Re: [CAD_CAM_EDM_DRO] Z axis servo reduction gear

HI Leslie,
I'll try 14 teeth motor and 18 teeth for lead screw and leave plenty of
adjustment room in the drive in case I want to change ratios later.
Thanks for the design selection/calculation method.
cheers,
Denis

On Saturday 28 March 2009 01:47:18 Leslie Newell wrote:
> Monitoring the temperature is actually a very good way telling if you
> are overloading the motor. If you can't hold on to it, you have a problem.
>
> > Are there any design rules or criteria that I could access because I'm
> > going to have to do calculate the ratios for XY drives also.
>
> How far do you want to go? Like anything, specifying motors gets more
> complicated the closer you look into it. The most difficult bit though
> is deciding on how much linear force you need on each axis. Once you
> have that you can work out the required torque. You then need to decide
> how fast you want the machine to move. Once you have these two you can
> then work out the required motor specs and power supply size.
>
> This is usually an iterative process. You go through the numbers then
> tweak a few values and try again. For instance you may not be able to
> achieve the required speed with your chosen reduction ratio. You then
> need to try changing the ratio and see how that affects the motor
> torque. Usually you end up with a compromise.
>
> Les
>
> Denis Casserly wrote:
> > Hi Les
> > thanks for the reply, I checked the Nook catalog where it specs the nut
> > as being 36% efficient. I like worst case calculations too, so I think
> > I'll go with a drive ratio of 1 off the motor shaft to 1.5 on the screw
> > shaft to couple the motor to the screw. I think this will provide a
> > safety margin. What would be a good way of determining I'd overloaded the
> > motor? The only method I know is if it's too hot to touch, then it's
> > overloaded. Are there any other methods to determine if a motor is being
> > overload. Are there any design rules or criteria that I could access
> > because I'm going to have to do calculate the ratios for XY drives also.
> > cheers,
> > Denis