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bed leveling routine question

Posted: Fri Apr 06, 2018 11:10 pm
by jferguson
For reasons not obvious, at least to me, I decided that it would be good to relevel the bed on my M2e. Using MakerGear's M2 software, I was able to set the center height and sample the height of three of the four corners using a .004" feeler, but the fourth one presemted a problem. The machine would not raise the table high enough for me to do the callibration. The Z-axis screw moved table up two MM, and then about 8 .1mm and then wouldn't go any higher.

It looks like the leveling software limits the height travel to no more than some specific height above the center indication. This means that if one corner of the table is too low, it will never get high enough to be measured.

Is this correct?

My initial solution is to remove the spider, straighten it (it may be distorted), Inidicate it and keep leaning on it until it is horizontal, then back the leveling screws a ways - not all the way down, and do the leveling routine again. But first, I'll back all of the leveling screws reset the heater and glass plate and see how that does.

Maybe I ought to indicate it in place first and see how bad it is before I remove it.

Does any of this make sense? Am I right about the limits on the leveling routine?

Re: bed leveling routine question

Posted: Sat Apr 07, 2018 1:29 am
by Gwhite
I ran into a similar problem with mine when I tried to re-level it recently. The problem turned out to be the corner bed clamps. I frequently remove the glass to get stuck prints loose so I don't distort the spider. I make a point of unscrewing the clamps counterclockwise, and then twisting them back clockwise. The fit of the screws in some of the clamps is tight enough that instead of slipping around the screw, it ended up tightening one of the screws. This distorted things quite a bit, and when I first followed the instructions, I ended up cranking one corner up against the clamp quite a ways.

The solution was to start by loosening all the clamps completely. With no clamping pressure at all, make sure the bed leveling screws are making contact on all four corners, and the glass doesn't "rock" in any direction. I then went through the leveling routine, and had no trouble making the required adjustments. Afterward, I LIGHTLY clamped the bed corners, and re-checked the leveling. It was fine. I also took a drill and opened up the holes in the clamps so I can rotate them without having it drag the screws along for the ride.

Another thing to watch out for: The spider is flexible enough that any downward pressure when you are using the shim to check the height can introduce errors. I hold one end up off the bed when I slide it under the nozzle, so the only pressure is that required to flex the shim against the bed. Also, ANY upward pressure from the adjusting hex key on the screws will flex things enough to throw off the results. When you make any adjustments, remove the wrench before you check with the shim.

Re: bed leveling routine question

Posted: Sat Apr 07, 2018 3:11 am
by jferguson
Hi GWhite,
I've been running on the original leveling which took about 6 tries but finally seemed satisfactory. That was last July. I had a jam in the nozzle last night, took it off, and then when it went back on I was uncertain of it's height so I thought I'd better recalibrate. It looks like emoving the spider could cause me problems with the belt connection, so I think I'll do something like you've suggesgted before pushing on to sometbhing more radical.
thanks for the ideas.

Edit; i suppose I should add that the only meaningful indication is with the test indicator attached to the extruder. For me this means I have to make some sort of fixture to clamp my test indicatoer to the extruder. Nothing I have will sork, so I guess I have to get the bed leveled first, then design and print a clamp which by then I won't need.

There is something insidious about having thr capability to make almost anything.


Re: bed leveling routine question

Posted: Sat Apr 07, 2018 3:00 pm
by Gwhite
Depending on the downward force of the test indicator tip, I'm not even sure how well that works. There is enough flex in the spider that I'm surprised people don't have problems with large asymmetrical prints tilting the bed just from uneven weight distribution...

Re: bed leveling routine question

Posted: Sat Apr 07, 2018 3:51 pm
by jferguson
As it turns out there was an easy way. with the machi9ne turned off, I put a 1/2 inch (surfaced both sides) small piece of aluminum on the table, then raised the table until it rubbed. I tried all the corners until I found the highest and set the Z-Axis to having the aluminum piece rub slightly on the nozzle. I jammed some carboard under the Z-Axis knob so it wouldn't drift. I moved the bed to each of the other corners and raised them until I got similar resistance. I then fired it up and did MakerGear's leveling program and it worked perfectly.

Best of all, it was easy.

Re: bed leveling routine question

Posted: Sat Apr 07, 2018 4:06 pm
by Gwhite
Glad you got it sorted out in short order. For the Z-Axis knob, there are several designs on Thingiverse for "Z-knob stops". Some require printing a new knob, but here is the one I like:

You can also flip it over and use it as a crank to manually run the bed up & down.