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SoliForum - 3D Printing Community → Solidoodle Discussion → When to use rafting?
I'm about to print out an iphone bike mount cover and this is the flattest , largest part i've printed so far. My concern is warping that will cause it to lift. I was wondering if this would be the type of print to use rafting? That also made me wonder, what is the type of print someone would use rafting?
I use raft always but for my SD2 I have found that I can only achieve 3.5" base before I begin experiencing warping at the edges WITH rafting. I have not modified my bed in any fashion.
I almost guarantee you this will lift. What is your bed set-up like? If you're using hairspray, it will help hold it down. If you're enclosed, it will help resist lift. Blue painters tape seems to encourage lift in my opinion. Raft will help, but only so much.
I almost guarantee you this will lift. What is your bed set-up like? If you're using hairspray, it will help hold it down. If you're enclosed, it will help resist lift. Blue painters tape seems to encourage lift in my opinion. Raft will help, but only so much.
stock SD3 table. It's leveled as best can be but it's warped as most of them are. I bumped my first layer up to 200%, I found on other large prints this help because i was pushing the first layer down so hard. I would like to use a good brim on it but since i have to use support, the brim is useless.
I have a cover that I just bought from pastprimitive but i haven't installed it yet. If not for my top load spool holder it would snap right on. I guess if the print fails i'll be doing my next mod, covers!
I'll let ya know how it goes.
ah.. so i just saw how to set my support threshold so that it only generates the support for the 90 degree overhang. that makes my brim useful again.
Charles, I am curious. If you slow down print speed to 3/4 or 1/2 would it help the part to cool as it goes, so the heated segment is always smaller, thus less able to lift? I seem to have better quality prints if I slow down a bit.
The print went very well. no lift using 6mm brim. What i did discover though was that my X and Y steps were off far enough that dimensionally, I was way off the design size. My Y length was supposed to be 130.5 but came out 133.55 and my X length was supposed to be 65.9 but came out 66.8. I made up a quick 100mm X 100mm test block to print out after i made the adjustments to the steps in the eeprom. I'm printing it now.
I also confirmed that i'm going to have to modify the design a bit as the top retainer clips broke off way to easy. I figured it would because of the layer pattern. This was primarily a test print for design verification any way.
I had a lift problem last night, my glass bed has made a big difference but the big and long piece I was printing has a spot that is just made to cause lift.
I'm going to rework my design a little to remove the tension at the ends hopefully I'll get a good result. Also going to try printing cooler so the temp differential isn't as high.
When I'm printing a giant piece I lay down the ABS glue. That's when things are getting serious 
. Can be a PITA to get it off the glass afterwards, but really resists lift.
ABS glue is a mixture of ABS and acetone. I use something like 60% acetone, 40% abs.
When you use the ABS glue at what stage do you apply it? When the glass is already hot? or before it heats up? Acetone evaporates so quickly I'm finding it hard to see how this would bond.
Just to be pedantic, the ABS+Acetone mixture is colloquially referred to as a Slurry.. and whilst it 'glues' ABS, its technically not a glue but rather liquified ABS that then has the acetone evaporate out of it thus re solidifying it.
"Actual" ABS (or PVC or other Styrenes) Glue is like this one: http://www.3dprintergear.com.au/Tetra_A … /tetra.htm .. Which works on the same principles as the acetone+abs mix (instead it relies on the parts to donate the ABS rather than pre-mixing it), but is actually what is sold to you if you went to an industrial supply shop and asked for 'ABS Glue'
</end pedant-ism> 
Just to be pedantic, the ABS+Acetone mixture is colloquially referred to as a Slurry.. and whilst it 'glues' ABS, its technically not a glue but rather liquified ABS that then has the acetone evaporate out of it thus re solidifying it.
"Actual" ABS (or PVC or other Styrenes) Glue is like this one: http://www.3dprintergear.com.au/Tetra_A … /tetra.htm .. Which works on the same principles as the acetone+abs mix (instead it relies on the parts to donate the ABS rather than pre-mixing it), but is actually what is sold to you if you went to an industrial supply shop and asked for 'ABS Glue'
</end pedant-ism>
I love kemistry. Post like this make me fill more smarter!
I love kemistry. Post like this make me fill more smarter!
You leave my written on a mobile posts alone!
Wish some pedant would answer the question though!
Wish some pedant would answer the question though!
Use a brim when you have a reasonable amount of points of contact relative to the size of the object - such as large rectangles where the disproportionate cooling of edges to centre of the print will encourage lifting. A raft may help but will leave a lower quality surface to which it is attached.
Use a raft when you have an item with a minimal set of points of contact with the bed, particularly when relative to its size and therefore adding a brim will not help relative to the object size. For example, if printing a table 'the right way up', then a raft would help dramatically compared to brim due to only holding the bed through the 4 legs vs when the 'top' is printed (ignoring the bridging challenges with this scenario 
). Or the Linux Penguin on thingiverse that doesn't sit flat properly and is instead cocked on one leg...
But thats just my opinion based on what I've printed...
For answering how to use the, ahem, slurry [which might be better names as a liquified smoothie, because slurry implies solid particles, you are ok if the acetone in the mixture evaporated. I haven't had problems applying the acetone to a hot bed, except you risk cracking your glass, and it develops bubbles that the extruder head has to pass through. I think usually I feel most comfortable applying a thin films while the glass is soft. The acetone will evaporate and leave behind some super well stuck abs, which your printer than prints to.
On an insanely more wasteful scale, industrial printers sometimes do this. they print on a disposable ABS tray about 1CM thick.
For answering how to use the, ahem, slurry.
I did say it was what its colloquially referred to - not what it was specifically in terms of a substance.. and I was trying to be helpful to prevent people talking about Apples when they really mean Bannanas... because the ABS+Acetone concoction is not the same thing as actual ABS Glue. But if you feel it should instead be called "Steve" or something - go for it... But if you look on RepRap forums or Printrbot forums.. you will see many many references to ABS Slurry/Paste.... but the ones to Glue are usually in specific reference to 'actual' adhesive solvents...
If trying to make sure you are on the same page with regard to taxonomy within the community caused some sort of offence... my apologies for trying to assist the thread with getting external or alternative information using the appropriate keywords and everyone should feel free to keep seeking info on Bannanas using 'Apples' as the search word - Or "Steve" if thats what you prefer it to be called And I'll refrain from trying to assist people to search for the right information at the right time since it seems to cause offense to people... despite trying to be a clear smart alec/jovial in my first statements
mwhahahaha
I feel chastised for using the 'glue' word!
In future I shall call the Acetone+ABS mix a banana... or was that an apple? Dammit, let it be a slurry and be done with it.
and thankyou Adrian for answering my question. I have some ABS dissolving in acetone at home, a good use for a lot of brim scrap, and I will try that tonight with my more difficult print.
Came home hoping to have a nice 'slurry' to try out, and instead I have a big bubblegum like blob of ABS at the bottom of the jar and pure clean Acetone on top. It started out as lots of fine scrap from brims etc. Is this normal?
Do I need to leave it longer? Or is my ABS weird?
Came home hoping to have a nice 'slurry' to try out, and instead I have a big bubblegum like blob of ABS at the bottom of the jar and pure clean Acetone on top. It started out as lots of fine scrap from brims etc. Is this normal?
Do I need to leave it longer? Or is my ABS weird?
shake it up. it should mix
Takes a few shakes. I have a tiny pinprick hole in my jar because pressure can build up and make it hard to open. Not all jars have this problem (like certain latches don't have that problem, this is an old pickled mushrooms jar from the polish store. )
I made a 7" piece the other day (slanted) with acetone slurry. Almost no warping, and the piece was a warpy kind of piece.
That said, I also broke my 2mm glass getting the piece off [i kind of expected that & wasn't careful enough.]
Thanks guys, I've given it a lot of shaking, but I'll leave it another day or so. perhaps I put in too much ABS? It's a pasta sauce jar and the ABS blob in the bottom is almost an inch high, and it is half full of perfectly clear acetone.
Thanks guys, I've given it a lot of shaking, but I'll leave it another day or so. perhaps I put in too much ABS? It's a pasta sauce jar and the ABS blob in the bottom is almost an inch high, and it is half full of perfectly clear acetone.
Doesn't sound like too much.
Worth asking- is this pure acetone, or 70% acetone? I have never tried the lower percentage stuff, just use industrial acetone which I think is fairly pure.
But what you buy for removing nail polish and so forth is often <100%
It's supposedly pure acetone from the hardware store. I'm wondering about the ABS.. I read somewhere that not all ABS is the same (not really ABS?) and some wont dissolve properly in Acetone.
Gomisan wrote:Thanks guys, I've given it a lot of shaking, but I'll leave it another day or so. perhaps I put in too much ABS? It's a pasta sauce jar and the ABS blob in the bottom is almost an inch high, and it is half full of perfectly clear acetone.
Doesn't sound like too much.
Worth asking- is this pure acetone, or 70% acetone? I have never tried the lower percentage stuff, just use industrial acetone which I think is fairly pure.
But what you buy for removing nail polish and so forth is often <100%
It takes time for it to dissolve.
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