The RS mainspring winder is a fully functional 3D printable watch mainspring winder, with accurately calculated design files provided for every possible size imaginable. Everything provided here is free and open source. This is the modern solution to hobbyist mainspring winding woes and it comes with absolutely zero warranty. You are advised to thouroughly go through this README, the wiki pages, video resources found here.
Watch mainspring winding for hobbyists has always been a problem, as most of us cannot afford the $1500 Bergeon set to wind vintage unbranded mainsprings/barrels. Or sometimes the appropriate size just isn't available. This forces most casual hobbyists to resort to handwinding, which may kink or damage the mainspring.
The RS mainspring winder was designed using FreeCAD+Python, and is easy to 3D print. It costs ~$10 to print a single set by most 3D print service providers. Alternatively, you may choose to just purchase a prebuilt kit from eBay seller AndyShap2 here (single set) or here (complete set).
The RS mainspring winder works very well when properly constructed. List of features:
- Guaranteed to work on all released sizes, since the generation process is scripted.
- Cheap and easy to print with no post-processing/finishing or support material required.
- Winds cleanly and safely, no more getting bits of skin stuck due to handwinding.
- Can wind in both directions, clockwise and counter-clockwise.
- Has knurling patterns on body for a good grip during use, along with clear size labelling.
- Mainspring will never get caught in between winder barrel and plunger due to unique design style.
- PLA/PLA+ material is tough/elastic enough to withstand the winding stress.
- Both PLA/PLA+ and staple pins are softer than steel, and thus it will not kink or damage the mainspring.
- Never need to worry about wearing out the arbor hooks, as staple pins are easy to replace.
- Pick any size from the generated set of winders (7mm-18.5mm) or customize it yourself.
Watch this YouTube video here or here (older) to better understand the RS winder parts and how it works.
Discussion/Feedback: WRT forum thread here, or GitHub discussion section here.
There are several parts to the RS mainspring winder:
- The housing barrel. This part is the barrel that houses the mainspring and plunger, with a rising sun knurling pattern on the top for no reason.
- The winder base. This part is responsible for winding the mainspring with the help of the arbor hook.
- The plunger. This part pushes the mainspring out of the housing barrel into the actual mainspring barrel.
- The arbor hook. Fashion this part out of a staple pin using the staple jig part (see instructions) and insert into one of the holes on the winder base part (see guide). Also called anchor.
- The setter bowl. This part helps the ejection of the mainspring by a very small amount so that the actual mainspring barrel can be easily fitted in by hand (see 2nd picture above).
- The arbor rod. Get a dowel pin (or equivalent) with 1.5mm-3.0mm diameter and place it at the center of the winder base.
- The staple jig. Use this part to easily cut the staple pins to form the arbor hook, watch instructional video here.
NOTE: The arbor hook and rod are too small to be 3D printed, hence metal parts are required.
Recommended 3D printing options:
- Material: PLA or PLA+ (best for high accuracy prints).
- Infill: 20% or more (parts may crumble under stress if lower).
- Layer thickness: 0.1 mm or better.
- Color: Any, go with white if unsure. Best if all parts are of the same color for equal tolerances.
- Printer: Any well calibrated 3D printer, best if the print job is done with high accuracy settings.
- Placement: Widest flat surface should face downwards on print bed for best results, applies for all parts.
Steps to build your RS mainspring winder:
- Use a caliper to measure your mainspring barrel inner diameter and the mainspring arbor diameter.
- Download the latest rs-winder.zip from the release section.
- Print your winder base part STL/3MF file. Choose from 1.5-3.0mm sizes, whichever matches your mainspring arbor the best.
- Print your housing barrel and plunger part STL/3MF files. Size is based on mainspring barrel inner diameter, make sure to select matching sizes. In-depth winder size selection guide here.
- Print your setter bowl part STL/3MF file, this part should universally work with all housing barrels.
- Print your staple jig part STL file.
- Fashion a staple pin into an arbor hook with using the staple jig (see instructions or watch video), use a metal file to reduce thickness if needed. Insert it into one of the holes on the winder base part (see guide).
- Install the appropriate dowel pin for your winder base part:
- Recommended online purchase links: AliExpress, Amazon.
- For normal size winder base: 1.5mm/2.0mm (M1.5/M2) diameter dowel pins, 18mm in length.
- For large size winder base: 2.5mm/3.0mm (M2.5/M3.0) diameter dowel pins, 18mm in length.
- Using glue/epoxy for the dowel pins are optional, apply only a teeny tiny amount as needed.
Please go to the wiki for instructions: Using the RS winder, or watch a YouTube video.
Make sure to study the correct arbor hook latching method.
Please go to the wiki for instructions: Customizing & Generating the RS winder.
To generate the STL/3MF files for the various different sizes of all the RS winder parts, just clone this repo and execute the Python FreeCAD script using the following command:freecadcmd generate_stl.py
Please read every single sentence below carefully:
- As stated before, everything provided here comes with ABSOLUTELY ZERO WARRANTY.
- While this winder works great for many users, it still requires you to be resourceful and competent in basic watchmaking skills.
- You must be competent enough to assess the health of the mainspring (see here for guidance). Tired or old mainsprings will break regardless of how expensive your tools are.
- It is recommended to practice first with spare mainsprings/barrels to get a feel of using the RS winder. Incorrect use can break or damage your mainspring, this is the case even with professional winders.
- Refer to the wiki for help with winder size selection, choosing the wrong size will damage your mainspring.
- When initially placing the housing barrel on the winder base with the latched mainspring, do not forcefully ram the mainspring into position. Watch the video (min 3:24) for an simple way to do this.
- Always hook the staple pin from the outside of the mainspring to avoid issues when winding. Study the correct arbor hook latching method diagrams to undertand this better.
- The height of the staple pin is extremely important, it must be trimmed correctly to fit. Make sure the staple pin height is adjusted such that the hook aligns with the hole of the mainspring, so that it will catch properly while winding.
- Always manually push the mainspring's tail end instead of forcibly winding it into the winder. This is to avoid unnecesary stress onto the arbor and mainspring eye.
- If the printed parts are stringy, it probably means your printer is not properly calibrated. Make sure to properly clean the stringy bits before using the winder to avoid contamination.
- Be very careful when unwinding, do it slowly.
If you like this work, please consider to:
- Please ⭐️ this repository if this project helped you.
- Notify me if the dowel pin part links are no longer functional.
- Buy me a cup of coffee
Credits and thanks to the following folk:
- AndyShap for sharing his setter bowl and staple jig ideas, as well as refinements to the overall design. Also for providing the design files, wiki guides and video walkthroughs.
- Yxoc for sharing detailed step by step instructions with pictures here to be used by the wiki guides.
- Fred and aac58 for testing and contributing to the metal rod idea (now dowel pin) for the winder base during the early stages of the project.
- Fratink for coming up with the first 3D winder design here in Thingiverse. While the RS winder is now very different from this version, it helped inspire the creation of this project. The same free Creative Commons licensing scheme is re-used.
- All those who tested the RS winder, gave constructive feedback, posted pictures and helped others along their watchmaking journey. Thank you.