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 (http://www.nookindustries.com/acme/AcmeGlossary.cfm) 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 (http://www.andymark.com/Lead-screw-fc12-50-p/fc12-50.htm). 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 (http://www.haydonkerk.com/LinearActuatorProducts/LeadScrewsAndNuts/Nuts/tabid/109/Default.aspx) 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]

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.