Re: size of drill and tap for grease zerk

Posted by Tim PloughNman Daley on January 03, 2006 at 16:35:58 from (206.148.168.198):

In Reply to: Re: size of drill and tap for grease zerk posted by soundguy on January 02, 2006 at 04:47:06:

Hey Sounder-
Pipe thread sizes refer to the INSIDE DIAMETER of the pipe it fits. Example- 1/8-27 NPT (National Pipe Tapered Thread). The 1/8 refers to the diameter of the inside of the pipe it would connect or cause flow to. For the 1/8-NPT, machinist chart shows Letter R drill [.339 decimal equivalent] Look at part or Zerk to be threaded into the hole you want to tap. Mic or caliper the smallest end by the opening. Is it a little larger than your drill size? If not you have the wrong tap size. The tap is tapered by 1/16" per inch or 3/4" per foot. It is meant to seal after a few turns by hand. If you keep turning tap into part, you will eventually strip it out by enlarging the hole size to the major diameter of the pipe tap. Re-drilling out to retap same size doesn't make sense-your hole size should already be there. Unless you have a 1/16-NPT Zerk. 1/4-28 UNF (Unified National Fine)is a straight thread as I said. 1/8-NPT has 27 TPI (threads per inch) Somehow it seems you will cross thread something and the mating part (Zerk) won't thread in. The OD of the largest part of a 1/8-NPT male end will mic close to 3/8". Seems your Zerk is smaller than that. You could open up smaller hole to next size up-i.e. 1/16-NPT to 1/8-NPT... HTH

Tim Daley (MI)
*8N15513*

Replies:

• Re: size of drill and tap for grease zerk soundguy 04:29:38 01/04/06 (1)
  • Re: size of drill and tap for grease zerk Tim PloughNman Daley 04:58:39 01/04/06 (0)

Add a Reply Name: E-Mail: Subject: Comments: Optional Link URL: Link Title: Optional Image URL: Email Notification: If you check this box, email will be sent to you whenever someone replies to this message. Your email address must be entered above to receive notification. This notification will be cancelled automatically after 2 weeks.

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]