Atari 800XL with inscribed plastic problem

dcarlson314

New Member
Jun 25, 2019
9
1
3
I have an 800XL and a 1050 drive each with their cases inscribed with what appears to be inventory numbers. Seems like it was done with a soldering iron and it's inset into the flat part of the case, so sanding it down will simply make an ugly "dented" looking surface.

I'd like to get rid of this but I'm not quite sure how to go about it yet. Anyone have any advice or ideas on how to tackle this?

Here's an image to show what I mean:
View attachment 222

Thanks for any feedback!
-Dave
 

Dale Mahalko

New Member
Jul 25, 2019
28
4
3
Take a look at what 8-Bit Guy did to restore his Bell and Howell Apple II, that had a huge fan hole carved through the top lid.

,

You will need to do something similar, finding or custom-mixing a plastic fill compound that has a close color match to the case. Though if you are not good at color-matching, you may be able to lightly spray paint the entire case afterward, to make it all the same color.

To make the markings seemingly magically disappear, you need to use a modeling compound to make a casting of the fine surface texture of the plastic case where it is not damaged.

To fill in where the engraving was done, you will need to attach the casting over the top of the engraved areas and backfill it with the color-matched plastic fill material.

,

Though you are probably not going to like this next bit.

You will likely need to damage the case to look far worse yet, in order to properly fill the engraving marks.

You need to interconnect all the separate engraved letter impressions so the filler plastic can flow and fill the whole area, without air entrapment getting in the way. And you need some way to introduce the fill material without disturbing the front side where the textured casting is covering the damaged area.

I expect you will need a small high speed rotary tool, to gently sand/grind down the case where the engravings are, to make an oval depression that is just deep enough that it obliterates the markings.

Then at the opposite far ends of this oval depression, you will need to drill two small holes through the casing to the back side, with the same hole diameter as the tip of a plastic syringe.

Next you attach the molding of the textured case surface and hold it in place on the front with spring clamps.

Then with the molding face up and you looking down at the back side of the case, you use a disposable plastic syringe to inject liquid plastic fill into one of the drilled holes. You need to do this slowly to prevent air bubbles from forming. Keep slowly pushing liquid into the first drill hole, until the liquid fill emerges at the opposite side from the other drilled hole and fills it.

Next you leave the case to sit until the plastic fill has solidified, and carefully peel off the front casting and check to see how well the surface texture of the cast area blends into the original surface texture. Fix up any ridges / blemishes with sandpaper.

If the plastic fill color match is not correct, get as closely matched color spray paint you can find and paint the surface to be all the same.


Finally, I would wait to see if anyone else has better recommendations for how to do this. :)
 

dcarlson314

New Member
Jun 25, 2019
9
1
3
LOL! Nice!!!

First of all, I want to thank you for the detailed answer! I had a feeling I'd need to make a mold for this, but I wondered if I could actually scrape some of the plastic from the inside of the case and make a paste out of it with some acetone. I would just need a mold that wouldn't be devoured by acetone and still allow it to "dry", if it's even possible. (Crazy idea?)

As for a mold, it sounds reasonable to grind down the damage into a divot that's easier to fill like one of your suggestions. Then I'd clean that out and take a negative mold of that with a bit of overlap where it extents to the good part of the surface of the case. I'd also take an impression mold of another part of the case that's not damaged so I could use that to make a nice surface that will blend in with the rest of the case around the damaged area.

I've seen Peri Fractic's inspiring "Extreme Fefurb" video on Retro Recipes so I figured this project I have is doable. (Also happens to be an 800XL, if you haven't seen it yet!)


Anyway I'll check out David's Bell & Howell Apple ][ for reference as well. I really appreciate your time! Once I finally launch this project I'll post my progress.

Thanks!
-Dave



Take a look at what 8-Bit Guy did to restore his Bell and Howell Apple II, that had a huge fan hole carved through the top lid.

,

You will need to do something similar, finding or custom-mixing a plastic fill compound that has a close color match to the case. Though if you are not good at color-matching, you may be able to lightly spray paint the entire case afterward, to make it all the same color.

To make the markings seemingly magically disappear, you need to use a modeling compound to make a casting of the fine surface texture of the plastic case where it is not damaged.

To fill in where the engraving was done, you will need to attach the casting over the top of the engraved areas and backfill it with the color-matched plastic fill material.

,

Though you are probably not going to like this next bit.

You will likely need to damage the case to look far worse yet, in order to properly fill the engraving marks.

You need to interconnect all the separate engraved letter impressions so the filler plastic can flow and fill the whole area, without air entrapment getting in the way. And you need some way to introduce the fill material without disturbing the front side where the textured casting is covering the damaged area.

I expect you will need a small high speed rotary tool, to gently sand/grind down the case where the engravings are, to make an oval depression that is just deep enough that it obliterates the markings.

Then at the opposite far ends of this oval depression, you will need to drill two small holes through the casing to the back side, with the same hole diameter as the tip of a plastic syringe.

Next you attach the molding of the textured case surface and hold it in place on the front with spring clamps.

Then with the molding face up and you looking down at the back side of the case, you use a disposable plastic syringe to inject liquid plastic fill into one of the drilled holes. You need to do this slowly to prevent air bubbles from forming. Keep slowly pushing liquid into the first drill hole, until the liquid fill emerges at the opposite side from the other drilled hole and fills it.

Next you leave the case to sit until the plastic fill has solidified, and carefully peel off the front casting and check to see how well the surface texture of the cast area blends into the original surface texture. Fix up any ridges / blemishes with sandpaper.

If the plastic fill color match is not correct, get as closely matched color spray paint you can find and paint the surface to be all the same.


Finally, I would wait to see if anyone else has better recommendations for how to do this. :)
 

Dale Mahalko

New Member
Jul 25, 2019
28
4
3
I am not an expert at plastic extrusion molding or metal casting, but I do know that air bubbles are a big problem for any sort of molding as they will create a void that then messes up the final product.

You may possibly have better success if you can fill the cavity with it standing vertically sideways, or sloped sideways at about a 45-degree angle, with the two drilled holes oriented one above the other. You would inject the liquid into the bottom hole, and fill the cavity until it emerges from the top hole.

This should prevent any bubbles forming inside the molding area. But if they do form, they should float to the top of the liquid plastic, and come out the top vent hole when the cavity is full.


Once the cavity is full, if you plan to leave it standing on its side or sloped, then you would need to leave the syringe plugging the bottom hole until the plastic hardens, so it won't flow out the filling hole with the syringe removed..

Or once the cavity is full, then turn the plastic shell and lay it down flat, with the two vent/fill holes facing up. This allows you to remove the syringe and not have to be concerned with the liquid plastic leaking out of the syringe filling hole.