Bed deviation
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Can we talk about Bed deviation and levelling?
I have priviosly worked in factories reparing machinery for the pharmacy industri. And this machinery needs alot of attention. Some of this attention is the zeroing of levels and rails, to get the precise working mechanisem for the product that needs to get manufactored.
In this world the precision is key. How about the 3D printing world?A wishing scenario is zero, but is that posible?
What could/would be accepteble for us?
Voron CoreXY with Duet 3 + expansion + PanelDue 7i - 300 * 300 * 300 and Hemera Revo
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@heide said in Bed deviation:
A wishing scenario is zero, but is that posible?
Any reasonable degree of precision is possible but it may not be practical from a cost point of view.
What could/would be accepteble for us?
I build moderately priced printers and I have found that I can get suitable results for my work printing functional parts (as opposed to artistic) using typical construction practices and components.
A skilled user here, @deckingman, has built a rather amazing printer. He might be a good resource for you. He has posted a good deal of information about his work.
Frederick
Printers: A FT-5 with the 713 upgrade bits. A custom MarkForged style. A small Utilmaker style and a CoreXY from kits. Various hotends. Using Duets (2 and 3) running 3.4.1
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@fcwilt What could that degree be? I'm thinking that 1/10 of a mm. is off. But it could also be 1/3 of a mm.
I think that anything over 0.04 mm. is to much, but again I don't now the accepted tolerances.
What is your opinion on that?
Voron CoreXY with Duet 3 + expansion + PanelDue 7i - 300 * 300 * 300 and Hemera Revo
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@heide said in Bed deviation:
@fcwilt What could that degree be? I'm thinking that 1/10 of a mm. is off. But it could also be 1/3 of a mm.
I think that anything over 0.04 mm. is to much, but again I don't now the accepted tolerances.
What is your opinion on that?
Well the first printer I built and still use regularly is a simple Cartesian using 1.8 steppers for the belt driven X and Y axes. The pulleys are 20 tooth. The micro-stepping is 16. The steps/mm setting is 80. So in theory, assuming perfect micro-stepping, a mm is divided into 80 parts. But for full steps a mm will only be divided into 5 parts.
Using 0.9 steppers will, in theory, double your resolution.
You can of course use multiple pulleys or stepper motors with built-in gear boxes to obtain greater resolution but you may sacrifice speed for resolution.
Now some folks are using closed loop stepper systems which have an encoder on the stepper which, in theory, allows greater accuracy.
Other folks are using servo systems. I have no idea what the benefit there is.
Frederick
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@heide it all depends on what you're printing, and what layer heights you want.
Obviously you'll need a reasonably flat and level bed to get your first layer to stick, but we'll take that as a given.
If you print with 1mm layer heights with a 1.2mm nozzle, doing large 'structural' prints, then you'll be able to get away with larger deviations. Maybe 100-200um (10-20%) of first layer? If you want to print tiny detailed models with 0.1mm layer heights, then you're gonna need to do a lot better.
Manual or auto bed levelling, and mesh compensation are also very good tools. One of my printers has a very warped bed (like 250um near the edges), but I can happily print at 100um layer heights all over with mesh comp enabled
Home-built CoreXY, Duet Wifi, Chimera direct drive, 2x BMG, 300x300x300 build volume
i3 clone with a bunch of mods -
I can see the point in what your both saying, and of cause the size of the nozzle and layer hight are also important. And I can also see the potential in stepper motors with a smaller angle.
I have a bed that is 8 mm. thick and a smooth surface. But I do not think that is is even/levelled enough.
I can maybe find something to adjust the last 0.1 mm. but is it worth it or will the compensation fix that?Voron CoreXY with Duet 3 + expansion + PanelDue 7i - 300 * 300 * 300 and Hemera Revo
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@heide level it as best you can first (e.g. using the manual screws or independent z motor levelling if you've got it), then use mesh comp.
If you've got a reasonably accurate z probe, set up with the right offsets etc, you should have no problems
Home-built CoreXY, Duet Wifi, Chimera direct drive, 2x BMG, 300x300x300 build volume
i3 clone with a bunch of mods -
@engikeneer I will use the mesh Comp. Thanks
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@heide said in Bed deviation:
I can see the point in what your both saying, and of cause the size of the nozzle and layer hight are also important. And I can also see the potential in stepper motors with a smaller angle.
I have a bed that is 8 mm. thick and a smooth surface. But I do not think that is is even/levelled enough.
I can maybe find something to adjust the last 0.1 mm. but is it worth it or will the compensation fix that?My printer has an 8mm thick cast tooling plate bed with a layer of PEI on top. It's flat enough that I can print a 200 um first layer edge to edge on the 300 x300 surface (I haven't tried thinner layers than that over the whole surface). I use the manual bed leveling assistant and a piece of paper to tram the bed. The last time I had to do it was about a year ago, I think. It takes about 1 minute.
One more factor to consider in keeping the first layer stuck to the bed is the print surface. PEI sticks to most molten plastics very well without having to add any extra goop.
