Should I be running the BLTouch with a G29 code in my slicer’s printer settings for every print ?
The Z offset value seems to need tuning each time I run the BLTouch levelling. I was advised that the setting was -5.3 but I found that value was too low and had to back it off to -3.7 to get filament onto the bed.
So should I be leveling each print and then manual tuning the Z offset for every print as the first layer goes down, or and I doing something wrong? Without the BL Touch, I would manually level the bed and usually it held the level for a number of prints.
You can add the G29 to the start code, there is no real reason not to, it only takes a minute or so to run the routine before a print. Do you have to, no. Levelling periodically is probably OK but why not do at each print then you are good.
Setting the Z offset seems to be more magic then anything else. I set mine to.76 and it works fine. You shouldn’t have to set the Z offset for each print. I don’t really know why different machines get wildly different settings.
Have you installed the Jyers UI firmware on your Ender 3V2. It has a built in routine that lets you manually level your bed (centre and four corners) using the touch that is very accurate. After that the G29 checks the bed at each print. It also has more functions the the Creality firmware.
I’ve found that the cheap BL Touch clones with the metal probes tend to have pretty inconsistent sensing heights across units.
I haven’t done any kind of analysis, but I suspect that when the metal probes are cut, there aren’t a lot of controls to ensure that they are cut square and of the same length.
How many clones are there?
The BL Touch and the CR Touch are both good although I think the CR Touch might be a better option but that’s just my view. There is a 3D Touch that is a cheap knock off of the BL Touch. I don’t no much about them but they are a lot cheaper then the other two so as they say you get what you pay for. I haven’t seen any others of the probe type.
I’ve got a genuine BL Touch and three clones, all three with different case mouldings and two with metal pins. Two of the clones have different LEDs (or at least operate differently from the BL Touch).
They were purchased over the past five years or so. Sourced in North America and China (AliExpress).
I purchased the BL Touch last year because I had seen such differences with the other ones and I wanted to see how a “real” one worked.
All four work reasonably well, although I have a clone with the tape falling off (discussed earlier on the forum) and all seem to have different probe activation points that rage over 0.5mm or so.
People buy these things where ever and OEMs (sic), stores and websites get them from where ever. If the only difference is in probe length/activation point, then things are probably pretty good.
Just to clarify, this is an ANTLABS BLTouch that I bought from 3D Printing Canada and it was also installed by them. I am running Jyers and I’ll look into that function.
I guess what confused me at the store, they set the Z offset to -5.3 and produced a beautiful print. When I got the printer home, that set was much too low and I had to raise it to -3.7 to get it printing. I’m just wondering why that would be. Maybe it was as simple as the bed going out of level?
I was curious to see if there were any documented differences between devices - there aren’t, but specifications vary by more than 10% on the length of the probe and position of the probe relative to the hot end. There doesn’t seem to be a specification on the trip point.
Here are some of the drawings I found (the first is by Antclab):
The closest I can see to a rule of thumb here is that the BL Touch module’s body must be at least 15mm to the left of the hot end and the nozzle should be 8mm below the bottom of the BL Touch module’s body.
The probe length seems to vary from 11mm to 13mm with, again, no specification for the trip point. That tells me that when setting up a printer, you always need to do at paper test with Z = 0 and adjust the offset from there.
I just ran a M48 probe test on my Ender3V2 CR Touch and it was repeatable to 0.01mm or 0.0004". Good enough for me.
RobM - The procedure for the bed levelling with the probe is
:go to prepare
:Go to Manual levelling, Turn on probe, click on centre (you only need to do this once)
then click on each corner and work your way around. It will tell you how far above or below each corner is from the centre. Adjust each corner as you go to get it as close to the centre as possible.
It will take several times around to get it close but .01mm is quite doable. A caveat to this is the repeatability of the probe. If you probe isn’t repeatable then your levelling will be off.
0.1mm (0.004") is probably good enough, less is better.
This is basically the same as paper levelling but more accurate because you use a probe (BR or CR Touch)
@RobM the BL touch are not a be all end all tool. The bed needs to basically be correct for it to do its job. If you are finding the prints to be good then not so good with nothing different in between, Look to the bed its self. The springs that support it can be inferior (stock creality are not awesome) and if they are the movement can shift the adjustment. (not enough tension to lock the knobs from movement) The bed can be moving as it heats and can be off.
You could check the ‘level’ make a few prints and check again. If it is moved.
Level the bed and just bring it up to temperature a hand ful of times and allow to cool. then check for level. If it is out with no movement carefully check the bed itself. If not look to springs.
I can second that. I checked my print bed and it was out quite a bit, even with the stronger springs. It should also be noted that even the “good” springs will fail over time and will have to be replaced. How long??? My son gets about 6 month out of a set but he prints a lot.
If you setnup Unified Bed Leveling you can have it probe many points. Mine does 15 x 15 then when it starts a print. in your start gcode you can load the mesh (the map of the bed) and have it probe 3 points with G29 J. This will match those 3 points to the mesh and adjust the tilt accordingly in case the bed is not in the same place. The only thing that short circuits this process is if the uprights are not parallel on the printer.
That is how mine is set up. After a lot of back and forth with Antlabs I was told the error for a BL was less than 0.8mm with a 0.4 mm nozzle across the whole bed. My original bed was wrapped by more than 2.4mm. They told me to replace the bed.
That’s what I thought. But it turns out it can adjust quite a bit of wave out of the bed I finally had something besides black to print for the first time in a few days so I devised a test. my printers use spring steel beds so I put a tooney under the middle and probed a mesh then printed on it. the money added about a 1.75mm hump in the middle of the bed, but when I walked away while probing the new mesh it tented up, and near the middle on the front was more like 3.5mm so I left it and stacked a quarter and a loonie under it before it printed for support. this caused a small issue because the probe during probing was able to slightly press down on it but it didn’t really ruin the test even though the nozzle was too close right in that spot.
Here is the cobbled-together video.
