Button spring and factory adjustment
Selected catalog spring: SDP/SI S78CSYM030035008, Type302 stainless steel, squared and ground ends. Manufacturer catalog D815 metric hardware, physical page64 (printed10-63), source cached in sources/sdp-si-metric-hardware.pdf. Catalog supply quantity/price remains a procurement quotation; the part selection is fixed.
| Property | Catalog nominal | Receiving acceptance |
|---|---|---|
| Outside diameter | 3.00 mm | ≤3.10 mm |
| Wire diameter | 0.35 mm | Verify selected item |
| Free length | 8.00 mm | 7.90–8.10 mm |
| Solid length | 2.80 mm | ≤2.90 mm |
| Rate | 1.26 N/mm | 1.15–1.35 N/mm |
| Force at installed5.20 mm length | 3.528 N | 3.20–3.80 N |
| Force at4.65 mm length | 4.221 N | ≤4.55 N |
The catalog does not specify dimensional/load tolerances. The receiving limits are engineering acceptance requirements; obtain supplier confirmation or inspect the lot. They are not attributed to SDP/SI.
The 0.8 mm cap stop, 0.05 mm minimum released gap and 0.20 mm minimum switch travel give a minimum spring length of 5.20−0.80+0.05+0.20=4.65 mm; solid-length margin is at least1.75 mm. Maximum accepted force is 3.80+1.35×0.55=4.5425 N, rounded upward to4.55 N. Minimum preload3.20 N exceeds C&K SK43 maximum operating force300 gf≈2.94 N. First-article overload/cycle validation remains necessary because the operating-force specification does not establish allowable sustained overload.
The retained floating-tip flange carries the spring preload internally at rest. Fit the tip against the actual mounted switch: nose Z=30.6+measured switch height+0.15 mm. Accept a released gap of 0.05–0.25 mm, measured with feelers; retain the flange atZ37.7..38.7. The nominal tip uses4.3 mm switch height. The worst actuation margin is 0.8−0.25−0.4=0.15 mm before the cap stop.
Finish and measure the stop travel to0.80±0.05 mm and installed spring length to5.20±0.05 mm. The maximum tolerance combination reduces minimum spring length to4.55 mm. Inspect force at4.55 mm≤4.69 N as an additional acceptance and overload-test point; the minimum actuation margin remains0.10 mm. The CAD sweep report separately identifies nominal0.80 mm versus accepted0.75–0.85 mm stop travel.
Assemble the tip through the open top, add spring, then bond the cap in a fixture. Finish the4 mm guide pin toØ≤2.05 mm. Inspect sliding clearance, stop travel, installed spring length, released continuity and actuation before bonding the diaphragm. The body/cap/tip are near-net PA12 parts requiring measured finishing; supplier process acceptance remains explicit.