Grinding noise on z lift at startup

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iworkinpixels
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Joined: Mon Sep 29, 2014 8:11 am

Grinding noise on z lift at startup

Post by iworkinpixels » Mon Oct 06, 2014 8:55 am

Ok, so I got my new hot end in, everything works great there, now I'm trying to get my AO-100 the rest of the way working... but the bed either doesn't want to level or doesn't want to stick in some places. Also there's a grinding noise when the z tries to lift at the beginning of the print, which I think is related.

I've created a video, and uploaded to youtube... if you know what the grinding noise is or why I can't get the extrusion to stick to the bed in certain places, please let me know. Thanks.

Here's the details:
  • I leveled the bed as best as I can by hand (while everything was hot).
  • The z height seems to change every time I start a new print, so I have to constantly re-set the z-height screw.
  • I'm using heated glass with a fairly thick coating of hair spray across the whole thing... seems to stick well in most places, but there's a few it just refuses to stick.
  • Printing 3mm ABS with a .35 nozzle at 230 deg C.
  • Using Slic3r and Pronterface on Mavericks.

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Orias
Aleph Objects | LulzBot
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Re: Grinding noise on z lift at startup

Post by Orias » Mon Oct 06, 2014 9:23 am

The grinding noise is occurring as soon as the direction of travel changes. The printer firmware has two different manual move speeds- a manual movement speed and a homing speed. Your Z axis homing speed is fine (provided you have not reflashed the firmware), but if there's any binding, will cause that noise. How often are you lubricating your Z axis drive rod? We recommend lubricating the drive rod once a month, with either a petroleum-free silicone-based lubricant, or with white lithium grease. Apply the lubricant, drive the axis up and down while wiping off any excess. Alternatively, you can recenter your Z axis drive rods within the two couplers, and even turn down the Z axis homing speed/rate by changing a value in the firmware and reflashing.

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piercet
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Re: Grinding noise on z lift at startup

Post by piercet » Mon Oct 06, 2014 10:14 am

Are you printing directly on the glass? You'll want to avoid that if at all possible unless you like buying borosilicate glass sheets.

The A0-10x stock Z axis endstop target is not the greatest. It drifting out of alignment with heating cycles is not your imagination. I solved that on the AO-TAZ linear rail modification by swapping in an actual micrometer head. Working within the confines of the stock piece. you may want to try dipping the threads of the z axis target in elmers white paper glue to form a light coat, then re-threading the piece. That should give it more friction but still allow you to adjust it.

You'll also want to look at printing and implementing one of the Dual z nut X end designs. WIth just the one Z nut per side, you do end up with a bit of Z axis hysteresis motion that can cause inconsistent layer heights from print to print, which is magnified on the first layer due to the Z endstip movement.

The grinding noise you hear may be normal starting to turn noises, or it may be one of the stock Z axis couplers failing. The stock coupler has a tendency to split at the bolt point and can allow the threaded rod to spin. There is a reinforced piece somewhere in the download.lulzbot.com archive called the "beefy coupler" that fixes that particular issue.

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Theycallmejohn
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Re: Grinding noise on z lift at startup

Post by Theycallmejohn » Wed Nov 26, 2014 1:12 pm

Orias wrote:.... We recommend lubricating the drive rod once a month, with either a petroleum-free silicone-based lubricant, or with white lithium grease. .....
Is there a brand you recommend and where could you buy that other than online, auto parts store?

nopick
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Re: Grinding noise on z lift at startup

Post by nopick » Wed Nov 26, 2014 1:41 pm

You can find white lithium grease at auto parts stores. They sell it in small tubes.

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Theycallmejohn
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Re: Grinding noise on z lift at startup

Post by Theycallmejohn » Wed Nov 26, 2014 2:53 pm

Thanks Nopick

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