Poor Man's Anti-Backlash Nut - No Assembly Required (Page 3 of 3)

I've noticed some substantial banding with my prints, saw this and tried it out. Unfortunately it appears to have not changed my banding at all, my before and after prints look identical. Any idea why this is?

Full disclosure - I am way new to 3d printing, I haven't tried any of the other banding fixes because I was afraid I would damage my machine or fail to get it back together correctly.  Also, I received my printer back in November if that makes any difference.

The well nut solution worked great for addressing my banding issues! Thanks for the suggestion. I had a bunch of solutions in different tabs on this forum, but this one was the cheapest, quickest, and easiest, so I tried it first. It worked really well.

One suggestion would be to fix the image links in the first post, I had trouble figuring out what a well nut actually was when I was at Home Depot. Luckily I eventually found that link to Lowes farther down the page and picked one up there.

Here is a solution that I'm going to be testing out tonight that is the same basic principle as the well nut. The only difference is that it will be about half the height of the well nut.

I'll be using a 3/8 x 7/8 x 1/16 rubber washer against the bed with a 5/16-18 Keps Nut tightened down onto it. The toothed washer on the nut should prevent it from rotating against the rubber washer, and the rubber washer should grip the bed well enough to not slip.

Ideally, I would have liked to use a serrated flange lock nut, but they didn't have any at Lowes.

From your pictures it looks like you're using your well nut upside-down, which means that it's only compressing a small amount of the rubber. I'm sure the thickness is comparable to my 1/16" washer (the thickness actually seemed closer to 1/8"). I tried it out last night and it worked great. Removed most of the banding I was getting. I do intend to design/print some sort of bracket that will prevent the nut from rotating. Unfortunately all the ones I've seen are not compatible with the workbench apprentice bed because it doesn't have the 4 screw holes.

The M5 rod should make a big difference to wobble, and allow for genuine metric layer heights haha.
Good luck with the modification, let us know if you have any trouble!

Talking about backlash in z, you can quite easily compensate for it in software without patching Marlin at all. The z axis only changes direction once during a print: when homing just before starting. My latest solution is to measure the backlash with a dial gauge, and then compensate in the start-gcode just before printing, like so:

G28 Z ; home Z
G1 Z0.23 F450 ; eat up the backlash
G92 Z0 ; reset z height to 0
;... print...

(yes, 0.23mm is enormous, have to investigate the motor bearings/mountings a bit more...)

Don't you ever use Z lift during retraction?  If not, you should look into it.

It can be very helpful in certain circumstances, but it assumes you can achieve accurate repeatability from your Z axis.

Hehe thanks for the excellent points... I got skool'd about 3 times over here!

Good point, I'll keep an eye out - hadn't considered drift over a long space of time / including vibration from printing. Could cause issues if the print effectively stretches out...

Hahaha so true. Looks like to my mind I find the z-offset setting more confusing than gcoding it, but yes.   (maybe this is the same reason I struggle with arduino but get along ok with regular AVR/GCC, for example).

I read "BRO, DO YOU EVEN Z-LIFT?"

With a z-axis this troubled, I haven't been brave enough. Makes a good argument to ensure mechanical repeatability.

Just thinking about this though, if the z-lift always brings the bed towards the nozzle before each layer, then wouldn't consistent backlash in the drive (like I seem to be getting) be irrelevant? I'd just need to increase z-lift distance to compensate (if that really is a critical parameter!). Turning on z-lift would negate the need for compensation at the start too. Hmmm. I shall experiment some more...

have you searched eBay? many sellers will ship world wide. thing is, it would be cheaper for you to convert to a metric rod than it would be for me to ship you a single wellnut, most likely.

thanks,

I did a serach on ebay, and found one in uk, but i don't know witch one to take

http://www.ebay.fr/itm/M3-M4-M5-M6-M8-M … 3386fc5b8e

can you point the one please

as for changing the rod, i'm a tiny bit overwhelm at doing it, i did change the carriage and the hot end and it definitely challenged my skill, and I'm gonna have to do it all again, so I rather not change it now.

if i change it I rather have something like this bed... ;°

http://bigbox-3d.com/features

overkill much  but I really like the idea...

not true if your rod is straight. if your rod is bent obviously the wellnut will not help because the platform will flop around as the screw turns. it's amazing how bent the Z screw can be without binding.

my rod is just fine :°

seriously, i don't  have a problem, the z rod is fine, it's just one of those mods,I do just to make sure.

so wich one should i take?

i 'm metric base, imperial does not speak to me...