Shifted ribs in mirrored housing parts

[hugosmid 0]

Hi,

As I am really new to this form and Ultimaker in specific, I'm doing the wrong things with a good tool.

We started to work with Ultimaker only 2 days ago and we encounter problems as you can see in our gallery.

Poor wall quality in a 2mm wall thickness product.

Poor outside surface quality.

Shifted ribs on the inside (though we're talking ga mirrored product here!)

Bridging in the top of the housing parts is not looking good either.

Am I overlooking the possibility to tune the area where bridging takes place?

Please be so kind as to have a look at the settings we used and the very first printing results of my life I was able to generate.

On print start-up I pressed TUNE and changed fan speed to 100%, Bed temperature to 60°C and nozzle temp to 200°C.

Where can we improve?

Thanks!

 

[dkaygee 0]

I assume by the temp that you're printing PLA? Myself, I get these thick bands when I try to print too cold. You could try increasing the temp. The temp is different with every brand of plastic and your own printing environment (ambient temp) and for me I have to test different temps whenever I get a new shipment of plastic. Have you tried the default Cura settings on a sample? It's a good base to start with. I think also I would increase your Bottom/Top thickness to like .8 or 1.0 and reduce your layer height to .1 I'm not a guru, but lately these things have been plaguing me as well.

 

[dkaygee 0]

The infill at 100% might be causing some warping. You could lower that significantly unless there's a reason it's so thick.

 

[hugosmid 0]

Thanks Dkaygee!

All feedforward is very much appreciated as we're absolute new bees...

H.

 

[gr5 2,265]

Well...

You have to first understand that FDM printers don't do so well printing in thin air, right? So the underside surfaces (except where touching the glass) doesn't look so good. It looks a little spaghetti - like. This is normal and most printers can't print *anything* in thin air so this is pretty darn good for surfaces with no support. Some of the surfaces have partial support and they look a bit better.

But do you care really about the quality of the inside? I assume not so much.

Regarding outside surface quality - you are doing .15mm layers with 50mm/sec and a .4mm nozzle. Multiply those 3 numbers together (I don't even need a calculator!) and I get 3mm^3/sec volume of PLA. This is difficult at 200C. I would recommend slowing down to 30mm.

You could improve the outside surface quality by *only* raising the temp to 220C but you will get even better quality if you are patient by lowering the speed to 30mm/sec instead. And consider .1mm layers which is significantly thinner.

The problem with printing 3mm^3/sec at 200C is that plastic is very thick at 200C (more like toothpaste than honey) and it takes quite a bit of pressure in the nozzle to get it to come out that fast but everytime the printer slows down or speeds up the mechanical springiness of the bowden keeps up the pressure and it over extrudes when slowing down and underextrudes while speeding up. People have tried to model this and compensate but the problem is it varies significantly with temperature and individual printer and PLA additives (especially different color PLA).

Obviously you are probably now realizing that there is a tradeoff between speed and quality. Going to .1mm layers will increase print time by about 50%. Going to 30mm/sec will increase by another 66%.

 

[gr5 2,265]

Shifted ribs on the inside (though we're talking ga mirrored product here!)

 

Well...

The ribs touching the glass should match up perfectly. I mean within .1mm which is thickness of paper. Or better.

If not then they weren't sticking to the glass well enough. Or they moved after removing form the glass. Don't use "raft" for a part like this.

To get it to stick to the glass better, 60C is fine (anything from 40C and hotter is fine for improving stickiness to bed so 40C is fine but 60C is better for other reasons). Also use some of that glue stick. Consider spreading it with a wet paper towel very thin with water. But just glue stick alone is usually quite excellent. The "BRIM" feature in Cura also helps it stick. I see you used that - did it add brim to the "ribs" where they touched the glass?

Maybe the first layer wasn't good? Did all the ribs stick and it warped after lifting?

You want the first layer squished a bit - the individual brim lines should be touching - no air gaps. So that's a possible source of having the ribs not stick to the glass.

If the problem is the ribs warp *after* removing from the bed I'm not sure what to do about that - a heated chamber perhaps.

Any ribs that didn't quite meet the glass probably need to have support added in CAD to keep them in place until the print is done.

 

[gr5 2,265]

It looks like the power connector for my volt when I plug it in. Be aware that parts printed with PLA can not handle the heat of a hot car in the summer - PLA is great for outdoor use all year. But not for going inside a car - for that you need ABS.

 

[hugosmid 0]

@gr5: thanks for your prompt reply, I'm sure it'll help me a lot!

Let's rebuild it!

H.