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Thread: I need a very slow set epoxy

  1. #16
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    You can slow down any epoxy by spreading it out thinly in a tub and then set that in a pie pan filled with cold water.

  2. #17
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    That would be fun but it would be too easy. I don’t want it to be too obvious. My objective is to produce something that will look fairly random unless you know the secret. I love adding a little twist. If you want ordinary, go to IKEA.

    I started my programming career right at the end of the teletype era. My first job was with Commodity News Service in Kansas City. They had recently converted from teletypes to a Tandem. When they gave me a tour, they showed me a back room with some teletypes just in case that new-dangled computer didn’t work.

  3. #18
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    Quote Originally Posted by Mike Henderson View Post
    Are you going to make the code look like strips of teletype paper tape? That would be cool and would be the way it would be read.

    Mike
    Ok, anyone else here actually used a teletype at home? In the '70s I built my first computer (6800) and for $800 I bought a refurbished ASR 33 teletype with a tape punch and reader. It could read or write 10 characters per second. The thing was noisy so I kept it in my living room closet. Used it to load and save software and for a keyboard and printer until things evolved where I could build a CRT terminal and we could buy floppy disk drives.

    At one time the only way to buy software was on paper tape OR type in the hex code printed on paper sheets, one byte at a time. My first drives used 1.2meg 8" floppies which changed everything. I could buy one floppy disk for $10. Orders of magnitude better than the paper tape! All this time the "internet" was through a telephone handset set on an audio coupler - my data rate was 10 characters/second.

    Somewhere I still have a bunch of punched paper tape I've saved for history.

    JKJ

  4. #19
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    I suspect that Tite-bond is a better adhesive.

    But you asked about a slow-cure epoxy. You'll need to experiment, but I've thinned epoxy with acetone so that it would soak in to the pores and cracks. It substantially slowed down the cure time. In my case it was several hours. But the amount of slow down depends on your dilution level. So, experiment first.

  5. #20
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    Yes, I had a model 14 teletype. It printed out on 1/2" tape that had adhesive on the back. It was probably what Western Union used to glue up telegrams. I got it for free. I hooked it up to a home made circuit that would decode audio teletype code. I am a ham radio operator. It actually worked surprisingly well. I printed out stuff from other ham radio operators as well as from a variety of unknown-source commercial broadcasts.

    I used paper tape with a "Friden Flexo-writer" to print out annual Christmas letters and also custom resumes. Plus I used paper tapes to load data to "burn" an Eprom.

    I also remember using punch cards for data entry on a CDC 6600 super computer (probably the power of a cell phone today). I enjoyed all the noise that it made.

  6. #21
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    Quote Originally Posted by Brice Rogers View Post
    ...I've thinned epoxy with acetone so that it would soak in to the pores and cracks. It substantially slowed down the cure time. In my case it was several hours. But the amount of slow down depends on your dilution level. So, experiment first.
    Very bad advice and tech. Never add anything to epoxy that is not expressly recommended by the formulator.
    "Anything seems possible when you don't know what you're doing."

  7. #22
    Quote Originally Posted by John K Jordan View Post
    Ok, anyone else here actually used a teletype at home? In the '70s I built my first computer (6800) and for $800 I bought a refurbished ASR 33 teletype with a tape punch and reader. It could read or write 10 characters per second. The thing was noisy so I kept it in my living room closet. Used it to load and save software and for a keyboard and printer until things evolved where I could build a CRT terminal and we could buy floppy disk drives.

    At one time the only way to buy software was on paper tape OR type in the hex code printed on paper sheets, one byte at a time. My first drives used 1.2meg 8" floppies which changed everything. I could buy one floppy disk for $10. Orders of magnitude better than the paper tape! All this time the "internet" was through a telephone handset set on an audio coupler - my data rate was 10 characters/second.

    Somewhere I still have a bunch of punched paper tape I've saved for history.

    JKJ
    I didn't have one at home, but when I received my commission in the Signal Corps in 1969, I was then sent to Signal Officer's Basic Course. One thing we learned (and saw) was how the military handled message "switching". They had a room with a bunch of teletypes which were point-to-point. When a message came in, it was punched to paper tape. Someone read the address of the message and then physically took that paper tape to another machine to pass the message on. It might go to the final recipient, or it might go to another "switching center" where it would be passed along again.

    It was like a modern computer router, but with people doing the routing.

    Mike
    Last edited by Mike Henderson; 04-05-2021 at 12:13 PM.
    Go into the world and do well. But more importantly, go into the world and do good.

  8. #23
    I think "Fall apart in a hurry" is a near-wild overstatement. Try it. The joint will have to dissolve from the outside edges in, and could fail after several/many dunkings.

    I would not advise using white glue, but it was/is a viable glue, even in high moisture situations.
    I want to stay as close to the edge as I can without going over. Out on the edge you see all kinds of things you can't see from the center.
    - Kurt Vonnegut

  9. #24
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    Quote Originally Posted by David Sochar View Post
    I think "Fall apart in a hurry" is a near-wild overstatement. Try it. The joint will have to dissolve from the outside edges in, and could fail after several/many dunkings.

    I would not advise using white glue, but it was/is a viable glue, even in high moisture situations.
    No, it is not an overstatement at all. I've been there. If the cutting board sets in a puddle, or someone unknowingly puts it in a sink of water for a few minutes, it will be the beginning of the end for that board. The glue in the outer edges of the joints will first fail quickly, leaving a small gap that moisture will readily wick into, further eroding the glue.

  10. #25
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    Quote Originally Posted by Brice Rogers View Post
    I suspect that Tite-bond is a better adhesive.

    But you asked about a slow-cure epoxy. You'll need to experiment, but I've thinned epoxy with acetone so that it would soak in to the pores and cracks. It substantially slowed down the cure time. In my case it was several hours. But the amount of slow down depends on your dilution level. So, experiment first.
    Thinning epoxy has serious implications for the strength of the joint. Check with the manufacturer, but even using solvents that they recommend will weaken the epoxy.

  11. #26
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    Yup. The upgrade from a KSR 33 at 110 baud a suitcase luggable 330 baud thermal printer was mind expanding back in the day. Writing and editing code on a teletype was just agonizingly slow. The HP 2100s we used for device controllers and time sharing took about 40 linear feet of paper tape to start. You'd key in the bootstrap loader using the front panel switches (probably 30 or 40 or so 16 bit 'words'), then stick the roll of tape in the reader and it'd shoot through at about 10 fps. That'd get you enough code to start the 5 Mb disk drive that was roughly the size of a big microwave, and be able to "talk" to the machine through a teletype.

    When we retired the teletypes, I liberated 3 boxes of the newsprint paper that they used, and stuffed them in our attic. My home schooled kids never lacked for paper to draw on, or do whatever. We used the last about the time the youngest was outgrowing that kind of "art."

    My first boss in the computer business used to give tours to school groups. We had a battery powered, hand held little spinner that we used to re-roll the boot tape after starting the machines. When a smart aleck kid would ask what the spinner was for, he would say that's how you "cranked" the computer into life if it was balky, and stick the business end of the spinner into a recess on the machine to demonstrate. We were in a farm community, so a lot of the kids were familiar with hand cranking a balky Farmall M or H, so more than one bought the story.

  12. #27
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    As I wrote, Commodity News had only recently retired teletypes when I started. But I got to hear stories of teletype chaff wars in the newsroom and other war stories. CNS distributed a number of news wires over what they claimed was the biggest uninterrupted copper network in the world, ATT 7073. Some stories would be of interest to multiple wires so the paper tape would be fed through one teletype machine first. The operator would coil the tap into sort of a figure 8 and throw it across the room to the operator of another wire and so on. I would have loved to see video of that. I’m told that it was well ordered chaos.

    I don’t miss the rat race, but I do miss the rats.

  13. #28
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    Unsubscribed.
    "Anything seems possible when you don't know what you're doing."

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