Hey
mike it's all dependent on the software you use as to where it's a format that can be used.....I can say for sure that SCAL3 does NOT support HPGL, neither does MTC...However I looked at Funtime Scrapbooking 2014 software, which I also have, and it DOES seem to support that format to import into it......and Funtime DOES work with the Silver Bullet Professional Cutters........you will be able to cut through this software, convert files and do a wealth of things with this program...however it is not ready yet for doing Print & Cut with the Silver Bullet Professional Cutters.....HOWEVER you ARE able to export the file as an SVG format and then Import that into the SCAL3 software...which is the software that comes packaged with the Silver Bullet.....and it's a very powerful program in itself.....it does AWESOME Print & Cuts.....
Now the Funtime Scrapbooking 2014 is a purchase you would have to make on your own...it's going to run around $100.00....but it seems it will import the HPGL format you're wanting....IF you wanted to verify first...you're most welcome to email me one of your files with that extension and I'll be happy to see if it imports correctly...... my email addy is
pennyduncan@outlook.com ....Hope that helps you some!!!