Sovella workbench V-7.0

grabcad

SOVELLA DRIVESCREW WORKBENCH V-7.0 In the Solidworks file go to UPPER FRAME-3 and under "Mates" select LOWER HEIGHT, MID HEIGHT, or UPPER HEIGHT to adjust height. Adjustable hand crank can be moved by click and drag. Also go to HANDLE-4 "Mates" select "STOW FLIP" and right click and select "Flip Mate Alignment" to flip the handle stow position. (Colors are for viewing purposes only) Screw drive with a 3mm 2 start square thread with 12mm pitch 25mm diameter, for better efficiency than a single start thread. The legs on this version have just a little more depth than the original design. The leg slider bushings are oil impregnated bronze with 2 bushings on the lower leg and 2 bushings on the upper leg for increased stability. The bushing material could also be hard nylon. The roller bushings from the other version benches could also be used. With the 12mm pitch thread it is possible to run all the same gear size, the high ratio is made with the thread and the hand crank. This version could also be run with a ball nut on the drive screws for more efficiency. This version also has the option of an auto locking device for mechanisms that have high reverse drive, which you might expect with a ball nut system. The attempt to further reduce friction is eventually going to lead to reverse drive. Large amounts of reverse drive could be dangerous, causing the hand crank to spin out of control, and the moving bench top to lower at a dangerous rate. This locking device is similar to an auto retracting seatbelt, it has a centrifugal trigger and a motion trigger. Any excess speed or jarring motion will cause it to lock up. It is located on the hand crank shaft near the main traverse shaft, loads are low at this location so the shaft will be easy to lock. This version uses a 25mm OD 10mm ID main transverse drive shaft as the loads in this area of the mechanism are reduced. The final ratio is 78:1 with the adjustable hand crank at the short 150mm position, and 157:1 with the adjustable hand crank at the long 300mm position, The hand crank could be further reduced in size to something like 125mm short and 250mm long. The other dimensions of the hand crank should be left unchanged as it has been optimized for ergonomic and power performance. 400mm travel is 33 turns of the handle Estimated cost $350 to $400, or $450 to $500 with ball nut drive screws and auto lock mechanism. The other features like gas springs and perfor...