If you're zeroing the nozzle .0005" above the bed and getting a transparent first layer, there's a good chance the nozzle is too close to dispense a bead of plastic, because that's exactly how it looks. You should be able to use a slightly thicker shim to zero the nozzle and fine tune the first layer height as a setting in the slicer. That way, the hardware settings remain standard and you can have different slicer profiles for printing different materials if you should need slight changes in first layer height, although the defaults should work well if the hardware is dialed in properly. If you're dragging the nozzle too close to the bed and you're trying to fix that by arbitrarily cranking up the extrusion rate, that's a recipe for a clogged nozzle and those are no fun. I'd recommend the process that Andy described where you mark 120mm back on the filament, tell it to dispense 100mm of filament, measure the filament to the mark and adjust the extrusion rate until it dispenses 100mm and leaves 20mm above the extruder.
The plastic bed surfaces vary in their ability to accept a first layer and the surface of the ones I've tried seem to be constantly wearing out with every print so the print surface keeps changing and what worked before no longer works. Quality is doing the same thing every time, and I never found that to be possible with a plastic print surface. The first thing I do with a new printer is preheat the bed to 110C to soften the plastic sheet adhesive and peel off the plastic sheet. I now leave the adhesive on the table and use it to adhere a sheet of borosilicate glass. If not, then the glass can be held in place with binder clips, but be careful not to crash a nozzle into a binder clip. The glass works great with the jumbo size Elmer's X-treme glue stick, with PLA (bed temperature of 40C) or ABS (bed temperature of 110C). It takes only a few seconds to apply a thin film of glue to the room temperature glass bed and cleanup requires only water and a paper towel. Prints stick great. ABS pops off when it cools. If the PLA doesn't release enough when cool, a teaspoon of water around the outside of the print will float the part off the bed in a few minutes, and you'd be watering the glass bed anyway to clean off the glue after every print. If you are having trouble getting prints to stick, or you need to use force to remove parts after they've printed, then you're doing it wrong. If you don't want to order a borosilicate glass bed for your printer, you can get a sheet of window glass or a mirror tile at your local home store. They'll probably cut it to fit your printer. I've been doing production printing lately and I'm definitely not messing around with problematic first layer adhesion. Get it right and it's easy peasey, and reliable enough that I'll start a print and walk away while it's preheating. When printing more than a few small parts with little surface area, I use a thin raft because if just one of those parts doesn't adhere, the entire array of parts is scrap. The raft is good insurance. As Chris said, CAD is the way to 3D printing happiness. To unlock the power of 3D printing you need to be able to design your own simple parts. CAD isn't as difficult as it was. It's a trick that even an old dog like me can learn. I write G code for my LinuxCNC machines by hand, but that's not possible with 3D printing. You need to be able to generate an STL file to feed into the slicer program. On 6/15/20 6:46 PM, Gene Heskett wrote: > On Monday 15 June 2020 16:10:41 Chris Albertson wrote: > >> Have you followed the link to the documents from Cura's "help" tab? >> It is really excellent. >> The help link takes you here: >> https://support.ultimaker.com/hc/en-us/sections/360003548339-Ultimaker >> -Cura Every printer setting is explained with examples showing parts >> made with and without the settings enables. >> >> I don't think anyone is using printable PDF files for docs anymore >> because PDF is so hard to read on different sized screens. They use >> formats that reflow and allow different font sizes. >> > Thats html, and a right pain in the rear orifice to get right both on > screen and on paper. Additive colors that look great on screen are > poorly translated to the printers subtractive color palates so you do > not end up with an easily readable document in hand very often. Perhaps > my blood is contaminated with printers ink, as a young teen 70+ years > ago I hung around the local print job shop who had both a darkroom and a > Heidelburg windmill job press and I KNOW what quality color printing can > look like. We are not getting it today from a printer I can afford. > > Anyway, change subject, to see thru prints because the 3d isn't using > enough string. Its getting better as I raise the extruder steps/mm. Im > now making the third of those fan duct attachments, but this time the > bed was zeroed on some .0005" alu foil. And the extruder was just set > up another .15% faster. Poor print, poor supports and I can see thru it > well enough to read todays newspaper. Thats air leakage, probably 75% > of it going someplace else besides the tip of the nozzle where it > belongs. I may give up and give it a coat of paint to seal it up yet. > > But this close to the bed, it sticks really well, and I may rip the > bottom plumb out of it, we'll see in about 20 minutes. > > Thanks Chris. > > Cheers, Gene Heskett _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
