How to modify SR axis mechanics to improve backlash characteristic
Problem
The design for locking the SR axis spigot to the top assembly initially relies on the friction of 4 off M6 cap heads to hold it firm
Under constant use, these bolts can loosen, giving up to 2 degrees of free play or backlash in the system. The symptom of this would be the axis suddenly jumping out of SR angle by a fixed amount up to 2 degrees. The only course of action being a recalibration.
A workaround solution was implemented on Z057 using a secondary sensor and a recalibration on each turn of the SR axis.
The procedure described below resolves the root cause of the issue.
Components
| Part | Qty | Description |
|---|---|---|
| M0001176 | 2 | Clinch shakeproof washer |
| F0000579 | 2 | Unbrako M6x16mm Capheads |
| D0015976 | 2 | Modified Shoulder bolt (dowel) |
| 8mm Reamer | ||
| 7.8mm Drill |
Solution
A simple modification has been designed to eliminate this problem. The solution involves repurposing one of the 4 fixing holes and using a dowel pin to lock the position. Only one is needed because the spigot has a central flange precision location, only one dowel is needed to prevent rotation. The dowel pin has a thread on it and a cross slot for driving it in to the threaded hole
| 1 | Drop the motor and gearbox off the bottom - access to the M6 cap heads is gained under the M12 bolts in the main saw base plate. These can safely be removed because the plate is dowelled in place. | |
| 2 | From the bottom, drill out one of the M6 clearance holes in the top spigot to 8mm in small stages with a reaming tool | |
| 3 | Insert an 8mm dowel with a screw thread on the bottom into the relevant hole in the gearbox | |
| 4 | Reassemble - the gearbox now bolts on with 3 off bolts that we would like to replace with unbrako steel and a plate washer so they cannot come undone |
Exceptions
Draft
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