Always check when in doubt... Mislabeled Taps

Ray C

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Close call today... I ordered and received 10 of these spiral flute taps costing about $15 each. They were supposed to be 5/16-18 and that is what the box says as well as the laser etching on the shank. Look closely at it while held right next to a 5/16-18 bolt. Look a little odd? Yep, it's a 7/16 tap. I checked the label on the box and the writing on the tap a couple times and was almost ready to proceed. It was setup in the mill and ready to go when my instincts kept telling me something was wrong. At the last moment, I measured with a caliper. Thank heavens I didn't plunge it under power.

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Ray
 
5 or 7 the're both prime numbers. That would have been impressive trying to shove that tap in the small hole
 
I once forced a 1/4-20 spiral point tap into a piece of 1/2" 6061-T6511 aluminum flat bar drilled for a 10-32. Made it almost all the way through before it broke. Half the back cut was showing.

I do a lot of 10-32 and 1/4-20. #21, #7, and F drills provide clearance and tap holes for the two sizes. with #7 being tap size for one and clearance size for the other. Somehow I grabbed the #21 instead of the #7.
 
someone was asleep on the packaging line. or was it packed by a robot?
I had the same type of thing happen with some rocker arms for ol' Blue. (3) three of them were completely different.
Summit did take care of it right away to their credit.
 
It does happen on occasion. I recently purchased a number of Thomson bearings and rods for a job. I ordered two 15" rods and six 12" rods. They all came in original boxes with the length and diameter clearly marked on the package. Unfortunately two of the rods were only 9" in length rather than the 12" marked on the box.

When I called the vendor to alert them to the problem all they said was "send them back". Their attitude was "no big deal it happens all the time". At one time ALL Thomson products were made in this country. Now I see they are made wherever they can be made the cheapest. It just so happened the mislabeled rods came from Mexico. Unless the vendor is willing to open and inspect every package for the proper content it's bound to happen from time to time.
 
Lots of miss labeled taps out there. I bet I have a dozen or more of small size ones that are off by one or two sizes, but wait for this...... they are all American made. Do Do happens.
 
Are they 18 tpi, and if so could they be helicoil taps?

I have to agree. I should have looked closer to the package. STI (Screw Thread Insert) is the designation for use when installing threaded inserts. Here's quote from Thread Supply Tool .com:

Our Screw Thread Insert (STI) Taps are used specifically to create threads for Helical Thread Inserts. STI Taps are oversized so the thread produced will accept a Helical Wire Insert of the same nominal size and pitch - meaning the hole created by the Tap goes back to the original dimension allowing the original fastener to be used.

In this case either you ordered incorrectly, or someone on the other end didn't realize there are multiple designations of 5/16" taps. Years ago I ordered a thread repair kit for 3/8-16 blind threaded holes. The vendor went into a long winded description about including oversized taps for the job. When I got the kit the tap said 3/8-16 STI. I called back a little upset mentioning he said the kit included oversize taps. I was alerted to the fact that below the 3/8-16 there were the letters STI which meant screw thread insert. It was a bit embarrassing, but a lesson learned
 
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It was setup in the mill and ready to go when my instincts kept telling me something was wrong. At the last moment, I measured with a caliper. Thank heavens I didn't plunge it under power.
This has happened to me a few times ,especially at work when taking over someone else's set up ,the funny thing is ,I only listen to my inner voice when I'm in a calm collected state of mind , that's when I double and triple check a setup, it is very hard hear that voice when you're in a rush or tired /hungry, or facing a deadline.
 
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