@sd_matt your tool 0 is currently off (it says under the tool name) so is not selected. Maybe add 'T0' to the very end of your config.

Also, unless you disable it, you will likely need to heat up your tool before it will let you extrude edit: M302 P1 allows cold extrusion

@gnydick I think you're confused between Pressure Advance and Dynamic Acceleration Adjustment.

Pressure advance aims to compensate for the elasticity of the filament and the extruder system which can cause under-extrusion whenever the extrusion rate is increasing, for example at the start of a straight line when the nozzle has to accelerate from zero or near-zero speed, or over extrusion when the extrusion rate is decreasing.
https://duet3d.dozuki.com/Wiki/Pressure_advance
It is mostly effective at stopping under/over extrusion blobs at sharp corners. If you want to calibrate this, I'd recommend the steps at the bottom of the wiki page above.

Dynamic acceleration adjustment is used to help ringing/ghosting in your prints by tuning out the frequency you set. I think this is what you want
https://duet3d.dozuki.com/Wiki/Gcode#Section_M593_Configure_Dynamic_Acceleration_Adjustment

I'm guessing you've already chased after all the mechanical things to aid ringing (belt tension, making sure your pulley mounts/axles are solid, reducing mass on your moving gantries etc). If after all of this, you find you can't get raise your printing accel as much as you want, you can always use your slicer to vary it by feature type (I know PusaSlicer, Cura and IdeaMaker all have this at least). That way, you can set much higher accelerations for infill, but drop it for internal/external perimeters to maintain quality. In Cura & IdeaMaker, you can also do the same with Jerk.

@tenaja That's down to how the firmware interprets the commands:

G1 E1 F5

Will extrude 1mm of filament at 5mm/min (RRF uses mm/min for speeds). As you are only commanding an extruder move, that sets the speed. So with F5, it will take ~12s!

G1 Z0.242 E44 F5

Will extrude 44mm of filament whilst the Z axis moves at a commanded speed of 5mm/min over a distance of 0.242mm. That will take ~3s, and you will be extruding 44mm of filament, so your extruder would be moving at ~15mm/s (that's over 900mm/min so a lot faster than the first one!)

All of this is also bound by what speed limits, accelerations and jerk settings you have for all of the moving axes (X, Y, Z, E etc) in your config, so your actual moves might be a bit slower/take a little longer depending on your settings.

@o_lampe you have two T parameters in your command. I think the first one should be P0 to apply the settings to Tool 0?

@Piet said in Using bed leveling screws with independent z motors:

For example in an extreme case where one point of the bed is 10mm off. If I were to level that initially using the ABL it would torque the entire Z-axis assembly and would put a lot of strain and resistance on the leadscrews.

Whether you're using manual levelling assistant or auto bed levelling, the process is taking the measurements from probing the bed surface.

I think your concern is that the bed is not level with the z-gantry (e.g. because one of the manual adjustment screws is way off). So you want to get the bed close to level to the z-gantry (and so level with the lead screws) so that they aren't kinked over later. The trouble is the Duet has no idea where the lead screws are as it is still only probing the bed surface. Only exception/caveat is if you are using independent endstops on them as well (and somehow worked out the offset for them all).

One option could be to remove the bed and try probing the z-gantry to get that near level (so the leadscrew are all level) using auto bed levelling. Then put the bed back on and use the manual assistant to get the manual screw right, then use auto levelling again to actually get it all tuned in fine (assuming you didn't with manual). Might work, but probably will end in tears trying to probe aluminium extrusions....

Alternatively, just try making sure your bed is level to your z-gantry when building the printer. Simplest way is to use fixed spacers (i.e. no manual adjustment). Or just a spirit level/your eyes? The lead screws should take a little misalignment. Unless you have a massive bed, if you build your printer 10mm out and don't see it, you're probably gonna have a bunch of other problems in there too...

@Raniot Hello and welcome to the Duet world!

I'm guessing you have already read up on what ringing is and things you can do to change/improve it. In general it comes to trying to push a heavy print head round a corner too quickly, meaning the flex in the system bounces a bit and causes the artefacts you're seeing.

As well as changing the belt tension, you might want to double check all the joints/bolts/connections on the gantries are tightened - In the past I have found a screw loosened in the printhead which gave me some ringing.

After that you're mostly onto tuning the printer to try and slow it down round the corners. For this you can play with speed, acceleration, and jerk, and you can adjust them in your printer config, and/or in your slicer. General advice is to set sensible limits for the machine in your config file (i.e. things that will mean it won't skip steps, break itself etc), then set more detailed/controlled limits using your slicer. In the Slicer you can usually set different limits for different move types, so you can have fast, high acceleration moves forthe infil where ringing/quality is less important, but slower and more controlled moves on the external perimeters where quality is paramount. On an 800mm tall print like yours can do, this can make a world of difference on print times!

Regarding the firmware flavour, you should definitely set it to Reprap. Reprap and Marlin are very similar, but some of the commands are slightly different and use different units (e.g speed & jerk are in mm/min in Reprap but mm/s in Marlin).

I would start by using the values from your config file provided by the printer manufacturer in your slicer. I mostly use PrusaSlicer which only allows you to play with acceleration, so would recommend starting with just that, then you can play with Jerk later if needed. Looking at your config file, your machine has acceleration limits of 1000mm/s^2 in X & Y (from the M201 command), but these are then limited to 500mm/s^2 for printing moves (i.e. moves where the extruder is moving) and 1000mm/s^2 for travel moves (both from the M204 command). So I would put 500mm/s^2 for all the printing moves, and 1000mm/s^2 for travel moves in the Cura controls. Cura will then start inserting M204 lines in the Gcode files where needed to change these limits as needed during the print.

From there on, you mostly need to play with the slicer values on test prints until you get to a result you're happy with. At the same time, you might also consider changing the speeds for different move types in Cura (e.g. slowing down external perimeters a bit). For reference, on my big home made CoreXY, I print external perimeters at about 60% the speed of my infill, and with 30% the acceleration. You may be able to go faster than this, or might need to go slower - only tuning will tell!

Whilst tuning things, you could disable the acceleration control in the slicer and manually send different M204 commands during a print via the web control to see in real time what the results are. It may be a little harder, but will be quicker. There are a few good forum posts out there on the best methods for doing this, e.g.:
https://forum.duet3d.com/topic/14250/tuning-jerk-accel-speed-settings/3?_=1592332339377

Regarding the slicer time estimations, you will probably find these get a lot better when you set up the accceleration control in Cura. I think the acceleration & jerk limits in your config are reasonably low compared to most printers (this is probably to be expected because your machine is so big, it will have a lot of mass to move around!), so will take a bit longer to accelerate/decelerate than Cura might expect by default.

If you're confused/unsure on the commands in the config file, you can always look them up here:
https://duet3d.dozuki.com/Wiki/Gcode
The descriptions are very good and will generally give you a good idea of what is going on, but it can be a bit daunting at first!

One final thought, you might want to consider using 'Dynamic Acceleration Adjustment' - M593:
https://duet3d.dozuki.com/Wiki/Gcode#Section_M593_Configure_Dynamic_Acceleration_Adjustment
This is a useful feature to combat ringing by tuning out the first natural frequency of your motion system. There's some details on what it is,how to use and tune it etc in the link above. First check if this is already in your config file from the printer manufacturer though!

@hackinistrator if the voltage was dropping so much that you got connection lost issues, I'm guessing the board kept resetting. Look for 'Last reset'. As far is the board knows, you turned it off!

Re axes marking as homed, all depends on what you have in your config for your endstops. If you have normally closed switches (which most do), they will trigger as homed if not connected. As far as the board knows, it was already sat on the endstop when you hit home! Far safer than normally open which will continue to move until you connect the endstops or hit the Estop!

@r123 Even better, put it in Start.g too (might have to create the file in the sys directory as I'm not sure it's there by default). This gets called when you start a job, before anything else in the file is run. That way you know it is set back to 100% no matter what has been done on the machine during the last job (or even since the last job was finished!)

@Tpmoses just to contradict @fcwilt here... I just run homeZ (G28 Z) at the end of my bed.g. in my case my homeZ just uses a z probe at a set point, so it means I can make sure I always probe the same point to reset the Z datum. If you use an endstop in your homeZ (e.g. in a delta printer), then this won't work and you'll have to use fcwilt's method (or something similar).

@matej1006 I agree with the others that your x-gantry is probably sagging down a bit which is causing the raised area in the middle of the bed, could also be your build plate has a slight curve to it (less likely).

One school of thought would be to try and stiffen up your gantry so it deflects less, but if you're getting decent print quality with the mesh compensation on, then I'd be tempted just to leave it. I'll admit my printer has a much worse looking buge in the heightmap that yours and I still get good, consistent first layers all over.

Comparing the cold and hot heightmaps you have posted, this might be expected - as things heat up, they flex. However, it could also be that the bed wasn't fully levelled the same (either manually or with auto-tramming) before creating either heightmap. On my corexy I always run the auto-tramming (via G32/bed.g) a few times until the deviations have converged before creating or loading a heightmap to ensure it is always levelled the same.

@ducati87 you only have two z lead screws, at the max and min of the x axis (left/right), so the G32 levelling can only level along the x axis. From you heightmap image, it looks like your heightmap is very level in X as expected

You should probably try mechanically levelling your bed a bit better from front to back. From your first image, it seems that's the direction the issue is in?

@gorf26 reduce your layer height?

@sinned6915 I guess the other question is when you want to pick up/put down the probe. I think that the deploy/retract scripts are called for every probe dive (so doing a 400 point mesh, it will pick up, probe, put down, pick up, probe, put down etc 400 times!). A BLTouch pin needs to be extended for every probe dive, whilst yours probably doesn't.
You might be better putting your own pick up/ put down macros and calling them explicitly in your homing, bed leveling, mesh creation etc macros?

@peter247 I believe there's an option for marking your post as a question. If you do that you can marked it as Solved, and maybe even highlight the answer that solved it (not tried the last part before though)

@typqxq I thought for ZTATP, it's the touch plate that's grounded, not the nozzle? Does seem a bad idea to try and use two systems which put power signals though the hotend metal work though...

Did the Duet recognise the issue and flag a fault? Maybe it wouldn't monitor it if the heater was meant to be off?

Even if it did recognise it, the only protection it could use would be to shut down the 24 PSU in this case. I have my Duet WiFi set up to do this using a relay and the PS_ON pin. It will shut down the power supply if the heater faults. I then have a separate 5v supply to the board so the processor stays up and I can clear the fault etc and carry on

@zabana Just to add to what the others have said about the drive gears, there are many reasons why a pair of meshed gears won't produce a perfect motion (even ignoring anything to do with how the hobbed gear bites into the filament). I design gearboxes for electric cars so this is pretty much my day job!

First reason is any manufacturing defects. There can be runout errors (where the gear teeth arent concentric to the rotational axis) which will cause once-per-rev errors. There can be pitch errors (where two consecturive teeth might be spaced slightly too close/far apart). There can also be form errors in the involute shape of the gear teeth meaning they don't roll over each other properly. As well as these issues affecting the meshing of the gears, they can also cause other issues (like double-flank contact where the backlash becomes zero and there isn't enough room for the teeth to mesh properly) that might change the loading on the gears & housings (particularly if they're only lightweight printed ones). Obviously on top of this, any errors in how the gears are mounted/aligned in the housings will affect them too.

I would also add that if your gears have come from two separate sources (one from the motor manufacturer(?), one from Bontech/extruder supplier), the gear teeth might not be perfectly matched (may have slightly different module, profile shift, base pitch etc).

The other issue is transmission error. Even if you have perfectly manufactured gear teeth, the teeth themselves will still bend a bit under load (particularly if they're plastic!). It might only be small, but it means you get some once/twice per tooth-pass error in the output shaft rotation. This will vary with load, but it may also interract with any manufacturing errors (e.g. to dampen them out as the teeth flex to compensate for them), so you often find that gears run best with some load on them.

All of these things are also often worse with small pinion gears, as 1% of a tooth pass is much bigger proportion of the shaft rotation, plus some other things on the actual tooth involute form.

So what does this all mean for you....

First thing I'd say is that if your issue is actually with the extruder mechanicals, it may be speed or load dependent. If you found that increasing the extruder flow rate helped improve things, it could actually be the increased load on the gears (from the nozzle back pressure) dampens out the variation source (whether that be because of how the plastic flows in the melt chamber, or something to do with the drive gears). I'd have another go at changing the nozzle temps, but look at going lower so that you build up more back pressure. Maybe you could also try a different size nozzle?

Defintiely play around with the tension spring that pushes the two drive gears tgether as @o_lampe suggests. Having it set too tight will only exacerbate any issues in the gear train

Edit: actually finished writing the post before hitting submit...

@rking post your config.g and homing files so we can see what you've currently got. Best if you use the </> code snippet tool when posting them on the forum as its easier to read.
Which exact RRF version are you running? M115 will report it

@wingtip I think you must have your bltouch mounted at the wrong height... for the V3, it should be 2.3 to 4.3mm above the nozzle height. (think the V2 was ~3mm?)

@o_lampe the smaller your arm spacing (between parallel arms), the less stable your effector is: https://reprap.org/wiki/Delta_geometry#Effector_stability

In theory you want to spread the parallel arms as far from each other as possible, whilst putting the corner joints on top of each other (like the Smart Effector, and most delta designs out there).

Might be that you can get away with it though? There's only one way to find out...

@peter247 just change the axis minima/maxima in your M208 commands in config. When you home, it just sets the stopped position to the max/min value depending on whether you have high end or low end endstops