Using Repetier by USB cable to Anet A8 - my extruder prints 20mm to high

VinnyVG

Using Repetier by USB cable to Anet A8 - my extruder prints 20mm to high.
I have two Anet A8 running on both 21inch Mac Sierra 10.12.4 and mac mini.
Background. When first assembled and using the Repetier items included in the files from Anet - I could never use the USB connection no matter what tip tricks and suggestions from helpful folk suggested. Dependent on the SD card slot - five days after arrival it was dead. No USB and No SD Card. Meanwhile my second A8 arrived ...
A link from a really nice guy on the FB group gave me a new/different driver for the Macs... using the SD card option via the USB cable and no problems. The motherboard replacement arrived and when fitted - I tried Repetier using the USB cable and new driver = first on the SD Card connection - it worked once - then - so far not again. 22

I tried the direct connection by USB - at this point what I tried on one computer/A8 applies to both. I can connect and I can go through the set up print right upto RUN... the extruders run out and they do not lower - and start to "print" about 20mm above the hotbed. Both computers and both A8s are the same. Start and end codes in Cura are the same. I tried Slic3r - but being a bit new- it confuses me!

If I use Cura for the G Codes and use an SD card and do the transfer on teh computer and put the card in the slot... it starts normally - same file opened on the computer - Load G Code" - it prints too high.

Any suggestion to get it to lower and print - without affecting the "manual" by SD Card option - will be appreciated.

Repetier

No idea what firmware you use, but I do not think sd card or usb makes a difference if it gets the same g code. So if there is a difference the usb print MUST have different gcodes send. In host you can define a start gcode as well and that gets printed first and then the cura generated code. So check if these scripts conatin any gcode and delete them.

If it still does not work send lines manually one by one till you see whcih command does the 20mm move. Normally I would expect

G28 to home Z to Z=0

Later there will be a G0/G1 with Z to move it on layer height.

What you need to look out for is G92 Zxxx whcih can change the height for following G1/G0 commands as it offsets the coordinate.For 3d printing this is normally only used for E0 but not Z.

VinnyVG

Repetier said:

No idea what firmware you use, but I do not think sd card or usb makes a difference if it gets the same g code. So if there is a difference the usb print MUST have different gcodes send. In host you can define a start gcode as well and that gets printed first and then the cura generated code. So check if these scripts conatin any gcode and delete them.
If it still does not work send lines manually one by one till you see whcih command does the 20mm move. Normally I would expect
G28 to home Z to Z=0
Later there will be a G0/G1 with Z to move it on layer height.
What you need to look out for is G92 Zxxx whcih can change the height for following G1/G0 commands as it offsets the coordinate.For 3d printing this is normally only used for E0 but not Z.

Hi, Thanks for taking time to reply -its appreciated because I have spent days trying to resolve this. Sorry if I repeat stuff here.
I have an Anet A8 - it was all set up and running fine... but only on SD Card operation. Repetier would not connect. This tuned out to be an Apple iMac / Driver issues which was sorted out with help from a very helpful guy on the A8 facebook book group. This came about because the mini SD card slot in the board - failed and we were trying to get a USB connection. However, the board itself was useless and a couple week later I got a replacement from the factory. This second board connects to the A8 via the USB cable. and the SD Card slot is fully functional ( so far) I cannot upload from computer to SD card I get an error report - WRONG target file name - Target name is not valid - Only 0-9, a-z and ) are allowed. " I have tried changing names etc,. It never accepts any file name.
To test your suggestion about different G Code - I downloaded a new file off Thingy... converted in Cura and used the resulting G code The same files on SD card - prints without issues - the same file used by direct via the USB cable - starts to print about 20mm above the bed. I agree it sound illogical - but I have seen a similar post whee I was searching this forum, the difference being that the other poster had a 5mm gap or so.

I was - blaming shoddy electronics used in the Anet A8 board - its only the previous issues with Repetier that has sent me looking for an alternative root cause.

I more than once done a complete - on delivery - set up and bed level process, unsettling end stops etc,. and starting each set up trial. I still get the same results.

I changed machine start code to Cura default - made no difference and returned to a start code that was suggested to me when I first completed the assembly.

<style type="text/css"> p, li { white-space: pre-wrap; } </style> G21 ;metric values G90 ;absolute positioning M82 ;set extruder to absolute mode M107 ;start with the fan off G28 X0 Y0 ;move X/Y to min endstops G28 Z0 ;move Z to min endstops G1 Z15.0 F9000 ;move the platform down 15mm (this does happen on SD card use - but NOT when in using USB ) G92 E0 ;zero the extruded length G1 F200 E3 ;extrude 3mm of feed stock G92 E0 ;zero the extruded length again G1 F9000 M117 Printing...
Dont know if this help you.

Repetier

The start code seems pretty legal to me. No apparent reason to omit the G1 Z15 move, also that would not explain why starting at Z20.

Have you tried using repetier-server to communicate and print with. Just to see if it makes a difference and also because it is resource friendly way to print.

VinnyVG

I have created a really bad video to show Anet the issue. But I don't expect any solutions.

There is something weird about the firm ware. Sorry if this repeat s my post - but I have 2 Anet A8s but the second using a v1 Omni motherboard - which apparently is what is sent with each kit - Unless - like me the buyer added their Auto Level module and the automatically send a kit out with the V2 firmware. The Omni works fine using the USB cable and Repetier. The v2 motherboard firmware I had in my original board - would not connect via the USB - but that was a driver issue. A link from an helper on Facebook gave me CH34x v1.3 and it seems to be OK on both Macs. Whatever the cause it cannot be a regular "fault" on the v2 firmware otherwise there would be a deluge of people every week looking for a solution.
The other issue I have is nnot being able to upload from computer via USB to a mini SD card in the slot on the board.
It tells me only 0-9 a-z etc are allowed for target filenames.... no matter what I rename the file... it will not be uploaded.

VinnyVG

Repetier said:

The start code seems pretty legal to me. No apparent reason to omit the G1 Z15 move, also that would not explain why starting at Z20.
Have you tried using repetier-server to communicate and print with. Just to see if it makes a difference and also because it is resource friendly way to print.

I tried your suggestion - sadly it caused me even more problems.

Check this please - https://forum.repetier.com/discussion/3654/repertier-server-killed-usb-connection-for-repetier-host?new=1

Stevenlgts

I believe my problem is similar except to VinnyVG's except my A8 is printing 5-10mm too high.

Repetier

Run
G28
G1 Z0 F600

Then nozzle should be at bed level. If not it is configured wrong in firmware/hardware. Don't know A8 only know they do not use our firmware, so can not say much to that error. Normally endstop not calibrated correctly or if you have z max homing the z length is not set correct.