1 Topic by Pueggel

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Topic: Platform going too high (should stop at z = 0)

Hello there,

I have just gotten my SD4. First of all, I want to say that I am a total beginner at 3d printing. I have the following problem: When I start a print (using the Repetier-Host software for Mac) then first the extruder goes to the correct X and Y coordinates, but then the Z starts decreasing (platform going up) and the problem is that it won't stop at Z = 0. So what happens is that it crashes into the extruder. I tried to set Z home at a position where there is about 20 mm distance to the extruder, but no matter how low I set it, it goes all the way up and crashes into the extruder. What am I supposed to do? Isn't the idea that the first layer starts at Z = 0? At least, that's what would make sense to me. Oh, and one more thing: at the back of the printer there's this screw that I  can use to set an end for the platform coming up. However, this is completely useless, because I cannot make it "long" enough. What am I supposed to do?

2 Reply by wire10ga (edited by wire10ga 2014-12-18 12:51:10)

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Re: Platform going too high (should stop at z = 0)

The screw at the back should be hitting a limit switch on the bed as it raises.  Look for a broken or bent part there where the screw end should be.

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3 Reply by Pueggel

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Re: Platform going too high (should stop at z = 0)

wire10ga wrote:

The screw at the back should be hitting a limit switch on the bed as it raises.  Look for a broken or bent part there where the screw end should be.

Thanks for your answer. So this screw determines the position of the bed for the first layer? Or is it more like a safety stop, which isn't needed in every print?

The problem is, I cannot turn the wheel enough for the screw to be long enough. The "sliding part" of the bed will hit the black weel first, which is a problem, because then, the motors do not stop. Let me show this more clearly in a picture:

i.imgur.com/oOzGzc0.jpg

(cannot somehow include URL, just copy and paste this in browser)

When the bed moves up, it should make contact at the green circle. However, at the red circle, contact happens first. It is also the reason why the black wheel isn't horizontal... Should I remove the black wheel? Could this really be that bad designed, or am I doing something totally wrong?

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4 Reply by wardjr

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Re: Platform going too high (should stop at z = 0)

The bolt does set the height for the first layer so you will need to fix this.
To start with is it possible to bend the metal tab on the switch so it would be close enough to the bolt?
It looks like the black knob is bent and possibly to far down on the bolt is there a way that you can just remove the knob?
What you are trying to accomplish is for that switch to be triggered just before the nozzle hits the bed. 
Hope this helps.

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5 Reply by wire10ga

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Re: Platform going too high (should stop at z = 0)

yeah you have something wrong there. Either missing an end of the bolt tip or something else.  That screw is what sets your Z height of your bed from the nozzle tip.

SD2 - Glass Bed, Fans on PCB and Y motor, Custom enclosure
Slicer - Simplify3D

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6 Reply by kimchi_25rr

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Re: Platform going too high (should stop at z = 0)

i figured out the Z tab pretty easily on my S4... Someone chime in if i'm wrong..  I basically set it where i felt i wanted the bed to sit. I didn't really matter i guess.. i set mine a little less than 1/4" where the screw sticks down and touches the sensor.. With our solidoodle 4 we have those springs below the bed.. I just let the (levelers for bed) spring tension move the bed up then leveled it there with the paper method...