What would be the correct way to calibrate BCF1 tip with FG-100 device? It has really small contact area of it's tinned surface, should I place it straight on the sensor or with it's side area (even if it is chrome plated) like any other small tips with bigger tinned surface (I and J series)? Because difference may be around 15-20 degrees at 300-350 range depending on the placement. Currently my calibration looks like this (all tips are burned in, using good blob of solder on the probe, adding a bit of rosin flux to refresh it when solder becomes mat, keeping tip on the sensor around 5-7 seconds and moving around to find hottest spot, letting sensor to cool down between measurements):
BCF1 - 250: 1875, 400: 3300
BCF2 - 250: 1800, 400: 3075
BCF3 - 250: 1675, 400: 2750
J02 - 250: 1800, 400: 3175
D52 - 250: 1700, 400: 2750
Is it ok that BCF1, BCF2, J02 are measured 380 C when set at 400 C (BCF3 - 385 C, D52 - 400 C), but all of them are very precise at 250, 300 and 350 points (I was measuring at them during manual calibration)? I am mostly interested in 300-350 C range precision.