Re: [CAD_CAM_EDM_DRO] Re: [DIY-CNC] need transmission ideas / advice re: gantry

Good points.

Summary;
- The speed does not matter. 1 minute is good, 2 minutes are ok.
- Motor overheating is unlikely, as long as the motor load is not large
than 1.5 Hp. Motors are rated for continuous duty at 90v, no fan, 1.5
Hp, in an enclosure..
- I will do about 25 lifts / day total. The use is thus very intermittent.
- Inverters are a problem because they are very expensive in the sizes
needed (her in Spain)

Danny Miller wrote:

> A 12VDC starter motor is a terrible idea. It's powerful for short
> bursts. It will quickly overheat in any other duty, so it's actually
> quite a weak motor for continuous duty. Even if you run it at low
> power, it has no means of cooling itself so the heat will build up.
> It's also inefficient.
>
> You may be underestimating you load requirements.
> Your lift requires a total energy of 11,760 watt-seconds, or 15.76
> hp-seconds. One hp motor out takes 15.76sec to lift. 2.5hp needs
> 6.3sec. That does not include the kinetic energy required, which can be
> very significant as higher speeds are used. The kinetic energy goes up
> with the square of the velocity used.
>
> The treadmill motor is probably an ideal, economic yet effective load.
> How are you getting the 12v to power the 130VDC motor? An inverter?
>
> The 200ah batts- or the cables connecting them, or the inverter- may be
> "bogging down" and dropping voltage under this sort of load, which kills
> motor torque. But it's not the motor's fault. If the batts were both
> under a 1C discharge- which is a lot of load for lead acid, in good
> condition, and they can only handle this sort of thing intermittently-
> then put through a 120v inverter and motor- then it'd be able to lift in
> about 4sec, but that's nearly "flooring" the batteries.
>
> How fast were you expecting to move this load?
>
> Danny
>
>