[MOD] Rod replacement for ultra-precise 50 micron (0.050mm) Z layers! (Page 1 of 2)

I strongly suggest you make the acme lead screw yourself, if you have the hardware and skill, and carefully test how much you actually tap.
The factory-made nuts (at least in hardware stores here) are all overcut. M8 fits just too freely, so does M5, and that is really bad.
When I went for a custom nut for 5/16, I only used tap # I and #II out of three to get a very tight nut. For M5 #1 out of two was already sufficient for the nut to fit. But a more or less precise drill press and and a few precise steel bricks, to hold the brass vertical are a must here.
P.S. Does anyone need the 3d design of that ugly coupler?

All sounds great! But as someone about to press th button and order one you're scaring the crap out of me! Lol

Is my SD going to work out of the box ?

Cheers

I gather that this is just a method of fixing some of the known issues and not a necessary upgrade to print. All I can say is that as long as your printer was made with the same quality mine was, it will work pretty much out of the box and standard recalibration after changing environments.

also it looks like there is some really exciting things going on right now! I can't wait to see some of these freakish frankendoodles on the loose!

How is the origonal threaded rod attached tot he stepper?

The original 5/16 (something close to M8, but not compatible) is drilled in the side, and tightly fitted on the shaft. Since there is no reliable way to drill it perfectly in the center (unless it is done on the same lathe, that produced the rod. But as I understand, these rods are not custom-machined), it gives us some wobble. And it is fitted really tight.

I'm getting my own lathe this summer, so I think I will also experiment with some custom threads as well.

I have to take a pic when I get home. But with stock rod and Zwobble and tighten nut I definitely seem improvement. Most of my parts are for a real world parts (brackets, fixtures, enclosures) so .28mm works fine and gets painted and sanded anyway and I am printing for speed now  BUT I do want an improvement.

I notice that around 1/5-3/4" into any of my parts I noticed a slight shift/skip in the X not the Y! I had massive Y problems with alignment and tension and replaced all my stepper boards and it is fixed now. But trhe X should have little play and I noticed if you look at the front ofthe machine the right side, oppsite the x motor always seem to overshoot and buldge out about 1mm around 3/4 down the Z then it clears up and goes back to normal

Just made like 6 prints and all had it. the ones that are only 1/2-1" tall it isnt noticeable but now that I making 4" tall parts I see it more

I am thinking it is a warp in the Z rod? or maybe the Y front bracket clips are warping or maybe my acceleration is too high in the X?

Those improvements look great!

I picked the M3 with the same concerns in mind.  To find out what sizes would be safe, I wanted to try the most extreme case first to maximize flexibility and minimize thread pitch, and back up to a larger size only if I ran into bending problems.  Then I'd I'd know what the cutoff size would be.  An M3 has a .5mm thread pitch compared to an M5 with a .8mm pitch, so if it didn't bend, I figured it would give the best results.  Smaller rods and couplings also cost less.

The M3, however, has been much stronger than I had expected and I haven't run into any bending problems.  I don't know if it makes a difference, but I went with a stainless steel version.

For best results ie less wobble would a larger diameter bar but really fine teeth be needed?

Yep, pretty much like that. ABS coupler, despite being ugly worked like a charm for me.
What concerns the attachment to the bed - see my linked post with the custom brass nut and an abs nut holder. You can adjust the openscad file to your liking, if you use a different acme nut.
Firmware only requires setting a different steps_per_mm value for Z axis, (something like M31 Z4000 if I'm not mistaken with the command number). But I hardwired the value in the Configuration.h of the firmware, since I wanted to update for a long time anyway.

Regular M5 nut, except two of them with an anti backlash holder.

Steps per mm was 4501.