Downhole sinusoidal vibrational apparatus

A device in place as, or suitable for use as, a vibrational tool of or in a downhole assembly, the device having a first magnetic assembly which is to be, or can be, rotated relative to a second magnetic assembly and which, when so rotated, causes the second magnetic assembly to oscillate and/or reciprocate at least substantially in an axial manner;

• wherein
• the oscillating and/or reciprocating magnetic assembly, at least substantially, at either one end, or both ends, is attached to and constrained in its oscillations and/or reciprocation by a compliant member thereby allowing the output force to be distributed to the outer body of the vibrational tool and/or any attached uphole and/or downhole tooling, from the compression and extension of the compliant member in a substantially sinusoidal manner.

The use of a compliant imposition(s) on the vibrational output of a device on demand downhole actuable to cause relative axial movement.

A vibrational device on demand actuable by relative rotational input to cause axial relative movement outputting via compliant constraints on the extent of the axial relative movement.