In the first version of my plotter I used single aluminum rods for the X and Y axis and short LM8UU linear bearings. In this improved version I am still using a single rod for the X-axis but made from V2A stainless steel and SC8UU linear bearing platforms. The advantage from V2A over aluminium is, that it barely bends at all when the Y-axis is in the middle of the working area. To achieve more stability on the X-axis and hopefully less wobbling, two SC8UU linear bearing platorms were used per side with little spacing. In contrast to the first version of my plotter the Y-axis is oriented in a horizontal instead of a vertical way and two linear bearing platforms were used to move the laser.
First I used my old China Nema 17 from the first build but was not very happy with. The overall results were better but not as much as I though. The only variable left to replace were the Nema motors. I chose to by new ones from omc-stepperonline.com via eBay. With the new motors in I think the plotter is as precise as it will get. Compared to the old ones there is a huge difference in quality, noise reduction and accuracy. TIP: Do not be cheap on motors !
I used two pieces of 2 mm aluminium to clamp the GT2 belt on the Y-axis. On the Y-axis I fixiated the belt with two flat washers and the 4 mm screws for the liear bearing platform. This did not necessarily improved the overall precision, but it definitively looks better.
As in the first build I used Multiplex ply wood for all mounts.
Electronics / Wiring
I have not changed anything on the driver board or connections from the first version. I attached the KiCAD schematic on the basis of which I want to build a proper PCB in the future (Feel free to use this as a basis for your own design). The complete KiCAD project is attached to this blog. However I have not done the routing yet. The KiCAD A4988 stepper driver carrier module can be found on the Pololu page.
Nothing much has changes here. I upgraded the Arduino from grbl 0.9i to 0.9j. Since 0.9i the G40 command is supported, this might come in handy for engraving tiny structures.