Clogged kitchen sink mystery...

So last night I did send some butternut squash skin down the disposal and when late last night the sink did not drain I figured I knew why. So first I disconnected the disposal expecting to find the clog right there and no... I have a 50's built house and the trap for the kitchen is in the basement. I opened the trap.... water came spewing out from both sides of the trap. Seemed like it was under pressure with the force it came out. Poured some water down the sink to see that that section was clear. I snaked the other section all the way into the main sewer pipe...three times. I know it went all the way into the large sewer drain. Put the cap back on the trap.. go to fill the sink and clogged. The larger sewer pipe is also fed right on the other side of the pipe from the bathroom. That drains fine. Hmmm...
Over at the hardware store the only thing they can think of is a clogged air vent to the roof. I am in the northeast.. ICE ?? The kitchen sink does not have it's own vent. Maybe the bathroom has it's own but I don't know where it would vent. If there was a clogged air vent would I have other drain problems from the 3 items in the bathroom.. Mystery ?? All copper pipes.

Sounds like the snake you used was to small and it's just punching holes in the stoppage and not removing it.

the tip was 1/2" and we moved that thing around a lot... if it was just punching holes wouldn't it drain a little bit... The drain is plugged solid.

This is the snake I used... Other forums doubt it's the air vent ?

A friend suggested cutting the pipe down where the clog may be.... hopefully finding a clog and then use a pipe repair clamp.. Basically because I have the time and would love not to give a couple of hundred dollars to a plumber.... feedback ??

Yeah, definitely not the vent and it looks as though there is not vent in the pictures after the drum trap anyways. So let's replay this again. You left the cap off of the drum trap and ran water in the sink and water flowed out of the trap. That part of the drain is clear. Your clog then has to be down stream of the trap.
You ran the cable to the cast iron stack, but are you sure that the cable went into the cast iron portion? One of the biggest problems with clogs in that area is where the copper adapter connects to the cast iron. The steel corrodes and chokes off the opening between the two.
It may be necessary to rune the cable several times into the cast iron stack from the trap, close it up, run some water, cable again and run the cable back and forth over and over through the copper/cast transition area to get it cleared.
By cutting the pipe you may still find the whole process to be the same only you may be able to stick a hose inside and flush it at the point of the clog.

Yes ran the water with the cap off and it was clear...
Yes I am sure we went into the cast iron... we fed at least 5 feet more then the actual distance.
Strange that when the snake came out nothing was on the tip...

Did the process 3 times... snaked... closed up.. ran water... clog.. open the trap water spews out and repeat.

Yes if cutting, the hose would be easy from there.

We have a very large cast iron paper cutter under the trap so it's tough working there and protecting the cutter... granted a tarp keeps it dry but still trying to avoid water spewing out.

So one thing... again it's odd that the snake did not pull out anything but maybe the stuff that is clogging just does not make it's way back out.

Of course the wife does not like the idea of cutting but my friend has done it before and his plumber also did it in his basement so he is quite confident of not causing a bigger problem.. what do you think. Thanks

Well.. a plumber didn't get paid today... Cut the pipe near the main.. pushed the snake through with some resistance and there it was at the joint. Put a pipe clamp on... ran the water and all is fine. I know from measuring that the snake I rented went 5 feet past that clog.. but whatever.. Done.

Nice to hear it worked out for you. Remember that disposals are primarily for small scraps rinsed off of dinnerware after the food has been scraped into the garbage can. They were never designed for most stuff that people put in them. I have found through conversations with friends and family that composting for personal gardens is becoming more common.

yes...we compost all of our food waste except meat... and whatever we were lazy with and pushed down the disposal. This was a lesson learned to keep it down to a minimum. The wife actually wants it removed.