HP-15C faceplate repair


Hi. I have an HP-15C that is a bit scratched up on the faceplate. Is there anyone to fix this? I have tried model paint, paint, marker, etc. None of this seems to work well. I don't need the calculator to be in collectors conditions, but I don't want to feel shamed showing it off.

Do any users have any tricks or techniques they can offer up?


Fortunately the HP10C/11C/12C/15C/16C metal faceplates are not smooth but have a bit of a 'grained' texture.

If you don't have huge gouges/dents in faceplate, try a light wire brushing - brush dragged horizontally across it. Or use a touch of moistened Bon Ami (feldspar) to buff it, followed by use of jeweler's rouge polish.

Remember to protect plastic LCD window from scratches and keyboard openings from grit.

Bill Wiese
San Jose, CA


I know some collectors like to keep their machines in "as-found", original condition. I, however, like to restore these calcs to "like-new" appearance.

I struggled trying to re-paint the silver trim on the original series. The paint would run, and even with a steady hand and a small brush, I'd end up with some bleeding across the rectangular edges, especially at the bottom of the calc near the label and on the "double bar" of the HP-35's. I also had trouble repairing the gold trim on the TI's and the "Texas Instruments" raised letters.

I found a pair of metallic markers at Office Depot-- gold and silver (how convenient). The markers, when held at an angle and glided over the trim, makes a great restoration... smooth, to-the-edge but not beyond, etc. Vastly better. Also, almost identical gold and silver to the originals. Not perfect, though. The paint is fairly easily rubbed off (but then easy to touch up again.)

If you make a mistake, it comes off with a little alcohol or paint thinner on a cloth.

I thought I'd post this, just in case it helps anyone else. Those markers have sure been used.... makes these calcs look great.. and when it comes to my calculators, I'm definitely a perfectionist!


P.S. Another great tool has been the "Roper-Whitney" metal punch I bought many many years ago to turn double density 3.5" disks to HD disks. I can punch holes into the cheapest (thickest) bicycle tubes, and have endless numbers of replacement rubber feet... again, for all the calcs with round feet (Not HP).

And all of this goes smoother if you listen to 1970's rock music loud on the stereo. Works for me!



If the scratch is in the keyboards' faceplate, I suggest using a white-board marker (brown or black, depends on the calculator) and, if the scratch is not so deep, it "shades" it enough so we can only see it if looking at it closer. I use it.

I would like to know how to "produce" a rugged mask as the one found in the HP41 and the clamshells (18/19/28) series calculators. If you notice, these are the only series that have a keyboard with protective coat (seem to be acetate). Classics, Spices, Woodtstocks, Voyagers and Pioneers do not have it, neither 48/49 series; if there are others that have a protective coat for the keyboard, I do not know about them because I do not have others. If there is such a mask for these calculators, there would be no scratches. Look carefully at the HP41 on any clamshell: their inscriptions are protected.

I would provide a protective coat for my calcualtors, if there are any.

Sorry not helping that much. I'd keep the white-board markers, but keep in mind that alchool dissolves their coat.



A project in my queue is to print a HP faceplate on a overhead projection transparent sheet. I would use a image from the museum and print on a inkjet. What do you think about this ? Cutting holes for the keys would be critical and tedious, so I keep delaying this project...



that's the worst part, UNLESS we have a mold...

Have you thought about it?


If I were to goto a hardware store, what materials would I need? Like how do I cut the square holes that size?

Also, could you just photocopy your hp-15 or whatever, and use that copy as a template?

Maybe we could figure out a basic guideline or howto, and then each try their own method, and see whats best?

Just throwing out ideas....


There are some sign making places around that have laser or computer controlled razor cutters. They should be able to cut the keyboard holes with great precision. Also should be able to cut out perfect rubber feet from sheet rubber.

I don't know what kind of input they want, but suspect they could use some standard software formats (Autocad, etc). I have been wanting to try doing this for some time. The ALPS ink jet printers are known for their non-watersoluble, durable inks. I know there are places that make model airplane decals using them.


Someone (if I just remembered...), sometime ( sigh.. I turned 40 last year), told me that some computer print shops can produce vynil adhesive, cut according to computer output. Does anyone know about this ?



I've been reading the posts again and I see that there are two major subjects, now:
1 - a protective, self adhesive, transparent and rugged coat, like the one that exists in the HP41 and the clamshells, to be placed over a keyboard faceplate and
2 - a new, reprinted, self-adhesive keyboard faceplate.

What worries me a bit is the second option. These kbd faceplates' replacements would look like the HP41's keyboard overlays, already existing as standard, clear (no functions printed) and custom, as the ones that come with some modules (Time Functions, Math, Financial, etc.). This type of kbd protective coat would demand a more elaborated project, with specific faceplates for each calculator instead of each family. Costs would be "higher".

The "transparent" protective coat would exist in one type for each family ( Voyagers, Pioneers, etc.) and there are two situations we should think about:
1 - damaged/scratched keyboard faceplate - in this case, the first "custom" type would be a better choice UNLESS the original faceplate is restored somehow; and
2 - how to put this protective coat without any trouble, I mean, I (we) expect this transparent coat has a transparent, resistant glue, and maybe there will be no option to remove and place it again without destroying original painting.

I'm posting this because I thought (as many of you, maybe) that all HP calculators should have protected kbd faceplates, as the HP41 has. My first HP calculator was an HP41C and I remember I noticed the kbd had a protective coat a few days after using it, when I took my old, broken TI57.

As we are all delving into the same problem, let's consider both coat types: one just to protect existing, clear faceplates and another, already painted, to cover damaged kbd faceplates.

I have an HP15C and I removed (no visible damage) the keyboard faceplate. It's somewhat easy to scan it at high resolution with a white backplane. Do you want this to be done?

I'll be reading this thread for answers, arguments, comments, etc.



Don't know if this helps, but I've scanned blank 71B overlays, printed them on a laser printer and then cut the keys out. I've laid a straight-edge over the tops, bottoms, and sides of each row, and then cut the holes with a scalpel. Using a graphics program, I can print whatever I want over the keys. Cutting the little diagnonal sides of the keys is the time-consuming and tricky part.

Spraying a clear-coat would be much tougher, of course. In the Woodstocks and others, you'd have to disassemble the keyboard or block each key hole from filling with any enamel or polyurethane spray.

I like the idea of a vinyl, adhesive overlay. Could be made to look just like the original.



That would be a good first step. Perhaps next we could try to find a place that could cut either Polypropylene, Polycarbonate, acetate (which is better???) plates, and another who could print the labels etc to the plate.

I think we need to find a place that will do a relatively small number of plates <50 <100? depending on the need. Google.com brings up a few vendors such as http://www.laserexcel.com/paper/index.html
http://www.precision-laser.com (I have emailed them asking for a quote)

If anyone out there knows of a good shop, please let us know. You can also email me at david@erdius.net if you want to discuss off list.



about this:

(...)"Polypropylene, Polycarbonate, acetate (which is better???)"

I'd bet the one that has less electrostatic relation, meanning the one that will not affect the calculator's circuitry. I mentioned acetate as the protective coat over the HP41's keyboard faceplate in previous post, but now I must mention I do not believe it's acetate, because acetate is a lot susceptible to maintain electrostatic charge. If I am not wrong, Polycarbonate is the best material in this case. I do not know about durability weather resistance.


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