|Re: I thought I did -- now, can it be fixed?|
Message #19 Posted by Ellis Easley on 30 Mar 2003, 4:35 p.m.,
in response to message #11 by Paul Brogger
Look in the Archives for David Smith's advice on using a solvent (methylene chloride AKA dichloromethane) to glue broken posts back together. Also how to replace them if they can't be fixed. I haven't used this solvent yet but I have it on my shopping list. Also, I use what I call a "burnishing tool" to smooth gouged plastic. I have a complete description below, but first ...
I had a similar Ebay experience with an HP67 with damage the seller hadn't mentioned (new seller, was courteous and refunded part of my money.) The unit appeared to be unused - no leakage, no wear on the springs that guide the card, the wheel was gummy but clear and stuck to the nylon (delrin?) roller at just one point. I actually removed the old wheel from the hub in one piece! That was the good news. The bad news was somebody tried to pry it open with a screwdriver from the front edge. They had found and removed the screws under the front rubber feet but couldn't find the others (I blame HP in part for hiding them. I suppose they used the label to cover a couple of screws so they could tell definitively whether a unit under warantee had been opened, but I think that kind of behavior is sort of like leasing, rather than selling, equipment to your customers.) Luckily the electrical damage was limited to slight bending of a couple of the gold hairpin-like contacts that join the PCB's. Most of the damage was displaced plastic around the gap that joins the top and bottom. Then I guess out of frustration from failing to open the unit, the "perp" stuck a narrow screwdriver in one of the screw holes and twisted, breaking the post and deforming the hole.
I don't mean any insensitivity to anyone, but this unit was raped.
I repaired most of the outside plastic damage with the burnishing tool I mentioned before and will now describe:
Regarding smoothing gouged plastic with a popsicle stick, I use a tool I inherited from my father which I call a burnishing tool (although I don't remember what he called it). It is like a short (1.65" long) stout (0.36" X 0.24" maximum cross section) dagger with blunt knife edges and point (though I think you could penetrate a skull with it!) and curved sides, with a wooden handle. The finish is very smooth but not a mirror finish. With it I can often push the extruded plastic back into the void by using many small strokes and trying to do just a little each stroke. It can leave a pretty smooth finish depending on the type of plastic (though I don't know different types of plastic apart - that is something I would like to learn more about.) When I want to get a smoother finish, I use a tiny bit of toothpaste and rub with my finger, adding a bit of water when it dries out. It seems possible to generate a considerable amount of friction this way, judging by how hot it gets - you can actually go too far (causing worse scoring than when you started) with just toothpaste and finger! I found a similar tool in the Small Parts catalog, they call it a burnisher and it is like mine except curved. It is in their catalog 22, which appears to be the same one available for download today (www.smallparts.com). I guess you have to download the entire 35MB file! but I think it is worth it, it's a real wishbook of tools and materials. The tool I found is on page 393 and the catalog number is HM-296. It is near deburring tools and files. There was no entry for "burnish..." in the index.