Replicator 2 limit switch doesn't work

[Chris Spurgeon]

I have a Replicator 2 that's worked like a champ for years, but in the last couple of months it's developed this odd behavior. When you start a print job the print head normally moves to the upper right corner of the print area, where it depresses a little limit switch and stops. But now when the print head reaches that spot it doesn't stop. It keeps futilely trying to move to the right, while the stepper motor makes horrific banging noises as it's trying to move the print head beyond its limit. This typically goes on for about 10 seconds or so and then stops. From that point on, everything functions normally, and the machine executes the print job perfectly, with no further attempts to move the print head outside of the defined area.

Any idea what's going on?

Thanks!

[Jetguy]

Well known issue, your wiring to the X axis has failed repeated flexing every single print. This is why the endstop and stepper cables are carried as replacement parts because again, they are know to fail from repeated use.

The community came up with several modifications to use better flex rated cables http://www.extrud3d.com/x-harness or alternate solutions like using flex rated Ethernet cables.

Just a handful of examples

https://www.thingiverse.com/thing:217494

https://www.thingiverse.com/thing:99811

https://www.thingiverse.com/thing:92894

https://www.thingiverse.com/thing:187882

https://www.thingiverse.com/thing:222629

Google hits dozens and dozens of pages on the topic

https://www.google.com/?gws_rd=ssl#q=replicator+2+x+axis+cable&spf=1498333083412

[Jetguy]

Again, the basics of what failed.

Your endstop wire have broken from repeated flexing every print.

Because they are no longer making good contact, now the endstop is not registered at the mainboard when triggered. So on homing, it attempts to home, never senses the switch, keeps trying and skipping steps, then finally times out on the homing sequence. That the sound you hear and the actions.

Meanwhile, your X axis stepper wiring is in the same bundle, has had the same number of flex cycles and likely has or will break very soon.

Always  replace BOTH cables  (4 wire endstop and 4 wire stepper motor cables) as a set to prevent problems.

If the stepper cable fails, this causes random shifts in position and grinding of the stepper (skipping steps) and can damage the stepper driver because this open circuit while in operation creates inductive kickback.

On Saturday, June 24, 2017 at 3:19:31 PM UTC-4, Chris Spurgeon wrote:

[Troy McLucas]

I just encountered this issue too.  Besides OEM from Makerbot, is anyone selling parts for a high-flex cable?  I'll likely make the cable chain, but will upgrade the cable if that's a fairly easy option.

Thanks,

[TobyCWood]

You could always try this:

https://www.thingiverse.com/thing:217494