Friday, October 29, 2010

Be square! (squaring my UP! X/Y axis)

How I squared my UP! after my ball bearing broke and skewed my machine...

One evening when printing I let it run for itself on a 5 hour print and I checked in on it a few times to see that it was behaving good. And towards the end of the print I found it sounding very bad and it had made a mess of the print because the X (?) axis was not moving. After a few minutes with my screwdriver I saw that the ball bearing was broken and a few tiny balls lay beneath it.

First thought was "crap!, machine downtime...". I tried searching for a ball bearing with the dimension (10x5x3 I believe) but without any luck in my small town (I have found an online retailer later though). Then I emailed PP3DP customer service and Shirley kindle said that they were going to send me a new bearing and a spare one with DHL: I must say that PP3DP have a great customer care.

Knowing that the ball bearing would arrive within a few days I looked at the possibility of repairing the bearing. What had happened was that the ball cage had come loose and jumped out.
After some work with pliers and tweezers all balls were back and I made a temporary fix to keep the cage put.
It seemed to work and I ran a  few prints without problems.
First thing I saw was that squared prints became skewed and circular prints was slightly oval.
And looking at the printer I saw that the angle between the gantry and the sledge, X and Y, was not 90 degrees. And comparing pictures before the bearing broke It was almost perfect 90 degrees. I assume that something became bent when I found it just standing still making bad noises.

Maybe a calibration would fix this but I would prefer that it looked good, often I find that what looks good works good :-)
So next step was to see what parts that the squareness relied on, I think that there are two points in the printer that can affect this:

The right guide looked straight enough but the left one was a little bit bent.I bent this part back and now the mounting hole in the back of the sledge fit better. 

There´s also a some adjustment possible just to loosen the screws under the sledge (where the X axis meets Y axis). Best solution I found was to loosen these four screws and then use something square adjust it while tightening the screws. You can see the four screws below where I have flipped the hole assembly over showing the underside.

After assembling I made a print without doing a calibration first and it printed much more square. I had to level my platform again but after a calibration I get great squareness and good prints. Now there´s really nothing I have to consider when printing except the warping in larger prints but the acrylic build plate fixes this for now until I have a better solution. Once I get the new ball bearing installed I feel like I can start the print and then leave it and expect a good result. 

Another thing that I have no idea how it happened is that before, my build plate wasn't centered, when moving to near left or right the nozzle would be a few millimeters outside the build plate. But after this this is gone and it´s perfectly centered. It was not intentional to fix this at all but a great surprise.

I like the way the UP! printer is constructed, it´s easy to design a device that´s hard to service and modify but to make it easy and mod-friendly is a lot harder, and the UP! is really easy to dig into. Large covers that shows you everything, fairly standard components and bearings, no need for expensive custom stuff...
It´s a great machine!


  1. And I see my printer and have the same next week I do the same . Chris.e I harvest but you are helping to me in everything what also I have been able to see that you are right in everything what it has done.

  2. To day I drink my beer One Budweiser it very fries and take a time to see your blog .