Z-axis binding

Has anyone had any issues with their Z-axis binding resulting in skipped steps? I have almost all of my problems solved, but I get this intermittent binding of the Z-rod. It happens more often when I'm printing something tall, obviously because there is more opportunity for it to occur. I printed Kim Brown's Big Blue the other evening, and the top half inch of it looked like cottage cheese from being compressed. I have cleaned up the gears, and even printed a set of Iamburny's double helix gears. I also hear a grinding sound sometimes that I believe was coming from the Z-rod and nut. The rod threads are cut pretty rough, and the nut does not ride terribly smooth on it. The nut did bind on the rod sometimes. I chucked up the rod in a drill, and used steel wool to attempt to clean out the threads. I also used a 5mm tap and die to chase out the threads in the nut and rod. I also noticed that there were metal shavings scattered on the top of the z motor mount and motor. I used some silicone spray lubricant, and it seemed to help a bit, but then last night I printed out ashsoft2000's bed support, when it was on about the last 5mm of the print. It's so irritating, and I'm getting very frustrated. I thought I saw that somebody had used a nylon nut. I would appreciate any suggestions. I've also searched the forum, but couldn't find anything on this topic.

Thanks
Tracy

Hi Tracy,
Some time ago it was suggested that the nut be changed for a brass long nut from ebay. I did this and also change the rod for stainless steel and I must say that I have not had any problems in the Z direction. I can't remember the thread but id would have been early Feb - Re: z- axis nut (long brass) Important Update!
February 02, 2014 09:49PM .

Hope that helps.

Bye the way did you ever deepen the enclosure? If so could you post the stl or scad files. Thanks
Paul

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appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1

Keep the rod oiled with something like 3-in-1 oil etc, this helps a lot but not if it's worn already.

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Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

I have seen z axis binding caused by two different things:

1. Using very old firmware that didn't correctly handle z moves before/after extruder-only moves;

2. My z-gears were too tight at one stage, leading to missed steps. With the Ormerod powered down, check that you can rotate the z screw easily through a full rotation.

Also:

3. Don't forget to lubricate the Z screw with light machine oil.

4. If the screw and nut show any signs of binding, get a new Z screw and nut. I use a hardened steel screw and a brass nut. The idea is that the nut wears in preference to the screw, and is easy to replace.

5. I suggest you don't increase the Z acceleration or Z max speed above the default. You might even consider reducing the Z max speed.

6. Make sure the Z nut sits squarely in the Z nut trap, otherwise you will get increased wear and more chance of binding.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I had the same kind of problems.

I replaced the threaded rod and nut withe the following two items from ebay:
[www.ebay.co.uk]
[www.ebay.co.uk]

The rod was lubricated with some unspecified grease,

It has worked perfectly since the upgrade - and the threaded rod is much more straight than the RS-supplied rod.

Best regards,

Carsten

Thanks everyone for the advise. I have ordered a new long brass nut, and a new stainless steel rod. I couldn't find a supplier of the nut in the U.S., so I ordered the suggested one from ebay in the U.K. which means a longer wait.

Thanks
Tracy

Paul,

I'm not sure which enclosure you are talking about. Do you mean the Duet enclosure? I would like to see a deeper one with a better fitting lid, and skip the spool holder. I would also like to see a larger opening where the SD card is, so that I get get the card in and out without using a very tiny screwdriver.

Thanks
Tracy

Hi Tracy, yes it is the duet enclosure.
I thought you said in a previous thread that you were going to modify the existing one to be deeper etc.
Perhaps I re-remembered.
If you haven't done it yet perhaps I'll have a go at designing one from scratch.

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appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1

My Z axis moves sometimes when I'm travel...(The printer clocks up around 1200 miles a month in the car)..
I only realised when I print some of IamBurnys gear, and they were horrible....
When I took them off and meshed them I realised there was an angle, and then checked my z axis with the square and found it way out.
I put it back to where it was supposed to be ans got perfect gears which are working really well.
I also found that I'd over tightend the side bearing which was twisting the X axis so much that the bottom of the motor mount was catching on the z axis motor by a fraction. I slackened it off abit, and all is fine now.

I keep meaning to make a 45' bracket for the z axis to keep it alined.... I might do it tomorrow...

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Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete

Quote
KimBrown
My Z axis moves sometimes when I'm travel...

Thank you for bringing this up, the assembly documentation say 12mm but that is way too long and will make the z-corner-bracket float instead of supporting the z-axis





..and on the other side of the extrusion, no support from the printed part at the top where you really want it, I did insert a spacer there



with no support at the top, the z-foot only act as a hinge



Erik

I had a similar problem and found the hot end, extruder and/ or fan cables were rubbing against the threaded z axis rod. This rubbing detritus fell into the threads and buggered the threads up. This was happening continuously so no amount of cleaning or oil solved the problem. Ultimately I put a giant flexible twist tie over the top of the z axis to hold the cables out of the way and it has worked well ever since.

Hopefully this helps in some way.

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Green Machine - slowly becoming multicoulored!