ABS brittle etc???

[dunginhawk]

I dont mind printing on a raft per sae. I just want to make sure i dont have artifacting as this is a customer print.
Also, i dont have any really good raft settings... so ill have to figure that out
so why would a raft not curl, but a part will?

[JFettig]

Its likely because the material can shrink on top of a raft and can't on the print bed.

The raft has thick spread out layers that don't have much area to pull on.

Bottom of the part should be about 1/2 layer above the raft, 75-80% infill on top of the raft. What slicer do you use?

[dunginhawk]

these are kind of the default settings for simplify 3d

[img]http://i1132.photobucket.com/albums/m562/dunginhawk/Capturedfd_zps6d3a8fce.jpg[/img]

[JFettig]

S3D really effed the pooch on the latest version raft settings. They made it "easier" to remove the part by adding a layer of separation. I have been making custom rafts until they fix it.

[dunginhawk]

what is wrong with making it easier to remove the part? does the part show evidence of quality control on the bottom "real" layer?

[dunginhawk]

so im attempting a raft print with those settings.. layers going down nicely... i guess ill see how it looks

[JFettig]

Sorry for the late reply - my phone didn't post the message.

The first layer with the latest version of S3D won't stick at all to the raft, it'll just noodle all over. Previous versions it was fine.

[dunginhawk]

i did notice it was a little less smooshed... i just quickly adjusted my bed and got pretty good adhesion.
one corner did peel up, but i just put a dab of abs glue there, and held it... for not its staying.

[dunginhawk]

you are totally right, after 3-4 layers the whole thing peeled up...
so with s3d how are you creating your own custom rafts? brims were easy, rafts, not sure how to handle that.
thanks

[JFettig]

I design my parts in SolidWorks - I'll design a raft that sits below it that is roughly 1/8" larger on every side and .875mm thick(for .25mm thick layers) then I print 80% infill with no top or bottom layers, first layer 150% wide and thick. I then set the height of the part I'm printing on top at 1mm so it leaves a .125mm gap between the two and it has worked great every time! Last time I added 1mm to the raft for a 25 hour print and it did well. Doing this, I can put holes in the raft if there is a big open space in the middle.

[JFettig]

Here is the first one I tested. remove the .pdf extension, its just a S3D factory file.

[dunginhawk]

thank you

[dunginhawk]

So this is all under the assumption that your bed is perfecly level, and that your z height is calibrated to leave that perfect gap in the print right? Im hoping that im that accurate im trying this now haha

[dunginhawk]

my 80% infill raft ended up looking like 100% fill amazing layers, but not 80% haha... wonder if i should try to print on it anyway

EDIT - upon closer inspection it looks about 80% infill, so it layed down great.

can PLA used if the temp of the environment may reach 120 degrees F?
Also, is it true that PLA degrades after 1-2 years?

[dunginhawk]

about 1/3 of the way through the print and it appears as though the make your own raft is working... ive said that before though
if any part can pull this raft up , its this one haha.
If it prints successfully, next step is separating from the raft... im curious as to how that will go.

[dunginhawk]

so its just finishing up.. that same corner as always (the one that always pulls more than the rest) came up a little bit. early indications are the other corners stayed put.
Ill have to pull it off the bed here when it finishes...


EDIT : So its finished and 1 corner pulled up slightly, but its still be far the best print (from a curling standpoint) that ive gotten from this model.. its very very good. Im not sure what i can do to prevent that corner from coming up, perhaps i should to push the model back on the bed as far as I can . i dont know..

[drwho]

@dunginhawk I wast having the same issues with printing taller ABS prints. It turned out that the reason for the splitting was the uneven rate of cooling. I agree with the other guys on here that slower is better, and that is what I do what something is acting up, or Im printing a finished product. However, I never did slow very well. I have found some points that may be good things to try. But keep in mind that if you drive it like a race car you have to maintain it like a race car, ie constant maintenance. For example in the last 24 hours I spent over 4 hours just tuning tower height, because at speed everything is amplified. All those that want to go fast keep that in mind.

The bigger the print in ABS the more opportunity it has to split, the speed didn't seem to affect that for me. I do live in the Pacific Northwest, so it is cold and wet most of the year. If a draft from opening a door got to a print it be guaranteed to split. I have been working on a case for the printer because I want to utilize the full print bed in ABS. I currently use a cardboard box to wrap the printer that is held in with binder clips. This is temporary until all the part are printed to install the poly-carbonate that should be going in this spring. I have switched to acetone/ABS slurry over kapton tape for adhesion for the really big parts but all the smaller things held fine with purple glue. The case has been a huge help to me in the ABS side of the house. I have done PLA as well and it is much less finicky than ABS. Also no case for PLA.

I run between 90-120 mm/s with ABS when Im prototyping. The finished product looks much nicer at 60 mm/s

I am nearing my 100 hour mark of printing things and have so much more to learn. Learning is half the fun. Keep experimenting and sharing your results. Good luck.

[dunginhawk]

Yeah I'm not prototyping anywhere near that fast.. my finished product is around 50-65mm/s
I am not seeing much cracking anymore so I may have that issue nipped with lowering the bed temp a bit to keep the temp more consistent rather than so variable from bottom to top.

Hoping I have my curling in the corner issue resolved by custom made brims that are .5mm tall about 15mm out each side.. 1 layer didn't keep it from pulling up the corner (of the print, not the brim), but 2 thicker layers seems to have done the trick

[drwho]

Well Im glad to see that you have found a way that works for you. That is truly the goal. If it works for you share that so that someone else may benefit from the information.

[dunginhawk]

well it was more or less in my last post.

bed temp at 100, and a 2 layer 15 loop customer brim (not the brim feature).
no more curling.