The problem
The handlebar and dashboard are where the rider meets the vehicle. A housing that fouls the windscreen at full lock, a display that reflects sunlight, or a moulded part with thick walls and no draft causes recalls, sink marks and poor usability. Students rarely get to design a complete plastic housing with real mounting, sealing and clearance checks.
Objectives
- Model a handlebar tube, clamps, grips, brake levers and switch pods as a top-down assembly.
- Design an injection-moulded dashboard housing with uniform walls, draft, ribs, bosses and a sealed display window.
- Check steering clearance across full lock using configurations and Interference Detection.
- Produce drawings with general tolerances and a short design-for-moulding review.
What you need
Tools and toolboxes
- SOLIDWORKS Part and Assembly — Handlebar tube, clamps, levers and housing, built top-down from a layout sketch with in-context references.
- SOLIDWORKS fastening features — Mounting Boss, Lip/Groove and Snap Hook features for the two-piece dashboard housing.
- Draft Analysis and Thickness Analysis — Checking that every moulded face has draft and that walls stay near the target thickness (Thickness Analysis is not in every licence tier; a section-view check is the fallback).
- Interference Detection and configurations — Steering at centre and at left and right full lock, checked for clashes with the body, mirror stalks and front panel.
- SOLIDWORKS Drawings — Assembly drawing with BOM and part drawings of the housing with ISO 2768 general tolerances.
Software
- SOLIDWORKS 2023 or later
- Excel for the requirements and BOM tables
Extra parts and data
- A reference scooter handlebar to measure (optional) — Measuring a real tube diameter, lever spacing and switch-pod size keeps the model realistic.
- 3D printer access (optional) — Printing the housing halves lets you test the snap fits and display fit before any tooling decision.
Key concepts
- Top-down design
- Parts are modelled inside the assembly from a shared layout sketch, so moving the display or handlebar rise updates the housing and clamps together.
- Uniform wall thickness
- Moulded parts cool evenly when walls are similar in thickness; thick sections cause sink marks and voids, so strength comes from ribs rather than thicker walls.
- Draft angle
- A small taper on faces parallel to the mould opening direction lets the part eject without scuffing. Textured faces need more draft than polished ones.
- Steering lock clearance
- Everything mounted on the bars sweeps an arc as the rider steers; the clearance must hold at full lock and with suspension compressed.
Step-by-step guide
- 1
Write requirements and a layout sketch
List what the assembly must hold: an example 22 mm handlebar tube, two grips, brake levers with a parking-brake latch, left and right switch pods, a 5-inch class display and a phone-charging port. Note an example steering lock of ±40 degrees and the IP rating you aim for, such as IP54 to IS/IEC 60529, with test details to be checked in the current standard. In a new assembly, draw a layout sketch on the front and top planes showing the steering axis, handlebar centre line, grip ends and display position.
Checkpoint: A requirements table and a fully defined layout sketch whose key dimensions are linked to named global variables.
- 2
Model the handlebar and clamps
Create the handlebar as a Swept Boss along a 3D path with bend radii and rise taken from the layout sketch, using a circular profile driven by the tube-diameter variable. Model the riser clamp with a split cap and two bolt holes using the Hole Wizard. Add the stem as a separate part mated concentric to the steering axis. Assign plain carbon steel or 6061 aluminium from the material library so Mass Properties gives a realistic weight.
Checkpoint: Changing the rise or width variable rebuilds the bar and clamp without errors and the tube stays concentric with the clamp bore.
- 3
Add grips, levers and switch pods
Model grips as revolved parts with a flange, and simplified brake levers with a pivot pin and a lever arc. Use Toolbox screws for the lever clamps. Model the switch pods as two-piece shells around the tube with simplified buttons. Mate each lever with a concentric pivot and an angle mate with limits so it can rotate from rest to full pull. Keep the throttle twist on the right grip clear of the switch pod by a stated gap.
Checkpoint: Each lever rotates through its full stroke without touching the grip, and the throttle gap is at least the value in your requirements.
- 4
Sketch the dashboard housing
Inside the assembly, insert a new part for the housing and reference the layout sketch for the display opening and mounting points. Build the outer form with Extrude and Fillet, or with Boundary Surface and Thicken if you want a curved face. Tilt the display face so that its normal points roughly at an example rider eye point, which reduces glare from overhead sun. Use Shell to set a uniform wall of, for example, 2.5 mm.
Checkpoint: The housing is a single solid with constant wall thickness and the display face angle is recorded in the design table.
- 5
Split and add fastening features
Use the Split feature or two bodies to create front and rear covers along a parting line. Add a Lip/Groove feature on the joint for sealing, Mounting Boss features with gussets for self-tapping screws, and one or two Snap Hook and Snap Hook Groove pairs to locate the cover. Add a groove for a gasket around the display window and a cable entry with a grommet seat. Keep boss walls near 60 per cent of the main wall.
Checkpoint: Both covers rebuild as separate parts, screws line up with bosses, and a section view shows the lip and gasket groove continuous around the joint.
- 6
Add ribs and draft
Add Rib features behind the display mount and around the mounting boss to stiffen the shell without thickening it. Set the pull direction and apply Draft, for example 1 degree on smooth faces and more on textured ones. Run Draft Analysis to find faces with zero or negative draft, and Thickness Analysis or section views to find heavy sections where ribs meet walls. Fix them before moving on.
Checkpoint: Draft Analysis shows no faces without draft in the pull direction, and no section is more than about 1.5 times the nominal wall.
- 7
Check steering clearance
Create three assembly configurations: centre, left full lock and right full lock, using an angle mate on the steering axis. Add simplified front panel, windscreen and mirror stalk bodies from the layout. Run Interference Detection in each configuration with Treat coincidence as interference off. Also use Move Component with Collision Detection to sweep the bars slowly and watch for contact, including with the brake lever pulled.
Checkpoint: Interference Detection reports no interference in all three configurations and the smallest clearance is at least your stated margin, for example 10 mm.
- 8
Review reach and visibility
Place a simple 2D rider sketch at the seat with an example hand position and eye point. Measure the distance from the grip to each switch button and confirm the thumb can reach the indicator and horn without letting go of the grip. Draw a sight line from the eye point to the display and confirm the handlebar and clamps do not hide any of it. Record any change you make to the switch pod or display angle.
Checkpoint: Every frequently used switch is within the thumb reach you defined and the display is unobstructed from the example eye point.
- 9
Prepare drawings and BOM
Make an assembly drawing with an exploded view, balloons and a Bill of Materials listing part number, material and quantity. Make part drawings of the two housing covers with section views through the bosses and lip, the draft direction, nominal wall and a general tolerance note to ISO 2768-m. Add critical dimensions for the display opening and mounting holes with tighter tolerances where they mate with bought parts.
Checkpoint: Drawings are fully dimensioned, the BOM matches the assembly and the title block carries material and tolerance notes.
- 10
Prototype and report
If you have a 3D printer, print the covers and check the snap fits, screw bosses and display fit, noting that printed parts behave differently from moulded ones. Write a short design-for-moulding review covering wall thickness, draft, ribs and sealing, and list what you would change for production. Render the assembly in SOLIDWORKS Visualize or with PhotoView 360 if available. Report mass, clearance results and open issues.
Checkpoint: A report with drawings, clearance evidence, a moulding review and photos or renders of the assembly.
Testing & validation
- Interference Detection passes at centre and full lock in both directions.
- Draft Analysis and Thickness Analysis (or section checks) show no moulding problems.
- Lever strokes and throttle gap meet the requirements.
- A printed prototype, where made, assembles with its screws and snaps.
Expected results
A parametric handlebar and dashboard assembly with a moulding-ready two-piece housing, clearance and reach evidence, drawings with a BOM and a design-for-moulding review.
Take it further
- Run a static study on the housing mount for a vibration or drop load.
- Use SOLIDWORKS Plastics to check fill and weld lines on the housing.
- Design a phone mount with a wireless-charging pad that fits the housing.
Viva and review questions
Why did you add ribs instead of thickening the housing wall?
Thick walls cool slowly and cause sink marks and voids. Ribs at around 50–60 per cent of the wall thickness add stiffness while keeping cooling uniform.
How did you check the handlebar does not hit anything?
I made configurations at centre and both full locks and ran Interference Detection in each, then swept the bars with Collision Detection to catch contacts between those positions.
Why is the display face tilted?
Tilting it towards the rider's eye point makes it easier to read and reduces reflections from overhead sunlight. I checked the sight line in a sketch.
Learn it at DIYguru
These DIYguru courses and programmes teach what this project needs.