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Printing tiny gears - resolution not good enough

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Posted · Printing tiny gears - resolution not good enough

I am printing some gears for a mechanical device. The gears are quite small. As a result the definition between the teeth is not good enough for the gears to mesh.

I am using the default settings on Cura so the nozzle is set to 0.4

What are the suggestions to make the teeth better?

Thanks

MM

th_gear.jpg

th_2014-11-14190509.jpg

 

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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

I would probably print at 20mm/s, certainly no more than 30mm/s. Probably worth trying fan on at 100%. Difficult to tell the size but you might want to print 2 up to ensure you have a decent minimum layer time

 

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Posted · Printing tiny gears - resolution not good enough

I would probably print at 20mm/s, certainly no more than 30mm/s. Probably worth trying fan on at 100%. Difficult to tell the size but you might want to print 2 up to ensure you have a decent minimum layer time

 

I had printed at 25mm/s

What does "print 2 up" mean?

The gear is 13mm in diameter

Thanks

MM

 

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Posted · Printing tiny gears - resolution not good enough

+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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Posted · Printing tiny gears - resolution not good enough

Does printing multiples improve the quality or simply give you a handful of choices to select the best result?

 

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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

In Cura->Tools there is the option to either print all at once or print one at a time. For the scenario you mentioned above you want to print all at once. That will give the extra time per layer for cooling.

 

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Posted · Printing tiny gears - resolution not good enough

Though this is generally only useful for if you have small objects that don't have enough time to cool. for large objects, printing multiples at a time just causes more retractions, longer print times and higher chance of failure for both parts.

 

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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

Would exchanging the .4 nozzle size for a .3 nozzle help improve the resolution? Is .3 the smallest nozzle size you can go?

 

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Posted · Printing tiny gears - resolution not good enough

Would exchanging the .4 nozzle size for a .3 nozzle help improve the resolution? Is .3 the smallest nozzle size you can go?

 

Did not know one could change the nozzle size! Printing "2 up" certainly improves the resolution. Will try 4 up now

MM

 

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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

.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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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

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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Posted · Printing tiny gears - resolution not good enough

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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