Langmuir MR-1 spindle servo - 8000 rpm

[Neale]

I think I saw that they have a 1:2 belt step-up between servo and spindle. Gain speed but lose torque.

They also talk about a spindle encoder although whether that is in the servo or attached to the spindle I don't know. I guess that it doesn't really matter as they are not talking about rigid tapping - they show thread milling instead.

[JAZZCNC]

I think I saw that they have a 1:2 belt step-up between servo and spindle. Gain speed but lose torque.

Would make some sense but the speeds and torque they claim still don't stand up to me because the figures don't make sense.? Here's why.

Langmuir state a 2.5Kw and 4.5lbf.ft or 6.2N.m servo motor which would put it in the 110/130 frame class and this is where the figures go wrong to me.?

I'm taking it that they are not claiming peak values, which would just be wrong, so I'm going to use Rated values to compare.

Most servos at this KW rating, even quality units like Yaskawa, are rated at 3000rpm or less, often 1500rpm. The rated torque for a 2.5KW motor is typically around 7.5Nm or 5.5lbf.ft.

So using the motors rated values with a direct 1:1 connection we can't get near the 8000rpm they claim, if we go with a 1:2 ratio we still only hit 6000rpm but now the torque is half the rated and down to 2.75 lbf.ft and if we pushed the RPM to the claimed 8000rpm would drop closer to 1.8 lbf.ft.

However, I doubt they are using a 110 or 130 size motor because they are heavy things, plus they show what appears to be an 80 or 90 frame size motor which is like a NEMA 32-size stepper size and I've yet to see a servo at this size much above 1.2kw and again usually rated at 3000rpm.

So how they are doing it I don't know.? The figures just don't add up and I doubt they have had the motors built special at this money.!