Tailstock tap holder
In the past my usual procedure for tapping on the lathe was to mount the tap in the tailstock chuck and then slide the tailstock up to the work held in the lathe chuck. The lathe chuck was rotated with my left hand and axial pressure applied to the tailstock with my right hand. This was continued until the tap was well started in the work. The tailstock chuck was released and pushed back and the work released from the lathe chuck. The work was then transferred to the bench vice and the tapping continued with a tap wrench.
Recently, Michael Horner suggested an alternative method on the Model Engineer website, http://www.model-engineer.co.uk/forums/postings.asp?th=114732&p=1
The method is very simple and it utilises a standard pin chuck type tap wrench. This slides in a sleeve with cut outs for the tommy bar, see the header photograph.
This method has some advantages since once the tap starts to bit then there is no need to apply pressure from the tailstock side since as the thread is cut the tap wrench is drawn into the work. An additional advantage is the tailstock can be just slid back and the work released from the chuck leaving the sleeve in the tailstock chuck.
Recently, Michael Horner suggested an alternative method on the Model Engineer website, http://www.model-engineer.co.uk/forums/postings.asp?th=114732&p=1
The method is very simple and it utilises a standard pin chuck type tap wrench. This slides in a sleeve with cut outs for the tommy bar, see the header photograph.
This method has some advantages since once the tap starts to bit then there is no need to apply pressure from the tailstock side since as the thread is cut the tap wrench is drawn into the work. An additional advantage is the tailstock can be just slid back and the work released from the chuck leaving the sleeve in the tailstock chuck.
The sleeve was made from 20 mm diameter mild steel bar. A 38 mm length was cut off and faced both ends. One end was centre drilled and then drilled out 10 mm diameter for a length of 13 mm.
A 38 mm piece of 10 mm mild steel rod was cut off and the ends faced. One end was lightly knurled for a length of 12 mm and then chamfered. Both pieces were cleaned with solvent and a little high strength retainer placed on the knurled end and in the hole. The two pieces were then pressed together in the bench vice. |
The piece was then chucked in the lathe by the 10 mm end and the end drilled with a centre drill. The end was then supported by a tailstock centre and the 20 mm diameter part turned to a good finish. The centre was removed and the end drilled out to 12 mm diameter. The tap wrench should be a good easy sliding fit in the hole. The edges were all chamfered.
The piece was then transferred to the mill vice and centred under the spindle. A 20 mm long slot was then cut through both walls of the sleeve using a 6 mm slot drill. The tommy bar should be an easy sliding fit in the slot. All the edges of the slots were cleaned up with a file.
The piece was then transferred to the mill vice and centred under the spindle. A 20 mm long slot was then cut through both walls of the sleeve using a 6 mm slot drill. The tommy bar should be an easy sliding fit in the slot. All the edges of the slots were cleaned up with a file.
This simple accessory is very simple to make and use and even works well when tapping under power.