I am in need of some advice

[karl112 0]

Hello there...

got an Ultimaker 2 last week and have been playing nonstop since then.

My first prints were the little robots which turned out not so well.

The main problem seemed to be to get the very first layer to the glass and prevent it from warping.

I reduced the bed temperature from 75 °C to 60°C and turned on the fan to a 100% at all times.

I also started to experiment with the brim and with reduced extrusion temperatures of 200 °C instead of 210 °C.

The picture shows my last attempt. After six or seven hours something must have happened. I did not see it myself as it actually took place but I am guessing the parts lost their adhesion to the glass plate and got shifted by the extruder ?

Does anyony have the same problems ? Could anyone solve that problem ?

Kind regards,

Karl

 

[jonnybischof 60]

Welcome to the community!!

Usually, printing the first layer works best with the fan off.

After that, you shouldn't crank up the fan from 0% to 100% in an instant as that may "shock" the plastic and make it warp right off the platform.

But that depends heavily on the material / brand / production batch..

As for good fan settings, someone else should answer as I only have an UM1 with different fan setup.

 

[yellowshark 153]

Ok reducing the bed temp was a smart move. Are you applying anything to the glass bed to improve adhesion? There are a variety of favourites noted on the Forum. Personally I use hairspray; extra strength using two light coats with about 20 secs in between. This may well last you several days before reapplying.

It would be useful to know your layer depth for 1^st layer and subsequent layers and also the print speed you are using for 1st layer and subsequent layers – I suspect 200c may be a bit low for the 1^st layer but without the information it is impossible to really know.

Looking at your pic it may well be that you have the fans OK – come back to that.

I see you are printing multiples. I suggest you move them away from each other, towards the corners of the bed. This will help you identify any issues with the bed levelling.

A brim will help. Personally I use between 10 and 20 loops.

I would suggest you

Get your temps/speeds/layer depth right

Try with and without brim (unless you are happy with brim in which case just use it. With some pieces I try and avoid brim, but I do use it a lot).

Make sure the bed level is OK

Experiment with the fan; i.e. slow down its application until you see adverse effects. With overhangs at the bottom as you have it can be beneficial to load up the fan immediately after layer 1 and go real slow, although yours are not that severe.

 

Your most recent problem; yes one of the models might have lost adhesion, or one might have got a blob or build up of filament on one of the corners that the nozzle hit during movement.

 

[SandervG 1,521]

I see you are printing with PLA.

With PLA you do not necessarily need glue or hairspray.

What you need is a bedtemp of 65-75º, printing temp of 220º and a speed of approx 30mm/s

If your print got detached from the platform, another reason can be that perhaps your first layer was just too far off the bed. Can you take a picture of your first layer?

Can you re-level your bed and try to put it just a little bit closer to the print head?

 

[Dim3nsioneer 557]

For giving a little help what the lines of your first layer should look like:

It's actually 'only' a brim but shows the perfect bed levelling.

 

[braddock 1]

Hey Sander, I'm finding glue is actually pretty important even for PLA with the colorfabb filaments. I had loose prints several times without glue, but never with glue.

 

 

I see you are printing with PLA.

With PLA you do not necessarily need glue or hairspray.

What you need is a bedtemp of 65-75º, printing temp of 220º and a speed of approx 30mm/s

If your print got detached from the platform, another reason can be that perhaps your first layer was just too far off the bed. Can you take a picture of your first layer?

Can you re-level your bed and try to put it just a little bit closer to the print head?

 

[anon4321 16]

I agree with Sander. I use 70 and 220 and for things that have a small footprint and so a small surface to stick to the bed, use a brim. I usually reduce the bed temp to 55 after the first layer.

I recommend you try those but the other thing is you need to get the bed level and the right distance away.

 

[gr5 2,172]

Quick answer: use that glue stick.

Yikes - conflicting advice about brim and temperatures.

 

With some pieces I try and avoid brim, but I do use it a lot).

 

Yes but if the problem is that the parts won't stick then brim helps a lot. Don't stop brim if parts aren't sticking.

I agree that this looks like your parts came loose. Looking at the photo I don't see any glue so try that glue stick that came with the UM2. Try to do a thin coat over the area where the parts will be. Print at any temp from 40C and hotter to get good stickiness. The problem with going over 65C is you start to get bad quality on the lower levels so I only recommend that if you have warping issues. Which you might.

Printing at 200C and fan on 100% on first layer is not good. That first layer is critical to get good flow into cracks and a good seal on the glass. 100% fan on second layer is okay but it will lower the nozzle temp significantly. Instead try 230C nozzle, 0% fan on first layer and you can lower to 200C on second layer if you really must. Then you are probably fine to jump to 100% on second layer but I let cura handle this and raise it gradually until 1mm off bed (this is a cura setting).

I'm usually pretty happy with nozzle at 220C, bed at 60C for entire print. If the brand of PLA I am using is making lots of strings then I lower to possibly even 180C but 200C is usually low enough.

 

[gr5 2,172]

By the way, there are special cases where you need a minimum of 75C on the bed - if you want to print a huge square thing that takes up the whole bed for example.

 

[gr5 2,172]

Brim porn! That's a sexy, perfect, brim!

 

[karl112 0]

Hello there....!

many many thanks for all your tips and really good advice.

I turned off the fan for the first layer which is 0,3 mm at 20 mm/s.

The bed temperature was raised from 60 °C to 70° C and the extruder temperature from 200 °C to 230 °C.

I now understand that the first layer must be hot enough to properly stick to the glass.

The very first layer looks much different now and seems to stick much better to the glass.

For now, I could print without any glue but I still used that brim.

My next test will be a print without brim but with glue instead.

I also came to think that it is not a bad idea to level the bed before every single print.

Again, thanks a lot ! I was quite surprised about this many answers...!

Kind regards,

Karl

 

[yellowshark 153]

Why do you say that George? (sorry Quote has never worked for me - ie refer to min of 75 bed temp). I have printed items that almost cover the bed and have never printed anything above 65c bed temp. I will admit though they have been plinths, not exceeding 2-3mm in height, which of course may make a difference.

 

[gr5 2,172]

The glass temp of PLA is around 50 to 60C. If you keep the PLA well above that temp you get good and bad results. The bad result is that it takes longer for the PLA to cool and (especially for small prints) can get what looks like warping but is actually PLA laid down in the wrong place due to pulling inward on a layer below that is still liquid.

The good result is if you can keep the bottom 5mm or so of PLA above the glass temp then it is more like putty than a solid which means no matter how strong the warping forces are it won't lift off the bed. It might deform a little but it won't lift.

Somewhat better however is if you can keep the bed at 60C (or colder) and still get no lifting. There are lots of tricks for this but the overall idea here is to get the part to stick like hell to the bed.

Another similar technique to the 75C technique is to use a raft. This allows the part to sit on a stiff but somewhat flexible raft so that if there are strong warping forces the raft can flex enough to keep it from ripping off the bed and also distribute the forces over a larger area. The problem with raft is the bottom of your part looks like crap. Many many slicers and printers out there use a raft technique. Or they used to in the "older" days. But now we demand more - now we want it to stick *and* have a perfectly smooth bottom.

 

[yellowshark 153]

Thanks for that George, a useful technique. It is not a geometry that I often print at the moment but the next time I will give it a try. Would I be right in thinking that you would tend to not use the fans when using the technique?

 

[gr5 2,172]

Would I be right in thinking that you would tend to not use the fans when using the technique?

 

I've never had to resort to this so I'm not sure but yes that makes sense. Most people who print with ABS print with zero fans always. If you are printing a very large part (over a minute per layer) then the fans aren't really needed except maybe for bridging (kisslicer I think has a fan-for-bridging-and-overhangs-only setting probably meant for ABS).