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Archive for January 4th, 2013

HP3970 Scanjet Lid Hinge Repair

When the second hinge on my father-in-law’s scanner broke, he asked if I could fix it:

HP3970 Scanjet Lid - broken hinge

HP3970 Scanjet Lid – broken hinge

It’s a flatbed scanner, so the lid is nearly 18 inches long and weighs 2.2 pounds with the slide / negative backlight illuminator. The stress raiser notches, located exactly where the cracks started, look like a perfect example of how not to do these things.

I solvent-glued the hinges back together, with a square brass tube applying clamping force to the joint overnight, but this certainly won’t last for long:

HP3970 Scanjet Lid - crude repair

HP3970 Scanjet Lid – crude repair

HP used to have some really smart engineers, but this looks like it was done by a Newkid (I was one, once, so I know the type) after a solid modeling and simulation session convinced him that those two thin plastic webs had enough strength for the job.

No. They. Do. Not.

Of course, HP provides no Official Way to repair that failure, as the hinges emerge seamlessly from the injection-molded plastic lid frame: you must scrap the scanner and buy a new one, because the lid would cost more than a new scanner. Equally of course, the fact that they don’t have a Windows driver beyond XP makes replacement a foregone conclusion.

It runs under Xubuntu 12.04, mostly, which is what I set him up with after the XP PC got compromised.

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