Model F universal barrel gaskets

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zrrion

14 Sep 2021, 03:25

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I've designed a gasket that works for any model F barrel (excluding the AT/XT space bar, but that's easy enough to do a 1-off or mod out as needed) Using these means you do not need to cut a sheet for every model F you have. I have a friend who has a laser cutter who was able to cut some for me to do a test with my beater XT.

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you put a single gasket on each barrel, either AT of XT style, and you are good to go.
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and they work very well. I really need to actually clean the parts on this XT before I do any more work on it as it feels very scratchy. The sound is very nice. much better than the dead foam that was in there. Wobble is greatly reduced and all the good stuff that replacing foam normally gets you.

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The biggest benefit of these things is that I can get like 500 of these and no matter what F I need to repair (other than F ET) I can replace the foam.

The one issue we are having with these, which you can see expressing itself as ragged edges, is the fan that cools the laser has a tendency to blow the foam around a little but not evenly, so one side is rock solid and cuts well and the other side vibrates and prevents clean and full cuts so they have to be torn apart.They're perfectly workable but separating them is difficult. Other than that the hole for the XT peg results in a bunch of little pieces of foam when you remove them from the sheet. I've adjusted the design so that this is no longer an issue.

If you want to try cutting this yourself (noncommercial use only) I've attached the file to this post. The square in the file is a 1cm square and is included so that you can easily resize the thing as needed, depending on how the foam you are using reacts to the laser there'll be some shrinkage so resizing may be necessary and having a 1cm square to check is handy. If you want to get a bunch of these made for you by my buddy you can see his etsy here: https://www.etsy.com/shop/QuartzCrafted You might need to PM him there as IDK if it is on his store yet.
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Last edited by zrrion on 15 Sep 2021, 06:44, edited 1 time in total.

User avatar
fohat
Elder Messenger

14 Sep 2021, 15:07

Good idea! I am curious how it really compares to a solid sheet of foam, but it looks like an entirely satisfactory concept.

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ifohancroft

14 Sep 2021, 19:35

I am sorry for my ignorance, but what is the use of the foam? I don't mean your mod in particular, but the foam around the barrels on a Model F? I thought there was only a sheet of foam between the PCB and the bottom metal plate to prevent shorting the PCB?

User avatar
zrrion

15 Sep 2021, 00:53

The foam holds the barrels against the PCB so that they do not move during use. If you do not use foam then the barrels may move far enough away from the PCB that the flipper could become dislodged and the switch will stop working.

While I have used the XT that is pictured in the OP without any foam at all and it worked just fine, it the switches were way more wobbly and I think under heavy use it would only have been a matter of time before a flipper became dislodged.
fohat wrote:
14 Sep 2021, 15:07
Good idea! I am curious how it really compares to a solid sheet of foam, but it looks like an entirely satisfactory concept.
Unfortunately I don't have another XT to compare with. I have a NOS unicomp bigfoot that I could compare too I suppose, but due to case differences (and one flipper that for reasons unknown to me clicks 2 times when pressed) it would not be a good comparison.

User avatar
ifohancroft

15 Sep 2021, 01:05

zrrion wrote:
15 Sep 2021, 00:53
The foam holds the barrels against the PCB so that they do not move during use. If you do not use foam then the barrels may move far enough away from the PCB that the flipper could become dislodged and the switch will stop working.

While I have used the XT that is pictured in the OP without any foam at all and it worked just fine, it the switches were way more wobbly and I think under heavy use it would only have been a matter of time before a flipper became dislodged.
Thank you! I never realised the Model Fs had foam there.

Btw, I am not sure how viable it would be, and it would be extra manual work but after cutout out the barrel holes, how about using a paper cutter to cut it into separate squares? You know, those big hand operated guillotine like things, where you align the paper with the blade and push it down.

User avatar
zrrion

21 Sep 2021, 21:44

Update on the barrels, I have now used them in the restoration of my F122 (purchased out of the lot that XMIT was selling, this one is one of the ones that had water damage) Other than these gaskets there really isn't anything super groundbreaking about the restoration. I was able to reuse the F122 spacebar stabs by carefully pushing them out of the plate, shaving off just a little bit of the plastic and pushing them back in after the plate was painted. I glued them in as well to make sure they would be fine going forward. If you are going to do this you should know that you won't be able to use a normal model M spacebar as those stab wires are way too thick for these stabs. I was able to bend a thin wheelwriter spacebar into shape and stuck it into my ABS spacebar. The ABS spacebar (and possibly other spacebars) don't have clips to hold the wire but rather have holes which do a much better job at holding a wire that is too small. I plan to come back later and use some sort of liquid latex-like substance on the stab wire pivot point so I can completely kill the spacebar rattle. Hopefully you will be able to use the spacebar+stab wire that came with the board but if you plan to use something else you will likely not be able to reuse the stab hooks from the plate.

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This test confirms that the design does work for AT style barrels as well as XT. The previous revision of the design didn't quite fit on AT barrels and I just eyeballed the change so it's very satisfying to see it work perfectly now. Process is pretty simple, set a gasket on the place and get it mostly lined up then put a barrel in. Not much different from the XT honeslty but because this is a lot cleaner I am able to evaluate the sound/feel way more accurately.

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And here we have it, the keyfeel is consistent and I don't notice anything that would lead me to believe that this method is worse than using a full sheet of foam. I suspect not filling the assembly with foam does effect the sound somewhat, but not majorly and not negatively if at all as I'm not noticing a difference in sound myself.

handyman

22 Sep 2021, 17:00

That's pretty fantastic.

Any guess on roughly how much it costs to make a batch of these? The materials are cheap, obviously, but I've never priced out having anything custom laser cut.

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