Here it is, as promised, my lead-screw for my homebrew T-square RT fence :
The main components are a piece of common 1/4-20 rod, a brad-hole T-nut (Servalite brand from the hardware specialty fasteners bins which I found at our California-based Orchard Supply Hardware), a piece of 1/2 inch MDF, and some 1-1/2 inch aluminum angle. The L-brackets are attached with 8-32 FH screws and threaded inserts to the edge of the table:
The MDF block and the T-nut are seen here with the rod and 5-star knob (a crank-handle would be faster to use, as it takes 20 revolutions to move the fence one inch):
This gives 0.050" in one revolution ( a little less than 1/16"), and 0.005" for 1/10 revolution, one hill or valley on the knob! One trades off speed for precision, which works for the type of projects that I primarily need the table for.
The nut fits easily into a 3/4" recess, just a hair deeper than the flange thickness, made with a Forstner bit, with a 3/8" through hole in the center to allow the nut to free-float just a little for smoother operation, as this is not precision machine work! A brass pin of 3/32" rod, just visible in the recess, pokes though one hole in the flange to prevent rotation.
This will come in very useful on my upcoming rocking-horse project, where I need to accurately rabbet an extension section into the 3/8" rocker panels. It will also make a big difference in attainment of the level of accuracy required for building woodwind musical instruments using the flat-panel, pyramid bore construction technique.
The main components are a piece of common 1/4-20 rod, a brad-hole T-nut (Servalite brand from the hardware specialty fasteners bins which I found at our California-based Orchard Supply Hardware), a piece of 1/2 inch MDF, and some 1-1/2 inch aluminum angle. The L-brackets are attached with 8-32 FH screws and threaded inserts to the edge of the table:
The MDF block and the T-nut are seen here with the rod and 5-star knob (a crank-handle would be faster to use, as it takes 20 revolutions to move the fence one inch):
This gives 0.050" in one revolution ( a little less than 1/16"), and 0.005" for 1/10 revolution, one hill or valley on the knob! One trades off speed for precision, which works for the type of projects that I primarily need the table for.
The nut fits easily into a 3/4" recess, just a hair deeper than the flange thickness, made with a Forstner bit, with a 3/8" through hole in the center to allow the nut to free-float just a little for smoother operation, as this is not precision machine work! A brass pin of 3/32" rod, just visible in the recess, pokes though one hole in the flange to prevent rotation.
This will come in very useful on my upcoming rocking-horse project, where I need to accurately rabbet an extension section into the 3/8" rocker panels. It will also make a big difference in attainment of the level of accuracy required for building woodwind musical instruments using the flat-panel, pyramid bore construction technique.
