First Layers

Here is a collection of first layers at different Z offsets to give you an idea of what to look for.

This one has been smeared on the bed.  The nozzle is pretty much making contact, and the extruder skipped a few steps trying to cram plastic into the kapton.  If you have an unheated acrylic bed, you are in for some serious scraping to get this off, and you may never get it all.

This is pretty flat, and will give you a little bit of a lip at the bottom.  If you are having trouble with corners peeling up, you might try going this flat to get some extra stick.  Be aware that  it will make holes a bit smaller at one end, for one layer.  If you don’t have a heated bed, this might be want you want to shoot for.

This is pretty good.  It’s a little flattened to give the thread more area in contact with the bed, but not enough to affect the dimensions too much.

This is getting a bit too high.  It would probably be fine for this part on a heated bed, but if it were tall and narrow with a small footprint, it would probably come unstuck.  If it was maybe 100mm wide and flat, there could be warping at the corners.

This is too high.  The thread is too round for very much plastic to be pressed down on the bed.  When the extruder changes direction, it pulls the thread along with it, “cutting corners.”  That is why the circles are misshapen, and if the straight lines were bumped into they would come loose and start flying around the bed.  If you started this print and walked away, you would come back to a giant ball of plastic orbiting the bed on the end of the extruder.

Each of these changes represented about a quarter turn of the Z offset screw.

 

 

 

 

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11 thoughts on “First Layers

  1. This is great…. Thanks.
    There is lots written about getting the first layer height correct, but pictures are so much easier to understand.

  2. Does the Z offset come adjusted properly or is that something we need to do when receiving the machines?

    Is each step in the photo’s raising the Z offset?

  3. The Z offset is probably correct or close to it, since they run a test print before shipping. It’s pretty easy to set, just pause the print, pull off the plastic, turn the screw a little up or down, and restart. It might change from movement of the bed or extruder due to heat expansion so it may need adjustment from time to time.

    The M3 screw has a thread pitch of .3mm so one to move the bolt .1mm vertically you’d make 1/3 of a turn. So I would guess that the change between the above photos were in the neighborhood of .08mm to .1mm.

  4. Ian, do you learn all these things through experimentation or are there books or web articles that would be good for newbies to read while waiting for our printers?

    How did you learn where all the adjustments are on the Solidoodle and how far they move things per turn?

    Thanks for all you share, it really helps and when my machine arrives I will be much better prepared.

  5. Follow these two blogs- http://richrap.blogspot.com/ and http://www.hydraraptor.blogspot.com/ Nophead, the guy who has the hydraraptor blog is one of the most knowledgable members of the reprap community when it comes to the theory. His printer is different from the rest, so a lot of his hardware stuff doesn’t really apply.

    Richrap covers a lot of the basic stuff really well, like Slic3r, calibration, low layers, etc. Also check in at http://blog.reprap.org/ and http://forums.reprap.org/index.php. I read the Makerbot Google group from time to time for topics that apply to FDM printing in general.

    A lot comes from experimentation and googling around to figure out why prints didn’t come out right, and Solidoodle support giving advice on failed prints. They gave me the tip on the Z offset screw thread pitch.

    I’ve also learned a bit from breaking things and trying to fix them. One reason people (mostly RepRappers) recommend buying a kit is by the time you have assembled it, you have learned a lot of what you need to know to troubleshoot it. With an assembled printer you gain that knowledge when things go wrong.

    When I literally fried my hot end, I went ahead and bought a kit and put it together on my own rather than ask Solidoodle for a new one, and learned a lot in the process.

  6. Thanks for the links and all the info you provide. I think it is better that my Solidoodle has not arrived so that I am having a chance to learn a lot before I start experimenting on my own. This whole area is fascinating to me. Did you buy the kit you assembled on your own from Solidoodle or elsewhere?

  7. Ian

    This post is great in my opinion, because it shows lessons I learned the hard way on the MakerBot cupcake and then the Solidoodle 1.

    One of the things I like most about the heated platform is that large parts (which tend to peel
    & warp) stick easily when it is hot, but pry off very easily when it is cold.

    Tony

  8. Could you tell me which is the Z-axis screw? Sorry, bit of a daft question, but I don’t want to get it wrong.

    I am guessing that adjusting this will stop the ABS lifting off the bed as the nozzle comes in contact with it. Not had much success yet as it just won’t stick to the bed.

    thanks for the help on the blog!!

    • The Z axis screw is on the inside back of the case, left of the rods that support the build platform. There is a switch on the platform that bumps into the screw and stops the movement. You turn the screw up and down to control how close the bed comes to the nozzle.

    • I second the question. I’m using Repetier, so I’ve been setting the filiment configuration for Slic3r with an offset of -0.09mm, since that’s what the feeler gauges’ are telling me. Seems to work mostly OK, except that sometimes the head peels up the first layer as it continues.

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