Keith Davis published a new build:

Read more about this build...

 

Makerbot? I hadn't even thought about makerbot. Their high price reflects their market dominance, not the value of the machine. On the other end of the scale, I can compete with Printrbot and still turn a profit. The components come in around the mid $500 range when all parts are bought retail. The actual sale price will be just as high as the market will bear, somewhere close to assembled Ord Bots.

As for electronics, it will use the new Azteeg X5 (mini) from Panucatt (I'm still waiting for them to ship their kickstarter batch so they can fill new orders.) The small, but powerful enough, NEMA 17s are from QU-BD (min v wheel guide systems have less drag than linear bearings) and the NEMA 14s are from Pololu. Heat bed is from Sainsmart.

 

I have a little over 1000 hours on a printer with that design, and no play in Y carriage wheels has developed. There are lots of printers that use an offset for the Y axis (printrbot, cube, up!, makergear m2, etc). The makergear uses wheels that are a lot smaller that the OpenBuilds Solid V Wheels. The others use linear bearings.

A nice thing about using wheels instead of bearings is that wheels can be adjusted as they wear. I have a printerbot that got wear in the linear bearings for the X axis and the same thing happened on an OrdBot's X axis, both after 5000 hours. The Ordbot was easy to adjust, the printrbot required bearing and rod replacement. By definition, most X axis designs use an offset belt and have a much smaller distance between bearings/wheels accentuating the effect you are referring to.

The main thing is having a truly parallel set of slots for those wheels to run in. I tried using two 20x20 extrusions separated by printed spacers. No go, the two sides were never parallel enough and that did cause wear. That's why I use a 20x60 for the center. I actually think a better setup for wear would be to use three wheels - two stationary and only one adjusting on the other side half way between the other two - creating a triangle, which is more rigid and automatically squarer than trying to get equal tension on two adjustable wheels. Deezmaker uses that concept with OpenBuilds wheels on their Bukito. But I haven't tried that on a Y axis.

Take a look at my other printer design http://www.openbuilds.com/builds/oneupsolid.1222/ on the third picture. You will see a different variation of the concept there. I'm cutting the extrusions for assembling that design this afternoon.

 

If you plan on using the OpenBuilds Build Plate, look it over before deciding on whether it will be an 80x20 or 60x20. The pre-drilled holes fit 60x20 exactly. 80x20 holes are not there, if memory serves me correctly.
It's a pleasure to share!

 

Proteus. I discontinued that model a few months ago. The design of the printed bracket connecting the X axis bar to the Z axis bearings is too flimsy after 1K hours of operation. I'm finishing a redesign using V Slot extrusions and Mini V Wheel Kits for Z axis. Much stronger and more rigid. The redesign also places the X axis motor in the center of the X axis bar, evenly distributing weight and torque along that axis. I'm just now completing an auto-leveling mechanism for the new design.

I'll post links to the new design here when I release it.

 

Rack and pinion moves the motor. We certainly do not want that weight moving on a high speed x axis. My x axis motor is stationary with the belt above the top v wheels (actually anchored to those v wheel axles). Here's some picts and the Sketchup file

Assembly


X axis front


X axis rear