Metric dimensions of McWire threaded rod

The McWire instructions[1] calls for a 1/4" 20 threaded rod. The 1/4" would be the diameter, but what does the 20 mean? 20 threads per inch?

In general, I am surprised that the instructions use imperial measurements throughout -- especially since some of them are obviously originally made in metric. I'd be happy to add metric if I could only register for the Wiki, but it doesn't send me to the registration page when I cancel like it says.

-Lars

[1] Yes, I know it's outdated, but it's cheap and I have ideas for improving it.

Yes it is 20 threads per inch.
If you go here [http://parts.reprap.org/part/module/McWire+Cartesian+Bot+v1.2] which is the online parts lister, and then select the item's middle column (ie in this case, select the link: "threaded rod", you get more information.

I am using metric threaded rod for mine (UK based) and have no idea of the specified threads per measurement. Basically just hoping it will work anyway, although I may have some adjustments to make to motor speed etc.

Good luck in your build - are you blogging about it? I'd be interested to see your proposed improvements, and I'm sure others will be, too.

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Hazel

[copycatbot.blogspot.com]

Hi again, Lars,

Two other things -
you probably want to put posts such as this under reprappers, or mechanics!

and, beware: the threaded rod lengths on [http://www.reprap.org/bin/view/Main/McWire_Cartesian_Bot_1_2] are wrong for the stages at the sizes they and the rails are built.
See my blog and others for variations - I don't think anyone has standardised the sizes, though.

Hazel.

The only thing that would need to change for metric/imperial is the constant for
Z_STEPS_PER_MM in the firmware. it's an easy change and metric will work fine.

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Reprapping blog and other rants: [renoirsrants.blogspot.com]
My Reprap: [sites.google.com]

I am in the middle of my McWire build and if you have any questions I would be glad to try and answer them. [themakersworkbench.com]

Its a shame they are using imperial measurements.......i'm getting quite comfused at comverting those back to metric