Tailstock offset.
One way to turn slow tapers, between centres, is by offsetting the tailstock. However, afterwards, resetting the tailstock on centre and parallel with the lathe axis is a complete pain. To overcome this I made this tailstock offset device. This just clamps to the tailstock barrel and any offset, up to +/- 15 mm, can be set using the adjuster knob.
This photo shows the front of the unit. On the left is the offset adjuster knob. The nut clamps the unit together once the offset is set. The pin to the right of the nut guides the top plate in the slot. The centre is on the right. This is a 60 degree conical shape made from 10 mm silver steel and then hardened and tempered. The knurled nut on the top of the unit is the clamp screw that secures the unit to the tailstock barrel.
This photo shows the rear of the unit. The large hole on the left is bored to a good fit on the tailstock barrel. To the right is the lead screw connected to the graduated adjuster knob. The lead screw is threaded M3 which has a pitch of 0.5 mm. The adjuster knob has 25 divisions so each division is 0.02 mm. The total range of adjustment available is +/- 15 mm.
This photo shows the clamping bolt. Notice the crescent shaped cut out. This cut out intersects the bore of the large hole shown in the previous photo. In practice the clamp bolt is securely bolted to the bar before boring the large hole. This ensures that when the hole is bored then the crescent shaped cut out is perfecly aligned. When the knurled knob is tightened then the crescent shape is displaced and secures the unit to the tailstock barrel.
I have used this system for clamping shafts several times. It has much to recommend it. It is compact, very simple to make and the torque required to lock the shaft is low compared with the more used pinch clamp system. Another advantage is it does not damage the shaft in any way unlike a simple screw pressing on a shaft. The crescent removed should be about 1/3 the clamp bolt diameter.
I have used this system for clamping shafts several times. It has much to recommend it. It is compact, very simple to make and the torque required to lock the shaft is low compared with the more used pinch clamp system. Another advantage is it does not damage the shaft in any way unlike a simple screw pressing on a shaft. The crescent removed should be about 1/3 the clamp bolt diameter.
This photo shows the unit view from the top. There is a scale on top of the unit graduated in mm. The back plate that clamps to the tailstock is made from 10 mm x 25 mm bar and the front sliding part is made from 6 mm x 25 mm bar. The end plate on the left hand side is also made from 6 mm x 1 mm bar and it is screwed to the end of the sliding bar with M3 screws.