If the mesh has low spots get some .2mm kapton tape and put on top of the magnet sheet under the flex build plate.
The bed will never be flat at all temperatures. The whole point of the bed mesh routine is to allow Klipper to compensate.
The PROBLEM with the SV08 is the bed changes shape AFTER the mesh is taken so Klipper is following the wrong map.
If you are printing functional parts that need high accuracy in the Z axis, unless you are willing to plunk down $400 for a precision ground plate cut from billet stock, print off a raft.
I had considered trying to engineer my own SV08 flat bed solution using a $44 350x350x4 mm glass sheet from Amazon that recently became available or the $65 8 mm Funssor graphite bed for the SV08.
I just watched Nadir’s video on the Funssor 8 mm aluminum build plate kit for the SV08.
He is getting slightly more than 0.1 mm of warp across the bed which is way better than the more than 1.1 mm of warping on my stock SV08, although it looks like Nadir’s bed mesh is cheating by only probing the ~240x240 mm center of the bed. I just purchased the $217 Funssor SV08 bed upgrade (including shipping). I’m tired of messing with the warped bed and this looks like a reasonably easy solution. I’ll let you guys know.
After the bed is flat, then I’ll need to address the other SV08 shortcoming, the slow and inaccurate proximity sensor that’s used to make the bed mesh. Sovol has promised to sell us a USB Eddy upgrade for the SV08 soon after the Zero and SV08 Max are shipping, and that sounds like NOW to me.
I’m looking forward to my SV08 finally living up to its awesome potential.
If Sovol lets me down on their promised Eddy probe upgrade, I might be tempted to swap to Nadir’s V5 tool head and gain LED lighting so I can see the prints, top of extruder filament run out detection so I don’t need to move the run out sensor on top of my custom enclosure and a lightweight extruder with better TPU filament path.
They use the same pictures for all their beds. The SV08 has the correct 6 bolt holes. I confirmed that with them before I ordered it. I rec’d confirmation that mine will be shipping on Sunday or Monday.
6 Bolts is a horrible design. That gives the frame the ability to twist and taco the bed as the heat from the bed slowly warms up the metal frame imbedded in the plastic base.
I feel like a bit of a schmuck. I waited and waited for a decent after market solution to the SV08 taco bed, stumbled across Nadir’s recent video and made the snap decision last Friday to get the 8 mm thick Funssor aluminum bed. I spent the $217 to have it shipped to the US and then almost immediately saw the graphite bed. Derp. I’ll console myself that the thicker aluminum bed should be able to maintain “good enough” flatness to within 0.3 mm, even if it can’t achieve the < 0.1 mm flatness demonstrated in the R3men graphite bed video, which costs $251 shipped to the US. The thicker Funssor aluminum bed will be much better than the > 1.1 mm warping on my stock SV08 bed. It supposedly shipped two days ago but UPS is still showing they haven’t received it.
The R3men site showed four screws and standoffs ship with the bed. I agree with cardoc that three points define a plane and any more is not only superfluous but even counterproductive, but I think a much better design would be a bed mounting system that positively supported the bed in Z while allowing some motion in X and Y. Screwing down the bed with 3 screws, or 4, or 6, is a recipe for thermal expansion induced warping. Maybe constrain the bed in X,Y and Z (and also the three rotational axes of freedom) at one point and allow the other points to support the bed in Z while allowing thermal expansion in X and Y.
Now I need for Sovol to sell me an Eddy upgrade for the SV08 and I’ll be very happy.
The trick with the R3men bed, though, is that graphite has a much lower thermal expansion coefficient than aluminium. Admittedly, the screws themselves may experience thermal expansion, but that’s likely to be a minimal effect.
I actually managed to get the stock bed to ~0.138mm with the brute-force method of shimming under the bed itself using washers and paper. However, that results in a really bumpy bed (measuring at 30x30 points using an Eddy Duo). I’ve got a R3men bed here which will go in later today…if nothing else, the lack of heat soak will be a major upgrade to my workflow. I’d also like to get back to using the stock build plate - I’ve been using a CryoGrip Glacier to reduce the print temperature in an effort to combat the problem, but I much prefer the standard plate’s bottom surface finish.
I just got my R3men bed installed on my SV08 and was very disappointed that the bed was giving me a difference of approx. .550mm. I thought maybe I had tightened the screws too much and changed them to finger tight. That brought it to around .400. The bed was relatively flat except for a drop of about .2 mm on the right side from the edge to about 20 mm in.
After lots of sanding (then checking with QGL and rapid scan and sanding some more) on the high side, I was able to get it down to about .204 mm which is very close to the dip on the right edge.
I have ordered some high temp shim tape 25mm x .05 mm and will be playing with that to raise that edge and hope to get it to .1mm or below..
So the graphite bed may be flat but the magnet plate is pretty bad. At least on the one I rec’d. Here is my current mesh.
I am running Demon Eddy - hence the rapid scan I mentioned. I will try what you suggest and see what happens. I print a lot of large objects so losing some of the bed is not welcomed. I tried putting a piece of paper between the plate and the bed magnet in about an inch and it made that edge too high so I am thinking building up the edge with the thin tape should work quite well by adding one piece at a time and testing the mesh.. Fingers crossed.
The best way to verify the mesh isn’t suffering from edge effects is to print a sheet.
ALL eddy current devices loose their accuracy at the edge of the conductive surface. I bet your eddy is mounted to the right of the nozzle. Different sensors react differently near an edge based on several variables.
Your “demon” macros can’t solve inaccurate measurements from the sensor.
I think your plate IS flat and the mesh is WRONG.
Print a sheet.
Shimming your bed is the wrong thing to do if your mesh isn’t accurate
Print a sheet.
Excluding the edge from the mesh measurement WON’T prevent you from printing on that edge. The software will “extend” the mesh based on GOOD measurements from close by points.
Use capton tape onl lair at a time until you get it where you are happy. The capton tape is heat resistant and should stay put for a long time. It is also very thin and will give a very acrid path to building up arias that is low.
R3men warns that the graphite bed is flat but there are significant variations in thickness across the magnetic sheet that will result in the print bed not being flat. Cardoc’s recommendation to print a first layer test sheet is a very good way to determine the Klipper compensated flatness of the bed. If Klipper is printing too low on the leading edge that Eddy is reporting as low, then the Eddy is probably experiencing edge effects and is reporting the bed is lower than it is, which is the direction the error would be if caused by edge effects.
To get an actual measurement of the flatness of the bed without inaccuracies from the Eddy probe or Klipper’s compensation based on the Eddy bed mesh, I plan on using a Sharpie marker on the tool head while G code scans the entire bed. Gradually lower the Z until the Sharpie marks the high spot of the magnetic sheet. Sand the Sharpie marked area and repeat. Once I know the magnetic sheet is flat and level, I can proceed with the rest of the process. Rotating the PEI spring steel sheet on the flat magnetic sheet and repeating the Eddy scan will determine any thickness differences across the PEI coated spring steel (should be minimal) and will also determine if there is an Eddy probe edge effect.
My R3men graphite bed for the SV08 cleared US customs several days ago and USPS is still showing they haven’t received the item. Hopefully, I’m within a week of having my new graphite bed. Now if Sovol will only release their Eddy probe tool head for the SV08.
