3D Printing: Is cutting the arm off the Z-axis switch a good idea?
The Question: We all know (or should!) that the repeatability of common spring-arm limit
switches is crappy at best. I'm looking to build & install one of the precision
height adjusters for the Z-axis limit switch, and noticed a post on some forum
suggesting removing the arm and triggering the switch button directly (e.g.
with a screw end).
Has anyone tried this, and if so has the repeatability of Z-homing improved
any?
**** Edit ****
Sorry -- this is a stock Prusa i3, which depends on physical contact between
the vertically-moving subassembly and a microswitch mounted on the frame.
Solutions: Please watch the whole video to see all solutions, in order of how many people found them helpful
== This solution helped 1 person ==
No. Buy a better switch if it's an issue (see below).
You would need to have some very tight tolerances to hit that micro button with
whatever your arm is. If you had a machine with good tolerances you would not
be considering this modification. That alone is why I would say this is not the
greatest idea.
Following it might work if your Z is connected to the hot end and smashing into
the bed. But I suspect you will still have a myriad of issues, such as the
switch getting out of position enough to cause the head to crash into the
machine. The real question now is how many rotations of the Z axis could happen
if the printer is moving at maximum speed and the button is pressed? That metal
arm is your grace period. Now your printer is potentially smashing into the
switch.
Lastly, just get a switch with a more solid and less springy metal tab.
The real question is whether there is actually a variance caused by the metal
arm? I would suspect that it hits the switch very precisely, consistently and
within an acceptable tolerance. Removing the arm will buy you little. Replacing
it with a stiffer-arm switch might serve you better.
== This solution helped 2 people ==
While I haven't seen this on a Z axis for a printer personally, there is no
reason it wouldn't work, and would improve your repeatability in theory.
Removing the arm on the switch is taking away the lever. Going back to simple
machine mechanics, the lever gives you a larger range of motion in which the
button could be triggered, with the tradeoff that you get a larger target to
hit. How much of an improvement depends on the exact switch, where the button
is compared to the axis of the switch, and how long the switch is.
My Shapeoko 3 CNC router has a switch for all three end stops that do not have
arms, and my Original Prusa i3 mk2 has switches without lever arms on X and Y
axis endstops, so there is is no reason it won't work for your i3 Z axis, you
just need to make sure you can accurately hit the small button on the switch.
With thanks & praise to God, and with thanks to the many people who have made this project possible! | Content (except music & images) licensed under cc by-sa 3.0 | Music: www.bensound.com/royalty-free-music | Images: stocksnap.io/license & others | With thanks to user Trish (askubuntu.com/users/8884), user StarWind0 (askubuntu.com/users/2146), user Jexoteric (askubuntu.com/users/4654), user fred_dot_u (askubuntu.com/users/854), user Carl Witthoft (askubuntu.com/users/2191), user Aaron Stoker (askubuntu.com/users/12602), and the Stack Exchange Network (3dprinting.stackexchange.com/questions/3027). Trademarks are property of their respective owners. Disclaimer: All information is provided "AS IS" without warranty of any kind. You are responsible for your own actions. Please contact me if anything is amiss at Roel D.OT VandePaar A.T gmail.com.
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