print quality at fast speeds

[alaris2 1]

I'm currently printing at 150mm/s (which Cura warns me I can't do..) and I'm curious whether anyone else is printing at speed and what quality of prints they're getting?

since I'm currently printing in black it's lousy for taking photos of, but I have noticed the top surfaces of objects are printing a little rougher than before.

I also note that the first layer is very shiny - the high temperature needed for printing at speed is applied to all layers and my first layer prints very slowly so heats up too much. other than this, no reported problems. I was expecting there to be accuracy problems due to backlash and such but haven't observed anything like this. did I just get lucky or what am I missing?

[joergen 2]

I'm currently printing at 150mm/s (which Cura warns me I can't do..) and I'm curious whether anyone else is printing at speed and what quality of prints they're getting?

since I'm currently printing in black it's lousy for taking photos of, but I have noticed the top surfaces of objects are printing a little rougher than before.

I also note that the first layer is very shiny - the high temperature needed for printing at speed is applied to all layers and my first layer prints very slowly so heats up too much. other than this, no reported problems. I was expecting there to be accuracy problems due to backlash and such but haven't observed anything like this. did I just get lucky or what am I missing?

I had good experience with laying down solid infill layers at 250mm/s and 0.2mm (0.56mm nozzle), which helps if you are building a solid part. skin/outer loops seem to have a limit of 75-100mm/s, otherwise skin defects start showing (ABS, 250C)

[destroyer2012 0]

So I know that you guys SET the printer to go to 250mm/s (That's the max speed according to daid's build me marlin. So anyone claiming to build at 300mm/s is suspect) but do you know if it actually reaches that speed? What is your minimal layer time and what is the largest build you have tried at this speed? 250mm/s is VERY fast I mean it's even faster than the speed my UM travels at which is quite huge; I can't imagine how you can print at that speed without massive vibrations happening during infill. Surely the look ahead feature of marlin will slow the printer down automatically so you don't actually reach that speed?

Pray tell, do you notice your UM making travel moves with a higher pitched motor sound when you are printing? That would be an indication that you aren't actually printing at 250mm/s. Do you have any videos of your ultimaker printing at 250mm/s?

[alaris2 1]

well I've not gone beyond 150 yet, because I notice roughness on outer surfaces and today I studied the effects speed has on infill. at 20% infill it's starting to break up - turning into fine strings with blobs on. which is why top layers are rough - they have precious little to sit on top of.

this probably means I need to tweak the temperature a little higher (I think?)

note too that Joergen mentions a larger than default nozzle - which might be necessary to get enough material out at that speed? it sounds like he's using ABS too, whilst I'm using PLA.

anyway, you're right destroyer, with dwindle switched on I find the print looks very good on the outside, but this is partly due to perimeters and details slowing down, however I believe it is reaching some high speeds (this due to the time to complete a print decreasing significantly) and on very large flat surfaces the head is certainly moving at the 150mm/s.

most of what I print is 'boxy' and falls in a 4' cube. yes vibrations were definitely an issue at first. I printed Daid's UM feet and coated them in silicone - I'm also working on the end plates to prevent the guide rails bouncing back and forth.

incidentally, (some of) the reprap boys are up to 400mm/s and laughing at us (

http://www.thingiverse.com/thing:7652

) they reckon the UM can't possible go this fast.

[Daid 306]

Don't forget the acceleration, you might never reach the set speed because of acceleration limiting your speed.

I highly doubt the reprap machine is reaching 400mm/s, and reprap based machines will always have less acceleration then we do (heaver head). Sure, we could reach 400mm/s, if you move from X/Y min to X/Y max. But is that useful?

[joergen 2]

well I've not gone beyond 150 yet, because I notice roughness on outer surfaces and today I studied the effects speed has on infill. at 20% infill it's starting to break up - turning into fine strings with blobs on. which is why top layers are rough - they have precious little to sit on top of.

solid infill layers on top of regular infill needs a much lower speed, almost bridge speed, in order to make good contact. same with regular infill, which, unless you tweak the speed and flow, is somewhat useless at high speed. I only use grid infills, which are limited by the FW max speed, since the sewing machine sound doesn't really change when adjusting the speed. it works at high speed because there is never any air below the extrusion, where regular infill only has something underneath where two infill line meet, and hence it can't work at high speed.

this probably means I need to tweak the temperature a little higher (I think?)

no, only speed.

note too that Joergen mentions a larger than default nozzle - which might be necessary to get enough material out at that speed? it sounds like he's using ABS too, whilst I'm using PLA.

yes, we had a lengthy discussion earlier (see "reasonable expectations") how much the UM can actually push through a nozzle, quantified as mm^3/sec. smaller nozzle means less extrusion per sec. since I know I wasnt going to print small items, but parts, I opted right for a larger nozzle from makergear. the 250mm/s at 0.2mm is unreasonable with the standard 0.35mm nozzle.

incidentally, (some of) the reprap boys are up to 400mm/s and laughing at us (

http://www.thingiverse.com/thing:7652

) they reckon the UM can't possible go this fast.

I watched their videos... not quite 400mm/s... I have 300mm/s jump speed, which seems ok. as I said, the 250mm/s at 0.2mm really depends on the capabilities of the hot end.

[destroyer2012 0]

reprap based machines will always have less acceleration then we do

You know I have heard many people claim the fact that the ultimaker is faster than the reprap because it has a lighter head. However, in practice, does this actually matter? I posit that the answer is no, or at least, it depends. If you are printing a plate of mendel parts, then the acceleration and speed matters. On any other print that is not an entire plate full, you have to abide by the "minimum layer time" necessary for plastic to cool down, so at that point it starts to not matter how fast you can go, only how effectively you can cool, and with really fast head motions it becomes very hard to cool the plastic if the head (with fan attached) is moving so quickly. Thus that puts a cap on your speed.

So it seems that the next breakthroughs in speed are going to come in the form of better cooling. And all this talk of "my printer can go faster than yours" is really meaningless when you come to see that most people don't print plates full of mendel parts on their ultimakers.

[alaris2 1]

totally agree with you there Joergen - I don't think I have the option of changing speed of infill (unless Daid tells me otherwise?) but I intend to test grid infill and the print order.

and destroyer is very right about the cooling - it takes me 7 minutes to print a long thin cuboid with the largest face on the bed. but rotate it 90 degrees and it takes 1hr 15mins.

so has anyone had any clever ideas regarding the cooling? we discussed some of the pros and cons of current fan shroud designs in another thread i think..

[joergen 2]

totally agree with you there Joergen - I don't think I have the option of changing speed of infill (unless Daid tells me otherwise?) but I intend to test grid infill and the print order

no, that is one of the biggest shortcoming cura is facing at the moment: the lack of differentiated speeds. daid decided that for simplicity (which is really good in the beginning if you just want to get something printed), that one speed for everything is fine. after months of printing, and slicing, the requirements change, and more complex print jobs require more different speeds.

[Daid 306]

totally agree with you there Joergen - I don't think I have the option of changing speed of infill (unless Daid tells me otherwise?) but I intend to test grid infill and the print order

no, that is one of the biggest shortcoming cura is facing at the moment: the lack of differentiated speeds. daid decided that for simplicity (which is really good in the beginning if you just want to get something printed), that one speed for everything is fine. after months of printing, and slicing, the requirements change, and more complex print jobs require more different speeds.

One of the big problems with Skeinforge is that I cannot get it to differ between sparse and full infill. So infill speed will adjust both.

In the good news department, I'm working on realtime-tuning, where you can adjust the speed of moves/perimeter/loops and infill independently during printing, without affecting the rest.

[joergen 2]

One of the big problems with Skeinforge is that I cannot get it to differ between sparse and full infill. So infill speed will adjust both.

In the good news department, I'm working on realtime-tuning, where you can adjust the speed of moves/perimeter/loops and infill independently during printing, without affecting the rest.

I love good news. does this mean we will have the option to set different speeds for perimeter/loop/infill sometime in the future?

[alaris2 1]

just for the record.. I tried using grid infill to see if it would improve matters. it does, but not enough. top surfaces are still very rough. I'll drop back to 120mm/s for the time being which seems to be the most before this effect kicks in.

[rewolff 0]

I love good news. does this mean we will have the option to set different speeds for perimeter/loop/infill sometime in the future?

I'm from the future. We can do this now. :-)

(Get the latest cura from github and it's included. Daid wrote something about him not having tested it, but I have.)

[alaris2 1]

whoa! you just like totally changed the past now man! groovy..

[Daid 306]

(Get the latest cura from github and it's included. Daid wrote something about him not having tested it, but I have.)

Most things related to printing directly from within Cura are not tested when I add them, because I always print with SD. So I have to setup my laptop specially to test those things.

I do test everything before I release a new stable version. I do not want to risk a "stable" release with critical bugs.