Belt balancers, an "Ah ha!" moment..

[Mr. Tact]

Balancers are a pretty common thing in Factorio. I certainly use them often and find them very useful. I'll admit though, I have on occasion used balancer setups I didn't understand -- like once I was looking for a 4 lane to 5 lane balancer. And frankly, I still don't understand that setup, but I've tested it and I know it works as advertised. A well known and commonly used example is the 4 to 4 balancer:

4 to 4 balancer.jpg (110.27 KiB) Viewed 5129 times

I have used this setup and seen it used in videos many times. Today, I was noticing ore piling up on some belts in a manner which didn't seem kosher... because I knew the load was balanced upstream. Upon investigation I figured out why, yes I was using a balancer (like the one above) -- however, I wasn't using all the outputs. Which led to unbalanced output. The "Ah ha!" is that it's okay to not use all the inputs of a balancer, that's kind of the whole idea -- the balancer will take an uneven load and balance it across the outputs. BUT if you don't use all the outputs, the result might not be balanced. In the case of the balancer shown in this post, that is the case. If you don't use one of the four outputs, you don't get a 33.33% output on the three remaining lanes. This makes perfect sense, you might even say it was obvious -- but it wasn't something I had considered previously. Anyway I just thought I would share my small epiphany in case others might find it helpful.

[Frightning]

Balancers are a pretty common thing in Factorio. I certainly use them often and find them very useful. I'll admit though, I have on occasion used balancer setups I didn't understand -- like once I was looking for a 4 lane to 5 lane balancer. And frankly, I still don't understand that setup, but I've tested it and I know it works as advertised. A well known and commonly used example is the 4 to 4 balancer:

4 to 4 balancer.jpg

I have used this setup and seen it used in videos many times. Today, I was noticing ore piling up on some belts in a manner which didn't seem kosher... because I knew the load was balanced upstream. Upon investigation I figured out why, yes I was using a balancer (like the one above) -- however, I wasn't using all the outputs. Which led to unbalanced output. The "Ah ha!" is that it's okay to not use all the inputs of a balancer, that's kind of the whole idea -- the balancer will take an uneven load and balance it across the outputs. BUT if you don't use all the outputs, the result might not be balanced. In the case of the balancer shown in this post, that is the case. If you don't use one of the four outputs, you don't get a 33.33% output on the three remaining lanes. This makes perfect sense, you might even say it was obvious -- but it wasn't something I had considered previously. Anyway I just thought I would share my small epiphany in case others might find it helpful.

There's a several pages long thread where a number of people, myself included talked about this particular issue at length. You might wanna search for it (it's a month or so old now, maybe a bit more). Apparently, building two of them in a row solves that particularly problem (this has been experimentally tested, though not exceedingly thoroughly).

[Mr. Tact]

You're kidding, right? Exactly what search would I do that wouldn't get hundreds (if not thousands) of results? Can you say which forum it is in, or the title, or preferably provide a link?

[searker]

You're kidding, right? Exactly what search would I do that wouldn't get hundreds (if not thousands) of results? Can you say which forum it is in, or the title, or preferably provide a link?

Click on his Username, click on "Search user´s posts" under "User Statistics" and you only got 99 results to deal with

[Mr. Tact]

Good idea! Thanks.

[Frightning]

You're kidding, right? Exactly what search would I do that wouldn't get hundreds (if not thousands) of results? Can you say which forum it is in, or the title, or preferably provide a link?

Click on his Username, click on "Search user´s posts" under "User Statistics" and you only got 99 results to deal with

I'll do one better, here's the thread:
viewtopic.php?f=5&t=25008

[Mr. Tact]

Okay, I read that topic and it had some interesting information. However, what I am talking about is more basic. With the balancer I displayed in this topic, if one of the outputs is not used, the remaining three outputs are not "balanced" -- period. It is independent of what the inputs are.

[Frightning]

Okay, I read that topic and it had some interesting information. However, what I am talking about is more basic. With the balancer I displayed in this topic, if one of the outputs is not used, the remaining three outputs are not "balanced" -- period. It is independent of what the inputs are.

I tested a (slight variant) of the very design you posted, and observed exactly what you are talking about. I had 3 of the 4 outputs connected to systems that could take their full throughput. No matter which 3 inputs I used, the outputs were not all being saturated. It didn't matter which 3 inputs I used. That thread was discussing a slightly different question, but only in that we were interested in k inputs to k outputs on an n belt balancer, instead of j inputs to k outputs on n belt balancer.

[tobsimon]

The gist is this:
- If an output backs up, it throws the balancer off balance.
- If you don't need an output stream, close the loop and backfeed it into the balancer. This way, you can balance any number of outputs. Be sure to give the backfeed a higher priority than the other sources, so that it does not back up (see above).