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Old Apr 15, 2014, 08:49 PM
Veni, Vidi, Feci
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Sometimes the truth hurts.
Sometimes a soft focus is a good thing.

But here is the hurtful truth in sharp focus-- 3D printed parts are rough!

Here is some of my 3DP anchor chain under the microscope. The parts are as-delivered from Shapeways (plus a little of my lint). They've been washed but not real well; parts should be washed again to remove the last of the support wax before being painted.

But you can see the jaggies and layering... and these parts are made at Shapeways' best resolution in their "frosted ultra detail" acrylic.

But really, with the naked eye, you see none of this. It does cause me some extra work, as those jaggies can stick to one another in my smallest chain, and I have to work EACH link by hand to ensure they're free.

The smaller chain here is printed with 0.5mm (0.020") "wire diameter"... smaller than the wire in most sewing pins!


.
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Old Apr 16, 2014, 07:09 AM
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Ooooo. Those look horrible.
More work cleaning them up than I realized.
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Old Apr 16, 2014, 07:40 AM
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just to ask a question what would happen if you put them in a tumbler full of fine sand (like people use for polishing brass shell cases.....
Foo
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Old Apr 16, 2014, 08:24 AM
Veni, Vidi, Feci
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Quote:
Originally Posted by Jerome Morris View Post
Ooooo. Those look horrible.
More work cleaning them up than I realized.
But as shown above Jerome, this is at a level you can't even see without a magnification. A baby's behind would look pretty gnarly too under a microscope.

Foo- tumbling has been used for larger robust parts... but I'm tempted to find a suitable medium for this delicate stuff and try it out. I have a rock tumbler just waiting for the experiment...

But again, this may be a solution for a non-existent problem... the chain looks fine to the naked eye!
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Old Apr 16, 2014, 11:03 AM
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I'd try a vibratory tumbler with walnut shell media as the abrasive. My parts from Shapeways aren't real smooth either. I should have them printed with an Objet Printer but then the costs go way up. Big difference between .2mm & .003mm. The $250 setup fee for high res prints stopped me..


Dan
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Old Apr 16, 2014, 12:12 PM
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I would think that if you could find a fine enough abrasive it would do pretty well even for the very fine imperfections you are talking about. Walnut, or even black magic (carborundum) is probably way too coarse and aggressive for taking the little stuff off your chains.
Foo
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Old Apr 16, 2014, 12:54 PM
Veni, Vidi, Feci
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I believe these parts are printed on a 3D Systems Projet 3500 HD. The specs on the machine’s high def mode (used with Frosted Ultra Detail) appear to align with what I see under the microscope:

XY (plan view) precision: 375 dots per inch, or 0.068 mm per dot = 68 microns per dot… or ~ 7 “dots” across my 1/2mm chain “wire”.

Z (vertical) precision: 790 DPI = 0.032mm per dot = 32 micron layer thickness, or 16 layers for my 1/2mm chain wire.


Now, we were all amazed when HP came out with 300 DPI print capability in the Laserjet 4… you simply could no longer see the “jaggies” in printed line art. So even though these parts look rough under a microscope, they’re actually pretty darn good!
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Old Apr 16, 2014, 01:36 PM
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Holy Crap Pat!!

Its a little jaggy .

Do you think maybe running the chain through a Casing Polisher for a few minutes would clean it up a little.
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Old Apr 16, 2014, 01:37 PM
Veni, Vidi, Feci
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a. Read above.

b. Read above.


I wonder how clay kitty litter work, since I don't have any walnut shells on hand? (Not all of us are set up for reloading work...).
I have to use a tumbler, but I bet one of those vibratory cleaners would be work better on long lengths of chain.

One fellow was using baking soda in a Paasche air eraser (mini blaster)... I couldn't get it to work...
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Old Apr 16, 2014, 02:29 PM
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Coal dust

Highly combustible and abrasive..

but may work?
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Old Apr 16, 2014, 02:40 PM
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Highly combustible? Say no more!
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Old Apr 17, 2014, 11:01 AM
Veni, Vidi, Feci
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Here you go, 10 minutes in a rock tumbler with rice. I'll try something smaller now to knock off the last of that wax... maybe salt?

In the second view, you can see some "flash" between parts... this can cause me some grief when it "welds" adjacent parts together, and I have to break the links loose individually, oy.


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Old Apr 17, 2014, 04:59 PM
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I would think that salt might work, and would in fact be better as it is made finer and finer by use.
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Old Apr 18, 2014, 07:17 AM
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Would pumice powder or rotten stone work?
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Old Apr 18, 2014, 07:53 AM
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Many things can work, but you want to match the media to your parts. I need tiny stuff, but not too aggressive for the plastic.
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