Unanswered First print with PLA - Help with settings.

Hey guys - been using ABS for some time and now just starting to use PLA. Not sure what adjustments I need to make. I started at 210/50 per the preset but it was very stringy so I am now down to about 198. Parts fan is off for first two layers and then on. Z offset is at -.2.

Here are some pics of the first layer - thoughts?
PLA first print. by acevedor2, on Flickr
PLA first print. by acevedor2, on Flickr
PLA first print. by acevedor2, on Flickr

 

Thanks Geof. What would you recommend to start with retraction settings?

 

Still printing but here it is after a few layers.
20160717_210424 by acevedor2, on Flickr
20160717_210444 by acevedor2, on Flickr
20160717_210432 by acevedor2, on Flickr
20160717_210451 by acevedor2, on Flickr

 

Mark - Going to check that out this evening. I noticed that after the perimeter was put down, it did not print the objects in the middle, but rather off to one side. They ended up printing fine, but again, off to one side of the perimeter and not directly in the middle. The only thing I can think it was that when I cleaned the bed I left the roll of paper towels behind the printer and I didn't notice. This is a problem because the printer is close to the wall, so with the paper towels behind it, when it went to start printing this piece (calibrating, auto level, etc) the bed kept trying to go back and kept hitting the paper towels. We notice this quickly and moved them, and then it started with the leveling, etc, but it might have been enough to put it out of whack.

Is there a way to calibrate this if it turns out that the rest of my prints are doing the same thing? This is the second time it has printed the perimeter and then not printed the object in the center of the perimeter.

it did end up printing fine and I was using aqua net as a bed adhesive.

 

From the first set of pictures, the nozzle appears to be dragging through the first layer. I would definitely try increasing you Z-Offset. -0.2 seems really close to the bed, but everyone's printer is different.

 

Thanks Mark. Going to print again tonight and see if the perimeter is off or if it is back to normal. Will report results. You were right about the stringiness. I started at 210, but went down to 198 and now the stringiness is basically gone. Much better.

Thanks Ryan. Think you're right. Going to try -.1 and see if that works better. The print actually came out fine, but I think I'll adjust it anyway and see what I get.

 

More negative moves the nozzle away from the bed, less negative moves closer to the bed (this can be confusing for anyone just starting out). If you change to -0.1, you will actually be moving the nozzle closer to the bed. Try -0.3 instead.

 

Ok - This makes no sense to me. If 0 is the bed itself, anything that is positive is above the bed or higher. So .1 would be closer to the bed than .8.

For negative, however, it makes no sense that -.1 would be closer to the bed than -.8 since -.8 is a higher value. On a standard z axis, it goes 0, -1, -2, etc as you move down the z axis. -2 isn't closer than -3 to 0, it's farther.

 

Can someone help explain?

 

I had a hard time understanding this when I started as well. I like to think the "-" is actually a dash, separating Z from the offset! But don't forget to use it. Trying to explain more negative will raise the extruder from the bed, is hard to get through to some people, since it really does not make any sense. If you leave everything the same in your starting script/firmware, just increase the number and it will move farther from the bed. Seems to make a little sense!

 

So that would make sense then that -.3 would be higher above the bed than -.2.

Does that mean that+.3would be down farther and into the bed more than +.2?