Carriage Stop
A carriage stop is useful for boring to a specific depth or turning to a shoulder. This design clamps on the back of the ways and uses a screw as an adjustable stop. The 1/4-20 screw allows for fairly precise adjustments, since each full turn is 0.050". I started by squaring up a piece of aluminum approximately 1" x 0.75" x 0.5". I located the center on one of the 1" x 0.5" sides and milled a slot 0.25" deep 0.020" wider than the thickness of the ways. I drilled and tapped a 10-32 hole 0.125" from the end on the top (0.75" x 0.5" side) for the clamp screw.
I started the clamp screw by turning the diameters for the threads and knob on a piece of brass. I used the lathe to cut 10-32 threads. The lathe can't thread completely to a shoulder, so I used a die to continue the threads. Unfortunately, my dies (or at least the 10-32) are too tight and the threaded end snapped off. Rather than scrap the piece of brass, I cleaned up the face, drilled and tapped the knob portion for 10-32. I took a piece of brass 10-32 threaded rod, faced and turned down the clamping surface then threaded it in to the knob. I knurled a fine pattern on the knob before parting it off from the stock.
I located the hole for the adjustment screw 0.25" from the end and centered vertically. This was drilled and tapped for a 1/4-20 screw. I was originally going to use a spring between the head of the screw and the aluminum body to prevent the screw from rotating due to vibration, but I didn't like the way it looked. I decided to make a brass lock nut with a lever. I turned, drilled and tapped a piece of brass about 0.4" in diameter. It needs to be smaller than 0.5" so it doesn't interfere with the lathe bed. I threaded this ring onto the screw (assembled in the body) so I could locate the handle in the locked position. I wanted the lever to be horizontal when locked, so I marked this position. I cross drilled the ring with an 1/8" drill bit, made a small brass lever about 0.0015" larger and pressed it in. I ran the tap through the lock nut again to clean up the ends of the lever that protruded into the threads. This design may be over designed for its purpose, but I used it to start my next project and it works well.
Click the pictures for larger images.
I started the clamp screw by turning the diameters for the threads and knob on a piece of brass. I used the lathe to cut 10-32 threads. The lathe can't thread completely to a shoulder, so I used a die to continue the threads. Unfortunately, my dies (or at least the 10-32) are too tight and the threaded end snapped off. Rather than scrap the piece of brass, I cleaned up the face, drilled and tapped the knob portion for 10-32. I took a piece of brass 10-32 threaded rod, faced and turned down the clamping surface then threaded it in to the knob. I knurled a fine pattern on the knob before parting it off from the stock.
I located the hole for the adjustment screw 0.25" from the end and centered vertically. This was drilled and tapped for a 1/4-20 screw. I was originally going to use a spring between the head of the screw and the aluminum body to prevent the screw from rotating due to vibration, but I didn't like the way it looked. I decided to make a brass lock nut with a lever. I turned, drilled and tapped a piece of brass about 0.4" in diameter. It needs to be smaller than 0.5" so it doesn't interfere with the lathe bed. I threaded this ring onto the screw (assembled in the body) so I could locate the handle in the locked position. I wanted the lever to be horizontal when locked, so I marked this position. I cross drilled the ring with an 1/8" drill bit, made a small brass lever about 0.0015" larger and pressed it in. I ran the tap through the lock nut again to clean up the ends of the lever that protruded into the threads. This design may be over designed for its purpose, but I used it to start my next project and it works well.
Click the pictures for larger images.