Michael
Just had a quick look at the exploded diagram in the manual you linked to. The reciprocating drive for the spindle is, I think, fairly straightforward (if I am correct that is
) and is derived by use of a worm gear on the motor shaft driving a reciprocating crank which moves a keyed sleeved up and down on the motor shaft to which the sanding drum is connected.
I more detail;
The motor shaft has a worm gear (15) fitted which drives gear (30), this gear is fixed on shaft (35) which drives the connecting spindle (28) via the connecting rod (18). This reciprocating motion is coupled to the spindle seat (22) which houses the spindle (60) and couples to the sanding drum . The drive from the motor to the spindle is made by use of a long key (12) held by a set screw (13) over which the spindle seat (22) and spindle are free to slide, a fairly crude spline.
The only thing which is not clear from the diagram is the coupling of the reciprocating motion to the spindle seat. This could easily be acieved using a couple of links coupled between the connecting rod ends and the spindle seat.
Cheers
Martin
Edited By Martin W on 13/08/2012 10:29:39
Edited By Martin W on 13/08/2012 10:37:15
Edited By Martin W on 13/08/2012 10:42:23