Antibacklash Nuts - Best practice for mounting?

Hi,

Currently working on a redesign of the printed components of the Ormerod (see other ormerod forum for detail) and I think I am suffering an over-constrained TR8 screw. What is best practice for mounting the anti backlash nuts?

With the sprung loaded tail supported like this:




...or free like this:

I can see some anti backlash nuts that are designed to have the tail assemble into the mount, such as this one:



Mine is this version (but from another supplier):

The tail side needs to be constrained from rotating and free to move along the axis. It's not clear in your second image whether or not the teeth on the tail are engaged with the teeth on the main nut.

I use openbuilds delrin nut blocks on my diy corexy 3D printer and these don't have any backlash and don't need lubrication. They are mounted differently so you may have to redesign some parts to install it. I use v slot extrusions to constrain the z bed in xy axes.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

I personally believe that you want to mount them upside-down in the case of a printer Z axis otherwise the platform is resting on the spring not the threads (if that makes sense)

Effectively you want to view it as a normal nut that is being pushed by a spring into engagement at all times. So you want the spring to push the nut down into engagement (working with gravity) so that the weight of the platform and spring are driving down stopping it from slipping up, rather than up into engagement where the weight of the platform is pressing down on the spring but the spring pushes up so that the platform is sprung (bad) and any forces on the bed will deflect the spring and move the platform (very bad).

Thanks for your feedback. My current z-nut-trap part has the lower, smaller part constrained a bit too tightly around its circumference by long bolts constraining the top part. I'll redesign to use much shorter bolts and ensure the only constraint on the sprung loaded tail is the tags that engage on the main nut.

And where do you need this anti backlash nut ? Better avoid its use in a 3D printer. When required, an adjustable like this delrin from openbuilds is better than the one using springs

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Had flatspots on my Delrin V-Slot wheels on a build for a previous employer. Granted the wheels - in error - were too tight against the rail, but the ease at which the aluminium extrusion wore a flat in the wheel in its extrusion direction doesn't give me confidence in its durability.

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WesBrooks
Had flatspots on my Delrin V-Slot wheels on a build for a previous employer. Granted the wheels - in error - were too tight against the rail, but the ease at which the aluminium extrusion wore a flat in the wheel in its extrusion direction doesn't give me confidence in its durability.

I agree - the wear on these plastic style ones will be massive.

You need good alignment for the vslot wheels. I use them in my 3d printer build and only one wheel suffers from this and you guessed it, it was misaligned. I also use them on the cnc ox build, no damage to the wheels yet and that with a 3kg spindle on it, total gantry weight is about 5-6 kg. I like it a lot better than the noisy and loose lm8uu, which can also wear a hardened rod quite easily.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

Quote
WesBrooks
Had flatspots on my Delrin V-Slot wheels on a build for a previous employer. Granted the wheels - in error - were too tight against the rail, but the ease at which the aluminium extrusion wore a flat in the wheel in its extrusion direction doesn't give me confidence in its durability.

Improper use/mount of any component will lead them to fail. Don't blame the component (except some crappy chinese that are bad fro the start of course)

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

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MKSA
Improper use/mount of any component will lead them to fail. Don't blame the component (except some crappy chinese that are bad fro the start of course)

My point was it didn't take sliding well. The delrin antibacklash block will always be subjected to sliding. It was only jammed for a build.

Finally got back around to tweaking the cad and went for the following. Spring fowls the cap heads but not that much on an issue. Ignore the printed coupler, that was a stop gap I haven't changed back out yet.



Edited 1 time(s). Last edit at 12/21/2018 08:53AM by WesBrooks.