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Project:Cupcake-o-Matic: Difference between revisions
From London Hackspace Wiki
→Adding a Cantilever Z Axis
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===Adding a Cantilever Z Axis=== | ===Adding a Cantilever Z Axis=== | ||
[[File:cupcake_cantilever_z_axis.jpg|thumb|300px|A cantilever | [[File:cupcake_cantilever_z_axis.jpg|thumb|300px|A cantilever Z-axis in laser cut acrylic.]] | ||
In order to move the extruder up and down in the | In order to move the extruder up and down in the Z-axis the Cupcake CNC used a platform suspended on 4 M8 nuts on threaded rods. These threaded rods were linked together with a timing belt such that if the motor moved one step (1.8degrees) then all the threaded rods would rotate by the same amount. This meant you could get an accuracy of 0.00625mm per step. Unfortunately this was very slow and relied on the threaded rod being exactly straight which it rarely was. What would happen is as the Z platform rose during a build one or more of the threaded rods would move in the x or y axes there by throwing off any precise accuracy in these axes. Another serious problem with this arrangement was the assumption that the 4 M8 nuts would always remain level and wouldn't jam. As a result the Z axis platform would be wonky which didn't help when printing. | ||
To first fix this I printed a [http://www.thingiverse.com/thing:3091 Z-Wobble arrester without pin]. It replaces a nut on the | To first fix this I printed a [http://www.thingiverse.com/thing:3091 Z-Wobble arrester without pin]. It replaces a nut on the Z platform and allows the threaded rod to move back and forth without necessarily dragging the platform in that direction. This was fiddle to install as it required the removal of a nut trap on the platform and then the nut to be moved down a bit, whilst still leveling the bed. It was hard to tell how well this was working but I certainly felt my Cupcake CNC worked better when the arrester was installed on the wonkiest threaded rod. However this did not fix the problem of having to level the Z platform so I began to research on Thingiverse for a good solution to solve my troubles permanently. | ||
The Thing-o-Matic had come out for some time ago at this point and I was rather interested in the Z axis which was made up of a cantilevered platform which had 2 smooth rods for stability and a linear stepper motor for positioning. One middle point solution was to replace the bent M8 threaded rods and nuts with an ACME screw thread on CNC machined rods, this would be booth smooth and straight. This | |||
[http://www.thingiverse.com/thing:18849] | |||
Replaced the 4 threaded rod suspended Z axis with a Thing-o-Matic inspired cantilever stage. | Replaced the 4 threaded rod suspended Z axis with a Thing-o-Matic inspired cantilever stage. | ||
