Prints shifting on Y axis

Hi guys,

I'm fairly new to the RepRap world. This is my first printer in which i bought all the parts from MakerFarm (including the steppers) with Gen 6 electronics and heated bed.

I'm printing on Kapton tape, with the bed at 100C

I'm having an issue now that is completely random, it happens 60% of the time.

In the pictures you can see that the print shifts on the Y axis from some reason, Its completely random, and not constant to reproduce.

Things I have tried,
1. Reducing and increasing the amp Potentiometer for that axis.
2. Putting a cooling fan and heat sinks on the y axis stepper.
3. Verified that the print it self is not slipping on the Kapton tape (its stuck pretty good)
4. I have added belt tensioner for the y-axis, though i have not checked the pulley itself for tightness.

Any suggestions would be greatly appreciated....

Thanks,
-Matt

Edited 1 time(s). Last edit at 09/11/2012 11:59AM by zeroaviation.

Check that the belt isn't slipping to off the bearing.
I had the same issue with the X axis, I'd reset it before a print then wonder why it kept happening

---

My Reprap blog

jds-reprap.blogspot.com

JoeDaStudd Wrote:
-------------------------------------------------------
> Check that the belt isn't slipping to off the
> bearing.
> I had the same issue with the X axis, I'd reset it
> before a print then wonder why it kept happening
>


Joe, thanks for your reply.

I have Mudguard washers on both sides of the bearing to prevent the belt from slipping off on both my tensioner and the opposite side mount.

Thanks!

I had this problem too with the makerfarm kit I bought on eBay. I came to the conclusion that the acrylic used to attache the heated bed starts to bow because of the heat. This creates binding on the Y axis, thus is why your prints are off. See if that's what is. If it is, I bought an aluminum-bed-mount-plate from lulzbot.

[www.lulzbot.com]

But you will need to buy or make Boltable PLA bushing to get it up and running.

[www.lulzbot.com]
[www.thingiverse.com]

And then you can print the Parametric LM8UU Y Stage Holder if you want LM8UU.

[www.thingiverse.com]

Hope this points you in the right direction.

-Cameron

I'm having an identical issue on my Mendel parts Sells mendel, haven't managed to fix it yet, thinking about removing the Gen 6 board and putting on one of my sanguino boards with SD reader to see if it's an electronics issue

---

__________________________________________________________________________
Experimenting in 3D in New Zealand

Try reducing max acceleration on Y axis to 1000 mm/s^2.

Guys,

Thanks for the replies! I'm going to build my own aluminum bed & reduce the acceleration.

Will report back soon!

Thanks again!

i had this problem this week after changing stepper drivers.

the pot was up too high and motor was getting too much power and causing a problem

i just turned it down a touch and not had a problem since

misan Wrote:
-------------------------------------------------------
> Try reducing max acceleration on Y axis to 1000
> mm/s^2.


This is the answer!

I had the same problem on mine and this was the answer: acceleration and jerk.

I don't think it's a hardware issue, at least mine wasn't and when I did the research I found others had fixed it the same way.

Do a search on here about 'shift' and you'll find a few good threads about it.

Edited 1 time(s). Last edit at 09/13/2012 06:43PM by a_shorething.

I caused this same problem on my printer by accident. Fortunatly i know what happened, I made the y axis belt skip a step on its pully.. Watch for that. Make sure your belts have proper tension and if your using printed pulleys maybe they are not very good

On my printer I use molded GT2 pulleys and GT2 belts and never had this problem unless I obstructed the Y axis myself (which Is what made it skip for me but there are other things that can cause this)

I do have a T5 belt and printed pulleys and the way they mesh together I see how they could skip.