On Sunday 27 December 2015 18:03:20 Ben Potter wrote: > > From: Bruce Layne [mailto:[email protected]] > > > > On 12/26/2015 05:17 PM, Ben Potter wrote: > > > I tend to use Amphenol connectors... > > > They are..._slightly_ pricey though - but very convenient if you > > > have to swap a motor out > > > > I've heard this advice before but I've never fully understood it. > > All of > > the stepper motors I buy have bare leads, so I'd need to add a > connector to the stepper motor and a mating connector to the motor > cable. That's not too bad > > > when building a machine, but the recommendation is specific to > > replacing > > the motor. If the motor ever needed to be replaced, I'd need to > install another connector on the motor leads. I have several > connectors in stock, and the > > > pins and sockets and crimpers, but finding the correct connector > > components is always more trouble than desoldering the old motor and > soldering a new motor. I guess the connector strategy works for > people who buy an extra motor or > two and install the connectors > while building the machine and keep the spare motors with the machine > so it's easy to plug in a new motor. > > I think it really comes down to 'how much will this downtime cost me'. > And that really depends on what the machine is being used for - I > _assume_ that the OP is building a hobby class machine, but I have > seen nema17 steppers used on industrial metrology gear. > > This approach for me comes from running and maintaining industrial > tools - where the reasoning is sound (it's not much more trouble for > the manufacturer to wire up 7500 motors instead of 7000 and keep the > extra as spares for when a customer's motor breaks). Spare drives > (with quick disconnects), cables, and motors (with connectors) are > then kept in stock and sold at usurious rates. > > On my own machines I keep the more predictable spares (including > prewired motors with encoder) ready to swap out. As I've moved to > heavier machines and industrial servos I've found that the motors > generally come with connectors pre-installed. My router (using nema23 > steppers) does have soldered in motors. > > If it's a hobby machine, or one machine amongst many - then the cost > of downtime is probably less than the cost of keeping the spares. On > an industrial tool 24 hours of downtime is likely to far exceed the > cost of basic spares. > > As an aside - some manufacturers (igus spring to mind) do put > connectors directly on their stepper motors. > > > My only caveat with soldered connections is that they must be > > protected > > from flexing and vibration. The solder wicks into the stranded > conductor and creates a stress riser, and the wire can break at that > point if flexed or shaken, > > > but if you secure the cable to prevent it from flexing or vibrating > > you'll > > have a very reliable (and inexpensive) connection. > > Good advice. It can be a frustrating fault to diagnose - particularly > if the connection is intermittent and the blasted motor moves _most_ > of the time. > > > I'd use connectors for things like a 4th axis or rotary table that > > you > > want to disconnect and remove when not in use. Obviously, you should > power down before plugging or unplugging stepper motors. > > I have to admit I'm curious how industrial 4th axes are set up - I > presume an extended ground pin at a minimum - or do they need a full > power down of the machine too?
A full power down of that motors driver will suffice. Its safe to power up the driver while the motor is disconnected, and when it is connected, but the intermittent connections of unplugging it while the driver is powered up will write a ~30~ to that drivers story a very large percentage of the time. I killed a xylotex board twice with bad connectors. Connector name starts with an M. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
