Warping and Bed Adhesion Issues

So I built this printer (Mendel Wilson TS version 1), I'm getting really tired of it not working quite right. I have spent the past 5 weeks trying to calibrate it correctly, and come very close to throwing it out the window several times now. Right now, I can't get past a bothersome warping and bed adhesion issue.

It has an authentic E3D Lite6 hotend on a direct drive extruder, controlled by a RAMPS 1.4 running Marlin 1.0.2, and a handmade heated bed using Nichrome wire as a heating element. After calibration efforts, using 1.75mm PLA filament by WYZ, I've come up with 180 C extrusion temperature, 65 C Bed temperature, dropped to 55 after the first layer or two. I'm running things through Mattercontrol, due to its software bedleveling (my handmade heated bed has a slight hill in the middle, and as this is my first printer, I do not have an autoleveler yet).

I've included pictures of my last few attempts in the hopes that someone can help me figure out whats going on. The first picture is straight onto the Borosilicate glass, naked, without any primer or adhesive aid. I saw warping corners after 2nd layer, before the bottom perimeters had even been finished. The second picture is a print onto the glass with Elmer's color changing gluestick added as an adhesive aid. On this one, the corners started curling after the 5th layer, and pulled up off the bed after the 8th layer.
In the third picture, I thought about increasing the surface area of the print by adding a 5mm raft. I forgot to get a picture of the print immediately after, so its actually a picture after I cracked it off. The corners curled after layer 7, and warping progressed a lot less, but its still there. There was, however, not a single instance of failed bed adhesion.

The (edit)5th 4th picture is the bottom of the 3rd print because I noticed that the layers seem, to me, to indicate there's an over or under extrusion issue, but I don't know.

Your thoughts and input would be awesome! I want this thing PRINTING!!!

Edited 1 time(s). Last edit at 05/31/2016 02:02AM by Sminky.

You have a bunch of problems at the same time conspiring against success.

1) The fourth picture showing the bottom of the print looks like you've got the nozzle set too high above the bed for the first layer. Layers should be no more than about 80% of the nozzle diameter in height.

2) Glass is an insulator. The heat will be very uneven. You'll have a lot of hot and cold areas. The filament won't stick in the cold areas. Heaters glued directly to glass don't usually work very well.

3) it looks like there may be some overextrusion. Have you calibrated the extruder?

4) how fast did you print the first layer? Typically you want the first layer to go down slowly- try 20-30 mm/sec.

5) the print is small. That means each layer finishes quickly, before the filament has had time to cool, the extruder comes along and adds more heat and plastic. People usually add a print cooling fan to prevent that type of problem when printing PLA. Until you can set up a print cooling fan, try printing two or three of the test parts at the same time and see if they don't come out better.

6) You can print PLA at room temperature on blue painter's tape. Try that.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thank you the_digital_dentist for confirming the complexity of the situation! Like I said, I've been fighting with this thing for several weeks, and I had a feeling there was something more than just one or two tweaks causing all the problems. In response to your other observations:

1) I am using the software autoleveling function of Mattercontrol, and I already know its not perfect. Several times now, I have noticed that the autoleveling function has set the extruder too low and it will jam the nozzle, or too high and it just squirts liquid plastic in midair. I hope to at least get it to the point where I can print a hardware autoleveler to use directly with Marlin. When I get home from work, I'll try to tweak that and see if I can get a better first layer. However, I want to note that that fourth picture was after I had removed the raft from the print. The settings I used for it were: Expand Distance 5mm from sides of print; Air Gap 0.2mm from top of raft and bottom of print, with a Fan Speed of 100%. The Standard Layer Height is set to 0.2mm, as I have a 0.4mm Nozzle, and I have it set to print the First Layer at the same height. Do you think there still might be an issue with my First Layer Height Settings? Or do you agree that its probably a fault of the software Autolevel?

2) As far as the heated bed, I agree and disagree. I made the bed from DIY Nichrome Heated Bed. I used 12 individual heating elements, wired in parallel, each one a maximum of 10mm away from the next, and they are firmly attached to the glass with an even layer of Kapton tape. The thermistor is wedged into a copper plate that spans a gap between two different elements, right in the center of the bed. The effective total resistance of the bed comes to about 2.4 Ohms, which comes out to a 5 amp current, and I was worried about this, but I noticed that the bed heats evenly and consistently during prints (even got out the kitchen thermometer). I had a mind to either activate the Marlin PID Autotune or tweak the PIDs myself, but only after I knew I was going to keep the bed as is. I still hadn't decided if I was going to scrap the higher resitance build and try to get closer to 12 amps, or if I was going to just get a PCB heated bed and call it a day. I was most hesitant because I have heard of serious warping issues with PCB elements and uneven heating that results from that. Do you think I should scrap the nichrome build for a PCB, tweak the PID or just concentrate on the other issues before considering that particular obstacle?

3) I have calibrated the extrusion pretty dang close, by taking the hotend off and measuring filament extrusion with a digital caliper, but I have not fine tuned the extrusion by observing infill quality during a print and sending G code modifications every few layers. The problem was, the prints were curling and warping off the bed so quickly, I couldn't get more than 8 to 10 layers out before it the nozzle started digging into the print, and I couldn't get a good look at the infill density. Would it be easier to print, say a large round cylinder with solid infill? Try to cut out the corner warp and hope that the large size would give the filament enough time to cool?

4) I have the First Layer Print speed set to 30mm/s, Infill Print Speed set to 60mm/s, and Inside and Outside Perimeters set to 30mm/s and 21mm/s respectively. Whats funny is the Raft Print Speed set to 60mm/s and it didn't warp at all! Do you think I should try printing the First layer closer to 20mm/s?

5) I have a print cooling fan already installed, and I have it set to run at a minimum speed of 35% the duration of the print, with the exception of the first 2 layers, which I set to 0% to give those first 2 layers the best opportunity to adhere to the bed. When I get home, I'll try printing 2 or 3 of the cubes to see if that helps with the warping.

6) I have yet to try the painter's tape, as I eventually wanted to print ABS in addition to PLA and wanted to be able to use the same bed. Is that practical? or am I missing some logic there?

Thank you again for your help! This thing has been waiting for me to get my S!@# together for over a month now and it feels great to have someone with much more knowledge giving me direction!

Edit: italics didn't come out right -> fixed it.

Edited 3 time(s). Last edit at 05/31/2016 02:13AM by Sminky.

Using a raft will account for the bottom of the print looking like it does. If you close the air gap a little the filament will be more flattened, but then it gets harder to remove it from the raft. That might help with the corners lifting. Try 0.15 mm for the air gap. If the raft is sticking the first layer speed and extrusion are probably OK.

Glass is a thermal insulator and the heat will not equalize across it. Most people use a heater attached to some sort of thin aluminum heat spreader which isn't flat, then clamp a piece of glass on top of that to get flatness and more even heating. I like to print directly on a flat aluminum plate (1/4" cast tooling plate) without glass. Both ways work.

There's more to extruder calibration than just measuring the filament coming out of the extruder. You also need to consider the filament diameter. See [reprap.org] and pay attention to the E-steps fine tuning procedure.

I try to keep all the speeds (except the first layer) about the same value. That helps print surface quality and strength.

You can use the same bed for printing ABS and PLA, but the surface coverings are different for the two. Fortunately, you can just apply blue painter's tape on top of kapton or whatever you have on the surface now, use it to print PLA at room temperature, and when you want to switch to ABS, just peel off the blue painter's tape and clean off the bed. Since ABS needs about 105C on the bed to stick properly, you'll need a fairly high powered heater (and matching power supply) to do that. Temperature variations across the surface become more pronounced and critical. If you don't want to wait all day for it to heat up, you need about 0.4 W/cm^2 (or more) areal power density from the heater. PCB heaters are usually no where near this. Stick-on silicone heaters are readily available at that power density.

ABS will also require a warm (45-50C) print enclosure or the prints will delaminate. You can't reliably print anything but thin, flat parts in ABS on an open frame printer. As soon as the parts get more than a couple cm tall, they will delaminate. This is what happens when you try to print ABS on an open frame printer:



This compares ABS prints made on an open frame printer and inside an warm enclosure (guess which is which):



Getting back to your current problem, try printing everything at the same speed, maybe 30 or 40 mm per sec. Print multiple copies of the cube in one go and see if they don't improve, or print a single, larger cube. One way to calibrate the extruder to match the filament diameter you're using is to print a single or double walled test object specifying the line width, then measure the print and use the target width and the measured width to adjust the extrusion flow rate to get the desired wall thickness.
new extrusion flow = old extrusion flow x (target width/measured width). You'll need a caliper that can read 1/100ths of a mm.

Make sure your line widths are set between 105 and 170% of the nozzle diameter, and layer heights are set to <80% of nozzle diameter.

Edited 1 time(s). Last edit at 05/31/2016 08:58AM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I've noticed that MatterControl doesn't have nearly the settings I'd like it to have, as far as slicing. It also has a tendency to fight using Slic3r as its object processor, but I'm going to try to strong arm it with the settings you suggest. Then, if I can get the pieces to not warp or curl nearly as much as they have been, I'll try to calibrate the extruder.

In the meantime, if my current bed holds up to the PLA I should be able to use it, right? And if it doesn't, I can just use the painter's tape and print like that. But, if I want to move on to printing ABS, I should get a silicone heater, an aluminum plate, and then modify to enclose the printer? By my calculations, my current build can only put out a maximum of 60 watts through the bed.

Edited 1 time(s). Last edit at 05/31/2016 10:02AM by Sminky.

As a point of reference, my 317 x 305 x 6.35 mm aluminum bed has a 450W heater and gets up to 105C in about 5 minutes. That's about 0.5 W/cm^2 areal power density.

Unless you're using a really small bed, I don't think 60W is going to be enough.

Look for an "advanced settings" or "expert mode" option in the slicer. Sometimes they hide that stuff to make life simple for noobs.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Well, matter control and slic3r definitely have some bugs when holding hands. Finally gave up and had slic3r just export the gcode for MC to pick up and send to the printer, but after diving through the looking glass, I now have to go to a birthday party. I'll have to run the print tomorrow. I'll let you know how it goes.