Brian Wood's Dore Westbury Mk Ⅱ Miller

摘要

Photograph 14 shows the head thus supported leaving a void where the support used to be. Also visible top left in this photo is the shim, coloured blue for 0.003 inches thickness, on the face of the uppermost packing slab. Photograph 15 is an inside view of the capstan after 9 years of service, but what cannot be seen and came as a bad shock was the state of the key, which is seen here in photo 16. It was made in silver steel, hardened and tempered as directed in the build notes but clearly the loading has been too much for the design in that form and it was cracked right through with maybe only 45% of it left on the remaining side doing any useful work. Returning to the motor drive, I was keen to avoid the risk of powering up the lift motor when the column was clamped, so I built in an interlock to isolate the motor while the column was clamped. A flat was milled across the plain section of the lower clamp bolt to activate a proximity switch that was wired to isolate the live feed to the motor while the column is clamped. Photograph 17 shows this part of the installation. Two further precautions were taken against accidental power application by first unplugging the power lead when height adjustment was no longer needed and secondly by getting into the habit of leaving the change over switch in the central OFF position I accept that with two clamp bolts it is not a completely fail safe situation, but with just myself using the mill I considered those precautions would be quite adequate. Even if a senior moment were to take place, it would be realised immediately and the power cancelled, with words like 'tut tut' being used. Photograph 18 shows the gearing arrangement from the motor to the capstan. The lock down bolt, with the short tommy bar, to clamp the swing away idler gear carrier can also be seen here.