Newbie from NZ

[Doddy]

Thanks for the link
i need a unit with right angle drive ( takes up less horizontal space) so the only ones sort of max out at 470rmp but need an encoder to set limits (i think?????)maybe not i dont know on this part either
could someone please check this out. im still not sure about torque etc . so appreciate feedback-comments
Thanks in advance
Richard
https://www.ebay.com/itm/1pc-High-to...m/264289703688

Don't overestimate these Chinese motor/gearbox devices. I've used a couple in the past for raising a poly tunnel vent panel (28ft panel of polythene wrapped around a lower 1" steel tube... rotate the tube and the tension on the polythene sheet either raises or allows to lower the tube, opening or closing the panel). They are adequate provided that they're suitably rated but for my application I normally go for 0.5-2 rpm models to get the necessary torque. I have had to replace them, but the environment (heat, humidity) is pretty severe. Part of my selection criteria is the worm gear to allow it to hold position without power. I don't know the actual power output from these but a similar 470rpm 12V Chinese motor/gearbox here (https://www.ebay.com/itm/DC-12V-24V-....c100008.m2219) claims 5kg.cm which translates to around 0.5nm.

Andy's recommendation of a 4nm rated motor is appropriate for a stepper motor - where you need to guarantee the step, or micro step in time to maintain a (potentially) rapid acceleration under load. In your case you're not quite so constrained and I think you can tolerate a lower torque to allow the motor to accelerate more gradually and less predictably. Even so, the order-of-magnitude difference is a little steep. Personally I'd trade the RPM for more torque (1rpm = 10mm with the 1610 screw, 900mm = 90 rotations, so the 260rpm motor would double the torque and give you a 900mm traverse in 20 seconds).

Limiting your choice to motors with integral encoders will reduce your choice of motor drastically. It's easy to add an encoder onto the shaft of any gearbox output (or better - if you get a twin-shaft one). The resolution of the encoder need not be so great - that one you link to is coupled to the motor shaft, not the gearbox shaft, so you're going to be counting small fractions of rotation of the output shaft - no need for this precision, provided that you have a positional sensor (e.g. micro switch) on the closed-position to avoid gradual drift in positional accuracy.

The motor controller is likely to be a dedicated device - a micro controller (maybe the Arduino range) with a H-bridge driver, and hook up the encoder accordingly. That's the easy part.