1 (edited by 2n2r5 2013-06-21 11:36:08)

Topic: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

http://www.thingiverse.com/thing:101308


We are all switching to a m3 or m5 rod because it it more flexible and has finer threads but no one is taking advantage of the flexibility of the rod. We are all still forcing the rod to be centered when driving the platform up and down which will cause banding of some sort. Here is a simple adaptation of m5 threaded rod nuts to allow for x-y movement of the center rod. This should allow the 3/8" rods to hold the platform in place and be a true x-y guide while the threaded rod only worries about the z axis. This solution allows for "slop" in the M5 rod. If anyone is interested, I will adapt this to the M3 and the original 5/16" rod.

http://2n2r5.com/pictures/printer/m5_upgrade/5mm_thread_adaptor_slop.jpg
You can see in this cross section that the mounting holes in the captive nut piece have lots of slack (.6 mm all around) compared to the base and enclosure. The enclosure also has 1 mm gap all the way around the other 2 pieces.

NOTE: Since we are deliberately putting lubrication inside the assembly, make sure you super glue the nut inside the "nut hugger" and let it set up before installing.
DO NOT use any other anti-backlash device with this setup. It will undo all the benefits of the slop nut. I promise you will not need it.



You can see the play in the rod now and it doesn't make the bed shift at all.

http://2n2r5.com/pictures/printer/m5_upgrade/printed_parts.jpg

Post's attachments

3mm_thread_adaptor_slop_anti-backlash - alu bed.stl 729.15 kb, 56 downloads since 2013-06-21 

3mm_thread_adaptor_slop_anti-backlash - wood bed.stl 757.81 kb, 37 downloads since 2013-06-21 

516in_thread_adaptor_slop - aluminum bed.stl 665.34 kb, 101 downloads since 2013-06-21 

5mm_thread_adaptor_slop_anti-backlash - alu bed.stl 732.25 kb, 74 downloads since 2013-06-21 

5mm_thread_adaptor_slop_anti-backlash.stl 761.6 kb, 33 downloads since 2013-06-21 

You don't have the permssions to download the attachments of this post.
SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

2

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Clever idea.

Now to adapt it to have two nuts for anti backlash.

3

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

lawsy wrote:

Clever idea.

Now to adapt it to have two nuts for anti backlash.

I think that will end up requiring replacing the stock screws since both nuts would have to be inside the housing.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

4 (edited by 2n2r5 2013-06-09 06:44:17)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

lawsy wrote:

Clever idea.

Now to adapt it to have two nuts for anti backlash.


http://2n2r5.com/pictures/printer/m5_upgrade/5mm_slopnut_anti-backlash.jpg

done

This should keep the nuts tight to the thread in both directions. Instead of using a spring (which I didn't have room for) I offset the nuts. Hopefully this will take all the backlash out.


Make sure the 2 dots on the center nut huggers are on opposite sides when you install them. The nuts are off centered by .2mm in that direction.


You want to be the guinea pig?

Post's attachments

5mm_thread_adaptor_slop_anti-backlash.skp 253.76 kb, 16 downloads since 2013-06-09 

5mm_thread_adaptor_slop_anti-backlash.stl 761.6 kb, 53 downloads since 2013-06-09 

You don't have the permssions to download the attachments of this post.
SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

5 (edited by 2n2r5 2013-06-09 05:18:04)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

The anti backlash version just starts to jam together when you get it lined up right. It seems to go together just fine. I am working on a test print now.
EDIT: This is the coarse test print. Layer Height .3mm
http://2n2r5.com/pictures/printer/m5_upgrade/results1.jpg

Before with original M5 upgrade hardware including anti-backlash on left and new m5 upgrade using my anti-backlash slop nuts. (please don't ask me to change the name. I chuckle every time I say it.)

The original fix was pretty good but the new fix is practically flawless. It did take some tweaking to make sure the nuts inside the housing were loose enough to move freely.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

6

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

I'm really enthused by this.

Unfortunately I'm not enthused by the thought of pulling the Z carriage to pieces again.

The results looks so good that I will test it soon, though.

7 (edited by 2n2r5 2013-06-09 07:09:00)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

lawsy wrote:

I'm really enthused by this.

Unfortunately I'm not enthused by the thought of pulling the Z carriage to pieces again.

The results looks so good that I will test it soon, though.

Yeah, no kidding. I tested 3 iterations of this. I am beginning to get a system.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

8

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

I have longer, better allen keys this time so hopefully it's less painful.

Printing now, will fit tomorrow. Any tips for fitting?

9

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

just trim the excess from the holes and get rid of any flares on the nut retainers to give you as much room for wobble as possible. Also, make sure to grease the top of the base and both sides of the retainers before putting on the housing.

I made a mark on the side of the nut retainers with a sharpie so I could make sure the dots were on opposing sides. It should feel like the nuts are just starting to tighten when you get them where they should be. It only took a dab of grease and running the assembly up and down once before everything felt right.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

10 (edited by 2n2r5 2013-06-10 00:28:50)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

More Results:

This is the first thing that I printed at .1mm layers. The grey frog was printed I think was printed with the 5/16" rod at .1mm layers. I just needed something as a reference for the pictures. My settings are off for .1mm but the quality is good enough to see that z-banding isn't affecting the frog hardly at all.

http://2n2r5.com/pictures/printer/m5_upgrade/frogs_back.jpg

http://2n2r5.com/pictures/printer/m5_upgrade/frogs_side.jpg

http://2n2r5.com/pictures/printer/m5_upgrade/frogs_green_close_up.jpg

Guessing by the vertical stripes, I am getting ready to do a GT2 belt and pulley upgrade. Funny, I didn't notice those too much before this.

http://2n2r5.com/pictures/printer/m5_upgrade/anais.jpg

Before is on the left in grey. Both models were printed using my malfunctioning .1mm layer heights which needs to be modified still to work with my new hotends. The After is on the right. You can see significant reduction of any bands. The bands that you can see may be an issue with y-axis calibration and belt tension. I had a skipped step in the after print which was in the Y axis so I am hoping to get even better results after a mechanical run through.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

11 (edited by ysb 2013-06-09 11:12:22)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

very good idea... so we need to go to 5mm rod screw version, or can we have one for the original 5/16 screw ?

12

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

I will adapt this to the M3

please smile

13

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

I too would be interested in a version for the original z-axis rod, though I'll probably switch to the M5 version of the upgrade once I find a source for long-handled allen keys.  Using short ones is a PITA ...
Matt

14

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Ok I've fitted the parts. I assembled them like in your SketchUp section view.

About to print test part.

15

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Results yet? How's it looking so far?

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

16 (edited by 2n2r5 2013-06-10 01:49:51)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Here is the experimental 5/16 slop nut. I don't know if the collared base plate will fit as I didn't measure the hole when I had everything off. If it doesn't fit then just use the un-collarded version. The 5/16 nut is too big to have 2 for backlash correction but you should see an improvement without it. An anti-backlash version can be made later but it will need longer hardware.

Print at 50% infill for strength.


Still working on M3 slop nut set.


Attachments removed... see updates below

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

17

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

if anyone makes one of these, please post pictures and give me your feedback so we can improve the design. Especially the 5/16th kit since I can't test it personally.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

18

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

hmm... i will test it but i fear that without the anti-backlash nut, the result is the same as the original wood plate that i mounted loose on my machine (so the screw can move on the x-y plane)

19 (edited by 2n2r5 2013-06-10 05:33:28)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

I was getting some pretty awesome prints without the second nut. I hope that you will be pleasantly surprised though.


ATTENTION: If you downloaded the 5/16" kit. I forgot to make the hole in the top of the slop nut big enough for the threaded rod. It is an easy fix, you can just trim the hole with your exact-o knife. I included the updated files here and will be removing the others. I have also included a fixed version of just the one part in case you wanted to download and print a new one.

Post's attachments

516in_thread_adaptor_slop.skp 168.96 kb, 32 downloads since 2013-06-10 

516in_thread_adaptor_slop.stl 673.89 kb, 99 downloads since 2013-06-10 

516in_thread_adaptor_slop_fixed.stl 166.44 kb, 109 downloads since 2013-06-10 

You don't have the permssions to download the attachments of this post.
SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

20

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Can I ask what the hysteresis is like on your setup?
From what I can see to get the slop you have put in the nut must rotate until it jams on the edges of your print. So when you then reverse the bed direction the nut would need to spin in the housing before you get any movement  in the z axis.

Not saying this is bad as if you have all that coded in then you shouldn't see any issues at all.

21

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Stupidly my tests prints are in clear filament, so I can't really see the results. Got a few more to do in clear and then I'll print the exact same objects and colour as my last tests and post up pics.

22 (edited by 2n2r5 2013-06-10 16:30:49)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Zarni wrote:

Can I ask what the hysteresis is like on your setup?
From what I can see to get the slop you have put in the nut must rotate until it jams on the edges of your print. So when you then reverse the bed direction the nut would need to spin in the housing before you get any movement  in the z axis.

Not saying this is bad as if you have all that coded in then you shouldn't see any issues at all.

If the rotation needed to jam the nut is  ~45° then with .8 pitch we are talking about .1 mm slack on the first movement that isn't accounted for. Since it is repeatable, I don't worry about because I can just take that into account when setting the z tab height. Just set it to where I need it and then 1/8th of a turn down.

Other than that, I currently have no compensation in software or hardware. I really should be using the hysteresis fix. So when I get home I will measure out my actual z-axis and change it to something like
M99 X0 Y0 Z0.1 E0 or whatever compensations I end up needing for the z-axis.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

23 (edited by 2n2r5 2013-06-10 23:10:53)

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

More results. I have no idea what this vertical banding is all about. Can someone shed some light? The bands appear to be around .5mm pitch. Which would be 1/4 of the belt pitch. Might make sense with 2 pulleys right? I just tensioned the belt on the x-carriage assembly. Lets try some more. Not that I am disappointed at all in my results, I think it is safe to say from the latest print that I Do NOT have a horizontal banding issue. :-) YAY


http://2n2r5.com/pictures/printer/m5_upgrade/wdf.jpg
http://2n2r5.com/pictures/printer/m5_upgrade/wdf2.jpg
http://2n2r5.com/pictures/printer/m5_upgrade/wdf3.jpg

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

24

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Very nice print.

Congrats and thank you on a great contribution to the community.

25

Re: Fix z-banding w/ no backlash- "Slop Nut" (Level 2 techie - Consumer )

Thanks, but it's only great if it works for others. How did your prints come out?

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.