shimano SM-EW90 Di2 junction A normally hangs under the stem on a rubber band, where it rattles and gets pulled by the bar bag straps. This holder clamps a 31.8 mm handlebar next to the stem and cradles the junction box in a snug pocket with the button and charging port facing the rider, and a 3 mm slot at each end for the E-tube wires. The clamp closes with one M5 bolt, the pocket walls are 2 mm with a 0.3 mm clearance, and a small ramp lets the box snap in. Print it on its side in PETG. 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 |
|---|---|
| handlebar outer diameter | 31.8 mm |
| clamp band wall thickness | 4 mm |
| clamp band height (Z) | 16 mm |
| split gap width at bolt bosses | 6 mm |
| bolt boss diameter | 12 mm |
| M5 clearance hole | 5.3 mm |
| hex head / washer recess diameter | 9.5 mm |
| recess depth | 4 mm |
| per-side clearance | 0.3 mm |
| wall thickness around pocket | 2 mm |
| wire slot width | 3 mm |
| snap ramp protrusion | 1 mm |
Example prompt
Design a handlebar holder with a 31.8 mm split clamp and one M5 bolt, a pocket 44 x 20 x 11 mm with 2 mm walls and 0.3 mm clearance for a Shimano Di2 junction box, a 3 mm wire slot at each end and a 1 mm snap ramp.
Fit notes
Junction boxes differ between the three-port and five-port EW90 and the newer EW-RS910, so a downloaded holder often does not fit at all. Measure yours, tell SpeakCAD the body size, bar diameter and wire exits, preview the holder in the browser, refine the snap in the chat, then download the STL.
Questions people ask about a Shimano Di2 junction box holder for 31.8 mm handlebar
The Shimano SM-EW90 Di2 junction A normally hangs under the stem on a rubber band, where it rattles and gets pulled by the bar bag straps. This holder clamps a 31.8 mm handlebar next to the stem and cradles the junction box in a snug pocket with the button and charging port facing the rider, and a 3 mm slot at each end for the E-tube wires. The clamp closes with one M5 bolt, the pocket walls are 2 mm with a 0.3 mm clearance, and a small ramp lets the box snap in. Print it on its side in PETG.
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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