Tuesday, April 29, 2014

Refrigerator vent cover

So I was asked if I could make a new vent cover for a vintage Italian refrigarator. The acrylic and gray end parts were all cut on the Shapeoko 2 CNC. The lettering and icon were milled using a .023 carbaloide end mill. I placed plastic tape on the acrylic before milling, then painted the inside of the icon and lettering with automotive touch up paint before removing the plastic tape. I'm very happy with how the lettering and icon turned out.  The vent slots were cut using a .057 end mill. The entire part would not fit on the CNC so I had to reposition and reindex the acrylic to cut the vents and lettering (bigger CNC would be nice but not in the foreseeable future).  The person that owns the refrigarator was blown away with how good it looks.

Tuesday, April 15, 2014


The photo below was taken with a microscope of a pocket cut.  The size of the cut is about 0.100. Notice that the top of the letter e is not there. This happened because I was using a V shaped cutter with an end point greater than 0.006 with a V angel of approx 35 degrees. The equivalent of using a hammer to thread a needle. I ordered some carbide end mills (square end) and some engraver bits (V end). Should look a lot better with the new end mills.  BTW the end mills are cheep, less than $10.00 

Oh, the microscope was set close to X100.

Next photo taken with IPad to give you a real eye view of the same cut

Broken CNC

Take a good look at the photo below. These are the brass Stand offs used to support the Z stepper motor. When I first put the CNC together I thought of how poor of a design using the stand offs to support a stepping motor. This story starts out with hearing what sounded like loose parts rattling on the CNC while fast traveling to a work position. Using the most sienctiffic analysis method possiable, I took my hand and held verious parts of the CNC to determine what was making the noise. Turns out the Z stepper was the source.  I did what every good technician would do, grabbed my  tools and started tightening bolts and of course the brass stand offs. One of the stand offs appeared to be loose so I tightened and I tightened until,"SNAP". Yes, I broke the threaded portion off in the Z stepper.... Unfortunately I have a reputation of over I tightening just about everything, so in my case it's either TIGHT or  it's BROKEN!   After taking the Z axis apart, I measured the length of the stand offs and found there to be a .010 difference in length.  I ordered new stand offs (they come 20 in a pack) and decided to measure them.  They are all different, close in many cases but different lengths by a few thousands here and there.  With this new information I decided to make my own version of stand offs for the Z axis (see second photo). The results were fantastic! With all three Stan's offs now having identical lengths the CNC runs much quieter when fast traveling to verious locations on the CNC. Once again SUCCESS at the cost of breaking something.