<p>I have been studying the differences between version 2.x and version 4 of the <a href="https://reprap.org/wiki/P3Steel" rel="nofollow noreferrer">P3Steel frames</a> - in particular the AC08 bracket at the top of the frame which secures the top of the smooth bars and threaded rods of the Z axis on both the left and right sides. Here is the laser cut parts, for version 1.x, showing the part labelled as AC08:</p>

<p><a href="https://i.stack.imgur.com/2AN9z.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2AN9z.jpg" alt="Laser cut parts for P3Steel v1"></a></p>

<p>Version 1.x/2.x has the AC08 bracket with two holes, one for the threaded rod and one for the top of the smooth bar (from the <a href="http://reprap.org/wiki/P3Steel_Vitamins#Lasercut_parts" rel="nofollow noreferrer">lasercut image</a>):</p>

<p><a href="https://i.stack.imgur.com/6yZMo.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6yZMo.jpg" alt="P3Steel v2 Z axis top bracket"></a></p>

<p>However, in version 4, the corresponding top Z axis bracket only has one hole for the smooth bar and just an indentation for the bearing which holds the top of the threaded rod (from <a href="https://twitter.com/AlvaroReyRdz/status/738406531943763968" rel="nofollow noreferrer">Twitter</a>):</p>

<p><a href="https://i.stack.imgur.com/MZe2i.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MZe2i.jpg" alt="P3Steel v4 Z axis top bracket"></a></p>

<p>Here is a close up of the <a href="https://drive.google.com/open?id=0BxUhvFbuwEAZNjA0dUhwNmFMd2c" rel="nofollow noreferrer">diagram</a> from the <a href="https://drive.google.com/open?id=0BxUhvFbuwEAZfkJDUUE0bm1pTXNfMFRKemdUUzJNZ2xIT0xybFJLdmdyQV9MZGFpcG42UlE&amp;authuser=0" rel="nofollow noreferrer">google docs repository</a>, listed in the <a href="http://reprap.org/wiki/P3Steel#Frame_versions" rel="nofollow noreferrer">v4 section</a> on the RepRap Wiki page for the P3Steel, which shows the bearing assembly just apparently "resting" against the indentation:</p>

<p><a href="https://i.stack.imgur.com/dAVUM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dAVUM.png" alt="Close up of P3Steel Z axis top bracket"></a></p>

<p>Here is the bracket shown with the bar and threaded rod (again, from <a href="https://drive.google.com/file/d/0BxUhvFbuwEAZQjkyTDM3SndMSTA/view" rel="nofollow noreferrer">google docs</a>):</p>

<p><a href="https://i.stack.imgur.com/X0fcG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/X0fcG.png" alt="P3Steel v4 z axis top bracket"></a></p>

<p>Does anyone know why the top of the threaded rod is not secured by a hole, as it was in version 1.x/2.x? It just does not look particularly well secured.</p>

<p>Under the list of version 4 changes, see <a href="https://reprap.org/wiki/P3Steel#Frame_versions" rel="nofollow noreferrer">2. Frame versions</a>, it is mentioned:</p>

<blockquote>
  <p>The extruder no longer hits the Z axis top bracket</p>
</blockquote>

<p>Is this the reason why the change has been made?</p>

[{'answer_id': 4146, 'author': 'Greenonline', 'author_id': 4762, 'author_profile': 'https://3dprinting.stackexchange.com/users/4762', 'pm_score': 2, 'selected': False, 'text': '<p><em>This is mere supposition on my part, and not a definitive answer. This was posted prior to Alvaro\'s answer.</em></p>\n<hr />\n<p>In response, or - rather - with respect to, to the comments under the question by <a href="https://3dprinting.stackexchange.com/questions/3015/z-axis-top-brackets-of-p3steel-differ-between-v1-x-2-x-and-v4#comment3919_3015">tjb1</a> and <a href="https://3dprinting.stackexchange.com/questions/3015/z-axis-top-brackets-of-p3steel-differ-between-v1-x-2-x-and-v4#comment3916_3015">Tom</a>, I have been reading around the topic, and found some interesting articles.</p>\n<p>The excerpt below from &quot;<a href="http://www.soliforum.com/topic/2342/backlash-hysterisis-and-wobble-an-exploration-of-the-topic/" rel="nofollow noreferrer">An exploration of the topic</a>&quot;, backs up Tom\'s argument about constraining the rods at both ends being bad practice, and explains why it is so. Whilst acknowledging that a loose, or floating end, is still an issue that needs to be dealt with, the article also states that constraining the end is not really a solution, as it can create more problems elsewhere (I have added the bold highlighting to the relevant text):</p>\n<blockquote>\n<p>Wobble is pretty simple. Because the lead screw is mounted rigidly to\nthe motor, it needs to be perfectly straight and square to the axis\nits trying to move. If it\'s not, as the motor rotates, that offset will\nbe converted into an elliptical motion instead of turning in a perfect\ncircle.  In big CNC world, as the axis is normally bolted to a\nhuge/heavy table which refuses to yield to this movement, it results\nin breaking your motor or motor coupling (weakest point in the\nconnection). This is what flex couplings are designed to fix – if you\ncan’t guarantee a perfectly square mating between motor and axis, you\nuse a coupler with flex so that any movement can be soaked up in\nflexing the coupler and the lead screw/rod moves in a nice circle\nwithout busting your motor or mounts.  This is true when you have a\ngood solid supported connection on the lead screw like you’d see on a\n‘proper’ CNC.  <strong>However on the Solidoodle, as the top end of the Z-Axis\nis ‘unsupported’ and its only connection to <em>anything</em> is to the table\nvia a tiny little nut, its free to ‘flop about in the breeze’ so to\nspeak.</strong> Even a small 0.1mm offset from center can result in a much much\ngreater ‘wiggle’ at the top of the screw clearly visible to the eye.\nThrow in even a 0.05mm bend in the rod, and it gets further amplified.</p>\n<p>Adding better support to the axis, through a taller nut, multiple\nnuts, or <strong>supporting the end, would reduce the influence of this\nwobble. You do however, risk moving it to something else entirely</strong> –\nfor example, making the lead screw rigid would mean that the forces\nwould end up moving the motor itself, potentially causing fatigue\nissues with how its bolted to the sheet metal case (mine already moves\na fair bit and its ‘stock’... making the screw rigid would see the\nmotor having to absorb all that movement instead of half of it\ndisappearing in movement of the screw...). Solving the motor movement\nby securing it ‘better’ to the case would mean that the movement now\ngets soaked up in the motor shaft and bearing, leading to premature\nstepper motor death.</p>\n</blockquote>\n<p>Thus, when first posting this question, I had originally presumed that the earlier versions of the model would be superior: Due to the fact that the earlier versions secured the top of the z-axis screw mechanism, then that would reduce the amount of &quot;flapping about&quot; of the loose end, which in turn would result in <em>less wobble</em>. However, I had not bargained for the negative consequences (such as the increased motor wear, mentioned above).</p>\n<p>So, is the reason that the top brackets of the z-axis, in the version 4 of the frame, lost their threaded rod/leadscrew top-end constraint, therefore to prevent premature motor wear, at the expense of exhibited wobble?</p>\n'}, {'answer_id': 8287, 'author': 'Álvaro Rey Rodríguez', 'author_id': 14559, 'author_profile': 'https://3dprinting.stackexchange.com/users/14559', 'pm_score': 4, 'selected': True, 'text': "<p>I've just seen this right now, I'm Alvaro Rey, the designer of the p3steel v4 mod. The change was made, because with previous versions with the extruder homed, if you go up in the Z axis, the extruder motor could hit the Z axis top plate. So, in order to avoid that, I just changed the design.</p>\n\n<p>The bearing in the z axis is not necessary but some people prefer to use it, in order to avoid wobble in the threaded rod. </p>\n\n<p>Anyways, I designed a printer part to fix the bearing in the Z top plate.</p>\n"}]
['https://3dprinting.stackexchange.com/questions/3015', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/4762/']