Why is the front (Y=0) of my bed consistently too high?

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insta
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Why is the front (Y=0) of my bed consistently too high?

Post by insta » Thu Apr 28, 2016 7:15 pm

I'm using MIC6 sheets with 3-point auto-probing. The front of my beds, consistently, is physically low relative to the back (so, Z high). I'm talking like, .5mm too low. It does it with the multi-point probing as well, but not quite as badly.

I have no springs, everything is rigidly mounted. My probe points are (10,10), (10, 240), (160, 240).
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zemlin
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by zemlin » Thu Apr 28, 2016 7:53 pm

Are you Z-axis bearings tight? Any free-play if you rock the table front to back? Wondering if the weight-shifting of the platform moving could tilt the entire y-axis on the Z-slide. Does that make any sense?

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Jules
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by Jules » Thu Apr 28, 2016 8:18 pm

Gonna paraphrase a very poor joke that was probably before your time.... If it don't fit....you gotta quit.

Did you change out to the new spider on that machine? (Bottom Z-stop, new corners?) I noticed that it is incredibly easy with a tight fitting MIC6 plate to not get the plate seated all the way down inside the rubber corners so that the plate rests flat on top of the HBP. If you get down underneath it and look at the gap between the MIC6 and the HBP you can sometimes see it.

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insta
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by insta » Thu Apr 28, 2016 8:36 pm

Jules wrote:Gonna paraphrase a very poor joke that was probably before your time.... If it don't fit....you gotta quit.

Did you change out to the new spider on that machine? (Bottom Z-stop, new corners?) I noticed that it is incredibly easy with a tight fitting MIC6 plate to not get the plate seated all the way down inside the rubber corners so that the plate rests flat on top of the HBP. If you get down underneath it and look at the gap between the MIC6 and the HBP you can sometimes see it.
It shouldn't matter where the MIC6 is sitting (as long as it doesn't move) because the auto-probing levels from the surface of the aluminum. Mine is noticably canted left-to-right because of the spider, but auto-leveling fixes that.

The Z bearings are snug.
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Slipshine
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by Slipshine » Fri Apr 29, 2016 1:56 am

Insta.

Flip the plate 180 degrees. See if the problem moves to the other end.

If it does the problem is in your plate.

If there is a problem with the plate try the other side and see if the problem is there as well.

I am guessing the problem is with the blasted side if it is it may be over blasted in that area.

If flipping the plate does not move to the other end then it cab be caused by slop or deflection in the y axis.

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PcS
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by PcS » Fri Apr 29, 2016 12:33 pm

My question is how are you checking for this low spot ?

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insta
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by insta » Sat Apr 30, 2016 4:44 pm

PcS wrote:My question is how are you checking for this low spot ?
I'm watching it air print, and mash in the Y=220ish area.
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ednisley
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by ednisley » Sat Apr 30, 2016 6:17 pm

insta wrote:mash in the Y=220ish area.
Perhaps a cable from the platform gets snagged where you can't see it in the back?

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PcS
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by PcS » Sun May 01, 2016 2:31 pm

Not sure about mesh leveling as I have never tried that. But with standard leveling I was probing six spots on the bed. Could it be an issue with the mesh leveling ? Or not enough probe points. I would think with a mic6 plate and a correctly leveled bed you would not even need mesh leveling. Or at least with a truly flat plate you should be able to probe 4 points and be perfect ? I always had issues with what you are describing until I got the new spider and got dead level with the mic6 and it is a non issue now. I will say marlins standard probe and auto tramming always working perfectly for me. Those were the best looking first layers I had ever printed up until late now.

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insta
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Re: Why is the front (Y=0) of my bed consistently too high?

Post by insta » Mon May 02, 2016 4:20 am

ednisley wrote:
insta wrote:mash in the Y=220ish area.
Perhaps a cable from the platform gets snagged where you can't see it in the back?
I don't think so -- even then, wouldn't the probing pick it up with the snagged cable? It's actually tramming the bed lower as it moves to the front though.
PcS wrote:Not sure about mesh leveling as I have never tried that. But with standard leveling I was probing six spots on the bed. Could it be an issue with the mesh leveling ? Or not enough probe points. I would think with a mic6 plate and a correctly leveled bed you would not even need mesh leveling. Or at least with a truly flat plate you should be able to probe 4 points and be perfect ? I always had issues with what you are describing until I got the new spider and got dead level with the mic6 and it is a non issue now. I will say marlins standard probe and auto tramming always working perfectly for me. Those were the best looking first layers I had ever printed up until late now.
I am doing 'standard leveling', not mesh. I've done multi-point standard, and 3-point standard, both do the same thing (but 3-point was worse). In both cases, I modified the firmware to poke the same spot several times and average the results, and while that helped a little, it's still far from perfect.

I'm trying to get more rev E spiders now and just fix it with brute-force.
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