Probably 310x310 mm as this seems to be the size of the Ultrabase platform?!
310x310mm is the size of the anycubic ultra bed.
If you use a biger size or original size you´ll need a solution to fix the glas plate (clamps…)
But this is why i used the ultrabed and designed my own brackets, with clamps there is the risk of glitching, struggle with the clamps and parts of the snapmaker.
Thanks. I ordered the full size.
When I was using glass, I used this sheet and applied it to the bottom of the glass. The glass will not move! It is thin and finicky to work with and you have to ensure you have no air bubless in it when installed but the benefit is there are no binder clips or anything else to interfere with the print surface.
If you have a thick pice of glass, wont a sheet/pice of Aluminium not work for the inductive sensor? hold it ontop the the glass while its calibrating, take it away when the print starts?
I tried the hold the build sheet on top of the glass method but it was just easier to do a manual cal when using the glass. Z probe works fine on the aluminum plate and i only run a 3x3 mesh because the plate is flat unlike the original build sheet and underlying cast build plate frame.
I’m really curious to try the Anycubic glass bed. Since it’s smaller than the original printbed, are there specific precautions you need to do to avoid printing off the edge of the glass, especially if building something that is close to 310 mm? Is there a parameter in Luban (or Simplify3D) so you can visualize the new printbed size, and adjust the zero axis, etc?
1 Like
so I use Simplify3D, and i did try the GlobalOffsets with shrinking the bed size and compared the resulting gcode vs a model with a “normal” print. I also redesigned the holders based on the ones linked here so they actually “clamp” the 310x310 glass to the bed (along with 0.5mm thermal pad). There are some… sever precautions with my setup, which is why i haven’t posted it yet (but i will, cuz it’s freakin awesome!).
but with the original holders posted here, they did work pretty well. What i found was that while they worked to “brace” the bed in place, pulling or prying the models off of the bed, because they stick EXTREMELY well, it tended to pop the bed off. Others have just added the thermal pad and that is fairly sticky so that likely helps. But the original braced holders don’t help with like “pulling” the bed to be against the glass so there is near-perfect contact for heating. Like i said I will update this, and i have a pretty big “showcase” planned with lots of mods, so this will be included in that.
so your specific question: what i do instead of the straight down/in-place purge, I “print” a line purge across the center right at the front of the glass (as lifted from the TH3D firmware starting G-code print for their EZABL). With that across nearly the “front” of the glass, that gives me a pretty good judge of where that front is in the S3D preview. From there, using just the grid, you can kind of judge the bounding box. It’s not perfect, but it’s something!
Here is my starting G-code. I have some different travel due to my clamping corners that i have to avoid, but this will work with no corners so shouldn’t be a problem.
;Start GCode begin
G28
G90
G1 X-10 Y170 Z10 F3000
G1 X25 F3000
G92 E0
M117 Purging extruder...
G1 X120 Y20 Z0.3 F5000.0 ; move to start-line position
G1 X200 Y20 Z0.3 F500.0 E15 ; draw 1st line
G1 X200 Y20.3 Z0.3 F5000.0 ; move to side a little
G1 X120 Y20.3 Z0.3 F500.0 E30 ; draw 2nd line
G92 E0 ; reset extruder
G1 Z1.0 F3000 ; move z up little to prevent scratching of surface
;Start GCode end
This results in a nice little line of filament across the front of the glass that you will have to remove with each print, but again it’s a very nice marker in the preview for where the front of the glass is, and marks the bounding grid relative to things. The X direction is less concerning since the glass mostly covers it.
Another “trick” if you have many small models is to use something like TinkerCad to arrange them, select them all, then you can see exactly their bounding box. You can then export them as a single model and arrange that as needed. What i tend to do is to set the models as close as i can together, select them all then move them around in the space close to the front.
hope that helps!
3 Likes
Thanks so much for this! I have ordered the same 310 x 310 glass so I’d like to copy your setup - I especially appreciate using Simplify 3D so your explicit info is very useful to me. I’ve been looking to add the extrusion line at the start like my older printer: I found this helps make sure the head is nicely primed even before the first outline brim is printed.
Can you clarify line “M117 Purging extruder…” should it be “M117 ; Purging extruder…” ?
I look forward to your more extensive posting - suggest in its own thread - hope to see it soon ! 
When you did the levelling - with the manual levelling does the A350 position the print head over the glass for all the points?
1 Like
Sure! So M117 is just a “message”: https://marlinfw.org/docs/gcode/M117.html so hopefully in the future SM firmware supports that. If seeing it from the console you might see messaging come out. These I just copied and kept from the TH3D starting G-code since they don’t hurt anything being there.
And yes, the manual leveling points for he 3x3 do all stay on the glass. For my larger full corner coverage though, I do have to adjust the “corner” points, so its a bit trickier to level and have to have the console hooked up and send commands during the leveling process to adjust those actual points. I do have this all recorded and want to run through it again to make sure it’s more repeatable before i publish it. ATM my machine is disassembled as i’m checking the linear rails for proper heating and will be adding a bit more thermal padding to certain spots since i’ve been experiencing some shifting for some more complicated prints. Luckily i bought 2 heights (0.5 and 1.5mm) for in between the glass and bed just in case, and a bunch extra when i bought that, so i have some to spare.
Yup, I’ll def be posting that here and all in my much larger post! Hopefully that’ll be soon-ish. I have some more things to print for that, but it’s in the works.
2 Likes
May I ask where did you buy a glass bed for the A350???
What is the thickness of the glass bed??
Couldn’t you perhaps simply get your glass, then apply a very thin sheet of steel on the underside for the sensor to detect, then simply remove and then adjust your z offset accordingly?
Or mayhaps a glass and steel with the same thickness?
Does the sensor only detect ferrous metals? If nonferrous metals, some aluminum foil might do the trick. The prox sensors we use at work are for nonferrous metals, but they will detect ferrous as well
The sensor detects aluminum. The sensing range is very short so you couldn’t put it under the glass.
If its anything like my sensors at work, it will detect steel too, from further away, but less accurately.
I think this is not like the sensors from your work then because the effective range is about 1 mm. The standard snapmaker bed uses spring steel and it only triggers about a millimeter away
Its a basic inductive sensor, there are many different versions that will activate at different ranges… the issue with using glas with metal affixed (either on top of then removed or below the glass) is that in both cases the sensor can not read the actual print surface. You would be better off figuring out a way to put a physical probe on the print head (like a bltouch). Because then you could read the actual glass surface you will be printing onto.
3 Likes
True buuuut you could z offset the thickness of the metal
Yes but the main reason for the auto leveling is to compensate for the small differences in the print surface. If the sensor cannot read the print surface you loose that.
Ahh yeah I see what you mean