Z offset and its effects

[bigone5500]

Turn on the printer and go to my menu and select 'level bed'. It probes 9 points on the bed. The following are the results:

---rear of printer---
___________________
| 4.94 | 4.99 | 5.03 |
| 4.92 | 4.97 | 5.03 |
| 4.85 | 4.95 | 5.05 |
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

When it starts printing, the nozzle is too far from the build plate. What steps are needed to alleviate this problem? I understand Z offset is used but I don't know how to set it.

 

[LooseNut]

Probably the best video that shows and explains setting your Z offset is this one. Don't know what unit you have, but he's demonstrating with an Ender 3.
Another good Vid to watch is by "Teaching Tech". He has a great series and covers many printer makers in his instructional Vids.

 

[Tony]

Yep, It's just the offset from where it was probed to where it needs to be. I think mine is at -69 (Negative NICE? lol)

 

[bigone5500]

I worked on this thing last night and got nowhere. I think the CR Touch isn't playing well with my machine.

Oh well. I figured I'd give it another go before I bought another machine. I have an offer in on a new ender 5 plus.

 

[LooseNut]

If the firmware is is set up for the addition of the CR Touch, that first video should get you you fixed right up.
The changes in the firmware for both the CR and BL are identical and the connections on most machines take the place of the Z stop. If the pin deploys and retracts on contact, then at least that much is working correctly. That is setting the "Z" when you run the ABL mesh. Once you set up the Nozzle offset for Z, you should be good to go.
BTW, The Ender 5 uses the BL Touch as well, but comes with it installed, so the offset is (or should be) already set up, and since they have released their own CR Touch it could be using that instead. As I mentioned above, the BL and CR are identical in connection and function, the CR is just Creality's own version.

 

[bigone5500]

One thing that has me perplexed is that I had to add 4 washers between the cr and the mounting bracket. Otherwise the nozzle hits the bed before the cr does.

I'll post pictures later of the setup.

 

[LooseNut]

Yeah, that was odd since the bracket they supply was for a E-3 to begin with.

 

[bigone5500]

 

[Tony]

They must not have had the brake set correctly when they bent that arm. I am running the same probe and I have no shims at all. Don't remember my spacing for the nozzle, but it definitely clears. But I have heard that some people do have to run spacers.

 

[LooseNut]

Well you guys are ahead of me, I bought a BL touch to put on the CR-10 (Frankenstein) but I have it down for more mods, one is putting in the Strain Gauge style Hotend probing. My other machines are CR-6 SE which are already set up that way. What I know is in talking with my friends that have them and have went through the problems.
So this morning I am up and running through Google and Vids, seems like a lot of folks have had that offset problem and as Tony noted, have installed the spacers to correct it.
One thin I did note on a couple Vids I watched were the height that the probe is operating at and some are pretty close to the nozzle touching. Vids with the BL Touch are a lot more offset on the same bracket, so I'm guessing the BL has a longer probe pin. If I had a CR touch here I'd open packages to check.
Another difference I ran across was on the Creality page where they compare the 2 probes and it states that the CR Touch does not work with an 8 bit board but the BL Touch does.

What is CR Touch? is it better than BL Touch?

Here are the CR-Touch Overviews and Comparison of the Creality Bltouch. Creality CR Touch auto-leveling kit, how it works? Should I purchase which one? Which Leveling Sensor is Better?

www.crealityofficial.co.uk

Another couple of posts that I read on Readit talked about solving the issue with the spacers AND flashing to the Jyers Firmware. The below video gets a bit slow but I found it pretty educational. He also put links to the Firmware and files he was using. So lots of stuff to consider.


Ok, took my pain meds, so if I disappear I went back to bed.

 

[bigone5500]

So I wonder now if I have too much spacers in there. Maybe if I used shim stock it could be fine tuned?

 

[Tony]

As long as you are within 1/16" - 1/8" when the probe clicks up into the body you should be good. Mind is right at about 3/16" above the bed and I use a pretty high negative offset for Z to set the first layer height. Remember, this is just for the first layer. Z will control the layer heights for layers 2 and up.

 

[LooseNut]

Ok, so where we started was that you ran a bed leveling mesh

Turn on the printer and go to my menu and select 'level bed'. It probes 9 points on the bed. The following are the results:

---rear of printer---
___________________
| 4.94 | 4.99 | 5.03 |
| 4.92 | 4.97 | 5.03 |
| 4.85 | 4.95 | 5.05 |
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

This was before adding the washers for spacers. If the nozzle was at Z zero, there is plenty of space.

From the numbers displayed, I'd be inclined to level the bed first the way you always have with a piece of paper of feeler gauge and set your Z zero.

Then I'd run the Bed leveling keeping my hand over the switch in case the nozzle wants to run into the bed.

Since most of the BL and CR Touch setups use the Z End stop, you now have to set the Z offset for the nozzle at a negative number. Let's just say that the 4.85 in the front left corner is your number for the home position. You want to set you Z at .2 above the Bed. So, 4.85 - .2 gives you 4.83, make that the negative number (-4.83) and that should be your negative offset.

Tony! Correct me if I'm wrong! Don't want to steer anyone wrong, but this is what I get from everything I've seen.

 

[bigone5500]

I had the washers installed when it got those numbers.

I don't want to kick this horse too much more. I bought a 5 plus from ebay. Was on sale at a good price.

 

[Tony]

Sorry, completely missed this... Work, new position, yea....

When you install the touch LooseNut you actually remove the Z switch and it only uses the touch to know when to stop the Z axis. My switch is still there, but is unplugged.

I have not printed anything in a long time. I need to figure out something useful to print lol.

 

[LooseNut]

Right, very similar to the setup for strain gaging. The exception being the optical switch to let it know it's in the vicinity of Z to initiate baby steps or Taring. My offsets with the Nozzle probe are 0, 0, 0.2.
Ha! I've always got something printing. Once I've got the CR-10 converted I plan to print a full blown plane. Friend has a Spitfire that he printed, very cool.