Wavy prints

[RogerV]

I'm having an issue with my new Mars Pro. I got 5-6 great prints out of it, maybe 20 hours at most, before every print started coming out "wavy" as if the z-axis dips every few mm. These aren't the usual horizontal layer lines, they're much more pronounced, like Ruffles chips.

I attached a pic of a sample print. This is the underside of a mini base, printed with supports at about a 60 degree angle to the build plate. The center should be perfectly flat. Instead, I get ridges all the way through the print, also visible on the top and sides. Every print comes out like this now, even reprints of my original good prints, using the same ctb files.

Any hints?

[cliffyk]

It appears the Z-axis trolley is binding and needs to lubricated and/or adjusted--view this Youtube video for more about doing this...

[RogerV]

Thanks, Cliff. I'll give this a shot. I do notice that the trolley is a little jerky when moving, so hopefully this is it.

[cliffyk]

I replaced the Z-axis mast on my Mars with an upgraded assembly from the UK (see my post here). Highly recommended... When I removed the OEM mast I was stunned to find it took 4.5 to 5.0 lbf to move the trolley--got that down to 4 to 5 ozf by properly adjusting the guide wheel--and that was free except for my time. Not at all complicated but be prepared to "fiddle" with it a bit to get it just right...

[RogerV]

Unfortunately I have a Mars Pro so the Jackson mast is out for me, for now. Too bad, their design looks very stable.

[cliffyk]

The Pro uses a recirculating ball single vertical rail--it's the same as my Longer 10 and 30 printers, and 1/2 of the Jackson upgrade. It is unlikely that that design could jam and/or be bound up like the mast used on the original Mars--there is no adjustment, it's a very much more precisely fitted linear bearing that needs no adjustment...

[RogerV]

In that case I'm at a bit of a loss as to why I'm getting severe z-axis issues, especially when this printer started off so well. I'll take a look at the trolley assembly tomorrow anyway and see if anything jumps out at me.

Thanks!

[RogerV]

So I replaced the LCD screen and cleaned and greased the trolley and... no love. I'm still getting the exact same wavy lines. I have already fired off a question to Elegoo support about it. The waves are so regular that it really feels more like a stepper issue than anything else.

Cliff, let me ask you - should the lift screw flop around loosely when the trolley is off? Mine has a few inches of play in it when it's not constrained.

BTW, for owners of the Mars Pro - be aware that this model is not like the ones shown in Youtube videos. It has a single-piece anti-seize nut instead of the two-piece nut (yay), but uses a recirculating bearing assembly to connect to the mast instead of wheels. The bearings WILL fall out of the trolley if you're not very, very careful with it, and they're a right bitch to get reassembled. You might consider cleaning and greasing with the trolley in place.

[cliffyk]

So I replaced the LCD screen and cleaned and greased the trolley and... no love. I'm still getting the exact same wavy lines. I have already fired off a question to Elegoo support about it. The waves are so regular that it really feels more like a stepper issue than anything else.

Cliff, let me ask you - should the lift screw flop around loosely when the trolley is off? Mine has a few inches of play in it when it's not constrained.

If you mean lateral, side-to-side, swaying/flexing, motion then that's to be expected as the lead screw is cantilever mounted at the motor with the free end restrained by the trolley (as is common in this sort of design to prevent binding as the trolley might approach a slightly misaligned (due to stress/temperature fluctuations/etc.) "far-end" bearing--and within reason. However if it feels as though it's "rattling/loose " at the driven end then that's not right. Also It should have very little to no axial ("up-and-down") motion.

BTW, for owners of the Mars Pro - be aware that this model is not like the ones shown in Youtube videos. It has a single-piece anti-seize nut instead of the two-piece nut (yay), but uses a recirculating bearing assembly to connect to the mast instead of wheels. The bearings WILL fall out of the trolley if you're not very, very careful with it, and they're a right bitch to get reassembled. You might consider cleaning and greasing with the trolley in place.

This is correct--it's usually OK¹ to put one together with one or two balls missing--but not good practice.

BTW it's an "anti-backlash" nut, not "anti-seize"); also FWIW, spring loaded two-piece anti-backlash nuts are generally considered superior to "split" nuts, as they are self-adjusting across their service life. The downside is that they take more time (iI.e. cost more) to assemble.

The Chinese are impressively adept at controlling production costs and nearly 100% of their model line revisions are driven by that goal. In almost all contemporary manufacturing product final assembly it the predominant cost.

Save 1¢ per unit, then make 100,000 units, and you just saved $1000...

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¹ - Those who know me understand that when I say "OK" I mean "barely acceptable" and "go with that if you really want to and cannot do any better".

[RogerV]

If you mean lateral, side-to-side, swaying/flexing...

Yes, side-to-side. It seemed reasonable since the trolley has no play in it - something has to flex.

BTW it's an "anti-backlash" nut, not "anti-seize"

Right you are! That's my crappy memory for you.

Thanks again. I hope support has answers for me.