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 Post subject: Nominal Resolution
PostPosted: Sat Feb 04, 2017 1:22 pm 
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Hi, I think about buying a Velleman K8200. On this Kit I will montage my own Print head. But before I have some questions:

- The nominal resolution is 0.5 mm in X/Y-direction and 0.2 in Z-direction. Is it possible to adjust a smaller resolution to reach a better print quality?

- My special Print head is very slow. Because of that the Printing speed is only 3.5 mm/s. Is that a problem? For example the motion won't be regularly.


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 Post subject: Re: Nominal Resolution
PostPosted: Sun Feb 05, 2017 12:13 pm 
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There are two relatively simple upgrades that you can make that will each double the resolution of the K8200.

First, consider using 0.9-degree stepper motors instead of the stock 1.8-degree motors. The stock motors are 42BYGHM811, but you can use 42BYGHM809 instead. The motors are identical in every respect, except that they have twice as many steps for one full resolution - 400 instead of 200.

The second easy upgrade is to use DRV8825 stepper controller boards in place of the 4988 stepper drivers that Velleman provides. The 8825 drivers will default to 1/32 micro-stepping instead of 1/16 micro-stepping, which will again double the resolution of any affected axes.

You then double (or quadruple) the STEPS_PER_MM setting for each upgraded axis in Configuration.h of your Marlin firmware. Of these two upgrades, the first one will yield better quality, as microstepping is not guaranteed to be linear. I have done both mods on my K8200's and they work very well.

See also:

viewtopic.php?f=47&t=16104
viewtopic.php?f=53&t=12178


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 Post subject: Re: Nominal Resolution
PostPosted: Wed Feb 08, 2017 6:15 pm 
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Okay, thank you for your answer.
I think you talk about the nominal mechanical resolution (X/Y-direction: 0.015 mm). That's right?
What's about the nominal Resolution (X/Y-direction: 0.5 mm)? What does this mean?
This values I found on the following Link: http://www.k8200.eu/specs/


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 Post subject: Re: Nominal Resolution
PostPosted: Thu Feb 09, 2017 3:51 pm 
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Quote:
nominal mechanical resolution:
+ X and Y: 0.015 mm / 590.55 µin (smallest step the printing plate can move in the X and Y direction)
+ Z: 0.781 µm / 30.74 µin(smallest step the printing plate can move in the Z direction)
nominal printing resolution:
+ Wall thickness (X,Y): 0.5 mm / 0.019"
+ Layer thickness (Z): 0.20 - 0.25 mm / 0.0078 - 0.0098"


I think this is possibly referring to the nozzle diameter. The stock nozzle is 0.40mm which will determine the size of the plastic bead extruded from the hot end. It's kind of like the difference between drawing with a fine-point pen vs. using a fat marker. Minimum (or maximum) layer height is also partially determined by the nozzle width.

The enhancements I described will only increase the resolution of the X-Y table. This has definitely reduced the visible "jaggies" in print jobs.

You can consider switching to a finer nozzle if you need a smaller bead.


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 Post subject: Re: Nominal Resolution
PostPosted: Thu Feb 09, 2017 7:21 pm 
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Actually the nozzle size is 0.5 see below.

Specifications

Linear ball bearings: 8 and 10 mm (0.314" and 0.393")
Technology: FFF (Fused Filament Fabrication) for PLA and ABS
Power supply: 15 Vdc / 6,6A max.
Connection: FTDI USB 2.0 to Serial
Dimensions of printable area: 20 x 20 x 20cm / 7.87 x 7.87 x 7.87"
Typical printing speed: 120 mm/s
heated bed: max. temperature 60°C
Maximum print speed: 150 to 300 mm/s (depending on the object to be printed)
Extrusion nozzle: 0.5 mm
Extrusion thermistor: NTC 100K
Extruded aluminum profiles: 27.5 mm / 1.08" wide
Movement: 4 NEMA 17 stepper motors
Resolution:
Nominal mechanical resolution:
X and Y: 0.015 mm / 590.55 µin (smallest step the printing plate can move in the X and Y direction)
Z: 0.781 µm / 30.74 µin(smallest step the printing plate can move in the Z direction)
Nominal printing resolution:
Wall thickness (X,Y): 0.5 mm / 0.019"
Layer thickness (Z): 0.20 - 0.25 mm / 0.0078 - 0.0098"

Velleman does offer the K8203 check this link.
http://www.vellemanusa.com/products/view/?id=527450


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