I have followed the wiki on how to set up the BLTouch but I

(Antonio Gil) #1

I have followed the wiki on how to set up the BLTouch but I can’t seem to understand how or to apply how to set the z min with the BLTouch sensor.The g30 command works and I use g30 z0. and store it with m500.The problem I am having and I have read soo many threads and I can’t find the answer is how to set the homing position for z axis because after I store those settings if I hit g28 to home the z axis keeps trying to go lower until it hits the mechanical limit of the printer and keeps trying to go lower.Can someone please give me a hand with this I have been at this for almost two months and I am at my breaking point with this.Thanks

(Johan Jakobsson) #2

The probe is used to probe, not set Z min.
You can use G30 to manually probe Z min but there is no automatic way of doing it (with a bltouch) as far as I know.

(Johan Jakobsson) #3

The way I have it set up is with a endstop at Z max to home. Then I probe down to Z min with G30 and add the distance between probe and nozzle when setting M306 Znn

(Antonio Gil) #4

So I am guessing the easiest way would be to add a z min endstop. I was really hoping I wouldn’t have to do that because I have no way of printing my own mounts for the endstop now that I swapped parts to build this machine. I may have to see if someone is kind enough to print a few for me or pay someone to do it.

(Antonio Gil) #5

I have read tons of threads online where people say they have and haven’t been able to use the Bltouch as a z min endstop. I hate that about looking online if you look long enough you can find contradictions to just about anything.

(Johan Jakobsson) #6

afaik, the official standpoint from the “smoothie team” is that probes shouldn’t be used as endstops. Especially true for the bltouch since you have to extend it before use and that isn’t implemented in the homing routine.
Still not sure what your setup looks like. I’m assuming you have i3 style printer with and endstop at the bottom so you home to Z min, ie downwards?
My suggestion is:
Home the machine then move the nozzle so it just touches the bed using a piece of paper to feel when it touches.
Enter M306 Z0 in your host software terminal (pronterface?)
Home again.
Now you should be good to go to print. To probe Z0 if you want/need to;
Move to Z10 in the middle of the bed or wherever you want to probe (G1 Z10 F200 in the terminal.)
Extend probe with M280_S3.0 and probe Z using G30. Check terminal to see the probed distance. The difference between the G30 and and 10 is the (z axis) distance - lets call it Dist - between the probe and the nozzle. Retract probe with M280_S7.0.
If you ever need to probe Z0 again you use this fast, but manual, routine;
G0 Z10 F2000
M306 Z = 10 - ((10-Dist) - G30 Output )

Say your Dist is 0.3mm and the output of G30 is 10.2mm, the calculation would be 10 - ((10-0.3) - 10.2 ) which is 10 - (9.7 - 10.2) which is 10 - (-0.5) ie 10 +0.5 = 10.5 so your command would be:
M306 Z10.5
I know my probe is 0.2mm from my nozzle so I just use this calculation: M306 Z = 10 - (9.8 - G30 Output )
That said, you’ll still use your endstops for homing. The probe is for probing. =)

(Arthur Wolf) #7

A probe isn’ta zmin endstop, and vice-versa, but there’s no limit on what you can do with your zprobe. If you want to use it to set your bed height ( with G30 ) just do that whenever you feel like it.
I think some users get confused because other firmwares mix them up and Smoothie has them well separated.
Just use G30 instead of G28 to home your Z.

(Antonio Gil) #8

I added a z min endstop to fix the problem. Everything is working now but when I try to probe the bed using g32 it starts in the middle of the bed. I am using a 220x220 bed. I was reading the wiki and it states that on a Cartesian when using an endstop at the min location to start in the center of the bed the alpha min should be - 110.would I also have to add the distance of the nozzle to edge of bed when triggering the endstop?

(Arthur Wolf) #9

You really shouldn’t have to add a zmin endstop, a probe is all you need. It’s ok if you do though.
Do you want your machine to have it’s 0,0 in the center of the bed, or in the lower corner of the bed ( most machines do the second one ) ?

(Antonio Gil) #10

It really makes no difference to me. I am just trying to make sure that the board knows where the bed actually is like I mentioned before the g32 command is starting the first probe point in the center and working its way to the left edge of the bed.

(Arthur Wolf) #11

Can I see your config file and the exact command you send ?

(Antonio Gil) #12

I am using g32 and I have tried g28 but g28 doesn’t work when entered into Octoprint.

(Arthur Wolf) #13

Can I get the exact answer to the “version” command ?

(Antonio Gil) #14

What do you mean by version command?I have no clue what that means?

(Arthur Wolf) #15

go to the terminal tab in octoprint and type “version” then give us the answer it gives you ( precisely )

(Antonio Gil) #16

Here is what it said

Send: version
Recv: Build version: edge-c819aa6, Build date: Apr 4 2018 16:52:08, MCU: LPC1768, System Clock: 100MHz
Recv: 5 axis

(Antonio Gil) #17

If you need any more info just let me know. I just need to clean up my wiring a bit and start printing.

(Arthur Wolf) #18

Please ask MKS for help first and read : http://smoothieware.org/troubleshooting#somebody-refused-to-help-me-because-my-board-is-a-mks-what-s-that-all-about

(Antonio Gil) #19

Arthur I get not wanting to help someone who is using the knockoff boards but I have both and am trying to get the MKS running so that I can swap in the Smoothie with out damaging it or the printer.I am brand new to all of this and it seems like you guys don’t really want to bother helping.I get that if I study the wiki I should know how to do it but I don’t and all I want to do is print.I think that approach to helping new users will hurt the Smoothie project because it will frustrate new users into going in another direction.I appreciate the help you have given me but I am stuck and cannot print at the moment and I have to figure out what to do.

(Arthur Wolf) #20

I’m sorry but reading " it seems like you guys don’t really want to bother helping." just makes me upset, especially when this thread has 12 messages.

I spend several hours a day helping people with smoothie questions ( and live like a student at 33 because I’ve spend all my days the past 5 years helping people with smoothie issues, pushing smoothie forward, and spent all my money for smoothie too ), we definitedy do help, if you don’t think so you have no idea what’s going on here
. We just want to not waste that ( precious ) time doing MKS’s job, it ensures we help people who deserve our help first. We tend to help everybody in the end, but we ask MKS users to ask MKS first when they have problems with that board. I don’t think that’s too much to ask.

I have been helping you. When I discovered you were a MKS user ( which you were not upfront about ), I only asked that you ask them first, which should be something you should have done anyway. MKS should help you before volunteers do. It’s the least they can do.

About your issue I’m still confused what is the problem, this works for everyone else out of the box. Could you please make a video of trying to do G32 ? Start from when you boot the printer, show the commands you send, and send M114+ show it’s answer before and after doing G32.