ACME Threaded Rod

[JohnG]

What's the difference between a 1/2"-10 ACME Threaded Rod and a 1/2"-10 ACME 2 Start Threaded Rod? I can't seem to find an answer using google. Is one better then the other? I would like to have a better understanding on the rods before purchasing them.

And what's the maximum length I could go with using this size before you would say its to flimsy? Would 5 feet (60 inches) be ok? I need it long for the y axis since I'm going with a modified jgro design using a moving table instead of a moving gantry. I would like to stick with 1/2"-10 since http://gonebowlin.com/dumpsterCNC/ sells AB nuts for this size.

[ger21]

Both have 10 threads per inch, but the 2 start is actually 2 seperate threads, and only needs 5 turns to move 1".

[JohnG]

Would the 2 start affect accuracy since it moves faster per turn?

[ger21]

Not accuracy, but it will give less precision. But, 1/2-10 2 start with a stepper still gives you .001 per full step.

[JohnG]

Thanks for the info.