LATE AND GETTING LATER AT THE PCB FAB
The JLCPCB.com site shows my board at 60% completion, currently having the silkscreening printed. It then has to have the tinning applied via Hot Air Surface Leveling, get electrically tested, be packed and given to DHL. Still has yesterday evening as the expected completion time.
There is a notice across the web site about 2-3 day delays due to orders 'surge and amassed'. This puts the completion near the end of this week. I am certain to have weekend delay added to the shipping time, by the time they have it on the plane to cross the Pacific, thus realistically I won't have the boards until late next week.
CUTTING OPENINGS FOR CONNECTORS AND CABLES
I went over to the Maker Space with high hopes that I could cut out the openings with their metal working tools, but I found a real dearth of tools. Only one round file. Nothing to cut out the outline except a hacksaw. A couple of midrange handheld drills and a partial set of drill bits.
I drilled many many holes just inside the outlines of my intended cutouts. In a few situations, where the hacksaw handle would permit its use, I sawed some cuts. However, I left with zero of the four openings completed.
On the way back to my shop, I pulled into a local Ace hardware and bought a small flat and a small round file as well as a 'close quarters' small hacksaw. With those tools, I made some reasonable progress. The circular opening for the USB connector is complete, as is the shaped opening for the power socket. With another hour of work I should be able to finish all these openings and be ready for assembly once the circuit board is prepared.
EXAMINING PYTHON CODE FOR THE PC SIDE OF THE EXTENDER BOX
The program I wrote to communicate with the IBM 1130 Extender Box over a USB link does quite a bit of the work of emulating devices, interfacing with PC side files and communicating with the operator. It is written in Python and uses the wxPython toolkit to manage the graphical user interface. It was working properly but the code can definitely be improved and any remaining bugs removed.
I will create proper testing scaffolds for each section of code and validate it from the bottom up. Too, I will probably refactor some code as I was clearly not very proficient in GUI programming when I wrote this.
It won't help at this point, but I think you will enjoy this video: cutting openings in metal box using a plasma cutter. https://www.youtube.com/watch?v=Bz1FpBQc5uo
ReplyDeleteGreat tools make for a great experience. I had used a water cutter to make some cuts in steel plate and it was just as enjoyable.
DeleteThere are some trick to make "chain drilling" work better, although my experience is with thicker material than a computer case. The idea if you are cutting say a 3/8 wide slot is to mark out the centre line then set a pair of dividers to slightly less than 3/8 mark and centre punch the hole positions then drill them all just under 3/8 then swap to the 3/8 drill and drill every 2nd hole out to full size, as they are < 3/8 apart they should break into each other leaving a series of "peaks" to be filled out (on thick material after removing most of the peak with a cold chisel). If you put sheet metal onto a solid piece of steel as a backing you can cut fairly neatly along a line with a sharp cold chisel (sharpened more acutely than a normal cold chisel). Finally file to shape, a bit of timber clamped either side makes filing sheet metal easier and quieter.
ReplyDeleteFor round holes in sheet metal stepped cone cut drills work well as do hole saws (need a bit of play as backing for hole saws).
Hi
DeleteThis case is thicker than computer cases, so in fact I did use holes, beginning with small enough bits that it wouldn't dance (since I had no center punch) then drill larger to create a 'perforated line' that I then cut through with a hacksaw blade and/or twisted off with pliers, depending on the area.
I got rid of almost all my tools before I moved out to Florida, so no hole saws, cone bits or anything reasonable. Also no jigsaw which would have done a great job with a metal blade.