Z axis resolution and step
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I was testing something on the printer last night and that got me thinking on a few things . How much do step/ interpolation improve the resolution on the z ? I tried to print a piece with .075 layer heigh at x16 interpolation my setup give me 1440 step , than I tried at x32 interpolation 2880 step .05
Funny part seem like the .05 part was better there was a little z pattern on both piece I need to fix a thing on my machine . Going to 64-128 or 256 for the interpolation how would that affect the overall quality of the z resolution ?
64 = 4560 step
128= 9120
256 = 18240 stepHas anyone ever tested this ?
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@Dad003 It's generally not a good idea to rely on microstepping for positional accuracy. The reasons are many and complicated but depending on a number of factors, a single microstep of say 1/16 might not necessarily translate to any physical movement of the Z axis. Increasing the microstepping won't help - in fact it might even make matters worse.
Taking your example of 1440 micro steps at 16x means that you have 90 full steps per mm. So a layer height of 0.075 mm would require 6.75 full steps. In reality, what is likely to happen is that the motor would settle at the nearest full step which would 7.
The main reason for using microstepping is to give smoother movement and less vibration but not positional accuracy. For best results, try and pick layer heights that are always multiples of full steps. In your case, 1/90 which is 0.0111 recurring. If I may say so, what you have is a bad choice of lead screw due to that recurring fractional part. Imo, the optimum lead is 2mm which gives 100 full steps per mm and so any layer height which is divisible by 0.01 will result in full step movement. -
@deckingman well i dont use a leadscrew , i use belt for the Z axis with a few pulley 20>60-20>60-20 that the reason at x16 it 1440 step . with that setup with no power the bed stay were it is doesnt fall down
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@Dad003 said in Z axis resolution and step:
@deckingman well i dont use a leadscrew , i use belt for the Z axis with a few pulley 20>60-20>60-20 that the reason at x16 it 1440 step . with that setup with no power the bed stay were it is doesnt fall down
Whether it be lead screw or belts and pulleys, my comments about positional accuracy and micro stepping remain the same. Although I would suggest that you choose appropriate gearing such that whatever layer height height you choose is a multiple of full steps, rather than having to rely on micro-stepping to achieve the desired positional accuracy. Having said that, your gear train is probably introducing inaccuracies which are greater than fractions of motor steps in any case. Either way, changing interpolation won't help to improve things.
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@Dad003 Z-banding when using a z height that is not a multiple of full step distance has long been an issue. @deckingman is correct in his explanation: it can be largely avoided by using the full step distance (or a multiple thereof), whether using leadscrews or belts.
Ian
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@Dad003 I have been using a belt lifted z axis for a few years. My printer has a 30:1 worm gear drive motor to lift the bed. The worm gear drive is extremely high quality and the 60 tooth drive pulleys yield an even 20 um/full step, which makes for nice round number full step layer thickness multiples. The bed does not move at all when power is cut. This is the Z axis drive unit in my printer.
I run the motor at just over 1/2 its rated current and it has no trouble at all lifting the 3.5 kg bed assembly and an additional 4kg of print mass. The Duet2 controller drives the motor directly- no external driver is needed.
