I need some help - I'm building a machine but I'm not sure of the best way of doing it.

Thanks a million for your help

Just to refresh my point - I've made one or two changes

I have two large wire spools. One empty and one full. The full spool (approx. 500kg) is much larger than the empty spool (100kg when full).

I wish to transfer the wire from the large spool to the smaller spools. I want to do this regularly so I want to set up a system that will not have to be monitored but can turn itself off when the smaller spool is full and/or the larger spool is almost empty - whichever happens first.

I want to keep this as simple as possible.

I'm looking to put a motor on the small spool and use this to turn the large spool through the pull of the wire

I will be using one small spool at a time along with one large spool at a time

I want the entire system to shut down once the small spool is full or the large spool is almost empty - whichever happens first

The wire in question is a high carbon wire with a very high tensile strength so this should not be a problem for the wire - I am confident hat the wire will be able to handle the pull as long as there is a slow start up and slow down

The large spool has a weight of 1100lbs (500kg), a diameter of 28 inches (70cm) and a depth of 12 inches (30cm) - in the picture attached there are two large spools stacked on top of eachother on one pallet

The small spool has a diameter of 19 inches (48cm) and a depth of 9 inches (24cm)

I want to unwind the entire contents of the large spool onto 5 smaller spools - each smaller spool will be manually lifted off and replaced with an empty spool each time the small spool is full - maximum rotational weight on the take up spool at any one time is 220lbs (100kg)

I would like to start and stop the small spool slowly - ideally a slow start/stop lasting approximately 3 to 4 seconds

I would like to turn the small spool - the one powered by a motor at between 3 to 5 revolutions per second (180 to 300 rev per minuet)

A uniform wrapping speed is not critical - I am conscious that the wrapping speed will change as the diamter of the larger spool decreases and the diameter of the smaller spool will increase. I don't need any footage count - just plain transfer from one spool to another

I do not have any motors at the moment so any suggestions would be greatly appreciated

I have access to 110 Volt, 230 Volt and 3 phase 400 Volt supply

I don't need the motors to run in reverse just in one direction

I'm hoping to get this done for as cheap as possible - at most €1500

Please give me some suggestions on how to start and stop both motors and the best type of motors for the job

Thanks very much for your help

  • \$\begingroup\$ a 500kg spool will need a lot of torque to get going, we are talking 1000lbft+, a dc motor will be rather large to begin with and gearing will be industrial size. Keep in mind that if you are using the spinning of the small spool to spin the large spool the moment of inertia of the large spool will be increased by (500kg)r^2 (where r is the distance between spools) since it is off axis, requiring an even bigger motor \$\endgroup\$
    – crasic
    Aug 27, 2013 at 21:48
  • \$\begingroup\$ Additionaly, depending on the thickness of the wire, its quite possible that the tension required to start the spool spinning will be too great and will break. In other words we are talking light-industrial equipment for a 500! kg spool \$\endgroup\$
    – crasic
    Aug 27, 2013 at 22:00

1 Answer 1


Due to the weight involved, I would look at using variable speed drives to allow smooth/controlled starting and stopping of the motors as well as speed control. You could use AC or DC motor for this application with correct associated VSD (variable speed drive). You could wire limit switches into the VSD start/stop logic as well as syncing the speed and preventing one pulling against the other using some hard-wired interlocks. Some good examples of typical schematics can be found here:




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