TEN-HIGH CO2 Laser Mirrors

Molybdenum is a hard, heat-tolerant metal. With no coating to wear through, there is no gold film to scratch, peel or burn off. TEN-HIGH describes the surface as extremely tough and resistant to high temperature and wiping, and says the mirrors suit harsh working environments.

• No coating: nothing to delaminate, even after many cleans.
• Hard surface: tolerates firmer cleaning than gold on silicon or glass.
• Heat tolerant: handles spatter and smoke better than a thin film.
• Flat, 3mm thick: standard beam-path mirror shape and thickness.

The trade-off is reflectivity. TEN-HIGH quotes a figure above 99.2%, labelled as transmittance, which for a mirror means how much of the beam it returns. Uncoated molybdenum is generally rated a little below gold-coated silicon; OMTech, for example, rates its own molybdenum mirrors above 98%. Across three bounces, that gap costs a few percent of beam power.

If your K40 lives in a garage or shed where dust settles on everything, molybdenum's tolerance for cleaning outweighs the small loss. If your air is clean and extraction is strong, gold on silicon returns a little more of the beam.

Unplug the machine, remove a retaining ring with a nut tool, support the mirror with a gloved finger and check the diameter with calipers. Do the same at all three positions.

Larger mirrors help on long beam paths where the beam drifts or spreads, which is why bigger machines use them. A K40's path is short, so changing mounts just to fit larger mirrors buys little. Change mounts when yours are loose, cracked or out of adjustment range, and pick the mirror size to suit the new mounts.

1. Choose the mounts first, with fine adjustment screws and positive locks.
2. Match all three mirror positions to one size.
3. Buy mirrors to that size, and a spare set if your shop is dirty.

Check the mount thickness too. All three TEN-HIGH versions are 3mm, the common size, so the retaining rings on most mounts will seat them without spacers.

If you want molybdenum in the stock 20mm size, the OMTech 20mm Mo set is the direct route. For 30mm with gold on silicon instead, BLUETIMES makes that size.

K9 glass mirrors have a place, but know their limits. Glass conducts heat poorly, so the beam spot stays hot, and once the gold wears or burns through, the mirror is done. They are the opposite of molybdenum: cheap and fragile where Mo is tougher and longer lived.

Handle K9 mirrors even more gently than silicon. Hold them by the rim in nitrile gloves, blow dust off before any wipe, and use a single light pass of isopropyl alcohol on lens tissue. Pressure or circular rubbing strips the gold quickly, and a scuffed glass mirror is scrap.

A K9 set makes sense as cheap spares, or to get a K40 with burnt stock mirrors cutting again today. For a longer-term upgrade in standard 20mm K40 mounts, gold-plated silicon or 20mm molybdenum from other makers lasts better.

• Light hobby use in clean air: K9 is adequate.
• Regular cutting: gold on silicon, such as the MCWlaser 20mm set.
• Dusty shop with stock mounts: 20mm molybdenum.

Whichever material you choose, fit all three positions in one session and keep the set matched. A mixed path of one tough molybdenum mirror and two tired glass ones leaves the worst surface setting the limit on your cutting power.

Firm is not careless. Grit dragged across any mirror scratches it, so remove loose dust first.

1. Unplug the machine and wear powder-free nitrile gloves; skin oil still bakes onto metal.
2. Blow loose dust off with a hand air blower.
3. Wipe with a lens tissue or swab wet with isopropyl alcohol, using more pressure than you would on gold if residue remains.
4. Finish with a fresh dry tissue and inspect under a torch.
5. Refit reflective face toward the beam and snug the ring only until the mirror cannot move.

Even molybdenum should be replaced if the beam spot shows a pit or a burn that cleaning cannot touch. A damaged spot scatters the beam and wastes power.

Set a routine that suits the shop. In a dusty space, a quick look at each mirror before a long job and a proper clean every week or two keeps residue from baking on. Molybdenum forgives a missed clean better than gold does, but it does not forgive a burn.

After fitting new mirrors, realign the whole path from the tube forward. The alignment walkthrough explains the tape-target method, and 10600nm safety glasses belong on your face for every test pulse.

Against the other sets, TEN-HIGH's molybdenum mirrors are the rugged choice for large mounts. Gold-on-silicon sets from Cloudray, CNCOLETECH and BLUETIMES reflect a little more but need gentler handling. The upgrade guide shows how extraction and air assist cut cleaning frequency whichever mirrors you run.