Home > SDIY, Synths > SEM – The Machined Panel Arrives!

SEM – The Machined Panel Arrives!

SEM Panel Ready for Wiring

If my work space is any indication, the hardest part of any project is the panel and enclosure. I have all kinds of fully stuffed PCBs sitting around that just need a proper panel or housing and they would be finished. I’m not even talking about one or two projects, a quick look around reveals 4 such PCBs and I know for a fact there are at least as many in various storage boxes hiding from my direct glare. I used Frontpanel Express in the past but while the product was good, I found using their software left something to be desired. in particular, if you wanted a dial gauge of some sort, getting it to line up properly was a frustrating exercise in 1/128″ increments. Even then it seldom was perfect. Equally frustrating was that the cost was just high enough to be on the edge of tolerable. Fortunately, I have found a better way and projects are now slowly ending up behind panels again much more quickly.

The key is to use HPGL graphic files for you text, gauges, etc. and import these into the Frontpanel Express software. The cost is considerably less and you have much greater control over graphic elements. This is probably no great revelation to any of you who have used Frontpanel Express. I had heard about this from the first time a made a panel. Unfortunately, HPGL is not the friendliest or widely supported format out there. I experimented with multiple methods on the web: using old HP plotter drivers, printing to file, and reimporting; saving to SVG or other vector files and uses translation programs, etc. None of them worked even close to satisfactorily. Typically one of two things occurred.  Either the output vectors were choppy because there were not enough points stored for the curve or the scale was off.  The later was particularly frustrating because a couple of the methods to get HPGL eventually yielded smooth outputs, but I could never get the scale right.  It always seemed off by just a slight amount so the gauges were always ever so slightly off.

The absolute best solution I’ve found is Corel Draw.  It supports HPGL natively, outputs perfectly, and is really easy to use and in many ways optimized for this kind of technical layout.  I also have Adobe Illustrator I still always use Corel for my panels (but Illustrator for pretty much anything else).  I’ve also heard that Inkscape supports HPGL but I’ve not tried it so I do not know.  In Corel, the trick is to scale everything up so that you get sufficient output points for all the curves to be smooth.  Just to keep the math easy, I scale everything up 10x larger than my desired final output.  Then I import the HPGL into Frontpanel Express at 10%.  Unlike my previous attempts, the scale is dead on perfect. I still use Frontpanel Express’ software to specify the milling of holes etc. but Corel does all the labeling, graphic, and gauge type stuff.  One really great thing about Frontpanel Express is that it is trivial to have them mill “d-holes” on your panel.  If you are using banana jacks, spend the extra dime for these.  You jacks will never turn on the panel again.  I even added Chinese labels to my panel as graphical elements and they came out great!

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