Two Z axis with separate drivers

It's possible to change the code Marlin for two separate stepper ,that drive the Z axis and that
have slight differences in the mechanics?
Using for example the driver Z and E1?
thanks for your opinions

Two Z axis screws driven by two motors is awful. Trying to get two with different characteristics to remain synchronized is beyond awful. It's horrible.

What exactly are you trying to do?

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

Geez dude... It's not awful... Maybe not as perfect as *You* like, but not bad either... I choose not to live my life in your OCD world.

If it's the same mechanics, you just change the pins.h for your board so that the E1 uses the same pins as Z.

The OP said it was different mechanics...

I don't think it's OCD to want to be able to produce prints with high quality surface finish, to print precision parts that fit together with very close tolerances, and to do that without a lot of preparatory messing around.

If you had an inkjet printer and its color registration wasn't perfect you'd consider it a piece of junk. Why accept any less quality in a 3D printer?

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

Quote
the_digital_dentist
I don't think it's OCD to want to be able to produce prints with high quality surface finish, to print precision parts that fit together with very close tolerances, and to do that without a lot of preparatory messing around.

If you had an inkjet printer and its color registration wasn't perfect you'd consider it a piece of junk. Why accept any less quality in a 3D printer?

Like I've said before, because sometimes we don't need a Ferrari to drive 5 miles to work when the Focus will get us there just fine. My parts look fine to me, they fit together as designed, and other than changing out filament spools require no messing around. I've taken them to work and back, and just plugin and print. I'm happy with my printers, and there's nothing wrong with that.

Funny thing is, I actually agree that if your using multiple Z lead screws that you should have them mechanically linked if possible. I just don't believe the other option is "Awful"

It's not OCD to want to produce to your standards... But it maybe OCD if you consider your standards the only standard...

To answer question:
If both z axis have the same steps/mm you can use second extruder to drive second motor
You can not have different steps/mm. You can have different current levels as this is set by driver.

In configuration_adv.h uncomment
#define Z_DUAL_STEPPER_DRIVERS // was commented out

In pins.h you have to find section that defines your printer.
In mine Z2 was not defined so I changed E1 code to this code - match Z2 to your E1 pins

#ifdef Z_DUAL_STEPPER_DRIVERS // add code
#define Z2_STEP_PIN 49
#define Z2_DIR_PIN 47
#define Z2_ENABLE_PIN 48
#else // original code
#define E1_STEP_PIN 49
#define E1_DIR_PIN 47
#define E1_ENABLE_PIN 48
#endif

Some boards allready define Z2 with same number as E1 pin so change not needed

I have to agree with DD. I have two z motors and every time I z home my x rods vary from left to right by as much as 16 thousands. Leveling is a nightmare. As soon as I can draw it I'm converting to mechanical z and one motor. To be fare I'm getting pretty smooth prints but I'm as anal as DD when it comes to perfection. It drives me nuts when a print doesn't exactly match my drawings. Oh yea, if your going to ask advice don't bite the hand that feeds you.

Here's a recent problem:



I tweaked firmware (extruder acceleration, junction deviation, etc.) and Slic3r settings (retraction, extrusion widths, speeds, etc.) through several hours of test prints. And here are the results:



These ABS cones are 10mm high with 6mm dia base and 2 mm dia tips, printed on a 20mm dia base, 0.2mm layers.

OCD? You might be right, but I won't have to tweak it again. It is going to deliver this quality in every print until I do something to screw it up or the machine wears out. In light of the time, effort, and expense I have invested in the design and construction of this machine, it would be crazy not to spend a few hours tuning it up.

Yes, I look at my prints under a microscope all the time. I look critically at every print and try to determine what caused the flaws so that I can correct them in the next print. OCD?

You can't come close to achieving perfection if you don't make perfection your goal.

Edited 2 time(s). Last edit at 08/06/2015 10:04PM by the_digital_dentist.

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

That's great and grand, but I've never have had a problem with your work or your goals... I applaud your efforts... The only issue I have is that you call everybody's stuff that is not up to your standards awful and horrible.

I can only think of three things for which I would use those specific descriptors:
1) Multiple Z axis screws (especially threaded rods) driven by multiple motors.
2) Printer frames that are so flexible they can't hold a level or zero adjustment from one print to the next or require readjustment after moving the machine. If you push on the frame and see it flex, you've got one of these.
3) Bed leveling systems that by their "design", flex the bed plate/undercarriage instead of actually leveling the bed. If you see four screws at the corners of the bed, you've got one of these.

Everything else, including what I have done, is simply less awful.

If people didn't accept this awfulness, it would not be enjoying the financial success it has, and printers would be on an upward spiral of increasing quality instead of a downward spiral of quality and price. I hope to educate people, by example, what can be achieved when lowering the printer cost isn't the only goal.

It may be too late. Windows gained its market dominance even through years of having to reboot every two hours and reinstall the OS every 6 months to keep a computer working because people accepted that as "normal" behavior for computers. I'd like that sort of thing not to happen in 3D printing, but it appears to be happening anyway, because people accept the poor performance of the printers they've been exposed to as "normal" for 3D printing. And they seem to think that $300 is as much as a 3D printer should cost.

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

I remember back in 2001, the first SLA (polymer/ laser) and (powder) printhead printers were $20,000.00. When I first started looking into printers I was as guilty as the rest. Had entry level printers been $1,000.00 that is what I would have paid. Instead I opted for the $400.00 model. Granted I learned a ton of things out of necessity because it was so poorly designed and the build instructions sucked at best. But, you are right DD. Had the public standards been higher we would all own better machines. Fortunately we have people like you to give us answers to our problems along with an explanation as to why that problem exits as well as a way to eliminate said problem through mechanical means. A very small handfull of pros take the time to help us lowly wannabees get through the learning curve. I for one appreciate your time and expertise. You can call my machine anything you like. With any luck and a good economy you'll someday call it bitchin.

I couldn't find your cones to print, but here's a benchy on a sub $200 printer. .4 nozzle .3 layer height. Actually looks better in person, but crappy old iPad camera in bad office lighting is the best I have at the moment. I don't own a microscope... Sorry...





The Printer is a Funbot. With 4 point bed leveling (I agree 3 point is better, and what I used on the second one I built.). No auto leveling. Single Z axis threaded rod. 3/8" Aluminum Tubes and Bronze bushings for linear XY Axis, and a simple Bowden extruder. It's basically maintenance free so far. Can load it up and take it anywhere. Then plug in and print.

That looks pretty good, specially considering what produced it. You've done a good job on that machine!

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