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medicalmodeller

Printing tiny gears - resolution not good enough

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It looks like you're either overextruding slightly, or too hot. causing a bit of imprecision.

What I would recommend is adjusting the model so that the teeth are hitting the bottom of the buildplate and doesn't poke out the top.

In other words, if you look at it from the side view, the bottom and top face of the gear should be aligned and parallel with the teeth as one flat object.

Then print it without a brim or raft and lower your temperature by about 5 degrees. or ensure that the MEASURED diameter of your filament is the same as is plugged into the UM2 profile.

 

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+1 on the lower temperature and speed, it can really make alot of difference...

Printing 2, means printing two of the same object at the same time, simply by placing them next to eachother on the buildplate in cura... its a common technique used when printing small objects, to ensure that each layer of the prints get enough time to cool down before the next layer is put on top, because the printer will print layer 1 of object 1, then layer 1 of object 2, etc... with an object as small as that one there, try printing 4 or even 6 or 8 at the same time, it will probably give you much better results, and as a bonus you can chose the best one once they are done...

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It actually improves both prints if you print two because it leaves more time for each of them to cool. And if positioned strategically you'll be able to get the fan to blast the part momentarily for each layer if they're far enough apart. This is especially useful for printing small cylindrical type objects.

The one drawback of doing this however is if you don't have your retraction settings up to snuff, you'll get stringing between the two parts.

 

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I never thought of that, I will likely start printing in multiples now. But it seems that when I print multiple objects, the printer completes one model before moving to the next, do I need to change a setting in cura to get the printer to jump between models during a print? Also what are the proper retraction settings for multiple objects?

 

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I never thought of that, I will likely start printing in multiples now. But it seems that when I print multiple objects, the printer completes one model before moving to the next, do I need to change a setting in cura to get the printer to jump between models during a print? Also what are the proper retraction settings for multiple objects?

 

Proper retraction settings vary greatly for the average retraction distance, printer, filament, etc.... Im afraid you would just have to try it out...

Start with something like 4 mm. retraction at 40 mm./ sec.... if you still have stringing try adding 10% to those values and try again.

In terms of stringing it also helps to lower the temperature and increase the travel speed

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Did You get your problem solved already?

Just a remark: I had the same problem regarding resolution. When I wanted to print something really small it just turned out to be really ugly. When I switched to layer view in cura itself I saw where the problem was: it was the file itself, so nevermind what printer settings I would have chosen it still did not get better.

 

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To be absolutely clear 2up is as referred to above using two, or more, copies of the model. Typically you need about 10 secs for the layer to cool before depositing a new layer on top of it, although some people do push it to 5 or 6 secs. With really small models this is unattainable so multiple models overcome it. There is a bug in Cura though that can blows this solution away as it often sequences itself so that it prints double layers on each model, alternatively, so you still get a minimal amount of time. The solution there is to print four copies and the two in the middle of the sequencing will be fine.

 

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I think there are .25

Bear in mind that the nozzle hovering over the layer below can re-melt it - so there is a trade off with speed and heat!

IMO 4 up would make no difference over 2 up

Using something like XT can help as this is slightly more resistant to the re-heating - so some things I can't do in PLA I can do in XT

James

 

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Hi Jamesh, 4 up can and does help depending on the geometry. Cura will print 2 layers on a model and then move over and print 2 layers on the next model, so you are not getting the benefit of 2up because alternate layers on each model do not get the extra cooling time.

I am not saying it happens all the time but I have seen it recently with 14.07 release but have not investigated.

 

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.3 or .25 nozzles. I have never tried them but I would not have thought they would help resolution except maybe on the very smallest parts. To be fair they must do something or why have them. They will slow the print time. I am sure that for most parts, unless you are a dungeons and dragons freak, you will better resolution and finish by slowing down and/or going to a smaller layer depth.

Thinking onwards if you are working in mechanical engineering and have to be really really precise then with certain orientations they may help - but you will probably have switched to an SLA printer or whatever by then.

 

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To me the best trick for small objects is print two or more at the same time as explained before :)

Something else i noticed is don't use very small layer heights, you would think a small object would need to be printed in 0.04 or less to turn out good. I found out that using 0.1mm layers would give better results.

This is a test print i did for a member of the french community

Printed in 0.06mm:

20141104 073910

 

Printed in 0.1mm:

20141105 071504

 

The size of the thin thread is about 3mm

 

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Didier that is really interesting, strikingly different. I assume that apart from extruder temp, maybe, all the settings were the same? Maybe if the extruder temp did not change you had over extrusion on the first set? - I am clutching at straws here.

Yesterday I was printing a small box with a series of triangular shapes, about 1.5mm/2mm thick which due to print orientation were printed on their sides, one above each othe,r with meshmixer supports in between. All the pointy ends, apart from the bottom one sitting on the print bed, were turned up. It was scaled down to a small size and as there was so little material around the point of the triangle I wondered if the heat from the tip of the nozzle was pulling them as it moved away because there was so little material to get good adhesion. I ran it again tonight making it bigger, plus pushing the fans up from 40% to 100%, and it was fine.

Maybe if you are working on a really small model then working with a thinner layer depth induces a similar problem?

 

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For the 0.06 test i reduced the temp to the lowest possible (if i remember well around 195°c - 200°c) speed was 30mm/s i think.

For the 0.1 test i did the same but temp was obviously a bit higher to prevent underextrusion. Probably around 205°c.

What i think happens here is that the layers being so small the nozzle re-melts the previous layer(s) and thus the result is worse.

It's important to cool down as much as possible on small prints like these. I print two at a time to have a better cooling. It's also possible that i oriented the two items better on the 0.1mm print (making sur the fan blows on one when it's printing the second one.

I should try the same position with the different layer heights to see if the difference is still as obvious

 

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