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ltc

print crack and clibration

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Hello guys , I'm a new comer to this forum. There some issues I didn't get clear replies from the support team of Ultimaker, so I come here. I suppose here must be someone who can help me.

1. These are coming with Ultimaker, and the support team told me they are tools for X,Y axis calibration. I don't know how to use it. Could anybody show me how to use them?

http://imageshack.us/photo/my-images/20/rmso.jpg/

2. How to calibrate the printing boundary? It is the result after I run the leveling wizard on a desktop pc. How can I move the print range back to the middle of the platform?

http://imageshack.us/photo/my-images/20/rmso.jpg/

 

3. I'm troubled by more and more prints getting the issue of layer marks and sandpits like pictures below. They are printed with PLA, layer thickeness 0.06mm, fill density 5 or 8%, print and retraction speed at 50 mm/s, feed rate 100%.

 

http://imageshack.us/photo/my-images/820/tsbg.jpg/

http://imageshack.us/photo/my-images/842/7azc.jpg/

 

 

 

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Thanks for your post.

The first 2 pictures are similar, is that on purpose?

The tool is meant to place the singular hole on the rod under your frame, and the other end with multiple holes on your rod that crosses your printhead. Put both tools on 1 end of the rod underneath your frame, so at the front and at the back for example.

It should indicate if your rods are straight or if they need any further calibration.

If one end is closer to the rod then the other one, you can open the corresponding sliderblock, loosen it so it has no tension and move the slider block in a way so the rod are parallel to eachother.

Regarding the prints, to me it looks like a problem with either the filament (inconsistant diameter?)

Or you could have some dirt in your nozzle that is occasionally interfering with your flow.

At what tension is your feeder mechanism? Can you sent a picture of the teethmarks in your filament?

 

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2. How to calibrate the printing boundary? It is the result after I run the leveling wizard on a desktop pc. How can I move the print range back to the middle of the platform?

 

If you look at the print head - the nozzle is to the side. That is why it prints like that. That is normal.

 

I'm troubled by more and more prints getting the issue of layer marks and sandpits like pictures

 

You are less likely to get the horizontal layer lines with a .2mm layer print as this hides issues like this very well.

The horizontal lines are either over or under extrusion. The piece with only one line appears to be overextrusion.

There are 2 common causes: feeder or z stage. It appears to be a Z stage issue where you ask the z stage to move .06mm but it actually doesn't move at all or moves much less. That's why moving .2mm will fix this issue. Or even .1mm might be enough. There are many things that can mess up your z stage - the most common is the Z nut. The z nut (the huge nut inside the z stage) is designed to slide left and right a little. Sometimes when the Z screw rotates, the Z nut also rotates so the platform doesn't go down.

You can fix this by taking apart the Z stage and building with tighter tollerances. If everything is perfect you might be able to clamp the Z nut in place, but if the Z screw is warped a little you want to allow the Z nut to slide but not rotate.

Other possibilites is the feeder. For example if the filament gets tangled or stuck - then you get a bad layer with holes in it (underextrusion). Or if you print to cold and too fast you also get underextrusion.

 

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I had many problems with the z-stage (the brass nut not sitting properly inside the designated cage). To me the horizontal lines do not look like issue restulting from wobble. You can simply test it if you move your z-stage up and down quickly (via the UltiController if you have one or with a tool on your pc). Check this video for reference - it shouldn't move that much (because I still have z-wobble :/ )

 

You could also print this object. Looking at the z-axis you will see immediately if you have the z-wobble issue:

http://www.thingiverse.com/thing:80126

 

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Thank you for all the enthusiasm and kindness.

@SandervG Sorry for my ignorance. The 2nd picture link about platform is supposed to be this?

I'm not sure if on filament are clear enough...

I tried to heat up the extruder to 250 degrees and the PLA filament flow went smoothly. So the surface problem may be caused by Z stage.

@gr5 and @Nicolinux

 

If you look at the print head - the nozzle is to the side. That is why it prints like that. That is normal.

So....is it default setting and no need to adjust?

 

There are 2 common causes: feeder or z stage.

I guess it caused by z stage. Here is the

at 0:58~1:00.

I want to make prints look more delicate. That's why I usually print with 0.06mm layer thickness. I thought the thinner layer the result better before I print out this here besides crack issue.

 

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To be able to print that fine you need to get your z stage working better. Personally I think .2mm layers looks very good. If I wanted to get finer detail I would go to a smaller nozzle (.25mm) before trying .05mm layers.

I built my z stage differently than most people. I built it very tight. The z nut DOES NOT MOVE. It's very tight. I had to put in shims to get the screw and the 2 rods to all line up perfectly and still have the stage move up and down very smoothly. It's easier to do this with the Z screw *not* connected to the Z stepper motor. To get it perfect. If you want .05mm layers you need to rebuild that Z stage. You might also want to print slower. Practice with smaller models maybe. It will take a long time to get very good quality.

Alternatively you could try laybrick filament and stick with .2mm layers:

http://www.extrudable.me/2013/08/13/printing-with-laybrick/

 

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I don't know... Looking at the video, it looks pretty smooth to me. My threaded rod wobbles like crazy right now and I am still able to achieve relatively fine prints.

@gr5: George, would you mind posting a photo of your z-stage. I don't know if you have already but I'd be interested to see where exactly you put those shims. Also, do you think it will work with washers?

Thanks.

 

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First let me say that I didn't really understand what I was doing when I built my UM.

 

Anyway, you can see in the photo below that I added shims on the sides (blue arrows). That was to get it perfectly lined up on the 2 smooth vertical rods and also centered on the z screw. I took the z screw out of the z coupler to make sure it would just fall perfectly into the coupler without any pushing side to side. I had to adjust the bed a few times (with shims) to get it just right. Those shims are not rectangular. They are wedge shaped. So they are thicker towards the back and thinner towards the front of the bed. The top right one is a thin piece of iron from an old PC power supply case. The rest are cedar shingles.

 

In addition, something must have been wrong with my laser cut plywood because I spent over 3 hours sanding and filing everything in order to get it to fit. For example the front panel and side panels WOULD NOT FIT. I had to enlarge all the square holes with a small metal file.

 

So when I got to this Z bolt it fit very tight. It does not move in there. I now suspect it is meant to move but I built everything to very tight tolerances and mine doesn't need to move. If I disconnect the z screw from the coupler, everything rides up and down very smoothly. No binding on the two rods.

 

So I think I was just lucky that I had a very tight set of wood from UM. It may have taken me longer to put it together than most people (extra sanding/filing) but I may have gotten lucky on the Z stage.

 

shimmed Bed

By the way you can see (green arrows) my wing nuts I use to support my aluminum heated bed from below (which I rarely actually heat up).

 

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So now, if your z nut is loose, I recommend locking it in somehow. Maybe with a mild glue. Maybe just wrap it in a few sheets of paper. I'd take it all apart and possibly just put hot glue in there (which shouldn't be too hard to get out again I would hope). Anyway put something in there with the big Z nut to keep it from moving.

 

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Those gaps look intentional to me George.

See they are bigger the closer to the back with the intention of the base plate being able to move horizontally with any wobble in the Z screw but the 2 arms and the platform remain steady around the rods. I think you may get away with it or even get an improvement if you don't have a wobbly Z screw.

 

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Thanks George. I will try it too. I found somebody with a laser cutter in my area and will replace the z-stage back panels. I will keep in mind to lock the brass nut and have the threaded rod be centered on the z-coupler. I really hope to put an end to this mess because it is the only thing on my UM that's not ideal (for me).

 

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Something I have seen the Solidoodle guys do is print plastic casings that go around the bearings

I don't have a picture on hand but wonder if a plastic (injection molded, printed of other material) that firmly encases the bearings and Z nut would be a good idea?

I had to strugle to get my build platform just right, but had no trouble with the z-nut....so far.

 

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