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.

14 thoughts on “HP3970 Scanjet Lid Hinge Repair

  1. ed:
    you did not finish the job !
    either make two shim stock splints to epoxy on the outside of the hinge,
    or glue a filler piece into the inner slot.

    1. you did not finish the job !

      I was finished!

      A plastic hoodickie snaps over those stubby white plastic buttons on each hinge to attach the cover to the scanner. The two hoodickies have slots that fit exactly around those delicate white flanges, with paper-thin clearance that allows not the slightest bit of additional material. I tried shimstock, but anything over foil wouldn’t fit… and there’s no way to secure it to the flange without a straight edge for a fold or room for adhesive!

      The only proper fix would involve an external plate on the back of the scanner and real metal hinges on the lid, but I took a deep breath, then stepped back from the project. He knows this isn’t a good fix and won’t last long, but it’s better than it was before.

      I hate plastic… even though I have a 3D plastic printer. [grin]

  2. No comment on HP engineering. I was a NewKid myself, too. :-) With respect to using the scanner on newer systems, VueScan (hamrick.com) handles a lot of older scanners with their own driver, but for the HP, you need a special gee-whiz HP driver for VS to talk to it. (Arggh!)

    I moved my 2003 vintage Epson to the Win 7 Dell, and Epson didn’t work, but VueScan handled it. As trial-ware, you have partial functionality with a watermark in the scans, and a cost of about $40 to unlock it. My Linux box is a Pentium II and I ain’t going there…

  3. Hmm, spam filter? mentioned hamrick dot com’s version of VueScan for older scanners. However, they don’t support the HP scanner, since HP demands the scanner talk only to their own driver. On other scanners, it looks like VueScan helps a lot. $40 to unlock it, and my 2004 Epson works well with it.

    1. spam filter?

      I set the filter to flag all comments containing URLs for moderation; that weeds out essentially all spam at the cost of my having to review the pile every now & then. Right now, it’s flagging about 40 spams a day and discarding 300…

    2. Oops, messier than that: VueScan will talk to the HP driver, which is the only thing that talks to the scanner. Don’t get me started on HP’s inkjet business plans, both implemented and proposed…

      1. VueScan will talk to the HP driver

        Makes the Linux driver look downright attractive, even if it’s rated only “good” and has trouble with anything other than color scanning. [sigh]

        HP’s inkjet business plans

        Cross-filed under “larceny” and “eco-terrorism”, if I recall correctly…

  4. Audited a finite elements course and near the end of the semester was surprised to hear the textbook’s author’s complaints about over-engineering interfering with profit. You don’t need that much extra material, think of the stockholders.

    1. over-engineering interfering with profit

      Yup, short-term business thinking at its finest: product cost is everything and consumers won’t care when it falls apart.

      I delete all over their censored

      1. At least scanners don’t come with region-encoding, like printers. HP is just about the number one computer-related brand on my Avoid list. My next printer will probably be a Brother due to decent-enough experience in the 1990s and supposedly pretty decent Linux support.

        1. I can only hope that, by the time both of our inkjets finally crap out, printing will finally become obsolete…

  5. Ed, I have repaired many such breaks. Here I will recommend a metal bracing piece that fits into that molded groove. Epoxy the metal bit into the grove and to make it stronger drill a couple of 1mm holes from the sides through the plastic, metal bit and back out of the plastic and glue that also. This repair will last the lifetime of the unit!

    1. I wish I’d taken a picture of the plastic hinge piece that fit over and around those thin webs: it left no room for any additional reinforcement!

      When it comes back for another repair, I’ll try to rebuild those pieces into proper hinges with a flange that bolts to the lid. It may be ugly, but it won’t come back again…

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