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maik-jaehne

Fan speed issue with small objects (shrinking)

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Hi There,

I figured out that with small objects the cooling fan does not start with full speed at the 2nd Layer...the result: printed objects has a shrinking problem just about the first 3-5 printed mm (high)... (right side/object in the picture)

As far as I have seen this only happens with small Objects. If I print larger objects the fan run at the second printed layer. Maybe the voltage set is to low (3-7% fan speed seems to be to low to push the fans to work)

Why does cura set this so different?

Up to now I just uses the tune menu and put it manually to 100%. (see picture to see the difference, left is manually fan set)

CoolFan Problem

 

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Hi,

You can go to Cura settings determine at what height the fan to run at 100 percent.

In the case of UM2 it is an absolute no-go to work with bed temperatures above 60 degrees, which is absolute hogwash. During cooling of the objects there are funny distortions of the objects.

Experiments with a variety of tools proven to improve the adhesion properties of the first layer. Glue stick, adhesive films, adhesive tape, various sprays, etc. all this should help to print colder and with precision.

The extruder temperature should be well below 210 degrees. Can you not get good printing results generally at 210 degrees and original Ultimaker filament, then something is wrong with your machine.

 

Try to get as cold as possible to print and probably you will receive accurate small objects. The temperature range of PLA is regularly from 180 to 260 degrees, and the temperature must be in harmony with the printing speed.

Speeds in the range of 35-50mm / s provide a good compromise between quality and speed.

All this is my opinion on the situation, but I am absolutely not an expert.

Markus

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He we may use some special temp sensors suggesting we have a special PLA here... ;)

@mnis with some PLA I have to go above 60 degrees bed temp. to have a good print, especially with long time prints (more 1h) :/

and if I use the glue stick... it sticks sometimes so well - so I´m going to get new problems: getting tiny small objects off the bed without breaking it :O

Maik

 

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@ yellowshark

Big thanks to you, but I think I know:

Ultimaker PLA is somewhere Produced mainly in the Netherlands, not here in Germany.

In fact, this filament roles are declared with 190-260 degrees. This stuff delivers pure in my opinion good to very good results. But the winding quality is crap, I wrap it before using it on an empty spool. Also the material in proportion to alternatives unfortunately is very expensive, even for buyers in the immediate neighborhood.

@ Maik

I use a desk cleaner that is ready to offer unfortunately anywhere. I give one to two puffs on a handkerchief and wipe it on the glass plate. Immediately after that I start to print. This allows me to print directly on glass large objects. More than 15 hours of printing time are therefore no problem at all and there is no visible distortion. After cool down which the printed objects dispatch almost by itself. It improves the adhesion properties and allows bed temperatures even slightly below 60 degrees. The stuff contains mainly water-soluble solvents and smells of citrus orange, so I think that a main ingredient is orange oil. The exact recipe is a secret, of course. A further advantage, it does not leave a visible residue on the glass plate. I can not make precise statements about the health impact, but you should ventilate the room well.

Antigraffiti 0Antigraffiti 1

Markus

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Interesting point Markus; I have not used Ultimaker but I do use Colourfabb filament from Holland which is 220. But if the manufacturer says 260 then you have every right to expect it to work fine at 260!

I think the important point, especially for newbies, is to always check the spec. on their new filament rather than just picking up a figure from this or any forum.

A good example is nylon; one will see references to temp figures on forums but I am using T-glass which is specifically designed to run at considerably lower temps than most other nylons.

 

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A few small additions:

-I think it's not so difficult to find other desk cleaner with similar composition. I do not mean ordinary glass cleaners, they do not have the special features that improve the adhesion.

-In the production of many small objects all first layer must be produced immediately for good results. In the production of a part at a time, the effect is not as good as the means quickly evaporates.

-I bought also pure orange oil to make more tests. The orange oil has many interesting properties. But I lack the time, because the job I'm doing completely different things.

OrangeOil 1OrangeOil 0

-Nevertheless, I have in my spare time UM2 slightly modified, adapted to my needs. I would like to know your own opinion and i would be very happy if you check it out.

-For information on good adhesive for 3D printing, just a look into the RepRap wiki. Additional information on individual substances you will find certainly at Wikipedia.

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Maik - the main point here is that you can either:

1) Start the fan stronger sooner on lower levels - not a great choice as this will usually drop the nozzle temp overly rapidly and you can get underextrusion for a layer until the PID controller adjusts.

2) Lower your bed temperature to 60C. This is the recommended solution.

 

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Hi There,

I still think this shrinking it is not an issue of bed temperature... but I´ll try.

Cleaning is a good point. I read about citrus based cleaning stuff some where in the forum. Any store in Germany where to buy? We´re using Alcohol based cleaner usually.

but during my print experience over 2 month now - I got very different results sometime PLA sticks well - sometimes not (even after cleaning, with the same stuff PLA as well as cleaning and printing with the same settings...strange)

 

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Alcohol cleaners bring, unfortunately, only a clean surface, but did not improve the adhesion properties of the glass. I had been thinking about a weak solution of sugar in water, could also improve the adhesion properties.

On eBay, should be something to find.

It must be a cleaner that is capable of removing the color from a wide variety of permanent markers and ball point pens.

Markus

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>I still think this shrinking it is not an issue of bed temperature... but I´ll try.

If the PLA doesn't have enough time to cool, when you put the next layer on top and there is a corner, the upper layer warps the layer below it and pulls it inward as it goes around the corner. This gives the part a warped shape that tends to pull it inwards. More complex shapes get warped in more complex directions.

The fan helps with this, keeping the PLA below 210C helps with this (although not the only method as I often print PLA at 240C). Minimum layer time setting helps with this. Keeping the bed temp at 70C instead of 75C helps quite a bit also. Or even at 60C.

 

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