Base plate not flat

Sure this was my process.

I removed whatever plate was on top.

I attached a digital depth guage (see pic) to the head, actually used some woodworking double sided tape.

Moved the head to home to ensure the Z was even

Jogged to the first measure point, top of washer, then zero’d the meter.

Lifted the meter rod with top lift button and jogged to next washer and lowered the head -have to lift the roof or it would get caught in the gaps).

See pics.








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@NeilL thank you for taking the time to do that, really appreciate it. I have the meter @brettd123 suggested coming in the next week or so.

I do notice with my work with the 123 blocks that while i can mostly level the X bar to minimize the gap on left side between 123 block and the X bar, but after a little bit of use the gap is back to where it was before - is this expected?

It has been mentioned before, but just to chime in, I have worked quite some time with the waste board milled flat and mounting the heated bed on top of that. Gave pretty good & consistent results. The added benefit is that it helps to insulate the bed which means it got to temperature a bit faster, but more importantly stayed a lot more stable.

Later I’ve taken it a step further and tried to create a quick-change solution that actually works pretty good: Idea for quick switch bed: feedback requested - #26 by brvdboss
(I should actually post an update on that as I did simplify the design a little bit to make it easier to create them)

The advantage is that these approaches are non destructive. I used water resistant MDF and it remains very stable despite the temperature changes it is submitted to. (disadvantages are the lost height & some extra weight)

Well this took an interesting turn.

Support asked me to measure from the underside of the Y linear to the base of the printer, not the waste board or plate.

Oh wow, the difference in height is the same as to the distance of the plate.

I had to use a laser measure, but the accuracy is not to multiple decimal points as I had with the gauge, but every measure showed the gap between the underside of the Y to the base to be out by 1mm left to right.

So my thoughts now, and waiting for support to respond again, is that the two Z linear modules are different. When moving the head to the right the head goes uphill by 1mm from left to right. This is the same distance as to the plate.

I don’t know if there is a way to alter these or if the two linear modules will need to be replaced.

As I type this I realise I have one other measurement to take. From the top of the washer on the plate to the base of the machine, or to the top of the X linear. I am now thinking the wasteboard is actually flat but the difference in the two Z linear modules is causing the difference.

Off course there is no auto levelling with laser or CNC, maybe if they added that, the same as 3D printing the issue could be fixed in software? But will take forever to get written and tested.

Just to make sure. Did you tram your device (along the z-axis). Are the z-axes at 90degrees?

Tram? You mean follow the instructions in the build? Yes that was back in Feb.

90 degrees. I see what you are saying, but to be out enough to lift the head by 1mm would make it impossible to align the holes to attach the head. Plus the 3D print would not be square to the bed and create weird prints, which it does not.

I have placed a square on the base against the upright just in case, they look ok.

It is as if the homing is not aligning both sides to the same height, which suggests one of other of the linear modules is out by 1mm. But which one?

That is because the axis don’t align automatically. You have to do that manually.

You can find a picture of how you can do it in this post (there are more, this is the first one I could find) :

Personally, I don’t have 1-2-3 blocks and use soda or soup cans (which are often pretty consistent in size)

A bit more explanation in this post :

I have read all of those but can’t find anything about how you are aligning. Are you saying using 123 blocks or similar and pushing the two to be the same height by hand?

How often do you do this?

Exactly. You push them down on the blocks. (or soup cans)
You must do this when the power is turned off.

I occasionally do it when switching toolheads. Just to make sure I didn’t unintentionally bump into them too hard. And I always do it after I had a little accident like bumping the toolhead in the platform or something like that.

An easier way is to pull it completely to the top. But that might not give as good results due to variations in the construction of the axis.

The important thing is you can do it in a repeatable manner.

I ordered some blocks after measuring some cans (all different).

Will do this when they arrive.

Fingers crossed.

Neil

I have some 123 blocks and have been trying to find my ~1.mm drop on the left side compared to the right too.

I have found that i can tram the X bar but that the 1mm gap betrween the left side 123 blocks and the X bar comes back almost immediately.

I also have ticket open with @Tracy

@NeilL i went as far as taking the platform off the Y rails completely and measuring from base to top of the mounts - i had no deviation i could detect with a square. I plat to repeat when my dial meter comes. Interested to find out if there are different batches of linear motors - i noted one of mine was different to all the others (its cable was bit wider) - this was the X bar. good luck.

In the mean time you could try and see if you get a better result by pulling the x-rail all the way up.
That should also give you a more or less repeatable way of aligning them, just not guaranteed to be parallel with with the y-axis plane.

I don’t know if they already asked you to validate if they travel at the same speed? There was an issue with the quality of the lead screws at some point. (which resulted in clunking noises)

Obviously, something similar could happen on the z-axis. You could try to validate this and possibly swap linear modules around to make sure you have matching pairs.

No clunks. In fact 3D printing is real smooth, but assume due to the auto levelling.

I already had a different linear module replaced as it vibrated. So wondering if there is a bad batch of these.

123 blocks come today hopefully, I will try that out, but not totally hopeful

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@WilliamBosacker having placed my machinists’ straight edge on the base i am unclear it is a flat and consistently level surface with maybe the exception of the (milled? cast?) areas the linear modules fit in?

I ask because each of my y axis carriage mounts when measured from the print head using a dial meter are 100% level. But my straight edge show that across the regular portions of the bed it is not level… I note you put your red things on the base, does this mean (at least on your unit) you are happy the ‘unused’ areas of base are level?

Also those are terrible squares - they are red, so i bought the blue ones for $0.90 more :slight_smile:

I would agree with that, that’s why I used the extrusion of the Y modules. My base is also warped and distorted.

Edit: could be the Z towers, but I’d think it would have to be visibly out of alignment for that to matter.

Is it possible you have 2 Z modules that have mismatched leadscrews? If you issue a 100mm movement does each tower move 100.00mm exactly? That was an issue for awhile, QA/QC issues at the subcomponent manufacturer (and then not verified at snapmaker, it’s just qa qc issues teh whole way down)

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@brent113 oh, i have never made sure the Z modules are the same height :astonished: never occured to me the bed could have them at different heights? Could that cause my 1.1mm drop to the left reported in the mesh?

(i think I finally proved last night that its not my y rails, my platform, my heatbed or build surface causing this)

A good point. I verified mine previously and would recommend others do as well. My towers were level and parallel, within what I would consider an acceptable tolerance:

I saw you? recommend loosening the bolts on the Z tower X-axis mounts for the first adjustment: I also agree with that, and also did that to relieve any residual strain. You should want any strain to be pulling it back into square instead of out.

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can either of you recommend the sort of digital angle finder on amazon that would be good enough for me (a mechanical dumbass) to use?

I have several.

In this case I used one like this: https://smile.amazon.com/GemRed-Digital-Finder-Protractor-Stainless/dp/B00W395R5E.
I also have these: https://smile.amazon.com/General-Tools-828-Digital-Protractor/dp/B00563TLSI, and Wixey Digital Angle Gauge Type 2 with Magnetic Base and Backlight: Amazon.com: Industrial & Scientific which are useful in frequent situations.