Abstract: An accessory device is provided for securement to a conventional portable type chainsaw to define a fixed predetermined distance of the cutting plane of the saw from an end of a work to be cut. With this arrangement, successive cuts of identical lengths can be rapidly made. The accessory itself comprises a plurality of straight cylindrical tubes nested in telescoping relationship and with appropriate frictional engagement with each other. With this arrangement, any desired length can be defined by the extent of telescoping of the tubes and the defined lengths remain fixed as a consequence of the friction between the tubes. This fixed length can thus be used for successively measuring off equal cuts of a log or other wood to be cut by the chainsaw and the operator need not be concerned with further adjustments until such time as the successive cuts are to be changed in length.