Z-Axis not moving correct distance

Hi there,

I've recently bought a second hand prusa i3 that came dismantled. I'm in the process of putting it together and for the most part it appears to be going in the right direction except I've hit a snag that I'm just not able to understand, namely, when I use e.g pronterface or the manual controls in slicer the z-axis does not travel the full distance. In fact it hardly moves at all and very slowly. It is currently set to move a maximum of 120mm but if it moves in total more than 4 or 5 mm I'd be surprised. I'm sure it's something in the config but nothing in there springs out as the obvious issue.
It may be worth noting that if I manually wind the z axis up and then use the home option, it looks to go back to the home position at normal speed. It may also be worth nothing that both the x and the y axis look to me to be moving correctly.

I've attached the config.h if that helps.

Any help that can be offered would be greatly appreciated. Not sure what additional info you need, but it's an arduino mega board (mother board 33) running the lates version of the repetier firmware.

Thanks in advance.

Just throwing out an obvious question, as I would be lying if I said I had a solution beyond obvious answers, have you checked the steps per mm? And have you calculated microstepping in your steps per mm?

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

hmm, I haven't done any specific calculations as of yet, but I had thought I had set each of the axis to the same values and as the x&y move ok, was expecting the z to also. Will have to have another look though.

also, thanks for the fast response!

Woah woah woah, lemme clarify; you have the same number in all three?
If so, that's exactly what's wrong, your Z steps should be significantly higher [eg, I have 88 steps per mm for X and Y, and about 2300 for Z]

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Here is a handy dandy thing I use all the time, as do many others.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Right - so that's probably the problem then

I have looked at the calculator you linked, but there's nothing there to suggest that the z axis should be any different (unless i've completely missed it) - how do you calculate what it should be in that case - is it a case of trial and error, i.e post a distance, measure it, increase/decrease the value as appropriate?

thanks again, I'm new to all of this and there is much to learn....

Use the "Steps per millimeter - leadscrew driven systems" part. Do you know the pitch on your screw? Also, do you know what microstepping you are using?

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

ah, of course - the z axis is not on a belt *facepalm*
That's sorted it out, many thanks for your help. Now I just have to configure the rest of it

Thanks again, and thanks for the rapid replies!

You're welcome. I've thought about making guides for basic things like this in ways people can actually understand and be hand held through. It seems secondary, fundamental, common sense to those who do this stuff already, but almost every day someone is asking for help on these basic things. I'd say a majority of Reprap Forum activity could be solved with beginner's guides.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus