Rambo Servo Setup for Auto Bed Leveling for Noobs

[printbus]

#define TEMP_SENSOR_0 1
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_BED 1
This is what it's currently at

Well, then you at least shouldn't be battling the problem we used to have with MakerFarm's manipulation of Type 6 thermistor table data leading to problems when that table was replaced in a firmware upgrade.

I'll have to try and find some older posts. We've been through thisrecently. I just don't remember the cause being something that was different in the firmware upgrade.

FOLLOWUP COMMENT: Came up short in looking for prior posts to reference. One thread did remind us how a slight change in room temperature or any drafts can mean a significant difference in the bed's ability to reach a high temperature.

Easy stuff to check: make sure all screw terminals in the heat bed wiring path are tight; the stranded wires have a tendency to shift over time and loosen up. Loose connections lead to high resistance, causing reduction of power applied to the heat bed and melted screw terminals. If you can see between the heat bed and your insulation material, try to make sure the heat bed thermistor is still snug to the heat bed; if it separates at all it could start to read low/slow. Ideally, the insulation material should not press up against the insulation - depending on the insulation material, that could draw heat out of the thermistor and cause it to read low.

Another possibility is that through a difference in bed leveling or a difference in where the clips are placed around the glass, you've shifted where the heat bed does & doesn't actually touch the glass. If there's even a slight bit of a gap between the thermistor area of the bed and the glass, that localized area (of the actual heat bed, not the glass) will heat up faster than if the heat bed in that area is pressing up against the glass.

[adamfilip]

running into weird glitches during the abl routine
sometimes it will decide to forget to move X between probings. other times its fine.
i dont get it.

[shook]

running into weird glitches during the abl routine
sometimes it will decide to forget to move X between probings. other times its fine.
i dont get it.

ya im having a terrible time with my abl too, ive changed 3 servos now, shit is so unreliable

[shook]

hey adam, how did you mount your servo on the inside of the xcarriage with the arm going out? did you change your fan shroud?

[sniffle]

Its odd to me you guys are having such a hard time with abl. It makes me wonder what your doing differently...

I havent had an issue with my abl servo since the twiching broke the internal gears and i replaced it rerouting the wires away from the extruder motor when i did so. Havent had a twitch since. I also havent had any issues with the servo hitting the bed when extending but i think my raise before homing keeps that from happening.

[TopJimmyCooks]

In my experience the cheapest 9G servos by TowerPro fail quickly if they hit the bed at a bad angle one or two time, which happens to everybody sooner or later. They are also twitchy and make small moves that weren't requested by ramps. I may have had a bad batch of examples because others have used them successfully. I had problems with literally 3 towerpro's before switching to a hexatronics for $2 more.

I also rearranged the wires for the servo to get them to the other side of the bundle from the extruder motor wires, not sure if that contributed to the fix or not but I was paranoid about some type of induction messing with things.

[walkercreations]

I am late coming to all of this and hope there are some folks still around this thread. I am just starting to wrap my head around the whole Auto Bed Leveling thing and understand how and where the servo plugs into the Rambo. I'm not sure where the Probe plugs in though. Does it take the place of the Z-Endstop or plug in somewhere else on the board?

[Roxy]

I'm not sure where the Probe plugs in though. Does it take the place of the Z-Endstop or plug in somewhere else on the board?

There are a couple of options. But typically, in most cases, people connect the switch for the Z_Probe to where the Z-Endstop used to be. If you do this, the Z-Endstop can just be left where ever it is on the printer just in case you want to back up to the way it used to be. The firmware will use the Servo to engage the Z_Probe and use the switch mounted on the probe leg instead of using the Z-Endstop.

[walkercreations]

Thank you very much. One other question, since I will be using a fresh version of Marlin Firmware and not the one supplied by Colin at MakerFarm, will the only files I need to modify the Configuration.h and Pins.h?

[Roxy]

Thank you very much. One other question, since I will be using a fresh version of Marlin Firmware and not the one supplied by Colin at MakerFarm, will the only files I need to modify the Configuration.h and Pins.h?

Pretty much... Yes, those are the only files you will have to modify. And you may not even need to touch Pins.h but I don't know the answer to that off the top of my head. The biggest reason you would have to mess with Pins.h is to make it agree with where ever you connect the servo to the electronics.