Thread pitch of acme screw

[redarrowmentor]

Can anyone tell me what thread pitch for the larger acme screw that acme in the kit of parts is? I want to order a tap for it but not sure what it is and I don't have one here.
Thanks!

[Nate Laverdure]

The "pitch" of a lead screw is determined by a) its lead and b) the number of independent screw starts. The lead is defined by the axial distance the nut advances in one revolution of the screw. Pitch = Lead / Starts.

I believe that the larger KOP lead screw is this model. If that's the case, the screw has a 0.125" lead. I believe it has 5 screw starts, but I can't find any data to verify this.

As for tapping this thread-- although it's possible in theory and practice, it would be easier and less costly to just buy a flanged nut from the manufacturer and mount it as required.

[engunneer]

that's going to be an expensive tap. I'm not finding it in the KOP checklist, so I'll have to defer to whichever team can measure it first.

[MrForbes]

I don't see a lead screw in the KOP checklist. Was it from a previous year?

Anyways....generally, you don't tap holes for lead screws, you use a special nut that matches the lead screw.

[Nate Laverdure]

Originally Posted by squirrel

I don't see a lead screw in the KOP checklist. Was it from a previous year?

Yes (2009), and it was also in this year's FIRST Choice. I believe 2010 and 2011's kit included the smaller (3/8") lead screw.