Maurice Rhodes improves his Unimat
This article originally appeared in Model Engineers Workshop issue 126, June 2007.
Although not used regularly, some workshop accessories can be assets when the need arises. These attachments are often put on the Must make list but we usually manage to do the job using an alterative method. Apart from a difference in size these items often vary little in design from one machine to another, so only the dimensions need to be altered to make them compatible with a particular machine. In my own case, even such a small detail tends to delay the project even more, until a few minutes are available, to study the dimensions, to make certain that the object which is designed for a bigger machine can be scaled down to suit my own smaller model, the Unimat 3.
Having the need for a handle to turn the lathe spindle for a recent job and managing some other way, it was decided that this item was definitely to be eliminated from the Must make list. Perhaps others who have not made such a simple and useful item, for the same reason may, having dimensions to hand, eliminate this item from their list.
Little can be said about construction, apart from turning the drawbar sleeve where, due to the limited space for the travel of the lathe saddle, the following may save a little time. Cut a suitable length from 1/2in bar, set it in the lathe chuck and support the other end using the fixed steady. Face off the end and bore a 7.5mm hole to a depth of 30mm finishing with a countersink bit to make the job tidy. Remove the fixed steady and support the bar using a dead-centre in the tailstock and with the cutting tool holder set towards the tailstock end of the cross-slide, turn down the blank for as far as the saddle will travel, to 10mm or a diameter to fit the lathe spindle.
Reset the tool post to the headstock end of the cross-slide and reduce the remaining section to the same diameter. Remove and reverse the piece, which will now fit into the lathe spindle and can be held more securely in the chuck. Complete this end and drill the 6mm hole through. Cut the two slots to allow the end to expand, when the collet is drawn by the drawbar. Silver-solder the crank-arm to the sleeve and secure the knob to the drawbar and the handle to the crank-arm using a suitable thread lock.