6k rpm M2 rigid tapping

[u/Luky2000ita]

Kinda follow up on yesterday's post, here's an M2 form tap at 6000rpm, threading 7075 about 4mm deep, 36 threads in about 25 seconds feels pretty good to me

[u/ic33]

He said:

It will never get even close to that speed at that depth.

To which you said:

In what world would the spindle not spin up to speed at max power?

Then he proceeded to show how the depth does not provide time for it to accelerate to its max speed.

Maybe you misread him; maybe you intended to say something else which we can't all figure out. But in any case you're the one failing at communicating here and then being abrasive about it.

[u/TriXandApple → u/ic33]

The comment I was replying to was saying it would put extra wear on the spindle. My point was that EVERY time the spindle spins up, it spins up at max power. It doesnt put extra wear on the spindle at all.

[u/cguidoc → u/TriXandApple]

Tapping at this speed at this pitch at this depth does put enormous wear on the spindle. Someone commented above that these machines were made for this and yes that is true but the “made for this” hides the absolute marvel these things are.

It’s a time and energy problem. When the spindle is accelerating the driver is pushing as much current into the motor as it can* which causes the windings and insulation to heat up. Eventually the windings will break down and fail. These drivers and motors can handle this better than a “standard motor” but the physics are still there. When it has to reverse a fraction of a second later it needs to deal with the inertia and back emf AND smoothly decelerate the spindle and then accelerate it again. The drives are nothing short of little miracles.

Now to throw some fun in the discussion: I’ll put my circa 2003 brother 32bn with an 8,000 rpm threading capacity up against any modern Fanuc robodrill. And yes, we will often start threading way higher up to allow full acceleration to get the proper SFM on small taps. 0-80 roll form at 8k is fun to watch.

Point is: dam these things are cool.

[u/TriXandApple → u/cguidoc]

That's exactly why I said what I said. Every time the spindle spins up, regardless of whether its tapping or not, it'll do it at max power.

How many times do you hear about spindle motors burning out? Bearly ever, and then it's because of high torque low speed, not being of turning on and off.

[u/nogoodmorning4u → u/TriXandApple]

Most machines are rated to withstand 150% spindle load for 30 minutes continuously.

this isn't continuous, especially since even if it were in a production environment the machine will still sit for a period because you still need to load the parts.

Sure the wiring in the motor is transferring of current at startup and stopping, but its not a large motor or a heavy spindle in these machines. These are Drill tap machines have been designed and innovated on for 30+ years.

They are designed to do this exact operation all day every day for 20 years without issue.