Small tube, how to print?

[anaxyd 0]

Hello! New with my Ultimaker, and have stumbled upon some challenges when I am trying to print small tubes. It looks like it is not cooled enough.

Recently I faced this when trying to print the back cover of this dial: http://www.thingiverse.com/thing:155464%20link%20to%20the%20file%20itself:%C2%A0http://www.thingiverse.com/download:30622

Those two tubes/cylinders are pretty hard to get nice and accurate. Do you have some tricks that will work well with this?

Printed with 0.10, 70mm/s, 200C, black Ultimaker PLA.

 

[illuminarti 18]

Be sure to set the minimum layer time to 7.5 seconds or more so there's time for the PLA to cool between layers. That might cause the print head to slow down to a crawl for very small parts - doing more harm than good.

In that case, try printing several copies of the part at once (set the gantry height to zero in Cura's machine settings to force it to print the parts all at once, not sequentially) - that will make each layer take longer (since it prints several copies of the layer, not just one) without having to slow down the print head so much.

 

[gr5 2,265]

You linked to a "dial indicator" and your link simultaneously links to the spring portion - some spiral part.

I don't see any cylinders.

But the biggest problems are usually cooling related. You might need to combine two tricks. The first trick is to lower the temp to 190C and make sure fan is on at 100% min and max and set layer time to at least 5 seconds.

The second trick is to print 2 at the same time - set the gantry height in your machine configuration and print two. It sounds silly and wasteful but it makes a huge improvement for very small objects such as these people I printed recently:

 

[gr5 2,265]

Just to explain further - after it finishes one layer of the main part, it goes to the second part to print a layer there and gives the first part time to cool down.

 

[Dim3nsioneer 558]

@gr5: May I ask at what speed you printed the figurines?

 

[anaxyd 0]

Ah, thank you for the input! That sounds clever, I never had that in my mind. I will try to print two at the same time, with gantry height at 0.

I see my links went crazy, so here are the product I am trying to print: http://www.thingiverse.com/thing:155464

It is the bottom part with two cylinders I am struggling with.

 

[gr5 2,265]

@gr5: May I ask at what speed you printed the figurines?

 

I keep notes on EVERY print. I have a notebook that sits in the bottom of the printer.

In cura speed was 50mm/sec and I ran at 50% so: 25mm/sec and temp 195C. I was printing 3 people at once so I don't think I hit the "minimum layer time" but I'm not sure on that as it isn't calculated perfectly.

When the printing got to the hips I noted excessive stringing which was surprising. So I lowered the temp for the upper half to 190C and slowed down to 40% (20mm/sec).

It still only took probably 10 minutes to print. Not sure (don't usually write that down).

Normally at 20mm/sec and 190C I get zero stringing with this particular PLA but I got lots of very thin strings. I think it has to do with the fact that it doesn't get much time to cool down. Fan was at 100%.

 

[anaxyd 0]

Tried to print two test parts at the same time, but I think the nozzle spends too much time on each layer now, it gets too hot. (7,5 minimum layer time)

Here are some pictures:

(The left one got more cooling, since I got the stock cooler)

I tried with 1 in minimum layer time after this, but it went a lot worse with more stringing and bad quality overall.

But the left one in my pictures above is absolutely within range of good quality, so the trick worked!

 

[gr5 2,265]

Yay!

Next print 3! Just kidding.

Well if you find you need to improve quaility more:

1) .2mm layers often comes out better than .1mm layers. It's counter-intuitive. But if there is any error in Z it shows up worse with .1mm layer because some layers are over extruded followed by an underextruded layer. If your Z has no stickiness or slipping and the z nut doesn't move and everything is perfect then .1mm might look better.

2) slow it down even more if you want high quality. For a small part I would lower from your 70mm/sec to 20mm/sec. It's so small it won't take that long. Be patient. I learned that from watching the UM people at the MakerFaire NYC. They have banks of dozens of printers in a room so they don't care if it takes 20 hours for a print!

3) If you are going that slow, consider maybe also going even cooler to 190C or even 180C only just to lower the stringing issue. Printing 2 parts means lots of stringing and that can be elimintated at 190C usually. Or if the second part is nice and big like a 10mm cube with 20% infill.

 

[Dim3nsioneer 558]

(The left one got more cooling, since I got the stock cooler)

 

Maybe you try rotating the whole thing by 90° around the z-axis? If your standard fan runs at 100% it should blow enough to catch the object on which the Ultimaker is not currently printing....