how stop z motors drop torq

got this works great wen z motors got power all stays rock stady but if loose the power to the z motors x -axis drops down

is there a way in marlin firmware to prefent that

Sooner or later, you have to shut off power and the X axis will drop. Consider it a sign that your Z axis rails are close to parallel and the X axis is close perpendicular to them, implying that the Z motors are in sync. When they get out of sync, and they will, the x axis will tilt a bit and then it probably won't drop when power is cut.

The only real fix is mechanical- get finer pitch screws, or put some spring clamps on the Z axis screws before you shut off the power.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

so you want an option in marlin to turn off gravity?

I think you expect to much from marlin.

But

This will keep the Z motors energized, but wont stop the axis falling on power off


In configuration_adv.h
#define DISABLE_INACTIVE_Z true // set to false if the nozzle will fall down on your printed part when print has finished.

[www.youtube.com]

this what i made

Yes, and now you know why people dont tend to use belts on Z...
There is also the issue of belt stretch...

deltas have the same issue


you need something like solenoid that when it has power its end is held out of the way
when power is lost it sticks out a rod into the belt that gets between the teeth and holds it.

Edited 1 time(s). Last edit at 08/21/2018 10:36AM by Dust.

Quote
Dust
deltas have the same issue

Only if the effector is heavy, for example if you mount a direct drive on it. I've never had that problem on my deltas. If the effector is only a little too heavy to stay up when power is removed, adding a constant force spring (aka keychain retractor) to help support it from the top of the frame may be sufficient.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
Dust
Yes, and now you know why people dont tend to use belts on Z...
There is also the issue of belt stretch...

deltas have the same issue


you need something like solenoid that when it has power its end is held out of the way
when power is lost it sticks out a rod into the belt that gets between the teeth and holds it.

Belt stretch is a non issue in Z axes. In a delta, the mass of the effector doesn't change as the print size increases, so there's nothing to make the belts stretch beyond their normal position. In my coreXY machine with a 3.5 kg bed, I've actually measured stretch and it comes out to 42 um/kg of print mass, a value that may as well be zero (unless you run multi kg prints in 10 um layers).
I use a 30:1 worm gear drive that completely stops bed drop when Z motor power is cut. See the UMMD link in my sig, below.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I was more concerned with belt stretch on his modified I3 with a X axis hanging off it,,, Heavy rods, extruder and X axis stepper

Both my deltas decend on power loss, both are bowden and light weight effectors..... even carbon fiber arms...

Quote
Dust
I was more concerned with belt stretch on his modified I3 with a X axis hanging off it,,, Heavy rods, extruder and X axis stepper

digital_dentist uses belts to lift the bed of one of his printers. I expressed concern that there would be belt stretch, but he assures me that it isn't significant.

Quote
Dust
Both my deltas decend on power loss, both are bowden and light weight effectors..... even carbon fiber arms...

Perhaps your deltas use smaller motors than mine, with lower detent torque. If it doesn't take much force to hold the effector up, the keychain retractor trick may help. Using 16-tooth pulleys instead of 20-tooth also helps.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Here's the bed loaded with about 4 kg. The gauge was zeroed without the load applied.



That's using two 10 mm wide, steel core GT2 belts. 42 um per kg translates to no more than 1.2 um per layer, if you cover the entire 300x300 mm bed with PLA.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]