The BLTouch is hitting the bed on the double-probing

Question

When double-probing, sometimes the BLTouch will hit the bed before the z-axis goes down:

The BLTouch deploys
The bed goes up
The sensor triggers
The BLTouch stows
The BLTouch deploys and crashes the bed before the z-axis goes down for the second probe

It happens only on the second probe of double-probing (slow speed) - the bed can't move out of the way fast enough. This happens in 2/16 probe points.

Probe Accuracy Test result:

Mean: 0.023075 mm
Min: 0.018 mm
Max: 0.027 mm
Range: 0.008 mm
Standard Deviation: 0.002584 mm

Hello David, I noticed your question has been up for a while now. Have any of the answers below been able to solve your question? If so, would you mind accepting the appropriate answer. If not, what is missing so that we may help you further? Also, if you have figured it out on your own, you can always answer and accept (after 48 hours) your own solution. Thank you! — 0scar, Oct 27 '20 at 09:09
Sounds like the height the printer is supposed to go to before second probe is too low. — Justin, Aug 05 '21 at 17:18

score 1 · Answer 1 · edited Jan 31 '20 at 07:30

First, make sure to check if stow, deploy and the trigger are working correctly.

Second, check the pins files to make sure you put it in the correct pins. Black and White probe pin might need to go to Z-min or probe pin depending on. Make sure to check that.

Third, add "BLTOUCH delay". It might be triggering too slow or too fast for the next one to react. So after the first trigger, there should be a time for it to "re-setup" for the second. But if there is no time to do that then it won't trigger.

To add examples: If you have SKR 1.4 Turbo, then use BLTouch probe pins (black and white) on the board. IT will NOT recognize. You have to use Z-min endstop pins. Reason for this?:

#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN

If this has been used, Z-min probe will use Z-min endstop pin instead of Z-min probe.

score 1 · Answer 2 · edited Nov 03 '20 at 15:20

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In case someone still has this problem I have a solution for what happened in my case.

I am using a 3DTouch and I also encountered the same problem and it was solved by commenting //#define BLTOUCH_HS_MODE

edited Nov 03 '20 at 15:20

0scar

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answered Nov 03 '20 at 14:09

Marcos Moura

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The High Speed mode is not recommended, so indeed this line must be commented out. – 0scar Nov 03 '20 at 15:21
Welcome, and please take the [tour](https://3dprinting.stackexchange.com/tour). – Davo Nov 03 '20 at 19:12

score 1 · Answer 3 · edited Dec 20 '21 at 08:16

I solved the same issue.

I had the same problem, just send the G-code M502 to your printer through Cura or whatever it is you use. The reason is that you already did an auto bed leveling and you more than likely send the G-code M500 which saves your auto mesh data so that you don't have to auto home for every print.

So M502 restores everything to its factory settings after you reset don't forget to send M500 to save the default settings or else your printer will be fixed up until the next time you turn it on and you'll have to start all over again hope this helps.

score 0 · Answer 4 · answered Feb 27 '19 at 20:17

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This sounds like the firmware setting for your BLtouch is not set up properly. Look at the line in Config H where it deploys the BLtouch. make sure nothing is commented out and that the 2nd deploy is shown.

answered Feb 27 '19 at 20:17

aaron elsey

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"2nd deploy is shown", Can you be a bit more specific about this? – David Souza Mar 01 '19 at 00:42
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Could you expand upon your answer please? – Greenonline Apr 14 '19 at 09:54
If the 2nd Deploy is shown on the line make sure that line is not commented out. Remove the "#" in front of the 2nd Deploy to activate that line. – aaron elsey Apr 15 '19 at 12:14

The BLTouch is hitting the bed on the double-probing

4 Answers4