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spiruline

Some various questions

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Hi,

After one week printing with my new Ultimaker with Ultocontrol I have some questions. I am using Cura for slicing. I have been trying to tune up the prints by reading all the information I can find here, but I am sure I am doing things right or not.

- I am adjusting the platform to a point where I can slide a piece of paper between the nozzle and the blue tape with a little resistance by pulling with two fingers, is this right?

- When you guys say the printers is overextruding or underextruding, how do I change that? should I use the flow control in the tune menu of the ulticontroler

- Temperature for PLA (supplied by Ultimaker: I am using 210ºC, What are the advantages/disadvantages of going hotter or colder?

- Should I print the first layer of large flat objects warmer (220?) to help avoiding warping?

- "Enable Retraction": should this option alway be used in Cura for good quality without stringing?

- "Wall thickness": this just affects the strength of the print, right?

- "Bottom/Top thickness" : does this affect the smoothness of the first and last layer, or just the strength of the print? what is a good value?

- "Initial layer thickness": what's the difference between the initial layer and the bottom layer? or is it the same? does this value override the "Bottom/Top thickness"? What's a good value?

- Any tips for smooth base and top finish?

- When should I turn on the fan? Is its good or bad regarding warping? should I print the first layer without fan and the turn it on? which speed by Ulticontroler?

I am sure I´ll have many more questions, but this should be enough by now.

Thank you in advance

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Here are some thoughts, based on my experiences with an Ultimaker for the 6 months or so....

 

- I am adjusting the platform to a point where I can slide a piece of paper between the nozzle and the blue tape with a little resistance by pulling with two fingers, is this right?

 

That's basically what I do - put the head near the screw, and then tighten the screw until the paper slides freely. Then loosen the screw until the head just starts to catch on the paper. Then I loosen the screw a further 1/8 turn to compensate for hte thickness of the paper. Then move on and repeat at each corner, before repeating at least the first one again, to make sure that everything is still right. Make sure that the screws are in a 'middle' position so that there is still play in the springs, while keeping the screwhead in contact with the bed when the bed is at rest. Also, remember to preheat the head before leveling, so that any thermal expansion is accounted for, and any plastic on the head is softened so that it doesn't get in the way.

 

- When you guys say the printers is overextruding or underextruding, how do I change that? should I use the flow control in the tune menu of the ulticontroller

 

If everything is set up right, then the extrusion should, by definition be perfect. Large variations in extrusion amount are typically due to either filament grinding or head blockages (causing major under extrusion) or big variations in filament diameter (causing under or over-extrusion). Cura calculates the amount of plastic needed for each head move, in terms of the length of raw filament needing to be fed in. So make sure that you have calibrated your steps-per-e setting correctly (so that the machine gets the length of filament it is asking for) and also measure your filament, and make sure that you set the diameter correctly in Cura (so that each mm of filament fed in is providing the total volume of plastic that Cura is expecting).

If your filament is highly variable in diameter, then you are going to get poor and erratic results - and some filaments can even be so far off spec that they are fat enough to block the bowden tube. So always go with good quality, consistent diameter filament. Once you have things calibrated correctly, then you can use the flow setting on the controller to adjust the amount of plastic requested in percentage terms, to adjsut for differences between filaments, or the specific needs of each print.

Note: make sure that you have a recent firmware that displays the flow adjustment in percent - defaulting to 100%. Older firmwares (before about December 2012?) had the display and adjustment screwed up, and displayed a number around 240-something as the default, iirc. That was harder to work with, so I recommend getting newer firmware. The ulticontroller display and functionality is also better in newer ones.

 

- Temperature for PLA (supplied by Ultimaker: I am using 210ºC, What are the advantages/disadvantages of going hotter or colder?

PLA can typically be printed between about 180 and 240 degrees or thereabouts. I typically print at 220 or 230. The higher the temp, the higher the gloss on the finished print, and the easier the plastic flows. This can allow for faster printing, but may come at the expense of blobbing and poorer overhangs if the plastic is too liquid to be controlled adequately in less forgiving situations.

Try printing the same piece at different temperatures, and see what works for you. Exact behavior can vary between colors and manufacturers, depending on the underlying plastic blends and additives and their effect on the plasticity of the material.

 

- Should I print the first layer of large flat objects warmer (220?) to help avoiding warping?

 

I often find that it helps to print the first layer warmer (esp when using a slicer like Kisslicer that easily supports a hotter first layer temp). Mostly I avoid warping by printing hotter onto a single layer of blue tape that has been wiped down with isopropyl alcohol before printing. (I prefer 6" wide tape for ease of application, and to minimize seams that mark prints and provide an easy edge to start to pull off the bed). I generally turn the fan on as late as possible (if at all) when printing large/flat items that I expect to have warping problems.

-

"Enable Retraction": should this option alway be used in Cura for good quality without stringing?

 

Yes, pretty much. Although if you have small fiddly prints you might want to turn it off or reduce the amount to avoid the risk of filament grinding from all the back-and-forth.

 

- "Wall thickness": this just affects the strength of the print, right?

 

Basically. This sets the target solid 'shell' amount on the outside of each layer. You want to make your wall thickness an exact multiple of the nozzle width (0.4mm by default) to make sure that you get an exact number of solid loops of plastic making up the outer wall. I typically use 0.4 for small fiddly parts, 0.8 for larger prints.

 

- "Bottom/Top thickness" : does this affect the smoothness of the first and last layer, or just the strength of the print? what is a good value?

 

This is like the wall thickness, but for the bottom and top of the print. It should be an exact multiple of the layer height. A higher value will cause more solid layers to be put on the bottom and top of the print, which can help give a better finished surface on the outside (as it means more layers to fill in any little gaps or overhangs).

 

- "Initial layer thickness": what's the difference between the initial layer and the bottom layer? or is it the same? does this value override the "Bottom/Top thickness"? What's a good value?

 

This is the height of the very first layer that prints. If you are printing with, say, a 0.1mm layer height, then the first layer will also try to print at that height, assuming that your initial layer thickness is set to 0. Having a thicker first layer will give more plastic for good adhesion, and also to overcome any slight variability in the flatness or leveling of the bed. I often use a first layer height of 0.2 or even 0.3mm if I have any concerns about a piece staying stuck.

 

- Any tips for smooth base and top finish?

 

A thicker bottom/top will give more layers of solid print to even out any defects. Correctly calibrating the flow and filament diameter will ensure sufficient plastic to give a smooth layer. Printing hotter will probably also help with the flow and gloss of the top and bottom layers.

A heated bed is the best way to get a smooth bottom, as you can then print directly on glass/polyimide tape without the blue tape. This will give a mirror-like smooth finish on the bottom. For relatively flat parts I successfully print PLA directly onto a polyimide-covered bed even without a heater.

 

- When should I turn on the fan? Is its good or bad regarding warping? should I print the first layer without fan and the turn it on? which speed by Ulticontroler?

Having the fan running all the time can cause excessive cooling, and so lead to warping. I generally avoid using the fan at all if I can when printing larger parts. Kisslicer has the option to turn the fan on only for the loops and perimeters (the outer shell) and off for the infill - I find this helps with warping also. Having the fan on whilst printing the outside surface can help improve print quality, especially on overhangs and bridges.

In cura you can set the height at which the fan turns on. If I'm going to be using the fan, I usually have it turn on a few mm into the print. And I just run it at full speed - I'm not convinced that lower speeds are useful. When you want it on, you generally want it as much as possible. And when you don't you just want it off.

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The flow shows 210.54, but this is a bug. (The actual value it tries to display is 866, but due to a bug it shows 210.54) so changing it has little effect.

The firmware in the 13.01 Cura pre-release has a flow setting in percentages, so that shows 100%.

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Cura with the UltiControler is great! Quick workflow, I love it. Nice job Daid!

Working with some white plastic now from ultimachine that is 2.78 mm. Getting enough plastic is a problem right now.

UltiControler is reading the 210.54. Updating the firmware to show percentages sounds like the answer. What firmware needs updating? The UltiControler or the printer?

From Daids message it seems if Cura talks in percentages then the UltiControler shows percentages. Or Cura 13.01 upgrades the machines firmware then the UltiControler knows percentages. Where the firmware resides that gets the upgrade is confusing.

That all being said, I appreciate the time Illuminarti took to reply to the topic message. Very helpful.

Thanks to all

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There is only one firmware... it lives in the printer, and drives both the printer and the Ulticontroller. If you upgrade the firmware using Cura 13.03 or 13.04 - you'll get the same firmware from either - that will fix the Ulticontroller display problem.

 

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