The big recipe for uranium ore processing says it gives an U-235 35% of the time. I've done about 50 cycles of the recipe now, and haven't gotten a single one yet. Is it not working, or was I just unlucky?

Game version is 0.17.14

It is actually just 50x the normal base recipe, so it produces 50, but only 0.7% of the time, and it displays that as 50x0.007=35%. There really isn't anything I can do about it, the game only displays the average production, so, for example, an item that might produce a random amount between 5 and 15 will just say 10. And anything that produces less than 1 on average just gets a % sign. I understand it is a bit confused though.

So, on average, you'll have to run the recipe 1/.007=143 times which is... 71,500 ore... wow. It might make sense to do the recipe in a normal centrifuge for a while if you're inpatient.

I ran a test just to make sure it did work, and I was able to get it to produce on my 46th run, so I got lucky. The 143 is just the average, so may even take you longer than that.

Good Luck! Thanks for the report, but I hope that explains it and makes sense why it is like that.

Okay, got it. I'm up to 100 now, let's see how long it takes.

At least I'll have enough to start Kovarex immediately.

It should be possible to make it so that recipes with chance modify their chance, up to 100%. If it has a chance-based part, determine if 50x would increase past 100%, and if so, cut it into factors to maximize probability.

Not actually sure if this would work, but I think it should.

It should be possible to make it so that recipes with chance modify their chance, up to 100%. If it has a chance-based part, determine if 50x would increase past 100%, and if so, cut it into factors to maximize probability.

Not actually sure if this would work, but I think it should.

From what i understand, the recipes are added automatically, so this would require manual override, and would also need all possible versions if any mod changes something. The mod takes the recipe and multiplies time and resources needed and then multiplies the output. I would prefer to not change it because it can ruin future compatibility if mod maker is not ready to update the game.

Not what I meant. I mean, when it generates the new recipes, which is clearly automated, have it use a conditional

Here is my crappy psudocode explaining it. I havne't done any factorio modding for a while, but this should be right.
percent is the chance of a result.

if 50x percent < 100%, then
..percent x= 50
else If 50x percent >= 100%
..If 50x percent is integer (eg multiple of 100%, so 200%, 300%, 400%, etc)
....Remove percent mechanic, return percent/100% normal items. (2% -> 100% -> 1x item, 4% -> 200% -> 2x item, 50% -> 2500% -> 25x item, etc)
..else
....Several options here.
....Try 2x, 5x, 10x, 25x. If any of these match the is integer, or is less than 100%, apply those, and add a multiplier to resource output. So 3%, increased by 50x, would give 150%. cutting it to 25x with x2 output gives a 75% chance of x2 item.
....
....Alternatively, add two outputs.
....3% at 50% bonus gives 150%, so give one output of 1 item, and a 50% of another item in a different output slot.
..Endif
Endif