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tottenham12712

Issues with very small part

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Hi all,

Ive been designing and printing very successfully up until this point. I have a very small part (5.6mm x 5.6mm x 2.2mm) that Im trying to print. Attached is the STL and gcode files. When I run this stl through cura it does not print the walls (.4mm). Ive tried tweeking the shell thickness, layersize, etc with the same results. Even the layer view in cura shows an incorrect object.

Would anyone be able to help me out? I realize this print is pretty small and may not actually be possible on the ultimaker, but at a very slow speed the bottom half actually comes out pretty decent.

https://onedrive.live.com/redir?resid=4CEE5233B14004D1!30652&authkey=!AJkvXJG95833Veg&ithint=folder%2Cgcode

Thanks,

Dylan

 

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I just downloaded your STL. Since the walls are .4 and since Cura insists on 2 passes it slices fine if you tell it you have a nozzle of .2mm wide and shell of .19.

I recommend overextruding (set flow to 150%) on this one to get strong walls. They won't be much wider than .4mm. I'm not sure how good the tolerance will be on the walls but better than you might think.

Alternatively consider truly getting a smaller nozzle. I recommend .25mm.

Or write the gcode yourself by hand?

Or give the STL a "top" and then slice it with "spiralize" such that it prints the outer edge .4mm thick with nozzle and shell set to .4mm. I'm not sure what it will do to the two holes though (cups and vases don't normally have holes in the bottom).

 

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I just downloaded your STL. Since the walls are .4 and since Cura insists on 2 passes it slices fine if you tell it you have a nozzle of .2mm wide and shell of .19.

I recommend overextruding (set flow to 150%) on this one to get strong walls. They won't be much wider than .4mm. I'm not sure how good the tolerance will be on the walls but better than you might think.

Alternatively consider truly getting a smaller nozzle. I recommend .25mm.

Or write the gcode yourself by hand?

Or give the STL a "top" and then slice it with "spiralize" such that it prints the outer edge .4mm thick with nozzle and shell set to .4mm. I'm not sure what it will do to the two holes though (cups and vases don't normally have holes in the bottom).

 

Well I guess you learn something new every day :) I did not know that cura wants to do two passes.

As far as strengh this is just a cover for a barometer for a multirotor (they are super sensitve to light and wind) the part really doesnt need any strength just decent tolerences so I can glue it over the chip.

I have considered a smaller nozzle as most of the things I print are smaller parts with holes and it appears the .4 nozzle is a bit big for that. Any place you would recommend getting one from, I see makergear sells them.

I write enough code at work :p I actually didnt even think of that... not sure why, ill give that a shot as well.

I assumed the holes would print pretty crappy but my hope was that there would be some type of hole there. I might just make it completely solid and poke it with a large heated pin.

Thank you for your help!

 

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I don't know what your tolerances are on the outside but I think it's sounding like it will print fine with .4 nozzle if you tell cura it is .19 nozzle. You just might need to play with "flow" setting.

As far as getting a smaller nozzle - no one sells these for UM2 yet. So it's tricky. You have to buy one from Ultimaker and they are expensive - something like $40 for the nozzle/heat chamber (it's an integrated part). Then you have to have a metal worker put some solder in the tip (tell him it needs to operate at 280C) and redrill it out to .25mm which is the hardest part of all because .25mm drill bits are very delicate. But with the right equipment (lathe or drill press) it's not too hard.

Personally I have the opposite - I have the normal .4mm nozzle plus a .7mm nozzle.

 

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This inability of Cura to print single line objects is something which has caused me quite a lot of trouble and I am surprised that I don't read more complaints about this.

As far as I understand some other slicers like Makerware can slice single line structures.

See this one for example: http://www.thingiverse.com/thing:289650

(Using Cura you will have to print such object twice the size to get the physical properties right :shock: )

Another situation where Curas double walls are really limiting is when printing text on surfaces. You have to go for a rather large bold font to make Cura print it. That has been a major limitation for me when it comes to how much information I can provide for the users on the printed objects.

Is there any particular reason why there can't be a "slice single pass structures"-button to make Cura slice single line walls?

That would help me hugely when designing tiny components for scientific instruments.

I have spent lots of time either trying to trick Cura or editing the G-code manually (which is quite time consuming).

Since I got my custom heater block I can print 0.6mm (2x0.3mm). The 0.25mm nozzle just seems a bit small to work properly with the UM2 for some reason though.

Also, 0.6mm is still far from 0.4mm, and if I could trick Cura to print single lines I would be able to print 0.3mm walls with my current setup, which would be very interesting for scientific purposes.

 

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Most questions in the format of "Why doesnt function 'foo' exist in 'foo2' software" can be explained by "Time, or a lack thereof."

Most functions that seem easy, tend not to be easy. Sometimes because the task is hard, sometimes because the current architecture/GUI doesn't support it (and needs to be changed, thus taking time).

 

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Is there any particular reason why there can't be a "slice single pass structures"-button to make Cura slice single line walls?

 

Because the whole design of the CuraEngine is based on enclosed 2D shapes which might need to be filled or not, and outline printed around them. Single walls simply don't fit in that structure&method.

 

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I don't know what your tolerances are on the outside but I think it's sounding like it will print fine with .4 nozzle if you tell cura it is .19 nozzle. You just might need to play with "flow" setting.

As far as getting a smaller nozzle - no one sells these for UM2 yet. So it's tricky. You have to buy one from Ultimaker and they are expensive - something like $40 for the nozzle/heat chamber (it's an integrated part). Then you have to have a metal worker put some solder in the tip (tell him it needs to operate at 280C) and redrill it out to .25mm which is the hardest part of all because .25mm drill bits are very delicate. But with the right equipment (lathe or drill press) it's not too hard.

Personally I have the opposite - I have the normal .4mm nozzle plus a .7mm nozzle.

 

 

One more thought - can you design the part with 1mm walls instead of .4mm? If you can do that then you can print this just fine with .4mm nozzle.

 

Thats a bummer on the nozzle, If a dual extruder gets released it would be pretty cool to be able to use two different size nozzles depending on what needs to be done.

Unfortunately i cant, this is a cover for a barometer on board an arduino, there are transistors that surround the area.

The good news is I got the print to come out perfect. I use color fab xt, so I had to drop the temp from 245 to 240, and actually reduce flow to 90%. It under extruded ever so slightly but I dont need strength so its perfect. I ended up pulling the holes out of the model and just used a hot needle to poke them in after the print was done.

Thank you very much for your help :)

 

Because the whole design of the CuraEngine is based on enclosed 2D shapes which might need to be filled or not, and outline printed around them. Single walls simply don't fit in that structure&method.

 

Just redesign it!! :p

 

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To my personal experience single walls might be helpful for custom support structures (easy to break away). But I understand that redesigning the slicer engine is not on the todo list.

Maybe Tim comes up with an ingenious algorithm for the support in Cura... so custom support structures will be obsolete...

 

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