9mm belts to replace 6mm? Ghosting

Discussion in 'Motion System' started by Joe Pomo, Oct 23, 2019.

  1. Joe Pomo

    Joe Pomo Well-Known Member

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    Is it possible to replace the 6mm belts/pulleys/idlers with wider, 9mm belts?

    I've yet to receive my TC, but I'm curious if artifacts such as ghosting/ringing could be eliminated with a 9mm belt set up?
     
  2. Jai Stanley

    Jai Stanley Well-Known Member

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    Only a cursory glance at mine over my shoulder whilst typing this tells me it would be an almighty pain.... As for how effective? Even my usual finger in the air estimates (I'm a mech eng., former production engineer and have worked with integrators and solutions providers) would mean absolutely nothing. The Gates belts are VERY resistant to tension given the flexibility they require due to the coreXY layout. Feel free to give it a go and report back!
     
  3. Jai Stanley

    Jai Stanley Well-Known Member

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    I meant to write: Ghosting isn't just a function of the stiffness of the motion system: the inertia due to the weight of course plays into this system: but also remember the magnetic flux in the stepper drivers for a given rotational inertia is; and the effective spring rate that that has. Even at full steps the motors will ring when called to stop on a particular step.

    Proper, DSP controlled servo motors can be programmed/calibrated to negate this to a certain extent. I've always wanted to fit a phone sized accelerometer into a print head so the machine can self-calibrate (think noise cancelling headphones for a hot-end) but haven't the huge programming/dsp skills it would require!
     
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  4. mhe

    mhe Well-Known Member

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    You could fit stuff like Clearpath servos, they are quite straightforward to program, however, they don't come in NEMA 17, only 23 upwards.

    If you struggle with ghosting, I think belt tightening, tweaking dynamic acceleration adjustment (M593 in the Duet config) will be a easier thing to start with. Also, given how line thickness will vary a bit unless you have pressure advance dialled in perfectly, it might be the case that a not properly dialled in pressure advance will look a bit like ringing or ghosting in some cases.

    Do you probably have any pictures of the issues you want to get rid of?
     
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  5. Cam_Motion

    Cam_Motion Active Member

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    You can't just simply replace the 6mm belt setup with a 9mm or 12mm as there isn't enough clearance where the top of the X Bar meets the aluminium sheet top. You'd have to somehow space the current Y axis design down.
     
  6. Andy Cohen

    Andy Cohen Well-Known Member

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    When you get your TC you will see that the primary source of ringing and "ghosting" is the interface for the tool. It simply is what it is. Correctly designed corexy motion control is pretty good at controlling the issue regardless of the width of the belt... and e3d did a really good design on the motion control system.
     
  7. Jai Stanley

    Jai Stanley Well-Known Member

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    Is yours loose???
     
  8. Cam_Motion

    Cam_Motion Active Member

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    Have you seen these alternate implementations of the tool changer?

    FunX4 Toolchanger tests


    First Multicolor Prints and Toolchanger Lock Explained
     
  9. Jai Stanley

    Jai Stanley Well-Known Member

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    I considered using two ptfe tubes and nylon filament to do something similar; but when E3D announced their TC system I just out-sourced the time and effort and bought theirs, took flipping ages though so I spent most of that time just using my tired and abused CR10 rather than making new printers.. Bit short sighted of me as it turns out designing and making printers is more the hobby I enjoy.

    There will be loads of them about in a shake; I'm guessing that was the design intent in this project. Then they can focus on selling whole tool-heads to a common ('copied') standard and keep the core of their business to these hot-ends and extruders. Good business sense and with the queue being at the 350-400 number ATM not even a loss-leader. They must've paid back the R&D time by now; especially using the 'intern' model they use (all friendly speculation as an outsider). I got the impression they don't want to be a printer manufacturer after the big-box and they also sell to a lot of other manufacturers so doesn't make commercial sense to make themselves a competitor.

    The guy that's designed the system above seems to have a good grasp of mech-eng. but I can't help thinking it's unnesessarily complicated. Maybe not; I didn't develop it after all....
     
  10. Andy Cohen

    Andy Cohen Well-Known Member

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    No it’s tight but the cam’s pressure is from a spring in the carriage. Also with the long barrel of the V6 there is a bit of distance starting from the carriage interface to the X axis rail to the hot end tip. The longer that distance the more likely ringing and other artifacts. The Hermès design seems to minimize that which is good. Note that this assumes a single tool print. When there’s lots of tool changing it IS a different game. There are more artifacts in the print from variation in the pressure fit from the cam tool lock, variation in the extruder on the tool and complications from drool and wipe travels.
     

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