Dr. Lawlor's Code, Robots, & Things

July 18, 2015

LaserJet 8500: a huge awesome ancient laser printer

Filed under: Random Thoughts — Dr. Lawlor @ 8:52 pm

At a surplus auction today, I picked up an Apple LaserJet 8500, a 60 pound black and white laser printer from the 1990’s.  Why did I bother buying such an ancient beast?

It can feed huge 13 x 19 inch paper!  I often do robot design work in CAD, then laser print a template to glue onto steel, plywood, plastic sheet, or whatever material for further drilling, cutting, and machining.  This means the size of my parts is limited by the size of my printer, so a big printer lets me build bigger parts more easily.

Anyway, the hard part was getting the printer’s IP address.  Once you have the original IP, you can reconfigure it via telnet (it will make you set a password), and then send it Postscript files via the JetDirect (9100) network port.  All you need is the LaserJet 8500 PPD file, version 1.2–link is plain text that I had to unpack from Apple’s ancient classic Mac smi.bin file using the BasiliskII emulator.

July 17, 2015

Flailing squid: 3D printer adhesion failure

Filed under: Random Thoughts — Dr. Lawlor @ 12:21 am

After starting an all-night print, I checked on my printer this morning to discover this many-tentacled glob of plastic, which apparently ate my print:

3D printer with orange plastic squirting in all directions from extruder.

3D printer with orange plastic squirting in all directions from extruder.

The problem here is the print head grabbed one corner of the print, and peeled it up.  With that corner sticking up as leverage, it incrementally peeled up the rest of the print, which stuck to the hot nozzle.  Since I’d left the printer running unattended (bad idea!), it KEPT PRINTING, with plastic squirting in all directions, resulting in an annoying-to-remove glob instead of a clean print.

The fix was to heat the hotend back up, and carefully clip away the gobs of excess plastic.  I had to be fairly careful, because the hotend’s heater and thermistor wires were buried in the goo.  I’ve wrapped them more securely in kapton tape for when this happens again.

This was with rubbery NinjaFlex, but I’ve had the same thing happen with ordinary ABS.  The trick is keeping an eye on the printer while it prints!

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