marka12161
Stainless
- Joined
- Dec 23, 2016
- Location
- Oswego, NY USA
The Reed Prentice did not come with a thread dial so making one is on the long, satisfying list of things to do. I'm not ready to start the build yet but i like to think through a project long before i start so i opened the good book and tried to slueth out worm gear design. I also read many of the old posts on building thread dials which convinced me i was overthinking this a bit.
In the end i figured out what i need to do; 4 tpi lead screw with smallest fractional thread the machine will cut is 5 3/4 tpi so i need a gear that will engage at a point that will turn the 3/4" fraction into a whole number. This means an integer multiple of 16 teeth with a circumference an integer multiple of 4 inches. So, either 16 teeth, 1.25" dia or 32 teeth, 2.5" diameter.
But, in studying the machinery's handbook, i couldn't seem to fit my lead screw dimensions into any of the standard worm gear tables. This leads me to believe that, although similar in appearance, an acme screw and a worm gear are not the same thing. I'm concluding that worm gears come in standard dimensions with tooth geometry designed to carry specific loads under specific conditions and that acme thread screws are not designed in quite the same way.
I know this may be a bit of an academic question but i'd appreciate the input from the experts if for no other reason to scratch this particular itch.
By the way, this'll be a nice practice project for the universal horizontal mill and dividing head. I may even get fussy and grind a tool bit so i can use the shaper to cut the final tooth profile.
Mark
In the end i figured out what i need to do; 4 tpi lead screw with smallest fractional thread the machine will cut is 5 3/4 tpi so i need a gear that will engage at a point that will turn the 3/4" fraction into a whole number. This means an integer multiple of 16 teeth with a circumference an integer multiple of 4 inches. So, either 16 teeth, 1.25" dia or 32 teeth, 2.5" diameter.
But, in studying the machinery's handbook, i couldn't seem to fit my lead screw dimensions into any of the standard worm gear tables. This leads me to believe that, although similar in appearance, an acme screw and a worm gear are not the same thing. I'm concluding that worm gears come in standard dimensions with tooth geometry designed to carry specific loads under specific conditions and that acme thread screws are not designed in quite the same way.
I know this may be a bit of an academic question but i'd appreciate the input from the experts if for no other reason to scratch this particular itch.
By the way, this'll be a nice practice project for the universal horizontal mill and dividing head. I may even get fussy and grind a tool bit so i can use the shaper to cut the final tooth profile.
Mark