How to Calculate Sewing Machine RPM?

Do you know the speed of your sewing machines? Do you know how to calculate the machine rpm (speed)? Read this post to learn the method of calculating sewing machine RPM from seam length and SPI.

Each sewing machine has a maximum speed limit. When a sewing operator performs a task on a machine, he/she does not run the machine at its maximum speed (rpm). How fast a machine is run depends on the skill of the operators and difficulty level of the operations.
sewing machine rpm
Sewing machine rpm calculation

When it comes about measuring machine rpm, you can find
- the maximum speed a machine can be performed or
- at what speed operator runs a machine
- average machine speed

I have written answer of all three.

1. If you want to know what is the maximum speed limit of a machine then refer to machine manual
or sticker attached to the motor.

2. If you want to know how fast a machine can be run, use the following steps. It is a reverse process of calculating machine rpm. 
  • Cut a fabric strip of 2 meters length and 15 cm wide.(i..e. loop length = 200cm)
  • Make a loop and mark a dark line across.
  • Set machine SPC (e.g. Stitch per centimeter = 4)
  • Thread needle and bobbin
  • Run machine at maximum speed (press pressure foot flat)
  • Record time - record how much time it takes to complete a cycle (2 meters long) e.g. cycle time 12 seconds.
  • Now, use the following formula to calculate machine rpm (max. limit)
         Machine RPM = (SPC X Loop length X 60)/cycle time
         In this case Machine RPM is = 4X200X60/12 = 4000

3. If you want to know at what average RPM operator is running a machine, easy way to find the speed is a laser tachometer. Use this tool to record machine rpm (maximum speed on running). To know how to use tachometer read this article.

Related Articles:

How to Estimate Sewing Time by Machine RPM?
How to Find Actual RPM of the Machines running on the Floor?

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