HP 65 plastic anti-spill sheet

[jay]

Hello,

I am in the process of restoring an HP 65. The keys seem to rattle more than the HP 35 I have (the only other Classic unit I have to compare to); it seems there is quite a bit of play in the keys along the axis normal to the calculator face.

I've disassembled the unit, and found that all the key switch domes are intact, but the plastic anti-spill sheet is quite worn.

Is it normal to have lots of play in the keys? Would replacing the plastic sheet help? If I were to replace it, any suggestions as to the material?

Thanks for your help.

[Geoff Quickfall]

ziploc freezer bag. use the old one as a template.

double thick if keys still rattle.

[TASP]

um . . .

that seems rather 'quaint'.

Perhaps the freezer bag material also needs to be rinsed in deionized, 5 micron filtered rain water (from the rainforests of Peru) at precisely 34 degrees C for 81 minutes and then carefully air dried with air that has been passed thru 2 HEPA filters and exposed to UV light.

Then the material can be inspected with a jewelers loupe for defects, and maybe even sent out for certification by a retired HP engineer with a small boutique business dedicated to this specific need.

Additionally, trimming the material should be done with a dedicated stainless steel blade as merely using the old sheet as a guide is definitely asking for trouble. Please download a PDF file, available in the MoHPC archives for precise dimensions, and please have the serial # of your calculator available to get the correct revision.

[Dave Frederickson]

(09-18-2016 07:53 PM)TASP Wrote:  um . . .

that seems rather 'quaint'.

Perhaps the freezer bag material also needs to be rinsed in deionized, 5 micron filtered rain water (from the rainforests of Peru) at precisely 34 degrees C for 81 minutes and then carefully air dried with air that has been passed thru 2 HEPA filters and exposed to UV light.

Then the material can be inspected with a jewelers loupe for defects, and maybe even sent out for certification by a retired HP engineer with a small boutique business dedicated to this specific need.

Additionally, trimming the material should be done with a dedicated stainless steel blade as merely using the old sheet as a guide is definitely asking for trouble. Please download a PDF file, available in the MoHPC archives for precise dimensions, and please have the serial # of your calculator available to get the correct revision.

As long as we're going through all the trouble, might we laser cut these as an alternative to the scapal? I wonder if "freezer bag" is among the new materials for 3D printing at Shapeways?

[TASP]

and if someone goes thru all that to make one, why not make several, and offer them here in our classified area ??

[jay]

(09-18-2016 07:00 PM)Geoff Quickfall Wrote:  ziploc freezer bag. use the old one as a template.

double thick if keys still rattle.

Thanks for the suggestion. I tried with two layers of Ziploc bag, but the keys still move quite a bit. To be sure I'm not missing anything, the stack goes: keys, plastic frame with square slots, plastic sheet, PCA with dome switches. Is that right?