Z Axis drives not syncing [i3]

I recently bought a Gadgets3D i3 and have hit a bit of a snag that i cant seem to resolve through searching.
the x & y axis move great, but the z axis has had a few problems, at first it would only move in 1mm increments and made a load of noise, I upped the power to them and now they move more (but still a bit noisy).
Now the problem i'm having is that the motors dont seem to want to work together very well.
If I try to move the z axis over any real distance, the carriage end up out of alignment as the motors seem to walk.

Anyone got any ideas?
Thanks in advance

Too much resistance on one of the threaded rods?

A little oil on the threaded rods to make them work freely

Slipage from the motor to the threaded rod?

I thought about drag on the rods so used a bit of wd40 silicone lube, didnt chsnge much. Will try a bit more when im home. Aslo I cant see any slippage.

I'm still stumped with this.
I've tried to make sure it's aligned properly to get the bearings running as smoothly as possible, Lubed up the bearings and threaded rods and even rewired the whole thing just in case i'd crossed a wire somewhere.
Here's a little demo video to give a better idea.... awful noise

[youtu.be]

What speed are you trying to move the Z? What is your Z acceleration?
What current limit do you have on your Z stepper driver?
The sound you hear is called slippage and it's the pulsing of the motors coils converted to audio because the permanent magnet rotor is stalled.

Hey Jay,

current settings are:
accel: 3000
Vxy jerk: 20
Vmax Z: 5
Amax Z: 100
Zsteps/mm: 2607.8

I adjusted each driver to 0.9v as suggested in the g3d build manual but have since fiddled with the z driver in a vain attempt at fixing it.... how does this translate to current limit?

Quote
LMColl

I adjusted each driver to 0.9v as suggested in the g3d build manual but have since fiddled with the z driver in a vain attempt at fixing it.... how does this translate to current limit?

According to their website, it's 0.8V per amp. So that translate to 1.125 A.

The also have another trimpot called OSC - ROSC. Not sure how that works, but it says to turn it fully counterclockwise for accuracy and lowest vibration.

Is your printer controller set for 1/16 microstepping?

Looks to me like you are trying to drive them too fast. What is your max feed rate set to for z?

Hay LMColl, Just out of interest, how easy was your build? as I'm having problems with mine!

I'm at work at the moment so I'm not too sure on the microstepping.

Last night I reduced the z velocity the the minimum possible and it seemed to work well, maybe you are right, lazymonk.

And as for the build, I did hit a few snags. Either my hardware was labeled wrong, or the manual was wrong, but a lot of bolts didnt match up, so I had to improvise. The printed parts seemed very tight to the threaded rods, so I had to bore them out slightly. They were also tight on the smooth rods of the z cariage, so alignment was a pain.
The last problem ive had is melting the hot end. I got it up to a measured 185 and the plastic part that connects to the heating block melted. I'm guessing I didn't have good enough contact with the thermocouple and overheated.

What problems are you having kay?

Same as you, a few miss match of bolts etc.

I cannot get the bed level atall.

I had to reverse the connections on the x and y axis motors

The Hot end decided to leak plastic and is now welded on (managed to get it off but was a pain in the ass)
The bracket that holds the fan next to the hot end has started to melt (may of been my fault, but no idea!)

finding it very difficult to get the filament into the hotend! and the motor sometimes decides to back the pla out before then putting it back in, and getting it jammed!

Also the firmware onto the arduino was weird, it says to put the prusa_i3 onto it, but that wasn't supplied, the only one available on their files was "marlin.ino"

The link to their firmware wasnt working for me so I just ended up going elsewhere.
I also had the same problem with the fan mount. Im thinking of just going for a j-head now.

What firmware did you use?

And sorry but whats a J head? lol complete newbie here! haha

Sorry for the late reply Kaylem,
I'm running marlin.
and a j-head is just a simple and fairly cheap hot and, seems to be working better.

I seem to be having a z axis problem, it's moving twice as far as it should be. I've adjusted the steps/mm from 2000 to 4000 which should have sorted it..... but it hasnt changed it at all. i've tried changing it both on the machine and through h.config.
Will keep trying.

Still Having Z-issues.
No matter what I do, i cant get the the scale to change.
I've checked eprom is enabled, but it doesnt make any difference what value I have for #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,760*1.1}

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LMColl
I've checked eprom is enabled, but it doesnt make any difference what value I have for #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,760*1.1}

You need to send a M502, to use the new settings, then test the z. If it's correct, then send a M500 to store the new settings.
When the firmware starts up or resets, it reads the settings from the eprom, not what you hard coded in configuration.h.

you could edit the marlin firmware on the computer and change that line manually and upload to arduino as well

Hay LMcoll,

I had the same problem, none of my edits in the config actually changed atall,

What i had to do was in Repetier host i have to change the EEPROM settings that EEPROM setting overright what you have written in the config file...

Feel free to pop on the reprap irc channel ive been on there nearly every day for the past couple of weeks and have learn ALOT

Got mine working to a good point now..