johnsmachines

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. I read every comment and respond to most. n.b. There is a list of my first 800 posts in my post of 17 June 2021, titled "800 Posts"

Tag: casting bronze

March 30, 2021

Chess Men. Next step, make a tree

2 trees of pawns. Standing in front of their casting cylinders.
And 4 castles. Obelisks actually.
inside their casting cylinders. Remind you of anything? Chinese warriors for example?

Next step, to paint the PLA models with investment medium, then fill the flasks with medium and let it set overnight.

Incidentally, I tried several methods of cleaning up the PLA.

Soaking in acetone – waste of time.

Sanding and filing- effective, but very time consuming.

Using a heat gun – caused the entire model to heat up, with resulting distortion.

Using a flame gun, propane torch – very hot, so extremely brief exposure, maybe 1 second. This was my best method. It melted the tiny zits, burned the loose strands and removed some, and made the rest easy to finger nail off. A bit tricky. You don’t end up with much hair on your hands.

Casting in a day or 2. Watch this space.

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August 12, 2020

Bronze Tyrannosaurus Rex

Actually, I had some spare space on the tree which I used to make some more small gears, and I had some PLA T. Rex’s, so I added one.

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And this was the cast result, in bronze.  Yet to be cleaned up, tree bits ground off, and polished..

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 Again, the gears are close to perfect.  I like bronze.

And the gears have a short length of shaft, printed in PLA and cast in bronze, which I will be able to hold in a chuck for tidying and turning.  Lesson learned.   Think ahead, how the cast part will be machined….

And at our society Zoom meeting, Frank M  asked about the colour of burning Borax.   I could not remember, so took a shot today…

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I would describe the colour as white-gold, with a touch of green.  Like a volcano.   Maybe I overdid the Borax?

Oh.  And I had a brainwave.  When degassing the investment mix with negative pressure, add some vibration.  I tried applying my sanding machine once, and filled the room with old fine sawdust.  But for this session, I placed the vacuum pump on the vacuum chamber, and could hardly believe the volume of air which came out of the mix.  The best degassing to date.

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and it takes less bench space.   A no-brainer.  Try it!

 

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