Tapping Synchronization

I’ve had some problems with rigid tapping on my 1100MX and I’m not sure where to start with troubleshooting. I couldn’t find any information on what size of tap is considered within the torque/power capabilities of this machine - I was running a 1/2-13 tap at 500 RPM in mild steel with flood coolant for lube. Is that expecting too much?

It did get through a few holes, albeit with evidence of poor synchronization at the entry - large burrs and a sort of cross-threaded look for the first rotation. Reducing the RPM helped somewhat. After that it started intermittently failing on the canned cycle after attempting to get the spindle RPM to stabilize at the programmed speed.

Any help is appreciated!

Probably too much for the machine. What belt were you on?

Low range.

I’m certainly willing to accept that as a limitation! It’s been a great machine, and I can always mill threads this size or larger.

I’m wondering though, about the issue where it fails to acheive the programmed RPM, and then eventually just errors out and stops.

Have you tried just to experiment drilling a slightly larger hole, see if you still have the problem with less torque?

@AnOminousCowHerd - welcome to the forums and thank you for posting!

1/2-13 is a big tap for a 2HP machine but a couple things might allow you get an adequate result.
Good chip evacuation will help. If you’re using a hand tap, switch to a spiral tap to help get chips out. If the tapping works for the first 1/2" of depth but then fails, try peck tapping to clear chips out.
Good lubrication will reduce torque requirements. Make sure you’ve got either a tapping lubricant or plenty of flood directed at the workpiece.
You might try tapping at a higher spindle speed. I think the max for a 1/2-13 on the 1100 will be 1100RPM. At really low speeds (below 5% of the rated speed) an induction motor can’t develop as much torque as it will at higher RPMs.
And as you mention, threadmilling is a great option, and easy to program on the thread tab of the PathPilot conversational notebook.

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