SoliForum - 3D Printing Community — Fun with cylinders

Re: Fun with cylinders

null@example.com (n2ri) — Thu, 04 Dec 2014 02:04:12 +0000

I have seen this effect periodically with my SD2 but only for so many layers then it will clear up for a few layers and maybe reappear elsewhere. also saw it on large flat sheets same way. it seems to be mostly due to the "chipmunk effect'. and I always use random start points to prevent the old masonry issue of weak joints that fall apart.

Re: Fun with cylinders

null@example.com (grob) — Wed, 03 Dec 2014 03:47:47 +0000

jagowilson wrote:

Your page is full of excellent information.

Hear hear. You're a couple of headings and a few buzzwords away from a proper engineering report there (by that I mean you're doing it right!).

Re: Fun with cylinders

null@example.com (jagowilson) — Wed, 03 Dec 2014 02:11:45 +0000

Those "flats" you mention are exactly the thing that got me realizing my circles had slight deviation. Many upgrades from now, I should be able to eliminate it entirely. I hate it! I mean, it's barely noticeable, but I want my printer following the g code as much as possible

Install that e3d now rather than later. It's like the difference between 480p and 1080p. It's so accurate and you should have no blobbing with proper settings and good filament. It has a really small melt zone.

Your page is full of excellent information. It's honestly more detailed and accurate than Solidoodle's own pages. Nice work.

Re: Fun with cylinders

null@example.com (Claghorn) — Wed, 03 Dec 2014 02:04:03 +0000

In case anyone is interested I have a couple of photos up on my web page with sample cylinders and extra babbling:

http://home.comcast.net/~tomhorsley/har … nders.html

Re: Fun with cylinders

null@example.com (wardjr) — Tue, 02 Dec 2014 14:32:41 +0000

Moisture will create pressure in the nozzle as it boils off. With the E3d I can tell instantly if my filament has moisture because it's the only time I get oozing. You are correct about the stock hot end acting like a chipmunk though I don't know if there is much you can do about it.

Re: Fun with cylinders

null@example.com (Claghorn) — Tue, 02 Dec 2014 14:11:34 +0000

wardjr wrote:

I would increase the retraction speed and increase the distance 1 or 2 mm's. If that doesn't take care of it you might have moisture in your filament.

I can't think of any reason why moisture would only create blobs at layer changes. I think my problem is more likely to be the stock hot end I'm using that tends to store excess molten filament in its cheeks like a chipmunk :-). I also wonder about the exact sequence of events slic3r generates. If it stops moving first, then retracts, then changes the Z level, that's likely to create a blob due to the "chipmunk" effect. I bet if I could get it to retract just before it stopped moving, it might work better (but I haven't tried to decode the g-code to see exactly what it does).

Re: Fun with cylinders

null@example.com (wardjr) — Mon, 01 Dec 2014 23:19:36 +0000

Claghorn wrote:

wardjr wrote:
Have you tried random start points?
Random start points just scatters the blobs randomly, but there are still blobs.

I would increase the retraction speed and increase the distance 1 or 2 mm's. If that doesn't take care of it you might have moisture in your filament.

Re: Fun with cylinders

null@example.com (Claghorn) — Mon, 01 Dec 2014 23:08:01 +0000

wardjr wrote:

Have you tried random start points?

Random start points just scatters the blobs randomly, but there are still blobs.

Re: Fun with cylinders

null@example.com (Claghorn) — Mon, 01 Dec 2014 23:07:15 +0000

Haven't tried fiddling with any speed settings, I saw one post that recommended putting a small negative number in the extra length on restart setting, but I haven't tried that either.

Re: Fun with cylinders

null@example.com (wardjr) — Mon, 01 Dec 2014 23:03:55 +0000

Have you tried random start points?

Re: Fun with cylinders

null@example.com (grob) — Mon, 01 Dec 2014 22:56:38 +0000

Good investigation - the layer change blobs are something I was hoping to tune out a bit. I was hoping retraction would affect it at least a bit. Have you tried changing the retraction speed as well?

Fun with cylinders

null@example.com (Claghorn) — Mon, 01 Dec 2014 12:53:17 +0000

I was experimenting with different things to measure print quality, and printed a bunch of single wall cylinders with different settings and found various bits of interesting information:

Even if circles look pretty good to the eye, if you rotate the cylinder under a light, it is easy to see places where there is a somewhat flat or somewhat bent spot, so now you can drive yourself crazy trying to fix defects you normally can't even see! :-).

A single cylinder also shows the blobbing at layer change effect. With the "wipe" setting turned on in the slicer, you get a spiral ridge of blobs around the cylinder. Without wipe, you get a blob line straight up the side. Nothing I tried with any settings for retraction really seemed to have any effect on the blobbing at layer change. (Turning it off completely, or making it retract even more than normal still left blobs that looked the same).

One thing that was kind of interesting: The moire you can usually see on cylinders disappeared completely when I turned off "wipe". Presumably that just means that the slight pulsing of the extruder lines up exactly the same on every layer.