Wobbly lines in lower layers

Hi there, about a week ago I completed my custom made printer (I think it is a prusa clone or something like that), I made some configuration and started printing, when I print my 20mm test cube I can get about 19.99 x 19.98y and 20.01z so dimensions are pretty okay but I'm experiencing a weird thing on lower layers.

[imgur.com]

these are some prints I've made, can illuminate me with what might be the problem and how to fix it. Thanks in advance

Something in your Z motion isn't moving smoothly in those layers. I had a similar issue with my z axis belt was rubbing the belt teeth on the edge of a slot for the bearing. I redesigned my part to use a bearing sleeve which increased the clearance to the slot and my lines went away. You might have something rubbing or binding on those particular heights, especially if you get the same lines in the same place on every print.

My parts look the same when my first layer is too low.

so any idea or suggestion ?

Correct your Z0 point.
If you have a Z switch with a screw or other adjusting means then you have to adjust up to the bed isnt so close to the nozzle.

The z=0 switch only affects the first layer.

It looks like a thermal problem, as in the bed is too hot. Are you heating the bed? Generally, you don't need heat on the bed if you're printing on blue painter's tape...

Are you running a print cooling fan? When do you switch it on? If the extruder keeps going over soft layers it can cause the print to distort. Turn the print cooling fan on earlier (maybe after just 2 or 3 layers).

Edited 1 time(s). Last edit at 03/23/2017 03:12PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I'm printing with pla so I've been told I don't really need a heated bed, and I'm using that blue tape on the bed. I don't use a print cooling fan atm. does it have such a great effect on prints ? and one more question, I found tennis ball feet for printers on youtube and designed one for myself, do they contribute to overall quality

Edited 1 time(s). Last edit at 03/24/2017 10:54AM by lyro.

Yes, a cooling fan is very useful and improves print quality.

Flexible feet are good to minimize noise if your printer's frame is very rigid. If it isn't, soft feet are the last thing you want. If your printer's frame is flexy you need to set it directly on a hard, flat surface because that surface is part of the printer and helps keep things mechanically aligned.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
Yes, a cooling fan is very useful and improves print quality.

Flexible feet are good to minimize noise if your printer's frame is very rigid. If it isn't, soft feet are the last thing you want. If your printer's frame is flexy you need to set it directly on a hard, flat surface because that surface is part of the printer and helps keep things mechanically aligned.

Amen!

But once you clamped the printer down, you could add three tennisballs below the bottomplate.

About the prints: Do you have straight lead screws running freely across the whole z-height?
Maybe the X-carrier gets pushed sideways at certain heights?

Edited 1 time(s). Last edit at 03/25/2017 03:32AM by o_lampe.

threaded rods are fixed to motors with couplers and they make z motion happen,aside from that didn't understand what you meant by running free

Make sure the motor shafts and lead screws are centered in the couplers. If they aren't it will cause problems at low layer heights that will get better as the print gets taller.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

What does your part cooling fan curve look like? Does the part cooling speed change harshly around the z level the prints start looking nicer? Does the temp of the hot end get shocked when the part cooling fan kicks on?

Edited 1 time(s). Last edit at 03/25/2017 05:57PM by rich1051414.

Hi folks. This is my first post, but I came here for exactly this reason. I recently had to replace my main board in my Taz 5. I can tell you that it was printing perfectly until the original board failed. (temp runaway on the heated bed due to a failure of the board.)

So after installing the board, updating firmware, loading my estep value, etc, I hit print. In the first 1/2 of the print, I get a strange wave along the X axis. After that, it prints perfectly. And yes, I have ripped the machine apart, literally. Both software, firmware, hardware. Nothing. I've tried different materials, temps, slicers, models. I've removed and reattached every piece of hardware associated with movement. I have reloaded firmware. Nothing.

In fact, the wave is so precisely accurate in form, I can line up every print, and they nest perfectly. That doesn't sound like a rubbing issue, it sounds like a communication issue.

So, I'm am totally open to any suggestions, because at this point, I think its a main board failure of some sort.

Thanks for any and all help!!

PeterT