Added glass to Maker Select and now I get worse adhesion?!
I recently added a 3mm borosilicate glass bed to my Maker Select. It's "floating" on silicone pads (.5mm) and has a PEI sheet on top (1-1.5mm?). I've removed the pseudo-buildtak.
I'm trying to print with PLA. I've been using 210C for the extruder. If I have the bed at 60-65, the model will pop off after 5mm or so in the Z axis. If it's at 70, I get warping. Regardless, my bottom layer looks pretty bad like it's not adhering well -- the filament doesn't follow the design exactly. It cuts corners and looks sloppy overall. It also doesn't have that nice smashed/spread look like it should. My bed seems to be level. It's a tiny bit closer than .1mm to the nozzle.
I have my flow rate set to 95% based on guides and other posts that I've seen. At 90%, the bottom layer especially looks too "wiry".
Could I get some help?
EDIT: measured my pads and updated the post
Posted Apr 21, 2017, 12:11 AM UTC · edited
Try taking it off those silicone pads and just put the glass directly on the heated bed. Some people swear by them but I found them to be a pain and actually have worse heat transfer.
I've got the same setup except my boroscilicate glass is clipped directly to the bed with PEI on top. As long as my bed is level, I get a glass like finish on the bottom and great adherence.
Will that work even if the bed is potentially warped? I don't know if mine is exactly, but it could be a problem!
The heated bed doesn't generally warp that I am aware of, it's the metal Y-Carriage plate underneath that does. The glass is supposed to be somewhat of a bandaid for that, where it should be fine.
Alternatively, let your heated bed warm up for longer if you keep the silicone pads (around 10-15 minutes if they are as thick as you say). If you start as soon as your temp readings say it's heated, the glass is probably still considerably lower than that.
Oh, well that's good news. The pads are actually only .5mm thick, but I'll try to preheat the bed for a bit first and print again!
I can say that the MOSFET mod makes that thing heat up very quickly, so I can see how the glass wouldn't actually be at that temperature yet. It's probably popping off due to inertia from the deposited filament before it is truly at the target temperature.
Definitely keep us updated. Just to note, while 210C may be perfectly fine for your PLA, most print the best around 190-205C. This is of course different if you have the Micro Swiss Hotend, where that usually requires around 215C minimum.
Also print with the fan off on the first layer to get good adhesion and double check the bed level. You can print 2-3 skirts first and watch them to make sure they look good.
Wow, I just checked and the glass is substantially cooler than the bed!
I'm going to remove the pads and see how it goes. Hopefully warping won't be a problem... I feel like the bed wasn't exactly uniform before, but maybe the glass on its own will be enough. As a side note, it's still the default carriage with four-corner leveling. However, I level it in the way where you set one corner to be the proper distance from the nozzle (both at temperature, of course) and then only adjust the other three after that.
Sounds like you are definitely on to the culprit, it sounded like that may have been the case. I only used thermal pads for a couple days and then yanked them off for that reason.
I've never heard of leveling that way but whatever works! As the adjacent corners affect each other, I generally do front-left, rear-right, then front-right and rear-left (about 4 turns each in that pattern). I then fine tune it with skirts, looking for any variations while those print.