Cutting Tiny Jewelry Parts: Hold Them in Place and Get Them Right
Cutting tiny jewelry pieces on a galvo fiber laser can be frustrating when parts move or cuts fail. We share our workshop's tested methods for keeping small parts stable and ensuring clean, consistent cuts every time, including crucial machine settings and design considerations.
Cutting small jewelry parts on a fiber laser can be tricky: the moment a tiny piece is fully cut free, it can shift, drop, or get lost. The key is to keep it attached to the sheet until the entire job is done, then free it carefully. This article shares the practical steps we take in our workshop to cut small sterling silver parts reliably, day after day, without losing them or ruining the piece.
The Core Problem: Parts Moving Mid-Cut
Unlike other cutting methods, a laser beam exerts no mechanical force on the material. Pieces don't fly off the platform. What actually happens is that once a tiny part is fully separated from the sheet, it loses its stable connection to the jig and can simply drop or slide slightly. If your design has multiple operations on the same small part – like an inner cut and then an engraving on that freed piece – any movement will ruin the alignment and the job. The solution is to use "tabs" that hold the part in place until the very end, combined with a strict order of operations.
Setting Up for a Clean Cut: Focus and Wobble
Before you even think about design or tabs, ensure your machine is cutting optimally. Two settings are absolutely critical for going through metal: focus height and wobble.
Focus Height: The Foundation of Every Cut
If your laser isn't cutting through, the first thing to check is your focus. Even a small error here can mean the difference between a clean cut and no cut at all.
On our machine, the factory-calibrated focus point (where the platform surface is in focus) is stored in EzCad3's Motors.ini as m_dFocusPos, which is -59.6 mm. When cutting sheet material that lies on the platform, the top surface of your material is one thickness above the platform. Therefore, the correct Z-axis height for cutting is: Z = focus + material thickness.
For example, to cut 1 mm sterling silver sheet on our machine, the Z-axis should be set to -59.6 mm + 1 mm = -58.6 mm. We've learned this the hard way: -58.5 mm cuts, but -56.5 mm does not cut at all. That's only a 2 mm defocus, and it kills the cut completely. If your cuts suddenly get worse, check your focus before touching anything else. A bent jig, a platform that shifted, or even slightly thicker material will all show up as "the laser got weaker."
Wobble: Kerf Management for Ejection
Cutting metal with a fiber laser relies on a setting called "wobble." This makes the beam oscillate sideways as it follows the cut line. The purpose of wobble is to create a wider kerf (the width of the cut) than the beam itself, allowing molten metal to eject cleanly instead of re-welding behind the beam. If the molten metal cannot escape, it simply re-solidifies, and your cut never goes through.
For our sterling silver cutting recipe, we use a wobble diameter of 0.15 mm, an end diameter of 0.05 mm, and a distance of 0.07 mm. This creates a sufficiently wide path for the melt to escape. A common and very misleading failure mode is a wobble that is too small. We once had the diameter set to 0.015 mm instead of 0.15 mm – a factor of ten error. A 15 micron wobble is effectively a thin line. It marked perfectly, looked like it was working, but never opened the cut. If a recipe that used to cut suddenly only engraves a line, check your wobble diameter first.
Designing for Tabs and Order of Operations
The core strategy for tiny parts is to use tabs – small, un-cut sections that keep the part connected to the main sheet. This, combined with the correct order of operations, ensures stability.
Inner Cuts First, Outer Cuts Last
This rule is non-negotiable for precious metal jewelry. All interior details, holes, and letters must be cut while the piece is still firmly held by the surrounding sheet. The final outline that frees the piece from the material should always be cut last. If you get this backward, the piece will move halfway through the job, ruining everything that follows.
In our workshop, we use a color-coded workflow for this. We draw the piece in Inkscape, using specific flat colors to define operations. For cutting, black (#000000) is our standard for inner cuts, and purple (#8800ff) is for outer cuts. This allows us to define the order simply by assigning operations to colors. Any design with interior details gets black lines for those, and purple for the final outline. We also use blue (#0000ff) for engraving. This approach means the drawing is the job: save the SVG, and the machine is ready to mark. For complex settings, remember that a test grid on scrap is always a good idea before committing to a final piece.
Adding Tabs to Your Design
Once you understand the order of operations, adding tabs is straightforward: simply leave small, un-cut sections along the outer perimeter of your part. The size and number of tabs depend on the part's dimensions and the material's thickness. For very small parts, even two or three tiny tabs can be enough to keep it from shifting. You'll need to experiment a little to find what works for your specific parts.
After the laser job is complete, you will manually sever these tabs and then finish the edges. This leads us to the post-processing. Remember that the laser leaves a black, oxidized edge on silver, so plan on polishing the piece thoroughly after cutting to restore its shine and remove any tab remnants.
Cutting Sterling Silver: Our Recipes (and Why Gold is Easier)
These numbers are from our workshop, cutting sterling silver on our 100 W MOPA fiber laser. They are a starting point; always prove them on scrap metal for your own machine and material.
Our common cutting recipe for sterling silver is: 95 % power, 190 mm/s, 60 kHz, with wobble enabled. The primary lever for cutting through is the number of passes, not increasing power, which often just widens the kerf and heats the piece. High frequency (60 kHz) is key for cutting through; lower frequencies (like 30 kHz) are better for deep engraving, not cutting.
| Sheet thickness | Sterling Silver Passes (our measured numbers) |
|---|---|
| 0.8 mm | 17 passes |
| 0.9 mm | 21 passes |
| 1.0 mm | 28-29 passes |
Sterling silver is a difficult material for fiber lasers. It's one of the most reflective metals and an excellent heat conductor, meaning much of the laser's energy bounces off, and the heat that does get in is quickly carried away. This is why it requires so many passes.
Gold, by contrast, is much easier. It reflects less of the 1064 nm beam, so more power is absorbed, and it cuts and engraves more readily. If you've only ever cut silver, cutting gold will feel like your machine got a significant upgrade. Our gold recipes use the same 95% power, 190 mm/s, 60 kHz settings, but require roughly half the passes of silver for the same thickness. It's important to remember that these gold figures are derived from our silver measurements and are starting points to be proven on scrap, especially since gold alloys and karats vary significantly.
| Sheet thickness | Gold Passes (starting point, derived) |
|---|---|
| 0.25 - 0.4 mm | 2 |
| 0.5 mm | 3 |
| 0.6 mm | 4 |
| 0.7 mm | 6 |
| 0.8 mm | 9 |
| 0.9 mm | 11 |
| 1.0 mm | 14 |
Always start with fewer passes and work your way up. Too many passes can widen the kerf, overheat the piece, and distort thin sections of expensive gold.
Managing Big Jobs and Material Specifics
Buffer Overflow: A Silent Killer of Passes
For very large cutting jobs with many passes and extensive geometry, your laser's controller board buffer can become an issue. The PC sends command lists to the board, which has a finite buffer (a few megabytes on our board). If the PC sends data faster than the board can process it, further commands can be silently dropped. You might think you're sending 39 passes, but the metal only receives 25. The symptom for this is always the same: "my laser got weaker," or "big jobs cut worse than small ones." The machine might even go quiet long before the software says the job is done.
The solution is flow control: ensure the software never sends more than a few seconds of marking ahead of what the board has actually played. (This was a major reason our own software came into existence; after implementing flow control, our required pass counts dropped dramatically.) If your big jobs consistently underperform compared to smaller ones, and adding more passes doesn't help as much as it should, this could be the culprit.
Material Considerations
- Silver Alloy: Not all sterling silver behaves the same. We specifically buy a harder alloy made for laser work. If your silver cuts worse than expected, the alloy itself might be the difference.
- Highly Reflective Silver: For very shiny silver, a crude but effective trick is to paint the surface with a thin coat of matt black paint. This absorbs the laser beam, transferring the heat to the silver, and you can clean it off afterwards.
- New Materials: Every new material or thickness, even if it's "just" a different karat of gold, needs to be proved on scrap first. A quick test grid can save a valuable piece.
Safety First: A Quick Reminder
A fiber marking laser is a Class 4 device. The 1064 nm beam is invisible and causes permanent eye damage instantly. Always wear laser safety glasses rated for 1064 nm with an appropriate OD for your source power. Everyone in the room must wear them. Metal is reflective, so stray beams are a real hazard. Never leave a running job unattended, and ensure you have proper fume extraction with a filter, as metal marking produces fine particulate. Physical interlocks on enclosures are your real safety layer; software interlocks are a convenience that can be overridden. For more on this, you can read Why EzCad3 Blocks Marking with the Door Open (and Why That's Not Real Safety).
Practical Takeaways for Your Workshop Today
- Check your focus height first if cuts are inconsistent or fail to go through. It's the most common culprit.
- Verify your wobble diameter. If a cut looks like an engraving but never breaks through, a tiny wobble is likely the cause.
- Always cut inner geometry before outer perimeters. This keeps parts stable.
- Integrate tabs into your design for small parts to prevent shifting after they are cut free.
- Test all new settings and materials on scrap. This costs minutes, not ruined pieces.
- Plan for post-laser polishing. Laser-cut silver will have dark edges that need to be cleaned and shined.