Firmware upgrade to solve Z-stepper heat problem and G28 machine stop problem

LowRider CNC Troubleshooting
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The steppers on my Lowrider2 have always run a little hot, the Z-steppers ran really hot. I must have missed the heat/melt damage when I last moved.

Lowrider2-MeltedToStepper
Lowrider2-MeltedToStepper2040×1530 134 KB

There are a number of similar posts on the forum. I had been running the Marlin_V1CNC_Rambo_DualLR_2.0.9.2_513 firmware on a Rambo 1.4a board from Ryan. One of the posts, Stepper Hot fix, provides a recommendation to fix the problem. I would also like to update the dimensions in the firmware, as when I Home (G28), it generates a machine stop.

The doc on the website suggests that the latest firmware is on Github - GitHub - V1EngineeringInc/MarlinBuilder: MarlinBuilder . However, I vaguely remember there was another Github project that was referenced that had the latest DualLR firmware pre-built. The MarlinBuilder doesn’t have the individual firmware builds anymore, but instead has machine setup files, such as src/configs/V1CNC_Rambo_Dual, correct? That is great. I just want to ask, is this the repo that should be used? Second, the last release was September 25, 2022, but the 20 changes since them seem to be relatively insignificant. Just use the source from the release tag?

In comparing the source between 2.0.9.2 on May 4, 2022 Ryan dropped the value of DIGIPOT_MOTOR_CURRENT to 125 from 138, past the 130 value in the post I referenced. So if this is the correct repo, using this new version should solve the heat problem, yes?

On 8/31/2022, Ryan increased the X_BED_SIZE and Y_BED_SIZE so the G28 machine stop should no longer occur, correct? If anything, I can reduce the values to my exact machine size 1092 and 2057 from 1220, 2440, yes? Thank you.

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You and find the tested firmware on this page. Clicking on a link will download a ZIP. You will find binary firmware in the top level of the source of the ZIP archive, along with another ZIP file containing the Marlin source used to build that binary.

As for your two settings, configuration.h has the bed size, and it is set as:

// The size of the printable area
#define X_BED_SIZE 1220 // 200
#define Y_BED_SIZE 2440 // 200

And the motor current is set in configuration_adv.h, and is:

#define DIGIPOT_MOTOR_CURRENT { 125, 125, 125, 125, 125 } // { 135,135,135,135,135 }   // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A)

If you don’t need any firmware changes, you can use XLoader to flash the firmware and avoid all the work compiling the source.

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The digipot values are stored in eeprom too. So it may use your previous values instead of the ones in the new firmware.

After you flash, you can send M502 to reset all the values from the code, and M500 to save it to eeprom.

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Thank you. I scrolled up and down that page and missed the highlighted link in RED. Brain fart.

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Thank you Jeff. I read about values being stored in the eeprom and being able to be changed, but didn’t understand. Your comment makes it clear. Again, thank you.