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Ghosting on vertical surfaces

Posted: Mon Jul 29, 2019 11:48 am
by DDXdesign
OK people I'm having an issue with ghosting on walls - like when I make a box with text embossed in the sidewalls, the text is ghosted very clearly.

I've reduced jerk all the way down to 5mm/s and accel is down also (in Cura) because I thought that was the cause - it changed the distance of the ghosting so it did have an impact, but it certainly didn't go away.

Is there a belt tension issue perhaps? Got a surefire dummy-proof way to adjust that?

Something else?

thanks!!

Re: Ghosting on vertical surfaces

Posted: Tue Jul 30, 2019 8:45 am
by geneb
Pics?

g.

Re: Ghosting on vertical surfaces

Posted: Sat Aug 03, 2019 11:18 am
by DDXdesign
sorry for the delay!

these are at two different settings - i think the one with the closer-spaced ringing is the initial, and then the farther-spaced one was after slowing the accel and jerk down.
IMG_0023.JPG
IMG_0022.JPG

Re: Ghosting on vertical surfaces

Posted: Sat Aug 03, 2019 6:41 pm
by geneb
That's weird. I've never seen that effect before.

What slicer are you using?

I'm hoping someone will offer you a suggestion - personally I never mess with the jerk settings in the firmware. (primarily because I have no idea what I'm doing with them. :D )

g.

Re: Ghosting on vertical surfaces

Posted: Sun Aug 04, 2019 11:46 am
by DDXdesign
So it's apparently from the effector head "bouncing" just a little from the in and out quick motion of doing the embossed areas, but accel and jerk are the only things I've read that can impact it (by making the approach to a direction change slower). And then maybe belt tension, which I don't know how to do. But everything I see about belt tension is "you don't want it too tight or too loose" anyway - gee thanks for those precise technical specifications. LOL.

I'm using Cura BTW. but there is no profile for the V4, only the V3.2, so I'm just using that profile with an updated build volume.

Re: Ghosting on vertical surfaces

Posted: Mon Aug 05, 2019 9:36 am
by geneb
Mechanically, the 3.2 and the 4 are going to be pretty close - the 4 will be stiffer due to the all-metal construction.

You might want to try tightening up your belts a little bit and see how that goes. How fast are you printing? Is the bowden tube & wiring harness in a position to "drag" the effector? (too much tension in the harness/bowden)

g.

Re: Ghosting on vertical surfaces

Posted: Mon Aug 05, 2019 8:24 pm
by DDXdesign
geneb wrote: Mon Aug 05, 2019 9:36 am Mechanically, the 3.2 and the 4 are going to be pretty close - the 4 will be stiffer due to the all-metal construction.

You might want to try tightening up your belts a little bit and see how that goes. How fast are you printing? Is the bowden tube & wiring harness in a position to "drag" the effector? (too much tension in the harness/bowden)

g.
I am only doing outer walls at like 25-30mms, and the bowden and wires are free moving. should I try to bundle them up closer to an arm or something?

As for tightening the belts, I have less than zero idea how to do that, let alone how to do it without screwing everything up.

Re: Ghosting on vertical surfaces

Posted: Tue Aug 06, 2019 7:27 am
by Mac The Knife

Re: Ghosting on vertical surfaces

Posted: Tue Aug 06, 2019 5:21 pm
by DDXdesign
Mac The Knife wrote: Tue Aug 06, 2019 7:27 am Read up, Skippy. https://seemecnc.dozuki.com/Guide/Rosto ... 27?lang=en
Alrighty, found the appropriate part of the guide. of course, I realize I actually don't know where the motors are, but I assume they're in the head. Hope I don't have to disassemble much to get to them; I may never get it back together right.

Re: Ghosting on vertical surfaces

Posted: Wed Aug 07, 2019 7:32 am
by Mac The Knife
It won't be as bad as you think, Just don't get carried away and take it all apart. : )

Re: Ghosting on vertical surfaces

Posted: Wed Aug 07, 2019 8:34 am
by geneb
If the v4 is like the 3.2, you only need to loosen the motor screws a tiny bit and lift up the motor a tiny bit before tightening the screws.

I would have mentioned this earlier, but I thought you'd built the v4 from a kit. My apologies.

g.

Re: Ghosting on vertical surfaces

Posted: Wed Aug 07, 2019 11:58 am
by DDXdesign
geneb wrote: Wed Aug 07, 2019 8:34 am If the v4 is like the 3.2, you only need to loosen the motor screws a tiny bit and lift up the motor a tiny bit before tightening the screws.

I would have mentioned this earlier, but I thought you'd built the v4 from a kit. My apologies.

g.
oh, no way I would trust myself to build a complex machine. I like things that work, and while I love making things, my personal margin of error is far greater than is required for something like this, so I buy all my 3d printers prebuilt. It's not that I wouldn't be able to understand how to build it, it's that my sausage fingers and my patience don't function well at that fine level of detail.

Re: Ghosting on vertical surfaces

Posted: Thu Aug 08, 2019 8:32 am
by geneb
Don't sell yourself short. To my understanding, it's a pretty easy build. :)

g.

Re: Ghosting on vertical surfaces

Posted: Fri Sep 13, 2019 11:56 am
by dc42
Dynamic Acceleration Adjustment can help with ringing (the cause of ghosting) on some machines. See https://duet3d.dozuki.com/Wiki/Gcode#Se ... Adjustment. There are also some threads about it on the Duet3D forum. But it's better to reduce ringing by mechanical means if you can.