Author: Liz | Technical review date: 2026-08-06
Quick answer: Choose a clock movement only after measuring the clock dial thickness and confirming both the total shaft length and the threaded shaft length on the supplier drawing. These three dimensions describe different parts of the installation and should not be treated as interchangeable.
Why shaft length matters
The shaft must pass through the dial, leave enough usable thread for the washer and nut, and still position the hour, minute and optional second hands correctly. A movement that is too short may not fasten securely. A movement that is unnecessarily long can leave excessive clearance at the front of the clock or require additional spacing.
Three dimensions to confirm before ordering
| Dimension | What it describes | Why buyers should check it |
|---|---|---|
| Dial or panel thickness | The thickness of the material through which the shaft passes | It determines how much of the shaft is consumed by the clock face. |
| Threaded shaft length | The threaded section used by the washer and fixing nut | It must provide sufficient usable thread after passing through the dial. |
| Total shaft length | The full front shaft dimension defined in the product drawing | It affects the final position and clearance of the clock hands. |
Important: Suppliers may label shaft dimensions differently. Always request a dimension drawing and confirm where each measurement starts and ends.
A practical measurement process
- Measure the finished dial at the mounting hole. Include coatings or laminated layers that remain in the final assembly.
- Record the mounting-hole diameter and check whether the selected movement requires a specific hole size.
- Confirm the usable threaded length required for the washer and nut. Do not estimate this from the total shaft length.
- Check the hand fitting standard, hand stack height and clearance between the hands, dial and front cover.
- If the hands are long or heavy, ask whether a high-torque movement is required.
- Approve a sample with the actual dial and hands before placing a bulk order.
Verified HR1688 shaft options
Heng-Rong's current technical materials list the following available shaft lengths. Availability should be reconfirmed for the exact movement version and hand fitting before purchase.
| Movement family | Listed shaft lengths | Typical selection question |
|---|---|---|
| HR1688 step movement | 7, 8, 9, 11, 13, 15, 17, 20, 23, 28 and 31 mm | Is audible stepping acceptable, and which hand fitting is required? |
| HR1688 silent movement | 9.5, 13.5, 16.5, 18.5, 20.5 and 22.5 mm | Is a silent sweep required for bedrooms, offices or studios? |
| Separate HR1688 high-torque I-shaft family | 14.5, 17, 20, 22.5 and 31 mm | Do long or heavy hands require a different high-torque SKU? |
The product family includes options for panels from 1 to 20 mm, but a panel thickness does not map automatically to the same-numbered shaft. The correct match depends on the product drawing, usable thread and hand assembly.
What is confirmed about the linked 31MM model?
The linked HR1688 product is a step movement, not a silent-sweep model and not a high-torque model. It is intended for Youngtown-style snap fitting (太阳轴) clock hands. The 31 mm and 32 mm names refer to the same long-shaft version: its total shaft length is marketed as 31 mm and may be rounded or labeled as 32 mm in comparison charts. Its threaded section is 24 mm, and the confirmed compatible dial-thickness range is 20–21 mm.
Reference-chart note: The supplied comparison image labels this longest version as 32 mm total shaft length with 24 mm of thread. Buyers should match the supplier SKU, threaded length and dial-thickness range instead of rejecting a compatible movement because one chart rounds the total length differently.
Review the 31MM wall clock movement product page and send your dial thickness, hand length, hand weight and required fitting to Heng-Rong for confirmation.
Buyer checklist for a reliable quotation
- Finished dial thickness at the center hole
- Center-hole diameter
- Required total shaft and threaded shaft dimensions
- Minute-hand length and approximate weight
- Step or silent sweep preference
- Standard or high-torque requirement
- Hand fitting type and second-hand requirement
- Target quantity and sample requirement
Frequently asked questions
Is shaft length the same as maximum dial thickness?
No. The 31/32 mm model has a 24 mm threaded section and is confirmed for 20–21 mm dials; the remaining shaft geometry is needed for mounting and hand installation.
Should I choose the longest available shaft to be safe?
No. Excessive front projection can create an unattractive gap or interfere with hand and cover clearance. Choose the shortest verified option that meets the mounting and hand-stack requirements.
When should I use a high-torque movement?
Consider a separate high-torque model when the clock uses long or heavy hands. The linked 31MM step model is not a high-torque movement. Provide the hand dimensions and weight to the supplier because shaft length alone does not determine torque suitability.
Technical basis: Heng-Rong Clock Movement Catalog, completed company FAQ knowledge base, product page and user-confirmed product facts.