Auto Bed level Issue! NEED Help

Hi Guys,

Have been trying to implement the auto bed levelling feature for my prusa i3. Have run into a couple of problems.
Initially had got the whole system to work properly.
But in one instance the angle of the servo arm was not very parallel to the bed and after homing in the Z direction it could not retract as the improper angle did not allow the free space required to retract.
Ever since that happened my servo is behaving badly.
The extend angle i have set it to is -150 degrees as my servo is configured in the direction as shown in the picture.
Here is the PROBLEM.
I have changed the Extend and Retract angles in the firmware and keep trying new angles on pronterface too.
But no matter what i change it does not move a degree MORE or LESS than -150 deg!!!

Could it be that the servo is damaged or is there any other problem??

Thanks a Lot!!

By the sound of things you have stripped the gears on the servo.
The cheap 9 gram servos only have plastic gears that are easy to strip im afraid.
In some ways that's a good thing ( like a fuse) if you had an MG version ( metal gear) you could damage the bed or extruder carriage etc.

it might be worth checking the connectors and wiring and making sure there's no interference from other DC sources ( extruder, fans etc) Remove it from the system and plug it directly into you control board to see how it works then.

Good luck

Thanks for the reply!!

I am guessing the teeth could be worn out like you said. Have ordered a couple of new servos just to be on the safer side.

1) By the way i didnt get the last part where you say i need to plug it directly onto the control board!! Sorry for being a noob but which control board are you talking of ??
I am using a RAMPS 1.4 and arduino mega 2560!!

2) I have an other issue. Whenever my printer is online and i touch the nozzle to remove the filament, the servo arm moves a little bit and the printer gets disconnected!
Could it be a case of a Short??
Have attached pics of the wiring on my Ramps Board!!
By the way the tweezers are metallic :p

Please have a look and let me know!!!

Thanks Again!!

Edited 1 time(s). Last edit at 03/09/2015 09:51AM by gnex16.

Quote
gnex16
Thanks for the reply!!

I am guessing the teeth could be worn out like you said. Have ordered a couple of new servos just to be on the safer side.

1) By the way i didnt get the last part where you say i need to plug it directly onto the control board!! Sorry for being a noob but which control board are you talking of ??
I am using a RAMPS 1.4 and arduino mega 2560!!

2) I have an other issue. Whenever my printer is online and i touch the nozzle to remove the filament, the servo arm moves a little bit and the printer gets disconnected!
Could it be a case of a Short??
Have attached pics of the wiring on my Ramps Board!!
By the way the tweezers are metallic :p

Please have a look and let me know!!!
Thanks Again!!

In reply to
1/Servos have 3 wires> +DC volts. Ground & Signal The signal is PWM ( pulse width modulation) it is a well known issue in the remote control world that servos can suffer from signal interference from surrounding cables and other signal cables. so my suggestion was that you remove it from its current location and plug it directly into the ramps board and see how it works there ( without hotend, thermistor cables around it.) If the PWM signal is subjected to interference it can manifest itself in many ways . Odd movements , lack of travel and being unstable ( commonly known as jitter) . I still think you probably have stripped the gears but all the above is worth considering as well.
A lot of people often twist all 3 servos wires together to try and reduce the chance of interference. Thats also why proper servo extension wires come pre twisted > see attached pic

2/ You need to be careful with this issue. It sounds like you have a bad ground problem some where ( and when you touch it you act as a ground)
I have seen this kind of issue before especially with people using converted PC power supplies. Make sure all your connections are good. Occasionally connector pins get corroded/ burnt . Especially the heavy users like hotend and heated bed. Make sure they are in good condition and everything is making a good connection. The main danger is that you may inadvertently cause a spike which fries the stepper drivers ( the drivers being users of both 12 & 5 volt DC).
Regardless of PC power supply or dedicated PSU, try and use a socket outlet in your house that has earth.
Not sure where you live but if you get regular thunder storms using a extension cord with surge protection is always a good idea as well.

Good luck

About the ground problem what you said was true!!
Would have mostly continued using it the way it is right now!!
Getting an electrician to sort it out tomorrow!!

As with the first problem i guess the gears were stripped. Changed the servo and it seems to be working fine now!
Thanks for that!!

Have another question:
What is the general procedure to print once auto bed levelling is set up?
Do i load the file onto pronterface and click "print" where the printer itself homes AND does the probing and then starts the print (OR)
Do i home the printer ,then manually input G29 and then hit the "print" button??

Asking this because when i give print on pronterface all that seems to be happening is that the printer homes and begins printing. My bed is pretty uneven on one side and i dont see the printer compensating for that!!
If i manually input G29 it probes the bed in 4 points but that too only if i manually input G29. Else it does not probe at all!!
I do not have another endstop for the z-axis.

Please let me know if i need to attach a copy of configuration.h .
Thanks again!!

i dont use autobed level at all because on Cartesian printers using M8 rods for the z axis i think its asking too much of simple threaded rod to be continually moving up and down to compensate for an uneven bed. It might be usable if you have anti back lash ball screws.
You will also need to really make sure your Z steppers dont overheat / stall with all the work they have to do.

As far as the procedure goes i believe that most people add the G code commands for the bed level measurement to the start procedure in the slicer software so prior to printing the bed level is measured then stored on memory somehow.
Im confident theres more info out there ....this forum or you tube, but like i said i dont use it so am not 100% sure how to go about it.

Good luck

Edited 1 time(s). Last edit at 03/11/2015 02:49PM by bigfilsing.

Yes definitely lot of educated ppl here.
Anyways Thanks a lot!!
Running into a lot of problems. Stepper drivers just stopped working. Luckily had a few extras!!

Have changed the start G-code file in slicer to this
G28;home all axes
G29
G1 Z5 F5000

What happens when i hit print is that the printer homes the axes and THAT's it.
NO probing.
Heated bed and the hot end are upto the temperature and the printer just stays still.
It would be great if anybody can let me know what the problem seems to be.
Running out of ideas!!

Thanks!!

Honestly speaking i'm not sure where to start here.
You seem to have a few problems , some of which may be related to each other.

If i were you id go back to basics. Forget the bed leveling stuff for a while and get your printer working reliably in its standard format. Auto bed leveling is NOT a substitute for good basic calibration anyway.

Stepper drivers ...it sounds like you have spiked them and still have an earth problem. So you can either address that problem or find a bulk supplier on ebay :-)

As for why it wont print. There are too many possibilities to write here. I cant think of 1 single one that would create the scenario your find your self in.
It would seem you have been editing G code in attempts to get ABL working.
Down load a clean/ new copy of pronter face and your slicer and start again with a simple test cube. Dont alter the g code.... you dont need to for a test run. Cura runs straight out of the box ( with a few settings for machine size etc).

Check your connection for the hotend thermisistor . An intermittent fault with it could cause your printer to freeze.
And if we are to stand any chance of diagnosing your issues you need to list out your set up.
Controller
Stepper drivers
Software controller being used
Firmware
Slicer
etc etc

HI,
Sorry for the late reply.
Was travelling the last few days so didnt have a chance to reply!!
By the way got everything to work to an extent.
Just trying out a couple of settings in slice3r.
Thanks a lot for your support so far.

I had another question for you.
Have you tried printing anything using supports generated by slicer??
Would be helpful if you can share any knowledge regarding supports as there are a couple of objects i need to print but cannot unless I use supports.
Also is there any way to view the generated supports before the print begins either on slice3r or any slicer for that matter or on pronterface??

Thanks!!

Edited 2 time(s). Last edit at 03/18/2015 09:46AM by gnex16.

Quote
gnex16
HI,
Sorry for the late reply.
Was travelling the last few days so didnt have a chance to reply!!
By the way got everything to work to an extent.
Just trying out a couple of settings in slice3r.
Thanks a lot for your support so far.

I had another question for you.
Have you tried printing anything using supports generated by slicer??
Would be helpful if you can share any knowledge regarding supports as there are a couple of objects i need to print but cannot unless I use supports.
Also is there any way to view the generated supports before the print begins either on slice3r or any slicer for that matter or on pronterface??

Thanks!!

Glad to hear youve made progress with your printer and at least now you can print.
I was seriously worried with the electrical issues you had. Im normally super careful with these hobby evolved electronics and ive still managed to fry a couple of drivers over the years.

Ok your question re slicer . Well this really isnt the forum section for that. Youd probably get better assistance in the correct section where people with much more knowledge on the subject than me hang out.

To be honest i havent used slicer in a long time and cant remember if it was any good with supports Maybe the latest version is i dont know.
I used to use Cura a lot . It always seemed faster and more reliable to me.
I have now coughed up the cash and bought Simplify3D which is fantastic at support . And you have full control.
maybe send me your STL and ill have a look and see whats best in my opinion
Cheers

Edited 1 time(s). Last edit at 03/18/2015 12:38PM by bigfilsing.