Strange Ripples in the Heatmap



  • Hello,

    I was just wondering if anyone might have any idea what is causing these "ripples" in my heatmap? I recently rebuilt practically the entire printer and installed a new carriage system with real Igus bearings on my x and y-axis. I also swapped out my leadscrews for 1mm pitch/lead screws on the z-axis. I have gone through and tightened all the linear rods, though I left the top of the lead screws free. I thought these ripples were the result of a bent linear rod or maybe a guide rod that had a bit too much play in it. Any insight would be appreciated.ripples in the heatmap https://ibb.co/vXZMqdd

    I use a bltouch for bed levelling. And I am on the duet wifi 2.0.4 firmware.



  • I trust that you know that you are talking HEIGHT map and not HEAT map ?
    I have strange abnormalities in my bed as well and the only thing I can suggest is that you are seeing manufacturing oddities. Are you using a removable top on your bed such as a glass plate? If yes then try to turn it 90 degrees and run the surface scan again to see if the ripples have also rotated which would indicate that the glass is slightly rippled.
    Having said all that, I would LOVE to have an even bed such as that !

    PS.: I have no idea why the color scheme on the map is called 'Heat' as it has nothing to do with temperature as far as I know.



  • @jens55 Thanks for the reply, you are absolutely right it is a height map. I saw the heat map label on the right and it just got stuck in my head that I should call the thing a heat map. The bed was a nightmare before the overhaul, I could never get the thing level. I am really happy with the current deviation range, but was curious if anyone else had seen ripples like that.

    I am printing on an anycubic ultrabase, but it is 240mmx220mm and i only have enough clearance for the 220mm width. I will try pulling it off and running the bed probing on the bare heatbed though. You may be right that it's just rippled glass. I'll let you know how it goes.



  • You could also try flipping the glass plate - that might move the ripples around. Be sure you grab a screen shot of each map so you can compare in detail.



  • What settings are you using for the BLTouch?



  • Here is my configuration for the bltouch
    ; Z-Probe
    M574 Z1 S2 ; Set endstops controlled by probe
    M307 H3 A-1 C-1 D-1 ; Disable heater on PWM channel for BLTouch
    M558 P9 F100 H5 T6000 R0.2 A5 B1 ; Set Z probe type to bltouch and the dive height + speeds
    M280 P3 S140 I1 ; Enable 5v logic for BLTouch
    G31 P25 X-22.00 Y-16.00 Z0.29 ; Set Z probe trigger value, offset and trigger height
    M557 X20:180 Y20:180 S15 ; Define mesh grid



  • Sorry it took so long to get this next height map done, I got distracted with attempting to align my leadscrews and seeing if that helped. Based on this walkthrough: https://www.youtube.com/watch?v=T9vI6DqAcmo. Unfortunately it didn't seem to make much of a difference, but I feel better about my rods now.

    So here is a second height map collected without the glass on the bed. I liked the idea of flipping the plate, but there is an adhesive layer, with it's backing sticker on it that has lots of wrinkles so I opted just to go with the bare plate. https://ibb.co/Rz9tNMk

    The ripple is still there, and I'm not really sure why. I have a second bltouch, I may end up switching them out, but it seems pretty consistent with the spacing on the ridge, so I'm not sure that it will help.



  • Is there something in your x axis Making it bump?



  • I can't find anything making contact or interfering. Funny thing is I also tried changing the probing density and I saw the same ripples with M557 X20:180 Y20:180 S50 I forgot to take a screenshot of it. but it does one row normal, then one row crests. I'll look into it more tomorrow. But this one baffles me. I think I can still print around it, but now I am curious.


  • administrators

    The clue is that when bed probing, RRF moves the head in the +X and -X directions on alternate rows. So your height map shows that the nozzle height depends on whether the last move was in the +X or -X direction. Your X carriage probably tilts a little depending on which direction the belt last pulled it.



  • @dc42 I think you've nailed it. While the linear rods are secure, the gantry is stable and the bearings seem to be snug, there is a bit of tilt play in the carriage. I will print a new carriage, thanks for your help, I would have been running circles around that problem for a long time.



  • @Grudairian said in Strange Ripples in the Heatmap:

    G31 P25 X-22.00 Y-16.00 Z0.29 ; Set Z probe trigger value, offset and trigger height

    I guess this is particularly noticeable with the probe offset in Y. Can you mount it in line with the nozzle, so no Y offset?

    Ian



  • @droftarts My previous carriage had it mounted in line with the nozzle(~ x:0 y55). I can definitely modify the old mount to fit on this new carriage. I switched carriages because I was having jamming problems due to airflow issues on the old carriage, so I wanted to move to the official e3d cooling solution for the heatsink. Thanks for the idea, moving the blTouch mount will be a lot easier than rebuilding the whole assembly. If the nozzle (centerpoint of the carriage) stays stable enough with the switched probe position, you will have saved me a lot of time and work.



  • I moved my bltouch to be in line with my nozzle on the x-axis, though it is a little farther away; x:0 y:-65. The heightmap is a lot cleaner.

    https://ibb.co/L93XHV8

    I think there is still a tiny bit of deviation, but I think it's within 0.01mm. For now, I think I should be able to print with this, but when I get a chance I'll replace the carriage. I'm glad I don't have to rush to replace it immediately though.Thanks for your help everyone.



  • That is amazingly flat ! I will have to examine my setup for possible tilt with travel direction change during probing.
    I use the Orion piezo sensor so my sensing happens right at the nozzle but I use a CR10 3 V roller carriage and the pizo sensor requires a sort of loose nozzle. There are a number of possible sources of oddities.
    I have a second CR10 printer that uses a BlTouch and I have always seen these ripples but could never track them down. This gives me a whole new dimension to check out so thanks for bringing up the issue and thanks DC42!


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