Tuesday, December 23, 2014

DIY 3D Printer - Printing Small Parts

Here is a picture of a printed 3D hand.  When I first tried to print it I had fingers flying all over the place.  I even tried gluing them down to no avail!

Here is what you can do to make printing small parts possible.
1. Clean the glass with a razor blade.
2. Treat the glass with acetone and/or hair spray.
3. Print a 3mm "Brim" around the base of objects.
4. Print the center or "infill" first, then the edges.
5. Use a soldering iron if needed to remove "bumps".
6. Slow down the acceleration to 1000 or 2000.

Here is a video of the results.
http://youtu.be/6_5nY8F2hQg?list=UU49j5FVUO2KIFyH2IXmGXjg

The problem is that the plastic expands in the Z axis as it cools.  Then when the print head goes over it the part is impacted and sent flying.  If the "infill" is printed first then the edge does not need to be passed over to print the infill.

Wednesday, December 10, 2014

EcoQuest Fresh Air II air purifier repair

I have purchased some junk EcoQuest Fresh Air air purifiers to repair.  I fixed one by replacing the capacitors in the power supply.  I like these air purifiers because they feature an Ozone maker, and Ionizer a UV light (to kill germs) and a normal air filter too!

I have two of these air purifiers that I cannot fix.  They come in two versions.  Version one has a 12 volt switching power supply in the lower left corner.  Then there are three Triacs in the middle that turn power on to the devices.  Then there is a 5 volt regulator over on the right side that powers the logic circuits.  On mine the IC for the 12 volt power supply blew up.  I tried taking a 12 volt AC adapter and powering it up that way.  The green LED comes on indicating that the 5 volt power supply is working.  However the LCD powers up but remains blank.

I labeled the parts in this picture.


My other air purifier is a version two device.  It uses a telephone cord or a SATA cable to connect the LCD Display.  The power supply in the front left corner only puts out about 2 volts and gets very hot. In this model the switching power supply makes 8 VDC, 12 VDC and 40 VDC.  The test points for these are located just above the power supply transformer that is covered in metal in the picture below.

This is a close up showing the power supply test points.

Once again I used an AC adapter to provide 12 volts and 8 volts but it would not power up even then.  However the AC adapter was not loaded down indicating that the switching power supply is at fault.

Does anyone have schematics or anything that would help me in fixing these?