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Clamshell battery doors
09-13-2019, 11:17 PM
Post: #1
Clamshell battery doors
I'm just wondering if anyone has tried cyanoacrylate and powder techniques for repairing HP-28 and HP-19B battery doors? I can't really imagine it being strong enough, but there's no harm in asking!

— Ian Abbott
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09-14-2019, 12:04 AM
Post: #2
RE: Clamshell battery doors
Just to be clear, cyanoacrylate and baking Sosa (not baking powder).

No, I haven’t but I am experimenting with bondic, a UV activated plastic which I think will be good when injected and cured in cracked posts. I have used it successfully on plastic no stress locations when repairing Transistor radios and the like.

Not a seller or in any way associated:

https://m.youtube.com/watch?v=xTsfwL61CR8

Just received two tubes and have some cracked posts to work on along with other repairs where strength and material must be built up.

Geoff
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09-14-2019, 02:40 AM
Post: #3
RE: Clamshell battery doors
Wasn't there someone in South America who was converting the 28S to a rear battery door? I believe he cut a piece out of the back and glued the original battery door on. I am describing it poorly but he did an amazing job of it. My google is off today but maybe another member can find the link.
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09-14-2019, 10:53 AM
Post: #4
RE: Clamshell battery doors
(09-14-2019 12:04 AM)Geoff Quickfall Wrote:  Just to be clear, cyanoacrylate and baking Sosa (not baking powder).

I was thinking of the commercial powder adhesive sets you can buy (available in black and grey, but brown would be nice!), rather than baking soda, but the principle is the same.

Quote:No, I haven’t but I am experimenting with bondic, a UV activated plastic which I think will be good when injected and cured in cracked posts. I have used it successfully on plastic no stress locations when repairing Transistor radios and the like.

Interesting. It's the high stress on the battery door that makes me think the powder sets (or baking soda) wouldn't work on the case surrounding the battery door. I think it might be too brittle (but I haven't tried it).

Quote:Not a seller or in any way associated:

https://m.youtube.com/watch?v=xTsfwL61CR8

Just received two tubes and have some cracked posts to work on along with other repairs where strength and material must be built up.

Good luck! You can put it in The Book if it works!

— Ian Abbott
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09-14-2019, 09:03 PM
Post: #5
RE: Clamshell battery doors
(09-14-2019 02:40 AM)Ken S Wrote:  Wasn't there someone in South America who was converting the 28S to a rear battery door? I believe he cut a piece out of the back and glued the original battery door on. I am describing it poorly but he did an amazing job of it. My google is off today but maybe another member can find the link.
You could also use a housing of a newer 19BII with battery door on the back factory-wise, and implant a 28S .
It's somewhat tricky getting the keyboard overlay and then upper case part off without damaging them.

Just for testing I did it the brutal way using two partly defective units, and of course damaged the housings.
However if you do it right, you should be able to separate the case parts in a way that they can be put together again later;-)

-- Ray
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09-14-2019, 10:46 PM
Post: #6
RE: Clamshell battery doors
Took a bit of looking but found a YouTube video of the modification I was referring to.

https://youtu.be/8NPo-zF58aQ

It looks like it would take a lot of care to do but looks like a much simpler proposition than switching cases. Just look at the number of heat stakes visible in half the battery compartment. I think the only really tricky part would be cutting out the back of the case so cleanly. If you had a parts calculator I would cut an oversized section out to use as a door. This would allow you to not have to make such precision perfectly straight cuts initially though you would spend more time fitting the new door.
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09-15-2019, 01:23 AM
Post: #7
RE: Clamshell battery doors
Someone fashioned a door replacement from brass here

https://www.hpmuseum.org/forum/thread-5673.html

I also remember seeing a post about someone who made a u-shaped sheet metal piece that covered the battery door then stretched across the back of the calculator to clamp onto the opposite side of the calculator body. A bit kludgy but it did work.

Who decides?
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09-16-2019, 07:28 PM
Post: #8
RE: Clamshell battery doors
(09-15-2019 01:23 AM)mfleming Wrote:  I also remember seeing a post about someone who made a u-shaped sheet metal piece that covered the battery door then stretched across the back of the calculator to clamp onto the opposite side of the calculator body. A bit kludgy but it did work.

I remember seeing that one too, quite a few years back. It looked a bit odd, but very solid.
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