Hey folks, I could use some advice.
I feel like I have my FT-5 reasonably well dialed in at this point, and can print small-ish objects fairly reliably. However, printing small items are not why I bought a FT-5. I have a queue of large/flat objects to print - some up to the full width of the print bed, and some lengthwise along the diagonal. I am just constantly plagued by "first layer problems". My success rate for large object printing is probably 1 in 20, and when you factor in how long a failure takes, it's a huge problem.
* White FolgerTech PLA
* 225 degree first layer
* 30mm/s first layer print speed
* 12x12" glass mirror tile print surface, cleaned with rubbing alcohol. (No gluestick, no blue tape.)
* WHITE heated bed running at 12V
* 65 degree bed temperature
* Mirror tile is clamped at four locations to the aluminum heat bed
* Heat bed is attached to the melamine Z-bed at four corners using the factory springs/screws
* Part cooling fan is OFF for first layer
* Factory nozzle (0.4mm?)
* Nozzle is clean, verified with an atomic pull.
* 0.2mm or 0.3mm first layer height
* Nozzle height set by the printer paper adjust until slight drag method
* Still using independent Z-motors
* Z-axis movement, stepper extrusion rates, filament diameter, etc, have all been calibrated.
Basically what happens is that I can level the bed nearly perfectly, and when I start my print, it lays down a nice three or four line perimeter for the skirt, and prints the part outer border OK, but then all falls apart during the zig-zags of the base layer. I either get ripples, ridges, thin spots/scraping, peeling on direction change, filament balling up under the nozzle, dislodging of the perimeter from the glass, or some combination of the above.
I use three or four lines of perimeter because it lets me verify that the bed leveling is correct at the start of the print, and gives me several passes to manually adjust the corners if necessary. So at least at the start of the print, I can be quite confident that the bed leveling is correct. However, once the print starts to fail on the base fill passes, the only way to salvage it is to manually tweak the bed leveling screws. I can "make" a print succeed with constant fiddling for the first layer, but could never just hit print and watch it go.
I'm sort of at a loss as to what is going on here. As I mentioned, I can print smaller objects with no issue, it's just larger that causes problems. I will be linking my Z-axis rods as soon as I can order the pulleys, and I've been investigating contact (bl-touch) and inductive auto bed leveling, but despite me being able to resolve the print issues by tweaking the bed leveling, I have a hunch that "leveling" isn't the actual problem. These giant first layers take a long time to print - I'm almost wondering if the melamine, aluminum, or glass are progressively warping or twisting as the heat soaks in?
I do all of my manual bed leveling with the printer pre-heated - Bed at 55, and nozzle at 185 so that I can be sure that it doesn't have hardened plastic on the bottom that offsets my measurements. I've tried countless prints changing just about every parameter to resolve it, but haven't had any luck finding settings that are good for repeated prints. Like I said, I've been investigating the auto-bed-leveling probe options, but while they may help, I'm not necessarily convinced that that is the problem.
Any thoughts? I'm all ears...