inventabuild
Posts: 79
Joined: Sat Mar 19, 2016 12:29 pm

Coast Compensation

Sat Aug 31, 2019 2:11 am

1. In some situations Coast is the only way to mitigate stringing.
2. Please add back the quantity of filament that Coast subtracts to prevent gaps from eventually showing up due to the cumulative affect of a large amount of Coasts.
3. Add back the quantity of filament that Coast subtracts over the path length of the next extrusion instead of adding it back with Extra Restart Distance which can cause blobs at the beginning of layers.

S3D-Jake
Posts: 602
Joined: Wed Jun 20, 2018 12:45 pm

Re: Coast Compensation

Wed Sep 04, 2019 3:06 pm

Thanks for your suggestion. Can you please be more specific about what common scenario you're having where this is an issue? I'm happy to present the idea to our development team once I better understand what it is we'd be fixing through adding this feature.
"A bird does not sing because it has an answer. It sings because it has a song."

inventabuild
Posts: 79
Joined: Sat Mar 19, 2016 12:29 pm

Re: Coast Compensation

Sat Sep 07, 2019 5:33 pm

Hello S3D-Jake,

1. I'm using Coast to completely eliminate stringing when printing a lot of little letters which entails a lot of retracts occuring on the same layer.

2. My extruders are dialed in perfectly, so I am not using coast to compensate for poorly calibrated extruders.

3.1 Let's use round numbers to illustrate the issue:
3.1.1 If Coast is set to 1 mm then every time a line ends, the extruder stops extruding 1 mm before the line ends.
3.1.2 If I have 1 million lines to print on the same layer then the extruder stops printing 1,000,000 mm short for that layer. That is short 1,000,000 toolpath mm, not short 1,000,000 mm of filament; nevertheless the cumulative effect of printing short causes under extrusion to start occuring because eventually there is no filament in the heater block to melt.

3.1 Straight Extra Restart is not a panacea because it is can be difficult to dial in precisely to work with Coast and can cause blobs at the start of lines if overdone and still allow for under extrusion if not done enough. Besides Extra Restart is really meant to work in conjunction with the Retraction Distance (the Units of Measure are the same), not with Coast.

4.1 What I'm recommending is the option for a "Coast Compensation Extra Restart" distributed over the length of the next line (or some fixed distance) that prints after a Coast.
4.1.1 So for example if I'm printing line # 1 with Coast 1 mm, then I print line # 2 which is 10 mm long and this new proposed feature "Coast Compensation Extra Restart" has a value of 1 mm (to equal the Coast value), this "Coast Compensation Extra Restart" would occur over the full length of line # 2 (10 mm) and not just shoot out at the beginning of line # 2.
4.1.2 This will prevent blobs from occuring at the beginning of a line when trying to use an Extra Restart value to prevent under extrusion.
4.1.3 This will prevent under extrusion from occurring when using a perfectly calibrated extruder w/ Coast to prevent stringing.

Can you please implement this?

S3D-Jake
Posts: 602
Joined: Wed Jun 20, 2018 12:45 pm

Re: Coast Compensation

Thu Sep 12, 2019 11:46 am

Hello again. I believe I'm still not understanding. If the extruder is perfectly calibrated, what are we compensating for? Your retraction of 1mm in this scenario happens in place, then the line is finished. That same amount is then advanced at the beginning of the next line. If you're getting blobs on restart you should be looking to adjust your extra restart distance.

More on this here: https://www.simplify3d.com/support/prin ... -and-zits/
"A bird does not sing because it has an answer. It sings because it has a song."

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