How NOT to Tap a Hole

MrWhoopee

MrWhoopee

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While working on the vertical conversion of a 4x6 saw, I was drilling a hole to be tapped on the upper guide mount bar. I realized I had not been taking pictures of the build, so I stopped and grabbed my phone.
20210723_124314.jpg

I then resumed, changing out the drill for a 5/16-18 gun tap. When I tried to tap the hole, the tap kept spinning in the chuck no matter how much I tightened it. Assuming I had a dull tap, I grabbed another and started again, making sure the chuck was "guten" tight. This one shattered as soon as it began to cut!?? Puzzled, I took a step back, grabbed one of my cheap 1/4 in. carbide endmills and set about removing the broken tap. It was slow going, but it was working. I kept watching for debris to fall out the bottom of the hole, but none did. Then came the crunching noises as pieces of the tap broke away and came up. I knew I was destroying the endmill, but it only cost me a couple of bucks and I have more. Finally I was making no more headway, so I withdrew the EM. It looked like it had been in a pencil sharpener. It was then that I looked down the hole and realized why no chips had been falling through. When I stopped to take the picture, the hole was not through the part. I forgot to finish it after snapping the pic.

Keep your mind on the work.
 
A pain in the butt way to remember things, I've had similar episodes. :)
 
MrWhoopee said:
While working on the vertical conversion of a 4x6 saw, I was drilling a hole to be tapped on the upper guide mount bar. I realized I had not been taking pictures of the build, so I stopped and grabbed my phone.
View attachment 373366

I then resumed, changing out the drill for a 5/16-18 gun tap. When I tried to tap the hole, the tap kept spinning in the chuck no matter how much I tightened it. Assuming I had a dull tap, I grabbed another and started again, making sure the chuck was "guten" tight. This one shattered as soon as it began to cut!?? Puzzled, I took a step back, grabbed one of my cheap 1/4 in. carbide endmills and set about removing the broken tap. It was slow going, but it was working. I kept watching for debris to fall out the bottom of the hole, but none did. Then came the crunching noises as pieces of the tap broke away and came up. I knew I was destroying the endmill, but it only cost me a couple of bucks and I have more. Finally I was making no more headway, so I withdrew the EM. It looked like it had been in a pencil sharpener. It was then that I looked down the hole and realized why no chips had been falling through. When I stopped to take the picture, the hole was not through the part. I forgot to finish it after snapping the pic.

Keep your mind on the work.
Click to expand...
This is basically why I forget to take pics. Hate to say it but the project sequence and how quickly it can turn to trash is why I usually don’t remember to take pics.
 
I can really relate to this process and subsequent accidents... :grin:
 
Frozen peas on the forehead...

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
Maybe in the future you might consider using these drill/tap combinations.

drillsandcutters.com

5/16"-18 HSS Combined Drill Bit & Tap (Drap)

5/16"-18 HSS Combined Drill Bit & Tap (Drap). Find this item and other cutting tools on DrillsandCutters.com.
drillsandcutters.com drillsandcutters.com

When I purchased my Jet floor model drill press from a company shop it was setup to use them. You'd set one depth stop for the length of the hole to be drilled, and a second for the length of the depth to be tapped. Then start the machine and hit the down feed button. It would drill the hole at high speed until it came to the first stop. Then switch to low speed for tapping until hitting the second depth stop. Then it would reverse itself until it hit the home position.

When I bought the machine I thought it came from the factory with these features. I contacted Jet several times for diagrams and information on how to diagnose some problems i was having. All the requests came back with statements like "our machines don't do that" or similar. I'm now thinking the modifications were made inhouse by one of the electrical geniuses. If that's the case all the prints were destroyed when the company was sold to the new owners. The new owners decided they didn't want to support an engineering organization and the related parts inventory. They junked almost all of the hundreds of millions of dollars worth of inhouse designed and built machinery, destroyed the prints, and scrapped all the spare parts. They thought it would be less expensive to purchase commercially built machines, and rely on their service and support organizations. Ten years later they were proven wrong in a big way, but since they destroyed the existing organization and documentation there is no recreating what once existed.
 
An extreme version, but one I've seen over and over in modern industry. It's what happens when you let college educated bean counters (accountants) run things. Glad I'm out of even the independent contractor business.

.
 
I was cutting the slots in my lapping plates yesterday morning. I couldn't get the 1/4 -20 bolt started in the hole. I assumed there was a burr so I got out the tap to clean the threads. Wait, there are no threads.
I stopped to take a pic of the three plates in the middle of the tapping process.
Craig, it appears we suffer from the same distractions.
 
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