ANET A6 X-axis modification for belt tension and E3DV6 hot end
Description
I’ve been addressing what I felt were the shortcomings of the ANET A6 X-Axis and thought I would share my progress. There is nothing revolutionary or ground breaking here, rather just my approach to the issues I perceived. Being a typical engineer, I looked at all that had come before and said – “I can do better”… It was also “fun”! I hope you will find it useful. 1) No X-axis belt tension adjustment. ** I followed many other’s approach by adding a sliding clevis for the right side idler pulley and found that when tightening the belt it pulled both sides inward and stressed the vertical guide rods along with the Z-Axis lead screws which caused unacceptable binding. So I scrapped the stock acrylic blocks and designed and printed replacements. a. I added a hard stop to the right side elevator block to hold the 8mm shafts in place. This meant adding 5mm to the elevator blocks width, on the outside face, for the 420mm shaft. (I didn’t want to have to cut the guide rods.) b. Next, I added threads to the outside of the left elevator block rod guide holes for two M10-1.5 set screws. These grub screws push against the 8mm shafts and provided an adjustment for canceling the inward force of the belt when tensioned. This too added 5mm to the outside of the block for the thread feature. Result, I can have very tight GT-2 belt while not applying any radial force to the Z-axis guides or lead screws. 2) X-Axis Aluminum cross slide and Hot-End. a. I found the Aluminum cross slide quite heavy at 115 grams (stripped) while the PETG replacement was just 39 grams. This was not the major goal for the redesign though. The A6 hot-end tube was a non-standard length which I found hard to find and the filament cooling fan (in my opinion) served no purpose while adding weight to the already top heavy cross slide. As I only run PETG at a max print speed of 60mm/sec, going fast is not a concern but the lighter cross slide was still a step in the right direction. b. I wanted to have the option of using Direct or Bowden filament drive systems without major modifications. This design provides for either approach. The new design centers around the common E3D-V6 hot-end with either PTFE or solid heat break tube. This gives me the option to run soft or high temperature filaments. c. Incorporated in the design is an internal anchor for the GT-2 belt loop - getting rid of “tie wraps” which sometimes limited X travel and homing. Two M3 screw with imbedded nuts hold the belt while allowing for coarse belt length adjustment. d. I built a custom mount for the BLtouch probe which has demonstrated very stable and repeatable Z heights control. Using double side tape for attaching the probe vs. CA glue, or screws, allows for “some” crash protection for the sensor, but CA glue worked best. Printing the major parts, one after another, using the same filament and slicer profile meant that any shrinkage was common to all three major blocks which came in contact with the 8mm shafts. The 80mm shaft spacing is not critical, having all printed parts the same is. I had to run an 8mm drill down all the holes for the shafts to get the slide fit I was looking for. I found that after assembly the cross slide moved smoothly and showed no signs of binding. I tried it with the both stock linear metal bearings as well as the Igus bushings. Included are the STEP and STL files for all the printed parts along with a Fusion 360 model link. https://a360.co/2QkvXpV ** I feel it important to acknowledge Roberto Gil (jgbbob8) for his contribution to this project. When in late 2017 I added the X-axis tensioner to my A6 I downloaded and printed the right side and clevis from his original design and used it until deciding to rework the entire x-axis of my printer. I was still using the stock ANET A6 acrylic drive motor side and suffered with the problems addressed above. I used Fusion 360 building all components from scratch. Obviously Roberto’s design had a significant influence and for that I thank him. I’m not sure if this qualifies as a “remix” or “plagiarism” of a functional design. Jeff
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