1 Topic by Aaron37

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Topic: Ridges on solidoodle 2 prints

Hi all,
I bought my solidoodle (used) a few months back, and it has always printed with horizontal ridges. They are quite notable, probably about a half mm or so. They match the z screw thread pitch, but there is no obvious damage to the screw that I can see. Also, the ridge pattern is uniform with respect to z height. If there were screw damage I'd expect to see variations.

Please see the attached picture files, and you can see the horizontal ridging I'm describing.

If I were to hazard a guess, I would say that layers are getting skipped, albeit consistently intermittently. I've tried adjusting the z axis voltage (it was around 0.4 volts) but I haven't noticed any change. The "bulges" are consistently all the way around, so they don't appear to be due to z axis wobble. It really seems like every other layer is being skipped.

I'm using Repetier host btw.

Is this a known problem with the solidoodle with a known fix? Any help appreciated, thanks.

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2 Reply by AZERATE

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Re: Ridges on solidoodle 2 prints

Looks like Z backlash to me. Have you installed any device to absorb lash?
Lowes sells a 5/16 wellnut which works quite well. I think it cost about $1.50
If it matches the Z pitch, it would be indicative

My second guess would be bed movement. If the screws are too loose, the springs have nothing to fight. But that would not explain the ridges matching the thread pitch. So I stand by my first statement....for now smile

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3 Reply by wardjr

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Re: Ridges on solidoodle 2 prints

A layer height of .2963 will also help.

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4 Reply by Aaron37

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Re: Ridges on solidoodle 2 prints

I haven't yet fitted a device to absorb z backlash, though I have a couple devices I've printed off (from thingiverse) but haven't got round to installing yet. So I'll get that sorted asap. I'll also try the 0.2963 layer height and report back how I get on. Thanks for all your feedback, much appreciated !

5 Reply by grob

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Re: Ridges on solidoodle 2 prints

Don't discount wobble just yet - as the nut gets pushed backwards and forwards, it can kick the bed up and down slightly, which would create this variation in wall thickness you're seeing in sync with the thread pitch. Try the above of course, but finding a way to reduce wobble may also be helpful.

If you can, try each fix one at a time, and let us know the results of each: would be good to get a clear indication of which fix was most effective for advice in the future. smile

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6 Reply by PheonixSD3

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Re: Ridges on solidoodle 2 prints

I definitely wouldn't do without my anti-backlash solution but to me this looks like more like wobble.  IMHO the wobble comes first from elliptical lead screws and then sometimes gets amplified by being off center to the axis of rotation.

First try one or two of the simple anti-backlash suggestions and if that doesn't work out consider changing your z-axis from the 5/16" screw that it probably came with to something like M5.

I say try the anti-backlash first because swapping out the Z axis is more involved and requires the purchase of a new Z motor, rigid coupling, and whatever arrangement you choose to attach the lead nut to the bed.

Do you have a wooden or aluminum printer bed frame?

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7 Reply by Aaron37 (edited by Aaron37 2015-04-11 15:28:16)

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Re: Ridges on solidoodle 2 prints

Update.

Have installed anti-backlash contraption w/heavy spring, changed layer height to .2963mm and have tightened up the plate screws. There is no discernible back lash at all.

Problem still remains.

I noticed there is a slight z axis screw wobble, so as an experiment I taped a mechanical pencil to the bed (facing out from max distance from the z screw - ie. where the door used to be), a sheet of paper attached vertically (in contact with the pencil lead) and then went from 0 z height to max.

I was expecting discernible ripples in the line, but surprisingly I can only make out a perfectly straight vertical line.
There are obvious vertical ripples on my prints, yet no ripples on the paper - so the bed doesn't appear to be wobbling from side to side at all (though maybe vertical wobble as that hasn't been ruled out yet).

As an aside, there is something wrong with the solidoodle board - and I've already ordered a replacement. Nearly every time I use the solidoodle 2 these days, I have to use arduino to reflash the 644P chip (marline.pde upload to chip) This solidoodle 2 unit has never run right since I bought it second hand - I'm suspecting the  banding problem is something other than the above (since the problem remains), I'm hoping replacing the motherboard will fix this fickle gremlin for good.

8 Reply by Manx

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Re: Ridges on solidoodle 2 prints

you are gettign wobble on the print head then

9 Reply by Aaron37

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Re: Ridges on solidoodle 2 prints

Hi all,
I think I may have found the problem, though still far from fixed. I've noticed that when the platform is lowered, looking very carefully, even though the z motor is turning uniformly, the bed actually is periodically slowing down and accelerating, in sync with the z screw thread pitch.
So this is looking like some sort of thread anomaly/damage.
Is this a known problem?

10 Reply by grob

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Re: Ridges on solidoodle 2 prints

Hmm... Bent/misaligned threaded rods are well known. They push the bed around in sync with the thread pitch. Pushing back and forth normally rocks the bed up and down as it moves, so you'd see what looks like changes in speed on the front edge of the bed?

What does this look like from the side of the bed? It should be clear if it's rocking from this angle.

If so, your problem would be fixed by the M3 or M5 threaded rod mod (it's pretty well tried and tested solution to this problem, with other benefits such as proper metric layer heights), or possibly some kind of "slop nut" arrangement (there's a few of these on this forum too).

If you're still not sure, do you have the capability of taking a short video of this errant motion and popping it on youtube for us?

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