| Gallery, Projects and General > How do I?? |
| Tapping Deep Holes?? |
| << < (2/2) |
| Pete W.:
Hi there, all, Thank you for your various inputs. I acknowledge that I was using too small a pilot drill. It seems that my trusty DTC chart probably gives thread root diameter - I'll investigate that further. It's never tripped me up before! Here's the part of the chart I used: However, I've done some more work today that suggests the pilot hole diameter isn't the whole story. I put through a 5 mm drill and tried the taper tap again - same result, it cuts a few threads and then locks up! So, I swapped to the second tap (not the second taper tap, the first second tap!) and it went through like the proverbial knife through butter. Backed off every turn or so but the chips were falling out of the other end of the test piece OK and it both felt and sounded right. My conclusion is that when the supplier ground the taps to convert them from bottoming to taper, they didn't back off the material behind the cutting edges of the flutes. If I could contrive a set of bench centres I could probably throw more light on that conjecture but I'm eager to progress my microscope repair. |
| Joules:
Can you rig an airline onto the opposite end of the tube you are cutting. My guess is its swarf getting trapped and not cleared out so getting trapped in the threads, wiggle the tap as you thread to break up the swarf and wear eye protection. That would be my try :scratch: p.s tap through a piece of cloth might keep the swarf from flying all over. |
| Navigation |
| Message Index |
| Previous page |