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machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment.

Category: 3D Printing

Repairing Failed 3D Prints

As a beginner, I have a fair percentage of unsatisfactory prints.

Print breaks free of plate.

Supports fall over.

Overhanging areas insufficiently supported.

Holes appearing due to wrong settings.

etc. etc. etc.

Most of the time I just bin the failure, change the settings or setup, and make another print. And wait another 2, 9, 12 or 24 hours……  Not a huge financial cost, but does involve waiting.  And I am not very good at that.

I used to grow olives and make olive oil.

Sometimes the bottles of oil were sealed with wax.  Melting point 85ºc.

After a failed print of 6 items today, due to inadequate supports of overhanging areas, I wondered if the holes and thin areas could be fixed with the bottle sealing wax.  After all, lost PLA casting is just a descendant of the lost wax method in the metal casting process.

So I found the left over remnants of the bottle sealing wax, and heated up a soldering iron.

IMG_8520

One of the failed prints.  This is a wheel trolley bracket for the model Armstrong cannon.  The moth eaten area was overhanging, and the support had fallen over.  The area was thinned and the holes were not properly formed.   If a brass or bronze casting was made from this, it would have been unusable.

IMG_8522

The 850g slab of bottle sealing wax, and soldering iron.  I do not know if this supplier is still available.  It was not expensive.

The soldering iron is heated, dipped into the wax, and the molten wax carefully dripped onto the deficient area of the print, gradually building it up.

The wax can then be shaped with the soldering iron, or a heated knife, or even a finger or thumb.  I also tried a blade shaver and sharp knife.  I think that my soldering iron, and finger were the best tools.

 

IMG_8521

The repaired area.  It looks unsightly, but of course the wax will all disappear during the casting process, along with the PLA.

I am probably reinventing the wheel with this idea.  Again.  But have not seen it used anywhere else.  So there it is.  I think that it will be useful to me.

PS>. 12 hours later.  I now realise that this is so old hat that I am embarrassed that I posted this.  Reinventing the wheel,… that’s me.

 

 

3D Printing Question

3D printing is really slow.  So slow, that the machine is left unattended to continue the print, overnight in many instances.  The print head is set at 205ºc and the table at 60ºc, and it does bother me that this hot machine is left unattended, unwatched.  I do not know if any fires have resulted, but fires are of some concern, particularly here in Oz.

A substantial component of the printing time is the hidden, internal structure of the object being printed, the “infill”.

IMG_8509 2

In this photo I set the infill at only 3%, but to compensate for that I increased the wall thickness.  The result was a nicely rigid article, but it was a 24 hour print.

My question.   At this point in the print job could I have paused the printing, and filled the cavities with a substance which set hard.  It would have to be done carefully of course, and keeping the level below the printing edge.  It would also have to be cool or cold, so the PLA did not melt or distort.  It would also need to be able to be poured, or injected.  Plaster of Paris comes to mind.  Car filler bog would be too viscous.

Any suggestions?

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