[HN Gopher] 3D Printer Auto Bed Leveling Mesh Visualizer
       ___________________________________________________________________
        
       3D Printer Auto Bed Leveling Mesh Visualizer
        
       Author : macinjosh
       Score  : 84 points
       Date   : 2023-12-19 03:27 UTC (19 hours ago)
        
 (HTM) web link (i.chillrain.com)
 (TXT) w3m dump (i.chillrain.com)
        
       | nycdatasci wrote:
       | Context?
        
         | mardifoufs wrote:
         | A 3d printer bed is never actually flat, especially since 3d
         | printers are cheaper and the tolerances are usually pretty
         | loose compared to a super flat, precisely ground CNC bed for
         | example.
         | 
         | One of the biggest issue/pain point in 3d printing for a while
         | was to adjust the bed to make jt flat, or at least as flat as
         | possible so that you can actually print without massive issues
         | on the first layer. The process used to be manual, tedious and
         | hit or miss (due to drift in the screws, or thermal expansion)
         | etc.
         | 
         | Nowadays most new printers come with a sensor that probes the
         | bed at multiple points (say in a grid of 4x4), then using for
         | example a lagrange interpolation you can get a mesh that
         | represents how flat your bed is. Then, using the visualisation
         | you can either manually adjust the bed (with screws that rise
         | or lower a certain corner), or even just let your printer
         | compensate for the deviations.
         | 
         | That is, the printer moves the Z axis even when it is still
         | printing on the same layer to make the print surface
         | "virtually" flat (not always ideal if the Z axis stepper is
         | trash, or if the deviation is too wide, or if there's too much
         | vibration). That means that usually, the issue of bed levelling
         | is mostly solved for newer printers!
         | 
         | Some printers also just use the nozzle itself as a probe,
         | combined with a load cell. But those are usually on the higher
         | end. The most common way is just a small probe of known size
         | that sticks out and then calculates how much it extended before
         | reaching the bed. (Some even use a pretty high res lidar to
         | make sure the first layer is fine, even in some sub 900$
         | printers).
        
           | NegativeLatency wrote:
           | Or an inductive sensor: https://help.prusa3d.com/article/p-i-
           | n-d-a-superpinda-sensor...
        
             | mardifoufs wrote:
             | Yep, having that by default since I think 2018, is one of
             | the reasons prusas have a reputation of being super easy to
             | use. It's way better than even a bltouch. Nowadays it's a
             | lot more common thankfully though I don't think other big
             | players use inductive sensors.
             | 
             | Even prusa is now using a load cell that apparently will be
             | used for much more than just bed levelling (the load cell
             | could be able to tell if filament is stuck, because the
             | motor will push without extrusion leading to a variation in
             | load for example). Very exciting times in 3d printing
             | honestly (and I say that as someone that is pretty
             | "bearish" on 3d printing usually)
        
           | lawn wrote:
           | It's often not the bed that isn't flat, but that the rest of
           | the printer itself moves and expands.
        
             | mardifoufs wrote:
             | Yeah or the bed itself is fine, but it's on a bad bed
             | support. That's why even a perfectly flat glass bed plate
             | can be completely uneven since the structure itself is
             | crooked! Considering that quite a few printers are self
             | assembled too (with basically no torque specs, and users
             | that have little means to build it accurately), it's just
             | compounded even more.
        
             | zokier wrote:
             | 3D printer made of Invar/Kovar next? :)
        
           | dotnet00 wrote:
           | There are also issues like even if extremely flat, the way
           | most printers mount the bed, it's going to bend measurably
           | simply from expanding upon heating up and the distance
           | between the mounting points not expanding the same amount.
        
             | londons_explore wrote:
             | As long as you always print with a hot bed, that effect
             | doesn't matter - just calibrate it when hot.
        
               | Mashimo wrote:
               | You mean "As long as you always print with the same bed
               | temperature"?
               | 
               | Because there is a difference how your bed looks from 60
               | C for PLA to 110C for ABS.
        
               | londons_explore wrote:
               | Just do the first layer at 110 for all materials. PLA
               | actually adheres far better at 110C, but obviously you
               | need to cool it down before building too many extra
               | layers on top.
               | 
               | Slicers have a setting for "Bed temperature initial
               | layer" for exactly this reason.
        
               | Mashimo wrote:
               | I find it easier and faster to just print PLA at 50 - 60
               | C bed and use probes for mesh and z level.
               | 
               | I never heard of anyone printing PLA with 110C first
               | layer.
        
               | Baeocystin wrote:
               | I usually start my PLA prints at ~80C for the first
               | layer, dropping to 65C for the rest. I first tried it
               | because I was playing with PEO plates that had an
               | iridescent pattern I wanted to strongly embed in the
               | layer, but it turns out to be a good general pattern
               | overall. Really reduced the amount of support material I
               | need on certain prints, which is a big plus.
        
               | bborud wrote:
               | I've never tried that. I've usually tried to not have the
               | build plate temperature vary too much for fear that the
               | plate might contract a bit if I cool it down and the
               | print might pop off?
        
               | londons_explore wrote:
               | Temperature changes above the plastic transition
               | temperature won't cause it to pop off. Only when you drop
               | a reasonable amount below the plastic transition
               | temperature will it pop off.
        
         | NegativeLatency wrote:
         | Kinda neat to see a scaled up visualization of the vertical
         | height differences of your printer bed.
         | 
         | https://marlinfw.org/docs/gcode/G029-ubl.html
        
         | shadycuz wrote:
         | Some 3d printers have automatic bed leveling. Which is a
         | process where the printer will touch the print bed in many
         | places with a probe. This allows the printer to detect peaks
         | and valleys, which it can then compensate for. The website
         | above allows you to visualize that data.
        
         | flatline-84 wrote:
         | 3D printers can do a variety of "bed mesh" leveling, which is
         | where they probe the bed in a grid pattern and then can
         | compensate for any deformities in the bed via software.
         | 
         | This ensures that the first layer (arguably the most important)
         | for any print is perfectly flat and level. This visualizer
         | takes the output of the bed mesh calibration sequence (where
         | each point is a z-offset, usually from what the printer has
         | defined as 0 based on the end stop) and graphs it so you can
         | see your bed deformation.
         | 
         | Most Klipper frontend UIs already have support for this though
        
         | Doxin wrote:
         | For a 3d printer the distance between the print bed and the
         | nozzle when printing the first layer is _very_ important. If
         | the distance is too big the print doesn 't stick to the bed and
         | you end up with spaghetti. If the distance is too small either
         | not enough plastic comes out so your print doesn't stick; no
         | plastic at all comes out so your print doesn't stick; or the
         | nozzle digs into the printbed, damaging it.
         | 
         | Since the thickness of layers in a 3d print is around 0.1-0.3mm
         | the margin for error is rather tight. Since no one is going to
         | invest in precision ground printbeds you need to get that
         | precision by some other method. One of those methods is to
         | probe the bed height at various points before printing, and
         | driving the Z-axis to correct for that during the print.
         | 
         | The linked tool can be used to visualize how nonflat your
         | printbed is given a set of such probes. The default example
         | seems to have a +-0.25mm error, which isn't amazing but should
         | be usable with mesh leveling and not at all without.
        
           | feiss wrote:
           | This is neat, today I learnt. Can an Ender 3 do mesh
           | leveling?
        
       | kayson wrote:
       | Octoprint has a plugin (Bed Mesh Visualizer) that does this.
        
       | smcleod wrote:
       | Klipper's frontend (Mainsail) has this built in.
       | https://docs.mainsail.xyz/
        
         | flatline-84 wrote:
         | There's also Fluidd
         | 
         | https://docs.fluidd.xyz/
        
       | cassac wrote:
       | Prusa Link/Connect also has this.
        
         | antirez wrote:
         | Are you sure PrusaLink has it? I've an MK4 with latest firmware
         | and I can only see the usual temperature graph and file
         | browser, and that's it. Not that the bed visualizer would be so
         | useful with the MK4: this printer (like the XL) really does not
         | have leveling issues.
        
         | yokoprime wrote:
         | I think you're confusing the control screen with leveling mesh
         | visualizer. Prusa Connect does not have this, Prusa Link is
         | even more bare bones.
        
       | numpad0 wrote:
       | IME, ABL is not that important. Personally I spray bed with a
       | hairspray and tweak leveling screws while first layer is going
       | on[1], that's just fine.
       | 
       | Old Marlin ABL also has bug/tendency to report erroneous tilt
       | towards the last corner it measures, I suspect due to Z axis
       | missing step from microstepping. Ultimately it was too finicky
       | for me without resorting to closed-loop drivers, which also
       | almost completely solved the leveling problem.
       | 
       | 1: I know it is a big flat NO to touch a robotic equipment in
       | operation, unless said robot is specifically designed to be
       | almost completely incapable of applying any force to any parts of
       | a human body, but I'm smart and I consider my printer a co-bot so
       | it's okay(it's not okay. A better solution is needed).
        
         | dotnet00 wrote:
         | ABL is not that important if you don't mind babysitting the
         | printer. But it's an amazing quality of life improvement
         | otherwise. Especially if you're printing stuff that needs
         | precision.
         | 
         | Manually leveling an ender 3 was tolerable to me for about a
         | month while learning 3d printing and figuring out if it was
         | something I would be into long term, but over the course of a
         | year I went from that, to trying various ABL sensors and bed
         | replacements, to now a custom built Mercury One.1 with 3 point
         | kinematic auto bed leveling, and it's such a night and day
         | difference in terms of usability.
         | 
         | It physically levels the bed and automatically determines the z
         | offset, so I don't have to do anything when using different
         | print surfaces and when operating at different temperatures/in
         | an enclosure. Heat expansion is pretty noticeable (I've
         | destroyed pei plates with the nozzle by calculating z offset
         | when cold but attempting to print when hot), and while sticking
         | your hand under the bed of a printer printing PLA is not that
         | dangerous, with ABS the bed is at 110C, not at all worth the
         | risk, so autoleveling is very helpful.
         | 
         | It makes it so much easier to just submit a print job, forget
         | about it and find it finished perfectly, without involving any
         | finicky adhesives.
        
           | lvturner wrote:
           | I'm with you, adding an auto bed leveler was the single
           | biggest upgrade on my 3D printer, for the type and printing I
           | do and the frequency I use, it's really just made it fire and
           | forget (I'm sure I could improve it /even/ further) where as
           | previously I felt I had to re-level after every print.
        
           | Baeocystin wrote:
           | 3D printing has a bifurcation in the hobby; some people enjoy
           | it for the objects they can make, some people enjoy it for
           | the printers themselves. I pass no judgement either way, just
           | an observation. I saw the same thing in the photography
           | world; some were gearheads, some couldn't care less, and were
           | focused on the image.
           | 
           | As for me personally, I spent many entertaining, delightful,
           | maddening and frustrating years playing with a frankendelta
           | of bodged parts, broken firmware and hacked wiring. Learned a
           | ton, don't regret any of it. But the moment I got an X1C, the
           | Rostock has been relegated to Spiral Vase mode only. And I
           | can't help but note my actual printing volume has increased
           | dramatically when the process became less of a babysit.
        
             | dotnet00 wrote:
             | Yeah, that I can agree with. However I'm very much in the
             | "gearhead" camp :)
             | 
             | That's why I went with a DIY design. Similarly learned a
             | ton, lately I'm finishing up a multi-material unit, then
             | I'll start again by rebuilding and modding the disassembled
             | Ender 3 to gift to a relative who has a slight interest in
             | DIY stuff.
        
           | rpmisms wrote:
           | I print working firearms and firearm parts. I follow the bed
           | levelling method detailed in GP, and I have never had a gun
           | failure due to lack of precision, which is critical in
           | firearms. I also do this with Nylon and TPU, zero issues.
           | Sure, ABL is nice, but I'd rather use the budget on a proper
           | hotend and direct drive.
        
             | Mashimo wrote:
             | > ABL is nice, but I'd rather use the budget on a proper
             | hotend and direct drive.
             | 
             | I agree with you, 5 years ago. But now days even cheaper
             | china designed hotends can be decent. And direct drive is
             | de facto standart.
             | 
             | ABL is cheap and convenient.
        
               | rpmisms wrote:
               | This is all true, but FOSSCAD world is a little
               | different, and a good hotend makes much more difference
               | than ABL. Microswiss is the minimum. I need perfect
               | extrusion, not perfect alignment along a non-critical
               | axis. For the hobbyist, you are correct.
        
           | londons_explore wrote:
           | I haven't levelled my bed in months or maybe years... Sure,
           | it was a pain to level it the first time, but once it's level
           | it should stay level unless you disassemble the printer.
        
             | rcarmo wrote:
             | Thermal expansion (especially in long cycles) tends to warp
             | beds.
        
               | londons_explore wrote:
               | Glass and aluminium do expand and might bend when heated,
               | but they don't bend _more_ when heated hundreds of times.
               | Therefore as long as you calibrate it when hot, it should
               | stay calibrated (unless you let the calibration screws
               | vibrate+turn or something)..
        
               | rcarmo wrote:
               | I have a 10-year glass bed on my Prusa clone that would
               | like a word with you :)
               | 
               | (I replaced it with a garolite sheet, am very happy with
               | that)
        
           | ravenstine wrote:
           | Interesting. I don't think I've ever knowingly encountered
           | heat expansion of the bed itself affecting the prints.
           | 
           | I print on glass and only occasionally have to do anything
           | about bed leveling. No need to pry or pull and mess up the
           | leveling when all you have to do is just wait a few minutes
           | for the print to cool and it pops right off. Never printed
           | ABS on glass though, so I can't say if it works as well for
           | that. Autoleveling would be cool, but I have very little
           | interest in it because I haven't needed it and it seems like
           | an added point of failure.
        
         | planb wrote:
         | I never got ABL to work with marlin, despite trying all
         | possible configurations and versions, so I just did it the same
         | way you do. With Klipper, it just worked when I first installed
         | it. Never looked back.
        
         | lawn wrote:
         | With proper bed leveling and the right bed temperature you
         | don't need to bother with hairspray.
         | 
         | Having to resort to glue is often a sign that something else in
         | your setup isn't tuned correctly. ABL is one thing that helps.
        
           | numpad0 wrote:
           | Mine is a 300x300x600mm frankenstein gantry build loosely
           | based on Tronxy X1, so that's indeed on myself. But Marlin
           | ABL didn't seem worth it even before I'd done upgrades.
        
           | bborud wrote:
           | It also helps to clean the build plate from time to time too.
           | 
           | Over time grease from your fingers will make it onto the
           | surface (no matter how careful you think you are). Some
           | filaments also seem to leave behind an oily residue that
           | builds up after a few prints.
           | 
           | I haven't done much research on what I should be using so I
           | have a bottle of iso and a sponge that I use to wipe down the
           | surface. (A microfiber cloth would probably be better).
        
         | TaylorAlexander wrote:
         | I have twelve 3D printers and I bought my first machine, an
         | Ultimaker 1, in 2011.
         | 
         | I managed fine without it but every advancement that means less
         | fiddling is a huge quality of life improvement that I always
         | strongly prefer. I got ABL for the first time by modding it in
         | to a printer I had. I then modded it in to my other printers,
         | and now would never consider or recommend a printer without ABL
         | unless someone is very broke and can only afford the cheapest
         | Ender 3.
         | 
         | The Prusa Mk4 improves upon older automated bed leveling
         | techniques by using a load cell in the nozzle itself to measure
         | exactly where the nozzle touches the bed, rather than using a
         | sensor near the nozzle which then requires manual height
         | calibration. I have five Prusa Mk3s but I really want the Mk4
         | in large part for that.
         | 
         | I am so bleeping tired of fiddling with my 3D printers, I just
         | want them to work.
        
         | starky wrote:
         | The idea of having to put anything on your bed and fiddling
         | with adjustment knobs seems so wrong when there are plenty of
         | printers out there that are good enough now where I can send a
         | print to them and maybe check on them in 10 minutes to make
         | sure the first layer didn't fail and be confident that they
         | will complete. From the very first time I used it I realized
         | that ABL is a must on any printer now.
        
           | yreg wrote:
           | Maybe if you don't care much about the budget.
           | 
           | I don't need a printer and only use it sparingly, so I chose
           | an Ender v2 for like 250EUR. It has bed-leveling problems,
           | but it's not enough of an inconvenience to be worth it to me
           | to cough up 3x of the money for Prusa.
           | 
           | If all else fails I use a glue stick, like the GP. There's
           | nothing wrong with that, it works.
        
             | Mashimo wrote:
             | > Maybe if you don't care much about the budget. > I don't
             | need a printer and only use it sparingly, so I chose an
             | Ender v2 for like 250EUR.
             | 
             | Now days you can get an Bambulab a1 mini for ~335 that has
             | auto leveling, auto z offset, nozzle pressure sensor and
             | can do a 14 minutes benchy.
             | 
             | You can also get a Prusa mini is ~2 times the money of your
             | Ender v2.
        
               | yreg wrote:
               | They both have smaller printable areas and +40%/+100% is
               | still a pretty big price difference.
        
               | Mashimo wrote:
               | Sure sure, but you can care about budget and get a
               | printer with decent sensors for auto z and bed level.
               | 
               | I started with bed screws, and never want back to printer
               | without probes or flexible bed sheet.
        
             | starky wrote:
             | I struggled with the cheaply built printer that requires a
             | lot of upkeep the first time like many (Tevo Tarantula in
             | my case), and in the end I realized that between the
             | upgrades to just make it work safely, and the time wasted
             | just fiddling around with getting it to print made the
             | Prusa well worth the money.
             | 
             | Buy the Ender if you want working on 3D Printers to be your
             | hobby, if you want 3D printing to be your hobby, then buy
             | something actually reliable. I would take a small build
             | volume and high reliability over something larger every
             | single time.
        
               | yreg wrote:
               | > if you want working on 3D Printers to be your hobby, if
               | you want 3D printing to be your hobby
               | 
               | Those two go hand in hand for all hobbyists I know,
               | including the Prusa owners. I don't struggle with Ender,
               | actually I was surprised how good it is, since my
               | reference point was much older (and much more expensive)
               | printers.
               | 
               | Maybe I have lucked out on the build quality, I don't
               | know.
        
           | nirav72 wrote:
           | ABLs are nice to have and printers should have them. But
           | every so often, a manual bed level with a piece of paper goes
           | a long way. Especially if you have a budget friendly printer.
        
         | yokoprime wrote:
         | I click print in my slicer and move on to do other things,
         | casually looking at the camera feed a couple of times during
         | the 1st layer
        
         | ehvatum wrote:
         | > unless said robot is specifically designed to be almost
         | completely incapable of applying any force to any parts of a
         | human body
         | 
         | Be careful, but don't beat yourself up over it. Many CNC
         | milling shops regularly run jobs that cannot succeed without a
         | human gripping the workpiece to control vibration.
         | 
         | The folks I really worry about are the waterjet cowboys. The
         | garnet particles that lend a waterjet the power to cut titanium
         | get embedded inches from the site of the wound, if that stream
         | touches skin. Amputation one or two joints up from the wound is
         | standard treatment.
        
         | stavros wrote:
         | I have a long history of woes with this stuff. I initially had
         | a Wanhao that didn't have ABL, that worked fine as long as I
         | didn't change anything. Then, I got a BLTouch, which made it
         | worse because the Z distance would always be inconsistent
         | somehow.
         | 
         | I realized that Marlin must have some sort of bug, because it
         | claimed to be able to print on tilted beds with ABL, but mine
         | just didn't. I upgraded to Marlin 2.x and that was fixed.
         | 
         | However, now I have this problem where the print lifts on
         | certain regions of the bed. I have no idea what's up with that,
         | I use one of those golden, textured PEI sheets and it works
         | fine, except for these holes in areas.
         | 
         | I wish someone would put a pressure sensor on the nozzle so it
         | would always know the exact distance in real time and could
         | compensate for anything, but we seem to be far from that.
        
           | Symbiote wrote:
           | > However, now I have this problem where the print lifts on
           | certain regions of the bed
           | 
           | If it's the edges of wide, flat prints, search for problems
           | with "warping". Draughts and uneven heating can cause it,
           | especially combined with poor adhesion to the bed.
        
             | stavros wrote:
             | It's not, it's a very odd issue in the middle of laying
             | down a layer line, where a tiny mm raises/blisters, then in
             | the next layer the raised part gets a bit longer, then a
             | bit longer, until it becomes a big hole within twenty
             | layers of this. It's very odd.
        
               | Baeocystin wrote:
               | I had a similar problem with my old Rostock Max, and it
               | turned out to be integer math errors in the
               | delta>cartesian conversion step. FWIW.
        
         | RoseyWasTaken wrote:
         | I can't agree with you on this. With bigger printer beds (I've
         | got a 500mm x 500mm x 500mm machine) it's crucial to have ABL
         | working, as the height of certain points of the print bed can
         | be within a range of over 0.2mm, which, as I'm sure you know,
         | is the thickness of a layer a lot of times.
         | 
         | With simpler/smaller printers, sure, you can get away without
         | an ABL probe.
        
       | bbbbbenji wrote:
       | I've also made something similar. It was originally for the Prusa
       | Mini, but I've updated it with a beta that accepts an arbitrary
       | array of probe points: https://bbbenji.github.io/PMSBLM/beta/
        
       | Mashimo wrote:
       | Title needs [2019]
       | 
       | It's something that is build in on most UIs now days.
        
       | m4rc3lv wrote:
       | This is really cool!
        
       | picadores wrote:
       | So that is two layers of filler to create a perfect bed to print
       | on?
        
         | Mashimo wrote:
         | ~0.6mm, two layers of you use 0.3mm, people often use 0.2mm
         | layer height though.
         | 
         | But I think mesh bed can handle this.
        
           | picadores wrote:
           | How does the printer compensate for precision loss do to
           | movement? In industrial robotics, there is the concept of
           | measuring the inprecissions in the machinery at any given
           | point (direct measurement) and compensate that via variables
           | in the robotic matrice. Is there something similar for
           | printers?
        
             | Mashimo wrote:
             | I'm not sure. But in the end you are laying molten plastic
             | on top of each other. Even with a perfect flat print
             | surface you will have slightly uneven extrusion that will
             | be noticeable on top down lighting.
             | 
             | Silver cubes with direct lighting https://github.com/lord-
             | carlos/mk3-upgrade/blob/master/asset... Same cube with top
             | down light: https://github.com/lord-
             | carlos/mk3-upgrade/blob/master/asset...
             | 
             | What we have is Pressure Advanced. Where we stop extruding
             | (as much) right before a corner. And we do that by doing
             | some test prints with different values and eye balling it.
             | 
             | Also some firmwares like klipper have some math in it to
             | compensate for heat expansion over time of the printers
             | frame. Or something like that.
        
             | numpad0 wrote:
             | Most hobby printers do not compensate at all. There are
             | input shaping to reduce vibration, and hacked together
             | closed-loop upgrades, personally I haven't heard of any
             | more sophisticated controls.
        
       | RoseyWasTaken wrote:
       | ABL has been recently improved with the Beacon 3D probe
       | (https://beacon3d.com/), I haven't had a chance to try it myself
       | yet, as my cheap induction probe has been working reliably ever
       | since I mounted it.
       | 
       | But, the Beacon 3D along with mesh leveling and selective
       | leveling area are my favorite recent innovations in 3D printing.
        
         | stavros wrote:
         | Does it work well? All I want is a reliable first layer, as
         | that's what causes 99% of my failed prints.
        
           | Kirby64 wrote:
           | Yes, I have one and it works exceptionally well. The only
           | caveat is that it's measuring the metal surface directly and
           | not the actual physical surface (such as PEI), so you need to
           | load different offsets if you swap between different material
           | surfaces such as textured PEI, flat PEI or bare steel.
        
             | stavros wrote:
             | Oh, how does it do it? I thought it used light/laser to
             | measure, if it's measuring the metal it might not be very
             | accurate with my two layers of magnet and PEI sheet on
             | top...
        
               | Kirby64 wrote:
               | It generates a field using the coil measures the eddy
               | currents in the material directly below it. As long as
               | you have a spring steel sheet and don't have those large
               | discrete magnets (either lots of tiny round magnets or
               | the sheet magnets) it works just fine.
               | 
               | It's accurate to single digit micrometers (yes,
               | actually).
        
               | stavros wrote:
               | Wow, that's impressive. Aren't most buildplates made of
               | aluminium, though? Also I always worry that the PEI sheet
               | over the plate will introduce inconsistencies, let alone
               | that mine has an extra layer of magnet sheet on it (and,
               | as you said, the magnet even makes the detection not
               | work).
               | 
               | However, it seems very doable to have a Beacon for the
               | bed scanning, and a BLTouch for getting the physical
               | distance over the sheet plate.
        
               | Kirby64 wrote:
               | Most PEI sheets are quite uniform so you don't really
               | have issues with that. As long as they're applied to the
               | build plate without bubbles they're generally as flat as
               | the plate surface.
               | 
               | Also, no, almost no build plates are aluminum. Modern
               | printers usually use a silicone heater bonded to an
               | aluminum frame, which either has magnets embedded in it
               | or a sheet magnet applied on top of it, then a spring
               | steel plate with some sort of PEI on top is what you
               | print on. That's what Prusa and Bambu use, for instance.
               | 
               | I don't know why you'd want to use BLtouch to get the
               | physical distance, since you calibrate the physical
               | distance when calibrating the beacon sensor itself. Not a
               | problem unless you frequently swap between materials of
               | different thicknesses.
        
               | stavros wrote:
               | > Also, no, almost no build plates are aluminum.
               | 
               | Ah, I must be misremembering, thank you.
               | 
               | > Not a problem unless you frequently swap between
               | materials of different thicknesses.
               | 
               | Yep, exactly, I have a PEI sheet (with a magnet) and it
               | has a smooth and a rough surface, and I end up swapping
               | between them sometimes. I guess it doesn't really make
               | any difference, since they're both the same height (as
               | they're two sides of the same sheet), but, as you say, my
               | magnet sheet ruins the Beacon homing anyway.
        
               | Kirby64 wrote:
               | Explicitly a magnet sheet does NOT ruin Beacon and is the
               | preferred magnet type for sticking down build surfaces.
               | The only problematic magnets are point magnets that are
               | very strong, as the magnet field can penetrate the
               | surface of the material being scanned and impact the
               | readings (but only at that point).
               | 
               | It sounds like what you're describing is sheet magnet
               | that is coated in PEI, but I highly highly doubt that is
               | what you have. The magnet is attached to the frame, not
               | the material that you print directly on.
        
               | stavros wrote:
               | > As long as you have a spring steel sheet and don't have
               | those large discrete magnets (either lots of tiny round
               | magnets or the sheet magnets) it works just fine
               | 
               | Hmm, from this I understood that a sheet magnet _will_
               | ruin Beacon.
               | 
               | I don't have a magnet that's coated in PEI, I have a
               | magnet sheet on the bottom (stuck to the big bed plate),
               | and, on top of that, a thin steel plate (the one you bend
               | to pop the print off) coated with PEI on each side
               | (smooth/rough PEI). If the magnet sheet _under_ the steel
               | plate doesn 't mess with Beacon, I'm going to buy a
               | Beacon right now.
        
               | Kirby64 wrote:
               | See their FAQ documentation:
               | 
               | https://docs.beacon3d.com/faq/
               | 
               | What you're describing is the ideal material stack up for
               | beacon. Only thing you may need to do is load a different
               | nozzle offset for the smooth vs rough side, since the
               | thickness of the PEI is probably not the same.
        
               | stavros wrote:
               | I did have a look, all it says is:
               | 
               | > Magnetized rubber sheets have a high number of poles,
               | and result in no detectable artifacts.
               | 
               | Which kind of sounds like what I want, but doesn't
               | _actually_ say  "you'll be fine if you have a magnetized
               | rubber sheet", "no detectable artifacts" might very well
               | mean "the sensor doesn't detect your bed".
               | 
               | Thanks for the clarification, this sounds great.
        
           | TaylorAlexander wrote:
           | Look in to the Prusa Mk4 which uses the nozzle itself with a
           | built in load cell to probe the bed, providing perfect
           | offsets every time!
        
             | stavros wrote:
             | Ah, damn, that's great! Not CoreXY, but I'm sure someone
             | will put this on a CoreXY printer, and then no more bed
             | leveling!
        
               | TaylorAlexander wrote:
               | Oh someone has put this on a CoreXY: ;)
               | 
               | https://www.prusa3d.com/product/original-prusa-xl-3/
        
               | stavros wrote:
               | Ahaha XLent.
        
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