08/25/00
Today I made the bracket that holds the crown wheel arbor. I jewelers-sawed it from 3/16" leaded engraving brass, using a Deltacad template. The bottom of the bracket is made of two triangular pieces, one of brass and one of .046" water-hardening tool steel ("gauge plate").
The function of the upper triangular piece is to have an ordinary pivot hole for the lower pivot of the escape arbor, made of brass. The lower steel piece acts as another "end stone" or thrust bearing, which actually supports the weight of the escape wheel and arbor. It is made of tool steel so that it can be eventually hardened. The lower tip of the escape wheel arbor is pointed, which will serve as a pivot bearing against the steel of the lower triangle.
The two triangles will be held onto the main bracket body with one 2-56 screw and a steady pin, which is made of 1/16" drill rod. But for now, the lower parts of the assembly are held onto the upper part of the bracket with Super Glue (which acts as a clamp) until the screw and steady pin holes are drilled and tapped.
This is necessary because the alignment of the escape wheel and arbor must be precise. The parts can be broken apart after drilling using moderate heat. I rarely use Super Glue for permanent joins, but it makes a wonderful quick clamp. When adhesive is necessary in clock work, I use Loctite.
The bracket was finished using a fine file to even up. When finished, the escape wheel and pinion turn freely and turn dead true in their bracket, because of the care taken towards that end.
After finishing the bracket, I clamped the bracket and escape arbor between the plates, which had the pallet arbor already in place. Now comes the time to try the action of the escapement for the first time -- always an aprehesive moment. A quick look has convinced me that the escapement will function! The drops at this point are close, and it may be that I will need to thin the pallets -- perhaps not.
The escape wheel bracket will soon be attached to the frames with screws through oversize holes. This will permit raising and lowering the escape arbor to adjust the lock of the escapement. The lantern pinion on the escape arbor allows for plenty of vertical movement vis-a-vis the contrate wheel which drives it. Usually, the pallets are raised and lowered to effect this adjustment -- but this is impossible given the "end stone" design of the pallet arbor in this clock.
Today's links:
Bracket drawing
Bracket clamped in vice to drill.
Tapping the bracket screw hole.
Crown and bracket.
Bracket clamped in frames.