HP-19C Printer

[teenix]

Hi all,

A long night, very noisy in the van when it rains, so no sleep.

Does anyone have a picture or description of the mounts for the 19C printer?

Looking at the semi-circular screw holes for the screw mounts, it looks like a similar setup to the Topcats that have a rubber grommet with a screw through the middle and maybe a washer on top.

The one I have here only has the brass screws. These only tighten so far leaving the printer a bit loose, so it looks like there should be rubber grommets or O-rings fitted as well.

cheers

Tony

[AndiGer]

Hi Tony,

As I was interested I searched a bit as I remembered there are youtube videos available.
This one from Jim Johnson
https://www.youtube.com/watch?v=ASshqrGtb5Y

- @5:15 remove 3 brass screws
- @17:13 I think you can clearly see the rubber grommet in one of the "ears" (right picture)
- @22:00 the rubber grommet IMHO is also visible

I also watched the HP19C video from Bernhard https://www.youtube.com/watch?v=K0JH8ZOfKkI (Allschwil 2022) but couldn't locate an appropriate picture as he doesn't focus on the printer.

Good luck
Andi

[teenix]

Thanks Andy, appreciated. I though a grommet would be a good choice.

I'll check out Jim's video when I get a chance.

cheers

Tony

[Jonas Sandstedt]

Hi Tony,

I have a couple of HP-19C and in all of them there have been dampening grommets made in some rubber compound that has dried out and become brittle over the years. If they are not already broken they break at a heartbeat. I have used rubber O-rings instead, and it works great. I love to read about your progress out of technical interest and also for having one HP-19C beyond hope that might be resurrected.

Best regards
Jonas

[teenix]

(08-18-2023 08:06 PM)Jonas Sandstedt Wrote:  Hi Tony,

I have a couple of HP-19C and in all of them there have been dampening grommets made in some rubber compound that has dried out and become brittle over the years. If they are not already broken they break at a heartbeat. I have used rubber O-rings instead, and it works great. I love to read about your progress out of technical interest and also for having one HP-19C beyond hope that might be resurrected.

Best regards
Jonas

Thanks Jonas.

I'll try to find suitable grommets, or just thin O-rings top and bottom which will provide clearance between the printer and case bottom and should keep it loose enough for dampening.

cheers

Tony

[teenix]

I looked around the auction site and found some 1mm thick flat O-rings with 3mm hole.

They seem to fit ok top and bottom of the 3 printer mounts and the top calculator casing fits on properly. Not as good as grommets, but they should do.

cheers

Tony

[tangdfx]

Hi，tony

I think these parts are not necessary.

Without these, the calculator can work properly.

[tangdfx]

Hi，tony

I think these parts are not necessary.

Without these, the calculator can work properly.

[teenix]

(09-14-2023 11:16 AM)tangdfx Wrote:  Hi，tony

I think these parts are not necessary.

Without these, the calculator can work properly.

Most likely true but I found that without them, the printer "bottoms out" on the lower calculator half and doesn't sit properly - it rocks back and forward. Then when the screws are tightened, the printer plastic frame is distorted a little bit. It is hard to notice unless you look closely. I'm guessing they also help to dampen vibration, or help isolate the printer from calculator shocks, ie when putting the calculator on a hard desktop.

cheers

Tony

[jjohnson873]

The HP-19c printer will work without the rubber grommets. But as you noted, there is some movement of the printer mechanism, without grommets, since the brass screws tend to float in the printer mounting holes and have a shoulder on them to limit the travel. I have yet to find a good replacement grommet, but there should be some rubber washers that may cushion the brass screws and provide some firm support for the printer.

Over time, the rubber grommets will deteriorate and become brittle and break apart. If I find a replacement, I'll post to the forum.
~ Jim J. ~

[teenix]

Sorry guys, you are correct that the printer will work ok without grommets, but just be loose. Thinking back, I forgot when I was playing around that I used small O-rings but only on the top of the mounts which allowed the printer to be tightened snugly but direct printer contact with the lower casing was causing a distortion.

I got flat flexible washers from here, 3 x 7mm, 50 qty for a couple of dollars.

They are 7mm diameter, hole size 3mm and 1mm thick. The brass screws fit nice and snug through them and pretty much match the screw head diameter and the plastic molded mounting flanges.

I haven't tried, but you can also get very thin stainless shim washers which (if thin enough) could serve to provide a more stable connection similar to how the 97 printer is mounted. If desired, you could stick these to the rubber washers with a dab of super glue or whatever.

screw head
thin steel washer
flat rubber washer
printer mount
flat rubber washer
thin steel washer
calculator base

I'm not sure if the brass screws need to be fully tightened as this just distorts the washers, so maybe 1/2 to 3/4 of a turn or so after the screws make contact with the washer would suffice. The screw has a lot of friction inside the washer so shouldn't undo.

cheers

Tony

[AndiGer]

(09-14-2023 01:55 PM)jjohnson873 Wrote:  If I find a replacement, I'll post to the forum.

Here in Germany I found some
https://www.pollin.de/p/durchfuehrungstu...-st-442583

Andi

[teenix]

I received some small sized rubber grommets today. The center hole and outer diameter are ok but they are still too high to fit properly. The main issue being the wide gap in the centre of the grommet.

The rubber washers I found fit ok so I think I will stick with them.

cheers

Tony