Noisy rotating bed brackets due to play

Topics around mechanical design, controller and electronics. Mods & hacks welcome.
DrExcess
Posts: 3
Joined: Sat Sep 02, 2017 9:00 am

Noisy rotating bed brackets due to play

Postby DrExcess » Mon Jun 25, 2018 5:29 pm

Hey all - the brackets that hold my bed to the z leadscrews have become very noisy due to the rotational play / slop.

My left is worse than my right but every z-hop or z movement I hear the clang as the bracket moves around until it reaches the edge of its tolerance.

How can I resolve this, as tightening the screws is now an option as they need to be left loose to prevent binding, is there nothing that actually fixes the bracket to the bed itself?

See video for idea of how much play / noise we're talking about.

https://photos.app.goo.gl/UrHSxtX81kQ6zchx8

Jetguy
Posts: 2513
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Noisy rotating bed brackets due to play

Postby Jetguy » Thu Jun 28, 2018 5:18 pm

I thought someone else had posted a mod like this, but cannot seem to find it even after hours of searching.

Here is my Z axis mod, to do something other than the loose screw and nut combination to provide compliance for the ball nuts to prevent Z wobble.
It's simple mod, I used 2 hold nozzles because they are M6 threaded and that is the correct size for the side holes in the Z ball nuts, and then a simple strip of aluminum bought at the local hardware store bent by hand after having 2 M6 sized holes drilled into the ends. Sure, I could have used M6 screws and even had them. I also have pile of nozzles that should go in the trash bin, and here is a perfectly good way to make them useful.

I know it's not pretty, but the idea is that if one ball screw is even the slightest out of being perfectly concentric during travel (bent during shipping or dozens of other errors) a straight bar would transfer that to the other nut. This gives some amount of compliance.

It meets all my requirements:
#1 hidden and looks relatively stock
#2 no mods to the existing hardware, only additions of a single cheap piece of aluminum
#3 Allows the nuts to move around compared to the build plate but prevents rotation of the nut
#4 eliminates the current system of the loose nuts and screws that can rattle and allow rotation when the axis reverses direction.

Due to the weight of the Z stage, I have zero concerns that even with Z hop of needing to insert the factory screws and nuts back into the assembly except maybe for shipping or transporting the printer. Simply put, gravity is all the anti-backlash you are going to need.
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DrExcess
Posts: 3
Joined: Sat Sep 02, 2017 9:00 am

Re: Noisy rotating bed brackets due to play

Postby DrExcess » Sat Jun 30, 2018 7:13 am

Yet again Vernon this is excellent and exhaustive. I'm absolutely going to do this.

I've foudn through days of testing that allowing them to rotate is useless, the effect is worse than the issue they are trying to prevent so I currently have them tight, but of coarse risk binding.

I will acquire some aluminium and do this for sure - simple and effective.

If you're not helping me on Facebook you're helping me here.

You truly are a 3d printing MVP.

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JohnSays
Posts: 595
Joined: Tue Apr 26, 2016 2:42 pm
Location: Saint Petersburg, FL

Re: Noisy rotating bed brackets due to play

Postby JohnSays » Wed Jul 04, 2018 2:01 am

Very cool and simple fix JetGuy. You mentioned this idea back in a thread about Possible Z-Wobble.

I see you don't have thumb screws to level the bed. Do you only use the Z-stop to adjust height and depend on the factory system to keep the bed level?
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection resistors on motion controller board, Firmware 1.1.8ABH - with Lin_Advance, Palette+

Jetguy
Posts: 2513
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Noisy rotating bed brackets due to play

Postby Jetguy » Wed Jul 04, 2018 3:40 pm

Correct, leveled the bed once using the factory method- but using a dial indicator as this makes seeing the adjustment visually much easier.
Again, no different than the exact method described here in a series of posts and the first one contained videos viewtopic.php?f=4&t=1564&p=13777

Correct, the Z stop is used to adjust the global Z gap to the nozzle, and because the bed remains flat (last time the bed was leveled was April of 2017- when that post was made), that's all I use.

zemlin
Posts: 323
Joined: Sat Oct 21, 2017 2:02 pm

Re: Noisy rotating bed brackets due to play

Postby zemlin » Tue Jul 10, 2018 1:40 pm

I am working on a printed fix for ball-nut rotation that will not constrain lateral translation.
I bungled the first print with a typo on a dimension, but should be able to mount the parts this evening and will share the STL if it works out well.
viewtopic.php?f=4&t=8421&p=33607#p33607

zemlin
Posts: 323
Joined: Sat Oct 21, 2017 2:02 pm

Re: Noisy rotating bed brackets due to play

Postby zemlin » Wed Jul 11, 2018 10:30 am

See a printed bracket here: viewtopic.php?f=5&t=9804


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