rostock with repetier z axis issue

I have a rostock using the latest Repetier (i think 0.91) firmware. When I drop the hotend to the heatbed (centered), it looks good. as I move along either the x or y axis, it seems to climb along the z axis. it drops back and touches the heatbed at center. The climbing seems exponential (increasing more as it gets further away from center). This deviance is equal when traveling on the negative axis as well. I'm sure it is a setting, but which setting might it be? Having a little trouble narrowing this down.

any help is appreciated.

can you post a vid so that we can see what is doing and assist?

I will ASAP. In the mean time, here is a description:

Assume x axis is identical in behavior to -x axis, y axis and -y axis.

as I move out from center along x axis, the z axis changes increases. The further out it travels, the faster the z axis climbs.

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(0,0)______________________________________________________(100,0)

as the hot end travels away from (0,0) the z axis climbs.
returning to (0,0) brings the hot end back into contact with the heat bed.

Edited 1 time(s). Last edit at 09/02/2014 05:38PM by wscroggins.

perhaps one of the stepper motors is backwards?

can you power unit off, and then set all 3 arms at different heights, then power on and home it. axis that goes down is likly backwards, or have you checked in firmware that stepper size is consistent and that microsteps are the same on the board, or if ramps in the firmware?

Edited 1 time(s). Last edit at 09/02/2014 06:41PM by jamesdanielv.

ALL axis do this. The motors are fine. This is a configuration error. I was just trying to get pointed in the right direction.

does the effector angle up when raising, or does it remain flat? IF it angles up it could be that the diagonal rods are off.

Also cross post on the delta google group for additional assistance: [groups.google.com]

It looks like there is a calibration issue as you guessed it, wscroggins. The point here is to modify a Marlin' parameter in order to bend the curve in the right direction (you can either make it more concave or more convex).
Here is a calibration guide, search for the "flat" calibration into it, paragraph 3. The steps explained here are for a right height calibration at each column, and an curve error at the center. You just have the opposite, so either you follow the guide in order to have a similar error to correct, either you make an analogy.

Thank you.
It had to be a configuration issue as no mechanical issue, save a different design, could make a perfectly symmetrical error. Using the Repetier firmware, I adjusted the Print Radius and it flattened out.

I feel that several did not read my posts before trying to help, though I do still appreciate everyone's help.

its hard to know what is going on unless a picture is provided of how it is printing, I'm glad you got the help you needed though. Personally I'd be grateful for people chiming in to help!

edit: i did not mean a flame war to begin! what i'm trying to say is more heads are better than one when someone is trying to communicate the problem.

Edited 1 time(s). Last edit at 09/03/2014 04:19PM by jamesdanielv.

As I stated: people didn't read my post. I am grateful just as I stated I was. I am merely pointing out that if a person asks "how many Oranges are in a dozen", and others reply "it depends on the type of fruit", it helps no one. I am glad people try to help, but often they do not realize that they are adding to clutter that makes it very hard to find or give actual help. I knew someone would try to make my statement into something it was not.

I have to say that I don't agree with your statement that "people did not read..." because just putting a text diagram of what the machine is doing with one tower in the picture is not enough information for everyone to pinpoint that you are seeing a bowling effect, which is natural in the configuration of a delta. I asked whether you could include a simple video so people can accurately see what is going on, and you know what? without a picture or video I even diagnosed wrong, and it was not because I did not read, but because I could not get a clear sense of what you were describing from your description.

I wanted to write after thib88 wrote that it may be a calibration error with the delta radius, that if it is a convex or concave issue that this is the weirdest or hardest description of a bowling effect that I have ever seen. From the responses, it looks like I am not alone in misunderstanding what you were seeing with your machine, as jamesdanielv believed that it was a stepping problem because your diagram can easily be seen as the machine is rising when you are approaching a tower, as if a stepper was off, and not the normal occurrence of 'I calibrated the towers, but my center is either too high or too low on the Z axis."

What I will point out is that people are happy to help, and I believe that in the reprap community people bend over backwards to help each other. What I don't believe you should be doing is claiming that people did not read your original post because they diagnosed wrong or misunderstood what you were saying when you did not even go through the easy step of taking a video with your smartphone, posting it on youtube and posting a link or even taking picture that could have helped people easily identify your error. You could have also said "at X, Y, and Z tower I am at z=0, but at G1 X0 Y0 Z0, my nozzle is above by Z=2.


To second jamesdanielv, you should be happy that people offered to help. If the standard that you are putting forward of claiming "that people did not read" is the norm if people diagnose wrong or did not clearly understand the issue, many may not want to help you in the future because this is not appropriate behavior of a person who is asking for others to help them troubleshoot their machine.

Edited 5 time(s). Last edit at 09/03/2014 01:53PM by Wildcard.

They did NOT read it. For James Daniel, it was not when he were trying to help, but when he tried to imply that I was not grateful. I CLEARLY stated that I appreciated everyone's help. Naturally, you are the type to try to make some drama on the subject, and that is even less helpful for any community. Even YOU diagnosed wrong...?? really? Listen. I don't want you to drag this into a petty shouting match. I know that is what you are shooting for, but I want no part of it.

As for those that "may not want to help" in the future... that would only be because you two attempted to cause drama. And for those who do not want to help me, then fine. They are the type that do not read. You write your high and mighty arguments about how I can not put down something that a normal person would see as constructive criticism, but in those arguments, you still miss all that I wrote. As for not posting a video, I did not because I figured it out last night before having time to make a video.

Here is what I don't get... Why are those who did not read the ones trying to make so much drama. Next time, just don't help. The world could use less drama.

For those who want to keep this going... you can feel free to. I will no longer be a part of the useless drama. I will not be dragged into it. Thanks again for those who tried to help.

"The high-center and low-center conditions can be adjusted in firmware with changes to DELTA_RADIUS. And in the firmware DELTA_RADIUS is calculated from SMOOTH_ROD_OFFSET, DELTA_CARRIAGE_OFFSET, and DELTA_RADIUS.

In order to correct low-center, DELTA_RADIUS must be increased. In order to correct high-center, DELTA_RADIUS must be decreased. Adjust your firmware accordingly, re-compile and upload."

I'm sure you know but you need to figure out delta radius as well as tower homing locations together unless you are doing this with an indicator. If you have an indicator you can mount, I would set the total Z height so hotend Z0 is 5-6mm above the bed and then do the delta radius and tower homing and once you have those figured out do the total Z height. If not you will be constantly fiddling with total Z height because the delta radius changes will make the hotend hit the bed at some point.

Edited 1 time(s). Last edit at 09/03/2014 02:19PM by tjb1.

Thanks tjb1,
I found the configuration guide that thib88 posted last night, and it showed me how to configure and flatten my x-y plain. The DELTA_RADIUS was the issue.

Thanks again.

You know I was hoping that you might be contrite, but it looks like ad hominem attacks are your new tactic. Truthfully, I do not care what you think of me (i.e. you calling me and other people "drama"). If you want accuse people of their intentions of not reading, then I will happily respond about my own. The fact that only one person could understand what you were talking about on simple problem as radius off, shows that your writing was not clear. Thus, instead of pointing fingers at people for not reading, it is clear that you need to be looking at how you explained it.

For your last message, I of course, did not read it all because bold letters and telling people to not help... are childish. People are on here because they want to help people who are new, figure out their printers. I think in the last messages it is clear to anyone who looks at this thread, of how you are treating people who attempt to help you. I truly hope that if this is the way that you respond to people that people on this forum do not go out of their way to help you.

Edited 1 time(s). Last edit at 09/03/2014 03:16PM by Wildcard.

I'd like to thank thib88 and tjb1 for reading the issue, helping out, and not attempting to cause drama. I'd also like to thank jamesdanielv for trying to help and not causing drama. For those who caused drama, I invite them to not post on my threads in the future.