3D printing: Garage wall bracket

 I am getting pretty familiar with Fusion 360 now...  it's pretty simple....   sketch then extrude, sketch then extrude, sketch then extrude....

I needed a simple bracket to hold a digging bar against my garage wall for starage and threw a model together in about 20 minutes. See Fusion 360 screen shot below:

A quick drawing is shown below to indicate size. The bracket is 3" wide:

The finished and installed bracket is shown below.  I anchored to the wall using  hollow wall anchors.  A nail in the bracket retains the digging bar in the bracket. 

click to enlarge

SWR Meter (14) - Box rear panel for SWR coupler

 I am modifying the rear panel of the 3D box to accomodate the shielded SWR directional coupler. The back panel is being modified into a box that holds the two sides of the coupler.

Rear view of modified panel:

Front view of modified panel: 

click to enlarge

Front view with cover removed, showing the two coupler compartments: 

click to enlarge

The lower compartment will have UHF connector inputs and outputs from the rear.  The upper compartment will have forward and reverse outputs, either through twisted pair connections are through SMA connectors. 

Developing....

SWR Meter (13) - 3D printed box parameterization fixed

 I started over with the parameterization of the box.  After watching a Youtube video on parameterizing hole patterns, I was able to figure out how to get the hole patterns to work correctly with the parameters.   3"W by 5"L by 2" H box is shown below.   The hole pattern algorithm needs a starting offset distance from the edge of the panel to the first hole for each direction W, H, and L.  Then an equation determines the number of holes and the interval in between:

The paramters for this box are shown below.   

• boxH, boxL, boxW:  parameters are the box outer dimensions
• thick1, thick2:  parameters are panel thickness parameters
• ??hole: parameters are for the screw holes,  clearance and tap
• offset?:  parameters are the offset distances to the first hole for H, W, and L
• nscr?:  parameters are the equations to determine the number of holes and interval between holes.

click to enlarge

Here is the same box with the length set to 3 inches.  Notice the number of holes along the length has been reduce from 5 holes to 3 holes

click to enlarge

SWR Meter (12) - 3D printed box parameterization problems.

Using Fusion 360, I have attempted to parameterize the design of the RF tight project box that I designed for the SWR meter.  The parameters I've used are: 

• width, length and height of the box
• thickness of the panels
• countersunk clearance hole parameters
• self tapping screw pilot hole paramters
• L: length of the box
• H: height of the box
• W: width of the box

It takes some experience to find the most efficient way of implementing the paramters.  The challenge right now for me is to get the screw locations to automatically adjust to the changes in the box dimensions and panel thickness. 

The photo below shows the SWR box after changing the box height from 1.5" to 2".  Note the row of screw holes on the side of the box is now in the wrong place.  So the challenge is to set up an equation to parameterize the screw hole locations.   

Developing....

click to enlarge

SWR Meter (11): Sheet metal box progress

 Continuing frorm SWR Meter (9)   we have built the first prototype of a sheet metal box for the SWR meter.  The box is made from 22 ga weldable steel for the bottom and 26 ga weldable steel for the top. Note that the holes have been drill for attaching the top to the bottom, The row of holes along the top are for fastening the top to the internal dividers. The inside dimension of the top is about 1 mm too wide.  That's not bad but we still need to work on making predictable bends. 

click to enlarge

The photo below shows the interior of the box, with a 3D printer divider (green plastic) mounted to the botoom.   

click to enlarge

SWR Meter (10) - 3D printed project box design in Fusion 360

 I tried another SWR project box design using 3D printing rather than a sheet metal box.  The design philosophy is as follows: 

• Use flat panels as the box components, no U shapes or L shapes.
• Use 0.113" (3mm) panels
• Use countersunk #2-28 self tapping screws to assemble the panels together.
• Use enough screws spaced close together to ensure no open cracks along the seams where the panels join.
• All inside surfaces should be flat to facilitate laying copper or aluminum tape on the inside surfaces. 
• Copper tape on the inside surfaces should form a continous conductive surface inside the box to be RF tight.

The resulting box is show below, it is 3" wide, 1.5" high, and 5" deep.

click to enlarge

You can see the places where the #2 countersunk screws are used.   there are quite a few of them. 

The drawing below shows the box exploded into two sub assemblies of 3 components each.  

click to enlarge

After 3D printing the resulting box is shown in the photo below. 

click to enlarge

The box has a few problems: 

• There are a LOT of screws.  I only installed every other screw.
• The Torx drive on the #2 screws doesn't really drive the screws well. The driver slips out of the screw head often.
• Driving the self tapping screws into the edges of the 3 mm thick panels tends to cause the panel surface to dimple.

Even with problems above the box will probably be practically useful.   Next I will work to fit the SWR meter parts into the box. See the photo below.  I will need to add a couple of divider shields. From left to right, the SWR coupler will be installed on the back wall of the box. The logarithmic detector PCB will be mounted on the floor of the box, which the OLED display and the ATTiny85 controller will be mounted on the front of the box. 

click to enlarge