Print Quality issues (pictures)

[JohnnyV]

I have two other issues/questions:
1. One of the things I notice with rafting and supports is that my bottom layers (or underside of the build object) aren't anywhere near as clean as the top and sides. What is that an indicator of?

2. I'm not sure how to resolve that, either. So for clarification as to my parts not fitting - when I print shells - do those count against my tolerances - if so how much? IE, if I print a 2mm radius circle cutout, will a 1.99mm object fit into that? How do I know how much room to give the build so the objects freely fit inside?

For 1, The part in contact with the raft will never look like the other surfaces. The bottom slightly fuses with the raft layer, so there will be some defects when you pull away the raft. The look can be improved, but only to a point. You can tweak the raft setting in S3D. My settings for Inland ABS are:
Raft layers 2.
Offset from part 2mm - how far from the each of your part the raft extends (I'm thinking about bumping this to 2.5 or 3 because I've been getting some curling).
Separation distance of 0.2mm. This is how close the part is to the raft - higher values will have less impact on the look of the finished part. Make it too high and the part won't stick to the raft.
Raft infill of 70%, lower values make the raft easier to remove but can affect the look negatively.

For 2, it kind of depends. This will vary a bit from printer to printer and how well it is calibrated.
Instead of drilling and tapping holes, you may want to consider knurled inserts, (sometimes called "press fit expansion inserts"). These are metal inserts you just press into the part, you can then use a machine screw into the insert. They are more forgiving on hole tolerances. I've used them on several models and they work great and look more professional.

http://www.mcmaster.com/#inserts-for...3bm0xfifmietqj

[jfkansas]

For 1, The part in contact with the raft will never look like the other surfaces. The bottom slightly fuses with the raft layer, so there will be some defects when you pull away the raft. The look can be improved, but only to a point. You can tweak the raft setting in S3D. My settings for Inland ABS are:
Raft layers 2.
Offset from part 2mm - how far from the each of your part the raft extends (I'm thinking about bumping this to 2.5 or 3 because I've been getting some curling).
Separation distance of 0.2mm. This is how close the part is to the raft - higher values will have less impact on the look of the finished part. Make it too high and the part won't stick to the raft.
Raft infill of 70%, lower values make the raft easier to remove but can affect the look negatively.

For 2, it kind of depends. This will vary a bit from printer to printer and how well it is calibrated.
Instead of drilling and tapping holes, you may want to consider knurled inserts, (sometimes called "press fit expansion inserts"). These are metal inserts you just press into the part, you can then use a machine screw into the insert. They are more forgiving on hole tolerances. I've used them on several models and they work great and look more professional.

http://www.mcmaster.com/#inserts-for...3bm0xfifmietqj

Rafts shouldn't even be in an experienced 3d printer user's vocabulary...

+1 on the threaded brass inserts, they are nice if ultimate strength is needed. For me generally either there isn't enough room for an insert or threading into plastic is good enough.

[JohnnyV]

Rafts shouldn't even be in an experienced 3d printer user's vocabulary...

This is a matter of opinion. Rafts have their place and benefit. I've worked for a professional rapid prototyping firm in the past using extremely expensive Stratasys machines with amazing engineers. You'd be surprised how often a raft is used. If you want the best quality and accuracy, rafts are the an excellent starting point.

Don't be so narrow minded.

[jfkansas]

No rafts are just a crutch for bad leveling and poor bed adhesion. They aren't needed if an operator knows what they are doing.

[JohnnyV]

No rafts are just a crutch for bad leveling and poor bed adhesion. They aren't needed if an operator knows what they are doing.

If you are such an amazing operator, please enlighten us and help improve our prints, rather than just making opinionated statements and not backing them up with fact and help for the opening poster.

I have made high quality prints for NASA, the US Air Force, and the Navy. I am a very experienced "operator".

Hairspray, glue sticks, and ABS slurry may work for for you, but I prefer to not mess with them. They are messy, flaky, and a pain in the but to clean up. I prefer rafts - just level your bed and go.

not-sure-if-troll.jpg

[jfkansas]

I doubt Nasa and the military use a $700 printer... ABS slurry cleans up easily off of Glass. Just scrap off with a single edge razor blade and vacuum up the flakes. In some ways ABS slurry is kind of like a raft, just thinner and already stuck to the bed. ABS slurry when done right fuses with the part and makes a near perfect surface. When cooled it usually just pops off the plate. Rafts don't adhere nearly as well to the part since there is a gap and less material in contact with the part. Warp city usually results when printing parts with large flat bottoms.

[JohnnyV]

I doubt Nasa and the military use a $700 printer...

You're right. We used a $100,000 Stratasys machine.

Rafts don't adhere nearly as well to the part since there is a gap and less material in contact with the part. Warp city usually results when printing parts with large flat bottoms.

I use rafts so stop warping. Maybe you're doing it wrong.

[jfkansas]

Exactly, and I am sure it did everything automatically except for making you a sammich.

The cheap machines take a little know how. Set up profiles, measuring/calibrating filaments, bed adhesion techniques, etc.

[JohnnyV]

Exactly, and I am sure it did everything automatically except for making you a sammich.

Hahah. I wish it was that easy. It may be that way now (i'm not sure), but I was using them 10-14 years ago when it was still young. You actually had to know a lot more back then, than you do now. You could always print a sammich.

The cheap machines take a little know how. Set up profiles, measuring/calibrating filaments, bed adhesion techniques, etc.

All machines take setup and know how, even the super expensive ones.

My point is that for some people/machines rafts are the preferred method. Don't discount them just because you don't like them.

[jfkansas]

Hahah. I wish it was that easy. It may be that way now (i'm not sure), but I was using them 10-14 years ago when it was still young. You actually had to know a lot more back then, than you do now. You could always print a sammich.



All machines take setup and know how, even the super expensive ones.

My point is that for some people/machines rafts are the preferred method. Don't discount them just because you don't like them.

It's not that I don't like them, they just aren't needed. Really just a waste of time and filament. New users for some reason get it in their brain that a raft is needed. Maybe it's because the models on the stock SD card have rafts. So they think well that one had a raft, I guess I always need one... So they go down that path and don't explore other options and methods.

Ya 10-15 years ago not many even knew 3D printing existed, heck probably could say the same thing 5 years ago. It's come a long ways. I have heard a lot of people talk bad about Stratasys and 3Dsystems, but you gotta give them some respect in inventing some of this tech in the first place. Cool stuff for sure. I imagine some of their early contraptions weren't as pretty as they are today.