Gap in cylinder

MrBaz

Gap in cylinder
December 18, 2013 09:41PM

Registered: 10 years ago
Posts: 154

I tried search, but I must not be very proficient with it as it returned no results.

When printing a cylinder (even with 3-4 shells) I'm getting a gap running straight up the wall. What am I missing here?

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rogerclark

Re: Gap in cylinder
December 19, 2013 04:45AM

Registered: 10 years ago
Posts: 273

What size is the gap?

What slicer are you using?

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uncle_bob

Re: Gap in cylinder
December 19, 2013 07:01AM

Registered: 10 years ago
Posts: 1,433

A picture would help.

What happens with a spiral vase?

Are you sure there isn't a gap in the stl file?

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chngyian

Re: Gap in cylinder
December 19, 2013 03:44PM

Registered: 10 years ago
Posts: 128

Can't remember where, but I read something that goes like this. If the thickness in the model is 1mm and the nozzle is 0,4mm, there would be a 0.2mm gap in between as there is no way the 0.4mm nozzle can form a 1mm thickness.

Anyhow, a picture would help. smiling smiley

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uncle_bob

Re: Gap in cylinder
December 19, 2013 05:55PM

Registered: 10 years ago
Posts: 1,433

That would not explain a vertical (z axis) gap in the cylinder. The description (to me) implies there is a big chunk in the wall that simply does not get printed. The cylinder winds up with a slot cut out of it that you might be able to stick a finger through. It could be an inch or two wide in a five inch diameter cylinder, it could be 1/100". It couldn't be in a spiral pattern since it runs straight up.

Guessing is so much fun ....

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MrBaz

Re: Gap in cylinder
December 19, 2013 10:10PM

Registered: 10 years ago
Posts: 154

You all are right. I'm an idiot. I didn't explain that very well. Here is a picture of the problem:

s663.photobucket.com

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uncle_bob

Re: Gap in cylinder
December 20, 2013 07:13AM

Registered: 10 years ago
Posts: 1,433

That's looks like a bug in Slic3r.

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MrBaz

Re: Gap in cylinder
December 20, 2013 01:15PM

Registered: 10 years ago
Posts: 154

I'm using Skeinforge 50 via ReplicatorG 40r22 Sailfish (ToM has been flashed with the REAL Jetty Sailfish firmware)

A plain cylinder shows this flaw. "Cylinders" within a print (surrounded by infill -- screw hole for instance) do not have this problem.

Edited 1 time(s). Last edit at 12/20/2013 01:16PM by MrBaz.

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uncle_bob

Re: Gap in cylinder
December 20, 2013 01:55PM

Registered: 10 years ago
Posts: 1,433

Take a look at the gcode with a good viewer. My guess is that you will find that it's a bug in the slicing software rather than a printer problem. I have seen very similar things pop up in certain Slic3r releases and then vanish when the next release comes out. It seems to be a problem related to turning corners while changing layers.

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MrBaz

Re: Gap in cylinder
December 20, 2013 03:20PM

Registered: 10 years ago
Posts: 154

Used a gcode viewer and could just barely see the tiny gaps between the lines in a plane thin-walled 20mm cylinder. This was were that layer/line began and ended. Is it possible there is a skeinforge setting that is allowing the printer to jump to the next layer too early causing a gap? Maybe a retraction setting?

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uncle_bob

Re: Gap in cylinder
December 20, 2013 11:09PM

Registered: 10 years ago
Posts: 1,433

...... or maybe it's just a bug .....

I'd play with the normal calibration objects to optimize things like retraction.

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MrBaz

Re: Gap in cylinder
December 21, 2013 05:43PM

Registered: 10 years ago
Posts: 154

I found out what it was.

I had deprime in the firmware enabled, and at the same time I had skeinforge calculating retraction for slicing. You apparently aren't supposed to use both at the same time.

I disabled deprime in firmware and played with the retraction settings. I also switched to running the loops before the perimeter. Hopefully, this will hide the zipper a little better. Thin walled cylinders come out MUCH better now.

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