Fine Tuning the Rostock ...Success!!

I spent this long weekend resolving some issues on the Rostock.
Two issues that were causing intermittent problems were:

1. The Teflon tube on the bowden occassionally working its way loose during a print.  
   This was a pain. If I tightened the clamp up too tight it would crimp the tube and restrict the path of the plastic filament. I tried a few things like filing the outside of the tube to provide more grip, adding some tape, etc.
   Finally I had a eureka moment when I suddenly woke up at 3am Saturday moning. I Then couldnt sleep, so I got up to try and implement the idea. I added a threaded nut onto the Teflon tube and redid the connection so the night is locked inside and cannot pull out. Success
     
2. The extruder sometimes skipped when feeding filament during parts of the print that involved laying alot of plastic quickly. Basically did not have enough torque. I redesigned the gears shrinking the drive gear a little and increasing the size of the secondary gear to increase torque. 

Basically this resulted in the quality of my prints going from this:

 

To this..



 

This last print was at .2mm layer height abd too about 4 hours. I had to vary the speed at certain points to allow the filament to dry on the smaller diameter parts

 

Rostock 3D Printing Vases

Well I printed one of my longest jobs on the rostock. A couple of vases. All up they took about 5 hours or so.
I have printed them in plain white as they are translucent and I intend to put some of those LED flickering tealights in them.
The one on the right is after doing more tweaks to the unit. I added sides and crossbeams to increase the rigidity of the unit which has decreased vibration during printing substantially.

 

 

Rostock Finally working Accurately- YAY!

Well I have been slack of late and never got around to debugging the Rostock printer.
I have had a long outstanding issue where prints were not perfect dimensions in X and Y
If for example I printed a large square 200mm x 200mm it would not be perfectly square. It would be out by a couple of mm in 1 corner.
I tried all sorts of measurements but could not work out the issue.
As I had a few days off over new years weekend, I decided to bite the bullet and fully rebuild it.

I totally dismantled it and cut new base and top boards. Assembled and squared everything up making sure everything was square and all rods are exactly the same length from the print centre, both Top and Bottom.
As mentioned in a previous post, I also replaced the printed rods and joints with manufactured Heim joints.
This time it all works very accurately.
Things that helped that I did not have as an early adopter for the first build:

• A good set of precise dimensions for the base and top boards. Previously its was all angles and distance from centre etc. Very difficult to get perfectly accurate. This set of dimensions lets you locate all the key points just by measuring from the top left of a rectangle board.  http://www.thingiverse.com/thing:34359 .  I still calculated the build centre point which is 175 In from the left and 175 in from the back. Lines going out from the centre point at 120 degree angles intersect the midpoints between each of the whole pairs.
  An important note about the diagram is that the holes on that are marked as 8mm. This is wrong they are only 3 or 4mm and are used to secure the plastic parts that hold the rods. The rods do not go through the board they are on the outside edges of the board.
• A good calibration guide: http://minow.blogspot.com.au/  This is an excellent source of information that clears up so much of the black magic. Thanks minow :-)
• A second try :-)  My experience from the first build made the rebuild easy. Basically it was done in a day.  

This time around I did not add the threaded rods for support. I am going to add some sides on the left and right sides that extend a couple of inches beyond the the back of the unit. I will then add a threaded rod X across the back for stability.

I will post an image once I have completed the build.