A blog of two hams.... Big brother is Mike, KA5VZE, in Tulsa, Oklahoma, little brother is Steve, KG5KCW, in Broken Arrow, Ok. Created for chatting about electronics projects, and maybe some woodworking and gardening too. Who knows?
Wednesday, June 28, 2023
3D printing: Garage wall bracket
Tuesday, June 20, 2023
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:
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.
Thursday, June 15, 2023
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
Wednesday, June 14, 2023
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.
The photo below shows the interior of the box, with a 3D printer divider (green plastic) mounted to the botoom.
Monday, June 12, 2023
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 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.