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woofy

Will UM2 print this

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Hi,

I don't have my UM2 yet so I can't try it myself.

Will the UM2 print this file:

http://www.woofys-place.co.uk/files/test2.stl

(after its flipped 180)

I'd like to print it with ABS for strength and impact resistance but I don't know if warping would be an issue, even with a heated bed. Maybe another plastic would be better such as PLA90. My UP plus can print 120x120mm ABS without warping but this is a lot bigger.

I'm not sure there is enough UM2 experience around yet but any advice is welcome.

 

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I wouldn't flip. Printing with the solid covered circle up (open side down) should have less warping issues.

This part is very open which will reduce warping but you will still have some. It's very tough to print something like this with zero brim and still get it to stick. Can you make it 1mm smaller on each side? There is only 1mm to spare right now and you probably need some brim if you want this to stick.

I don't know the answer to your question - it *should* be printable but I don't have much experience with how to get things to stick to glass yet.

I would personally add brim to the cad where it can be - so those square corners should get a brim (like a hat brim) which should be .2mm thick (so only one layer!) and the wider the better, but 5mm should be enough. This helps hold down the corners. Corners have more issues than rounded edges.

 

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I don't have one either, and I haven't done a lot of ABS printing either. I would think it would have a reasonable chance of being ok, since it's mostly empty space. However, since it totally fills the build plate, I wonder if you might have some adhesion/warping problems on the square corners. Depending how even the heat distribution is, the bed might be a bit cooler at the edges, plus you don't have room for brim, or even manually added pads, to help hold the corners down and spread the loads.

To save anyone else having to go get the STL, here's a screen shot of it in Cura:

A sample object

 

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I've just downloaded Cura 13.11.2.

My model no-longer fits and if i scale to fit it shrinks it to 0.88.

Can Cura really only do 202x198mm build size?

I've check every setting I can find including Width/Depth in machine settings, but everything relevant is the same as Cura 13.10

 

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1) Go to "file" "machine" and make sure the dimensions are correct there.

2) Go to "machine" menu and make sure ultimaker2 is chosen

3) Turn off brim and skirt. In fact I don't think you can turn off skirt without going to expert settings and set line count to 0.

It's probably the skirt that is messing you up.

If you look at the print in "layer view" you can see if it was the skirt that was messing you up - look at layer 0.

 

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1) Machine settings are width/height 230x225, in fact every setting on that dialog is identical to 13.10.

2) Yes, Ultimaker2 is selected.

3) Platform adhesion type is set to None - is that turning off brim?.

I tried setting skirt line count to 0 anyway but no difference. Also tried setting Brim to 1 (it won't allow 0) with no difference. I think its off anyway.

I cannot see the model in layer view, I think because it is black and unsliced.

The only thing I can think of is 13.11.2 has some gray rectangles shown on the base plate corners where 13.10 does not. I don't see anyway of removing those. Looking at UM2 photos, these may be the mounting clips, but my model should not touch those.

The model loads and slices fine in in 13.10

 

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3) Platform adhesion type is set to None - is that turning off brim?.

 

Yes. But leaves skirt on.

You can click on the object and scale it to 0.9 (90%) and let it slice and look at the bottom layer to make sure brim and skirt are definitely off and to see how close the part is to those gray squares. If you are really sure it isn't going to hit your clips then for now I would just slice with cura 13.10 until this is fixed.

 

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Just to illustrate the issue with a few pics

This is the model loaded into 13.11.2, both brim and skirt are off and it clearly misses the gray rectangles.

um2a.jpg

Here I have put skirt back on and scaled to fit, Cura scaled this to 0.88. Here is the layer 1 path. The skirt is nowhere near the edge or rectangles, but that's as large as it will go.

um2b.jpg

Now the same thing with the skirt off. This time Cura scaled it to 0.91 with as a Max size. Still nowhere near the edge or rectangles, but that's as large as it will go.

um2c.jpg

And finally for reference, the same model loaded into 13.10. Skirt and brim off and 100% scale. Again, the layer 1 path.

um2d.jpg

Either there's a setting I'm missing or this is a bug.

 

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I just tried slicing your test2.stl from earlier in the thread, in Cura 13.11.2.

Basically the problem is that it's doing very crude bounding-box checking for interference with the clips in the corners. So if you make the print no wider than 180mm in X, then you make it up to 224.99 mm in Y. Alternatively, if you keep it at 204.99mm or less in Y, then you can go to 230mm wide.

Either of those cases ensures that the imaginary box around the print fits totally inside the part of the bed where the clips are.

If you have a part that is over 180 x 204.99 in both dimensions, then Cura will currently not slice it, even if the actual geometry would not foul on the clips.

I think Daid probably needs to refine this a bit to allow folks to get a bit more total print area out of the bed.

 

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Ok, to finally answer my own question:

Almost!

Sliced in Cura 13.10, printed at 40mm/Sec, 220/75 degrees with 0.15 layer height.

It printed in around 25 hours, but I have got a lot of warping that lifted the edges of the platform.

I'll be doing more experiments to get this right.

base1.jpg

There's a high res image here:

http://www.woofys-place.co.uk/files/base1H.jpg

 

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Nice! Yah! :) You finally got your own printer and tried it yourself!

Did you:

1) use gluestick or hairspray?

2) try to use brim? Even just 2 passes maybe? I assume the "back" two corners are the worst - those should have room for some brim - you can add it in the cad if you can't do it with cura. If you can't do that you could try a "raft". I've never done it. I'm not a fan. But a lot of people swear by it - it allows a little flexing and warping without actually seperating from the print bed. Usually. Raft is very popular among cheaper printers and among people who do ABS (which has much worse warping than PLA).

3) Is the bottom layer squished a bit into the glass? This is important - if the bottom layer just is laid down without being pressed in it won't stick as well.

I recommend .2mm layer height for this part since it is so large and there isn't a lot of critical detail I would think. Either that or increase the speed to maybe 80mm/sec (but don't do both). This recommendation is only to save time - it won't help the quality (it might hurt but it should be okay).

 

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I printed directly on to the glass without glue or hairspray as the first few small prints I did stuck like s**t to a blanket. Unfortunately the model is too large to use the brim but I have just added some to the cad.

I'll try at 0.2mm as well.

 

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stuck like s**t to a blanket.

 

Then you need the next advice - how to get the damn parts off. First make sure it cools down to at least 50C as hotter than that and you risk deforming the part. I usually use a putty knife or knife with a razor blade. Once I get a corner up I always switch to a putty knife if I didn't start with that.

If you use the glue stick it dissolves nicely in water so sometimes I take the whole sheet of glass out and put it in the sink.

You could just put the glue stick under the corners that tend to lift.

Also freshly cleaned glass sticks better than glass that has oil from your fingers on it.

 

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Arrg!.

Disaster struck today. About 10-15 seconds into the new print the nozzle blocked. I've tried unloading/reloading the filament without success. I've nothing fine enough to poke in there and unblock it, so I've just ordered a pack of 100 30G (0.3mm) disposable syringes from Amazon. Hopefully, I'll be able to unblock it without taking the head apart.

Ah well, the best laid plans etc.

 

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That sucks. Maybe you have a steel bristle brush where you can cut off one bristle?

Another solution is to heat the head to 180C, remove filament, loosen the 4 screws about 4 turns each, then remove the blue clip, push down on the outer ring that the blue clip held up and lift the bowden tube out while pushing down on the ring. Now with head at 180C cut a short piece of PLA and insert it. Then change head to 90C. Walk away and come back after the head has been at 90C for a full 3 minutes and pull firmly the PLA out. This should hopefully pull out some or all of your plug.

Reheat to 180C and see if you have good flow. If not, repeat several times.

Or, take the head completely apart (not really that hard after you got this far!) Including removing the thermocouple and heater (very carefully!) and do this while at 180C so the pla doesn't lock any threads.

Then take the nozzle and put it in a hot gas flame.

 

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I added an issue on Cura's github tracker for this - #641.

 

I see Daid has closed this issue, but it is still not fixed.

The latest Cura 13.12 still will not slice the model, despite the fact it is within Ultimaker's size limit and does not hit the clips. It prints fine with 13.10.

@Daid, you can use this test2.stl to verify.

 

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13.12 seems happy to slice it at 99% scale. Indeed I can get it up to 227.49mm by 222.49mm - so much better than before, but it doesn't seem to want to go to the final 1.5mm of size.

I notice that when you pick the 'maximum size' option, it scales it to fit totally within the limits of the clips still, rather than taking advantage of the new corner cut outs logic.

If I try to slice a square block, then I can get it about half a mm larger in either x or y than those dimensions, but not both at the same time because of course that would catch on the clips.

 

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