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bob-hepple

Surface Finish Problems On an Going Saga

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I have posted problems with this print before but this one is a new problem. Has anyone any idea what is causing the de formed suface finish it is ruff to the touch the inside is fine I Placed a pice of paper over the bed to stop heat rising and causing other problems. I have also installed a different fan cowl

Fan Unit

 

The print was done via Simplify 3d as I have put supports in where Cura would not let me. the resolution was 0.1 the print bed was set to 60 and a print temp of 180 was set at a speed of 25-30 (Cura equivalent) Print time 6 hrs

 

Surface 1

 

when you look close the layer is slightly open in places

 

Surface 2

 

could this be Under Extrusion

 

I posted question about surface finish before

problem shown

 

when attending Print show in London the Um2 Tech Guys thought this was down to heat off the bed and recommended using no heated bed and print on tape I tried this but the print quality was not good so decided to try blocking the heat from the bed using a ??better cooling cowl and an extra fan mounted onto point down at the print..

 

Any Help Appreciated

 

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That's an issue caused by overhanging.

The point is that, if on a particular layer, the perimeter starts to curl in a region, it will evolve vertically, and perhaps extend horizontally as the layers build up. There is definitely more heat in the affected area. Could be that retraction takes place nearby, before jumping to the next layer.

As with any overhang, the factors affecting the result are temperatures, cooling, speed and layer height. You already have good values for the parameters, but seems that they did not suffice for the filament you are using and/or the part you are printing.

Also note that "screening" the bed may also have side effects. Since the heat has to escape somehow, it will find the "least resistance" path. This could be along the edge of the "screen" that is on the printed part side. Which is something you don't want.

I would try a slight increase in layer height (1.2-1.5 mm).

 

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Hi Bob Hepple

A sheet of paper is easily penetrated by heat, that does not help enough. Basically keep overhangs from the heated surface away, or use adjacent support material (...angled deflection (thin) walls with thick & directly between lying bottom) that grows along without direct contact. Better is a repositioning of the object, so that overhangs arise far above the platform. Create support materials as possible in the interior of the object, so a later possible visible outer shell remains clean.

What material are you using for this item?

 

Anyway, 180 degrees is probably too cold, PLA is incredibly tough at this temperature for example, almost like chewing gum! The material flow could be very uneven. Amazing that you can print with this low temperature at all, or is it perhaps BioFila from TwoBears? Try 205 <<< 210 <<< 215 degree nozzle / 45 <<< 60 degree bed, Layer 0.1 >>> 0.15mm, speed 35 >>> 42.5 >>> 50mm/s.

Use "only" for the first layer 220/77 degrees / 20 <<< 25mm/s., For these advanced settings use the "Tweak At Z" plug-in. Made so get your object better adhesion for direct printing on glass.

Markus

 

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Hi all

thanks for your input I am using std Um PLA I went low to 180 to try and reduce setting time for the over hang the resolution was set to 0.1 as a previous print at .15 the over hang issue reduced look at 3rd pic with arrow saying stringing this was done via Cura and everyone told me to use supports. Now dura would not let me just supports in where I wanted them so I went to Sm3D the first print was promising setting to 0.15 so I went to 0.1 the curios bit is that the stringing in pic 3 reduced a lot but left me with this problem.

Mnis thank you for the added speed / temps I will try in a few days.. I am also thinking is it possibly the PLA as two prints don't come out the same even on the same setups...

 

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3dMaker 4U

sorry forgot to answer some of your points layer height a slight increase 1.2 to 1.5 from 0.10 is not a little increase or am I missing your point. I thought the parameter i was using was hopefully better than the result but the print before had no problems except the usual one which is in the 3 rd pick called stringing. hence as I said the move to Sm3d. I take your points about covering the bed I did have a 3rd fan going at the same time 1st pic top left you can just see awhile funnel channelling the air...

Thanks for your reply.

 

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