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grue

is this a good first layer?

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hi.  i just got done with a 47hr print which has a similar 1st layer to the one i'm showing here. the previous model was pretty stringy, the 1st layer is somewhat uneven feeling on the bottom, but other than that it's printed fairly well for 47hrs!

 

so this is another component of the 47hr print, the attached picture is of the first layer.  it's about 5in x 5in square.

 

i have glue stick on the bed. the glue stick is probably just too uneven. bed temp 60 nozzle temp 200.  i tried changing the nozzle temp to 195, the many of the lines did not connect! so i went back up to 200 for the attached image 1st layer.

 

i went through the level procedure 3 times (4 corners and center with a piece of paper). that needed to be done for sure (amazing how it changes from print to print). this image is after it's been re-leveled.

 

however, even with re-leveling this 1st layer is similar to the other 47hr print 1st layer. i'll have to wait and see how this turns out though to know if it is as uneven as the 47hr print.

 

its funny how these patterns seem geometric like.  also, there is a very fine diagonal hair which is showing up in the first layer.  so all the patterns seem like something might be pushing up from underneath.

 

anyway does this look OK for a 1st layer of this size 5in x 5in?  thanks!

ps print speed is 40mm. it's a creality cr10s printer.

 

 

20180217_180316 sm.jpg

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attached is a pic of the finished 1st layer and it's laying down the 2nd layer, which despite this pic, looks a bit smoother.  there will be several layers.  so maybe it just evens out.  this is only about a 7hr print.  it's basically a thin box with 2 other smaller but taller boxes on top of it, one on front half and one on back half.

20180217_182640 sm.jpg

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Yes it can, indeed should, be better. Some things to do are; reduce your 1st layer print speed, i.e. walls and infill, to 20mm/s; use .300 layer height for you 1st layer. Yes you can use a thinner 1st layer but the thinner you go the more difficult it is to get good adherence. Also a thicker layer will do a better job of overcoming imperfections in your glass plate.

 

I would suggest you do some testing with a small simple cube, say 20*20*1.2 rather than a 47 hr print! Firstly you want to get your extruder temp right so you are not under/over extruding. Also maybe you need to practice a bit with your glue stick? Have you done previous prints where your 1st layer was better? If so think about what is different between then and now.

I assume from your bed temp that you are using PLA; is that white? Not the best colour for getting great prints from; maybe you have another colour you can try. Is it from a reputable supplier? Cheap filament is cheap because it is not as good.

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thats a great idea! i didnt know i could do that really, change the first layer height to be thick. my current layer setting is .12.

 

pictured is silver hatchbox 1.75mm pla. why do i hear that lately, that white is no good for anything? ha.  i just ordered some white verbatim pla purely on company reputation and affiliation with mitsubishi chemical. im willing to bet it is top notch quality and consistency. some utubes i have seen bare that out except for thier first gen stuff.

 

edit - the 47hr print was kicked off based on a previous print that looked fairly good so no reason reason to wory. i wonder if bed leveling was more of an issue. maybe glue stick is old now too?

 

Edited by grue

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doh! so thats what that setting is right under layer height.  i was thinking it just built up the .12mm layer until it got to the height i entered.  so if i entered .24mm initial, i thought it would lay down 2 .12mm layers.  it actually puts down 1 layer that is .24mm?

 

thanks

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Lol, yes that is probably your problem, at least it will not help. The first layer is printed as 1 layer at the height you specify and all subsequent layers are printed at the generic layer height you specified. 

 

You will always get a difference in the printing quality of different coloured filament because the dyes react differently with the PLA - that may not be an entirely scientifically accurate statement! I have had trouble with some whites and I have seen others, more experienced/knowledgeable than I, make similar comments. Having said that these days I use Faberdashery's Arctic white which is great for me.  Probably if they released an Antarctic white that might be problematical!

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cool.  ok for color got it, makes sense but i thought there was some special case with white the way i've read about it ha. learning quirks for different things in printing!  consistency will be the key in terms of filament i'll bet.  we'll see how the verbatim goes.

 

one last quick question, does cura raise the z-axis depending on the height of the first layer and subsequent layers?  it must huh otherwise the nozzle would be digging into the pla it's laying down.  so it can compensate for the whole build - it might be .4mm thick on the first layer but then it says i can skip 3 layers .1 layers overall becasue we doubled or tripled up on the first?

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You can breakout the first layer and “bottom”

layers (lowest vertical surfaces of the skin) to allow you to tweak just that distance and also the bed temp, active cooling, and extruder temp, depending on how machine is configured. My advice tends to be to raise bed temp a touch and make sure to get height right, but to be honest, i usually find my bed calibration isn’t true, my plate wasn’t clean, i wasn’t getting even heat transmission from my hbp (dust/glue etc between plate and hbp), or my extruder has muck on it when i’m tearing up first layers. I say that, but i think i just tend to reload material, reset bed, and bruteforce test it until i get good firat layers, as what is going on is very printer and material specific. If those bottom layers stick like they appear to, though, you can just up the number if bottom skin layer count (which are solid instead of sparse layers) so that stuff irons over and self corrects before you really get into sparse infill above.

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3 hours ago, grue said:

...

 

one last quick question, does cura raise the z-axis depending on the height of the first layer and subsequent layers?  it must huh otherwise the nozzle would be digging into the pla it's laying down.  so it can compensate for the whole build - it might be .4mm thick on the first layer but then it says i can skip 3 layers .1 layers overall becasue we doubled or tripled up on the first?

Question 1 Yes that is how it works although it lowers the build plate it does not raise it, unless oyu have a weird printer that woks the other way :). Question2. No not really. You have two settings; "Layer height" and "first layer height". The first setting is the layer height which is the layer height you want to print your model with. The second setting is an exception and only applies to layer 1. When printing layer the first layer Cura moves the bed down by the distance in the second setting. When printing layer 2 and all subsequent layers it moves the bed down by the distance in the first setting; there is no reference to or any calculation based on the height of the first layer.

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thanks everyone.  so that goofy looking patterned layer print failed. lots of stringy gooey goodness.  i was away from it for several hours, 4 maybe.  ugh.  i whipped off that mirror, got a new mirror and put it on the bed. leveled and it was great leveling it until i heated up the hotend and bed. then, like the first mirror, it was cupped in the center.  when cold, it was perfect!  so, this AM i went and got tinfoil and stacked up several layers of 6x6" or 5x4" squares of it in the middle of the bed under the mirror.  it was back to "perfect". this time thoug, i'm not using glue stick. i sprayed on 2-4ish layers of hairspray so ugh!!

 

also i took the advice and printed some test squares, 9 of them, see attached (wow nice like 8mins to print the squares so much nicer for testing!).  also attached is in progress of the crazy patterned print fingers crossed!  the other thing on this reprint is that i'm using a lot more "draft" settings, but keeping speed down to the 40mm/s.  although my infill seems to print a lot faster than 40mm/s?

 

anwway so far so good, 2hrs into the reprint.  i'll have to read up on more sticky type stuff for the bed. like how to do an even coat of gluestick oor maybe i can order some spray on stuff or try another brand of hairspray.  right now using suave extreme hold ha.

tin-foil-squares-test.jpg

failed roof print and geo patterning-sm.jpg

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I agree with @mattgriffin totally. As long as you are printing your 1st layer at 0.3000 and with a bed temp. of, let us say, 60 or more, your problem will be external to Cura. Accuracy of bed level, cleanliness of bed surface, consistency of level of surface, e.g. no blobs of glue everywhere, correct/optimum surface to nozzle distance (termed z-gap in the Ulitmaker levelling procedure?).

 

Also, and this will vary with printers, e.g. on my printer the heater/sensor is located in the middle of the bed. When that reaches the temp. that I want to print at, the perimeters of the bed, i.e.outside of the central area, will be 10 degrees cooler. This is no problem for small items but for larger items such in architecture where a wall or a floor can extend to the extremes of the bed surface it equal disaster. I always measure my bed temp with an IR thermometer in these cases and wait maybe 15+ minutes for the touter areas to catch up.

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yeah, that seems to be catching me more and more - i keep looking at software settings instead of bed leveling or mechanical issues with the printer etc... i'm quickly learning to master that!  do test prints ha instead of testing on a big complicated print!  which i'm pretty amazed at how the last one turned out given i did nothing but hit print and try z-hop. ha! i'll attach.  right now you've all see pics of the "roof" i'm printing separately, i'll  attach the base.  it's bad, i know stringy like you can't believe, some details didn't print - the window lines, but most did so i'm happy enough :)  but next time will be better!  i'm slowly but surely assimilating all this info :)

 

PS - thanks everyone, this is a great forum, everyone very nice!

 

PPS - i'm experimenting with the infill stepping feature in one of these images.

20180218_130133.jpg

20180218_130829.jpg

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Great that you seemed to have cracked it :), even if maybe a little way to go. Hey money comes into this of course but why not just buy  a glass plate from your "local" 3D print supplier or visit  your local glazier and get them to cut a glass plate for you - need a discussion with them on how level the plate will be and its consistency across the plate. The latter is probably more important as a small slope can probably be addressed by the levelling procedure. But if it is working fine for you why change!

 

Re your question "I think that lines that do not connect or blend together means nozzle is too high?". Well yes but I am sure I have experienced the opposite where moving the nozzle away from the bed has fixed the problem. I am not sure on this, it is a long time since I have reset the distance and my memory is failing me. One of the two will fix it!

 

Using hairspray. Well I have only ever used hairspray, for 4+ years now, so I suppose I am a hairspray expert ':D not that there is much to be expert about.

 

The same with many things there are always alternatives to what I am about to say and some personal experimentation is always a good thing.

 

I use  L'Oréal Elnett Satin extra strength - it was recommend to me by my printer manufacturer and I have never flet the need to try something else.

 

Cleaning the plate. Go to a sink and hold the plate under running warm/hot water; using a clean J cloth wipe off the hairspray. You should find it bubbles up and leave the surface as you wipe. Dry the plate then spray onto the plate some Isopropyl alcohol and wipe over with another J cloth. Put the plate under the running water again and give it a good wipe to remove any alcohol residue. Dry the plate and warm it up in your printer to 60 or so. Remove the plate from the printer, you do not want any hairspray in there, and holding the plate about a foot or 30cm from the can spray on LIGHTLY a coat of hairspray. Wait about 20 secs and spray a second light coat on. Two coats is normally good for me although sometimes I have needed to remove the plate and spray on  another coat or two.

In my experience that should last you several weeks. When adhesion starts to falter just spray on another two coats. Repeat until the time comes when another good clean is needed; 6 months?

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Nice looking print, I see you are an architecture guy too:). I assume the inside is hollow which makes me think your furry strands could be due to the fans if you have dual extruders. One thing you can do to try and help is to print as cool (extruder) and as slow as possible. Use you little test plates, you will need them to be higher, say 10mm? and see how much lower you can go in temperature (using the print speed and layer height for your print) before you get under extrusion. I do not know how large the building is and can understand that going slower may be problematical in time. But dropping from 40 to 30 should help.

 

What is your retraction length and speed?

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yep architecture.  i got this as a hobby for myself and set it up at work because well, my hobby(s) are my work ha! if it works to do for clients then it's just a bonus!  yeah i read about test prints for extrusion  tests, temperature tests, all in one. little pyramids as i recall.  i will have to look those up again or make my own.  4 tall thin boxes shaped like pyramids.

 

it looks like i messed with some settings in my custom profile i saved with the cura project for the 4 walls and base, but retraction distance is 3mm (i think that was the default of 5), all of the retraction speed are set to 40mm/s.

 

i have enable retraction checked, combing off, retract at layer change unchecked.  also, i did mention i tried z-hop with this printing and i'm not sure that was a good thing.

 

EDIT: the dimensions of the building walls are ~5 1/2" w x ~5" deep x ~5" tall

Edited by grue
added info

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Ok you might want to experiment with a bit of tuning. My retraction distance for PLA is 5.5mm and the speed I am sure is 50mm/s. I also normally use a z seam alignment (or whatever it is called) of random and retract at layer change is on. About a year ago when I was trying Ngen I had a similar problem and found that experimenting with the retraction settings resolved it. I moved retraction distance up to 6.5 and made another change but off-hand cannot recall what it was.

 

As always everyone has differences and what works for one person may not work for another but I do suspect that if you make sure you are not printing hotter than you need to and you lengthen that retraction distance you may well see an improvement.

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yeah i think it makes a lot sense to start doing more calibration prints like you say start tuning.  i am getting some of the basics down now in terms of machine setup anf some basics in the prgram settings.  one thing i was just reading about on printed solid.com blog was corner quality and ringing. i am seeing a lot of rimging.  i know why it happens, just have to tackle the 30 different things that can cause it haha.  but yeah i should focus on temp, retractions, speed etc kind of low hanging fruit with test cubes and stuff.

 

ps print of the roof finished, looks pretty good!  i had to bolt right after it finished. will post tomorrow.

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There are a bunch of places where you can grab a borosilicate glass place that will remain flat at high heat from many suppliers, not just for 3D printing. Though there are plenty of off-brand suppliers that will offer you cheap borosilicate glass printing plates at the same or better that you can get from a local glazier! I would not just use any sort of glass, especially if you play with materials like PC or tough nylons that might bond to glass and break it! You'll cut yourself!

 

But that said, glad you are able to make progress and get some good prints off of there, though. Those projects are starting to look great!

 

One quick note re: hairspray. The reason people use cheap hairsprays like Acquanet is because ... it has a lot of PVA glue in it. Yep, this is glue for your hair -- which might explain why it is so aggressively effective at sticking things in place, and then washes away in the shower. Well, spray dispensing it is kinda handy (you need so little) until you start gumming up your drive rods over time. But what about a glue stick? Or grab a polyester sticker label or a piece of PEI material, and you'll be happier. Or BuildTak and its peers! I am no fan of hairspray these days, but the good news is that which "flavor" of PVA you use will probably work fine, as long as you don't pick one (like UHU gluesticks over time!) that crusts over between heating cycles, requiring you to clean the plate and re-apply. 

 

As for z-hop and cura ... well, it works in certain cases, but might not be doing what you assume for a z-hop. If you look at the paths in the layer viewer you may see some oddities in the paths that explain what happens with your actual print. If you just want clean top surfaces, look at the "ironing" features to do another pass with the nozzle at the end to rework the top surface and help eliminate some travel scars and other weirdness.

 

Matt 

Edited by mattgriffin

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thanks! ive read a little about pei, am i mistake or is it some type of flexible very thin overlay like a sticker?  id like to avoid stixk on type things especially tape.  the borosilicate glass seems lukje a great idea, id still have to have some type of tacky substance on it im guessing.  the main thing is that it is flat haha no tinfoil!  ill get around to orderinf one but will stick with what i have for now... which mean next week ill probably order so mething.

 

my hairspray doesnt seem that tacky when i touch it, but so far so good. ill see.  maybe that pei isnt what i think it is?

 

i did use uhu gluestick that we had ijn the office.  it seemed to work but it seems like it is so uneven in thickness so hairspray.... it all washes off well with dawn dishsoap!  aldo when i spray, i take the mirror off and put on the floor.

 

oh, i read about a firmware update for my printer that does 3d mapping of the bed.  it sounded like its supposed to let you print on uneven surfaces.  but still i seem to be in a good spot for now and im sure id still need something tacky.

 

oh and i did see a video where drops of windex helped separate parts from the plate. but so far ive had very little sticking issues.   i did have the little bechy boat fly across the room a few weeks agousing the uhu ha! 

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here's the final product. you can see some weirdness on the roof on the right box, i'm assuming those are seams, a blob and the top looks a little rougher in the middle than the ends.  the bottom and roof surface look pretty good though.  funny how the reflection changes on the big flat roof where the hvac and roof access boxes are, it's like a darker color.  i wonder if that's due to slight temperature fluctuations or maybe inconsistency in the filament?

 

i'll be doing some testing today for sure!  on little test cubes and such!

20180218_150750.jpg

20180218_150758.jpg

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