Strange salmon skin - Moire effect on my Delta

[totalitarian]

Some more examples

[dc42]

What layer height are you printing at? Try making the layer height an exact number of full steps, if you are not already, for example 0.2mm.

What is the rated current of the tower motors and the extruder motor?

[totalitarian]

@dc42 I've tried all the 'magic' numbers, doesn't seem to make any difference

0.0809, 0.1618, or 0.3236
0.1294, 0.2589, 0.3883
0.2 even 0.2589

No idea what the rated current is, the motors have no markings on them

[totalitarian]

I would guess standard 1.5A

[dc42]

If you change the extrusion width (or, if it is a vase-mode print, you could just change the extrusion factor in DWC) while keeping the layer height constant, does the angle of the banding change? If so, that suggests an extruder issue.

[totalitarian]

Left is 0.4, right is 0.8 width. I had a brainwave and converted it from a flying extruder to a full bowden. Unfornately it didn't make a blind bit of notice

[dc42]

What is the vertical spacing between the diagonal bands?

[totalitarian]

Bit tricky to tell but they look around 4mm

[dc42]

I was wondering whether it was related to the tooth pitch on the belts, which I presume is 2mm.

[totalitarian]

@dc42 If that was the case, would that indicate an issue with the belts or the toothed pulley?

[dc42]

@totalitarian said in Strange salmon skin - Moire effect on my Delta:

@dc42 If that was the case, would that indicate an issue with the belts or the toothed pulley?

Yes, or perhaps with the toothed side of the belts running over non-toothed idlers. But I would expect the vertical pitch of the banding to be 2mm, not 4mm

[totalitarian]

Such a shame as otherwise it is a very well put together machine.

[Veti]

@totalitarian said in Strange salmon skin - Moire effect on my Delta:

I would guess standard 1.5A

measure the resistance of a phase. that will give some indication as to what kind of motors they are.

[bondus]

It looks like typical delta waves on your printed parts. Bent diagonal patterns on flat surfaces. That's a sign that something is not perfect with the linear motion. It could be the pulleys, idler, linear bearings, ...
The bend in your patterns is not very sharp, the predator is a very large machine. A smaller machine will get sharper bends. If you move the model to the edge of the platform the angles should change, and the patterns will get tighter or more spread out depending on what/which towers is the cause.

When it is motor/driver related you usually get a tight, highly repetitive patterns. If you turn off microstepping it will show up very clearly. That's not a suggestion to solve your problem, but a fun experiment to see what it looks like

[totalitarian]

@bondus Thanks, i'll certainly give that a try. Do you not suspect the rods at all?

[bondus]

@totalitarian, I don't know how play in the arms looks like in prints. But I suspect it would not leave nice patterns. Who knows, deltas are complex machines.

It's easy to check for play of the ball joints, just wiggle the arms, any click-clock sounds are bad. Rumour says that if you have play in those small joints you can gently squeeze them on the edge in a vice or with some pliers to increase the preload.