Nice test print - almost (and a question)

This is a test print I completed last night. The design results in many overlapping shells which require fixes before any slicer can slice it correctly. Fortunately the Windows 3D Builder app handles this OK. I wanted to do a test print first to make sure I could in fact get the part to print properly - and it does. The real part will be considerably larger.

After fixing the STL file I sliced it with the current version of Craftprint. This is the ideal slicer for parts like this because Craftprint has the best post-slice visualization out there, and I took advantage of that to make sure all the geometry would print OK. I usually go through several iterations of design/slice/inspect/redesign before I actually print something, so Craftprint's rapid slicing and great visualization are just what I need. In this case I had to do only 2 iterations before I decided everything was OK to print.

My printer is a large delta machine, and I print PLA on an unheated bed. This print failed to print properly because it became partly disconnected from the print bed during printing. Near the end of printing the part became totally disconnected with the typical result of spaghetti all over the place. This has happened to me before, but only during the winter when my room is cooler than usual.

The cause is thermal contraction. what happens is the hot PLA cools too quickly and contracts. This causes some warping in the part, and this, in turn, tends to pull the part off the printbed. Thermal contraction is a well known consequence to glass blowers, which is why just blown glass is put into an annealing oven which slowly lowers the part's temperature, thus allowing even contraction and no warping. For glass, warping results in cracking.

For PLA the problem is simpler because the temperature change is much smaller and PLA tends not to crack. In the case of this part I set Craftware to turn off the printer's cooling fans for the first layer only. What I should have done, and what I will do with the real part, is to set the fans off for the first 3 - 5 layers. This should allow the hot PLA to cool more slowly and (hopefully) prevent contraction problems.

It might be that a heated bed could also prevent this type of problem, but my printer does not have one so I can't test it.

My question is "what happened to the prime/retract setting?" Delta printers have Bowden tubes, and these require some fussing with prime/retract to minimize/eliminate stringing. I could not find this setting in the current version of Craftware. Did I miss it somewhere? Fortunately the default setting worked well - there was no stringing at all with this print, and that was a nice surprise. But it seemed to me that the setting was larger than it really needed to be, and it would be nice to try a smaller version.

November 9, 2018

Birk Binnard Birk Binnard
Exalted
705 posts

7 replies


Hi Birk,

Whoah, long post!
I won't answer with an equally long one, because I also have to work. :)

So, if anyone wondered where the Retraction/Prime settings are, scroll down in the slice options, they are just below the new settings for Far Travel.

Regards,
Norbert

November 12, 2018

NorbertF NorbertF
Admin
151 posts

They are?
Nice test print - almost (and a question)
(Short post)

Oh wait - you meant scroll the whole window down. Now I found them.

Have the Slice windows been scrollable before? It never occurred to me to try scrolling them. Maybe I'm just getting old.

November 12, 2018

Birk Binnard Birk Binnard
Exalted
705 posts

Yes, it was scrollable, but we are getting more and more parameters in that right column of the Advanded tab.

Maybe we should work on features which are not in this column :D

November 13, 2018

NorbertF NorbertF
Admin
151 posts

Or just split to another tab on the pages: advanced2
;)

January 22, 2019

Jörg from RUHRSOURCE Jörg from RUHRSOURCE
Beginner
9 posts

Even More Advanced :D

January 22, 2019

NorbertF NorbertF
Admin
151 posts

I am not sure ;)
Nice test print - almost (and a question)

January 22, 2019

Jörg from RUHRSOURCE Jörg from RUHRSOURCE
Beginner
9 posts

I am not sure ;)
Nice test print - almost (and a question)

January 22, 2019

Jörg from RUHRSOURCE Jörg from RUHRSOURCE
Beginner
9 posts
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