Denford Viceroy knock-off trigger concept
Posted: Wed 27 Mar , 2019 10:48 am
Hi
The carriage on the Denford Viceroy features a knock-off mechanism that can be used when threading up to a shoulder. When the bar is pushed by the stop, it knocks off the half nuts.
The problem with this mechanism is that the exact knock-off point is not well defined. The knock-off is more like a slow push. Also lots of use will probably wear the half-nuts. A significant improvement would be a mechanism that snaps open the half nuts in a way that is precise and repeatable. It also needs to be easy to reset. I like to make this sort of retrofit look like it was factory fitted. That means no obvious levers or other stuff that looks like a hack.
I have come up with the attached concept. It is based on the trigger mechanism of a sniper rifle. It uses the shortened existing knock-off bar. The bolt could be made from the piece cut off the full knock-off bar and fit into the existing guide way. I have figured out it will fit between the apron and the bed, so no obvious bits to see. Everything in the drawing would be between the apron and the lathe bed. Nothing visible.
When activated, the mechanism will snap open the half nuts. Not shown in the sketch are the guides and pivot points needed to hold the whole thing in place. I just haven't made it yet. I have too many projects on the go to start this one. Someone might find this useful.
The carriage on the Denford Viceroy features a knock-off mechanism that can be used when threading up to a shoulder. When the bar is pushed by the stop, it knocks off the half nuts.
The problem with this mechanism is that the exact knock-off point is not well defined. The knock-off is more like a slow push. Also lots of use will probably wear the half-nuts. A significant improvement would be a mechanism that snaps open the half nuts in a way that is precise and repeatable. It also needs to be easy to reset. I like to make this sort of retrofit look like it was factory fitted. That means no obvious levers or other stuff that looks like a hack.
I have come up with the attached concept. It is based on the trigger mechanism of a sniper rifle. It uses the shortened existing knock-off bar. The bolt could be made from the piece cut off the full knock-off bar and fit into the existing guide way. I have figured out it will fit between the apron and the bed, so no obvious bits to see. Everything in the drawing would be between the apron and the lathe bed. Nothing visible.
When activated, the mechanism will snap open the half nuts. Not shown in the sketch are the guides and pivot points needed to hold the whole thing in place. I just haven't made it yet. I have too many projects on the go to start this one. Someone might find this useful.