It's a tension issue, caused by a too large variation between top (loose) and bottom (tight) tensions.

It's a very common issue on domestic machines when you try to run T70 and 18 needles, because 18 needles is really the absolute smallest size that works with T70 and you're basically having to "force" this through the fabric causing additional tension problems and strain on the motor. If it's only something that happens at the start, it's probably a weak motor that doesn't build up enough power until after it's had a few stitches.

Solution: Buy an industrial machine OR step down in thread size.

Ahhh, gotcha.
Hopefully one of the more seasoned users can chime in with an exact cause.
In the meantime, does it do it on different stitch lengths?
Also, it's good to hold the threads out of the way until you get past your starting point.
I had that issue at one point, can't remember the cause....but I was suspecting either needle deflection or the needle was pushing the top thread tail back through after reversing to lock the stitch in.

Have you changed the needle and rethreaded the machine?

I'm pretty new to sewing, so maybe this is a no brainer but I can't seem to fix the issue:

On my first stitch, I always get these ugly loops on the bobbin side of the fabric. Image of the issue is linked below, showing the bobbin side of the fabric. It looks like the needle thread is getting pulled through and looping. Tension adjustments don't do anything. If I physically hold the thread in place, that sometimes works... but definitely not a solution to the problem. Structurally it probably doesn't affect anything but it's really ugly. Any thoughts on how to fix this?

Machine: Singer 1050 c
Needle: size 18
Thread: V69 nylon
Fabric: 500D Cordura (but it happens on everything, even multiple layers of webbing)

https://imgur.com/hQNsrhn

Hey everyone, I've been reading the forum for awhile now but this is my first post. Lots of great info around here, so thank you to everyone that contributes!

I'm 6'6" and 200 lbs, which is not really a typical body type. As such, the world doesn't really make things that fit me. Shirt sleeves are always too short or I have to size up so far that I'm wearing a trash bag sized shirt. I was so happy when I found Crye... the only pants that other than a tailored suit that feels like they fit. Only downside is the wife is not a huge fan of me walking around in multicam all the time.

I'm not Military or LE, just a backpacker and sport shooter. I just like the gear because its easier to customize the functionality to what I'm doing and it doesn't fall apart after a year. I was on my second warranty pack from Osprey when customer service pointed me in the direction of Mystery Ranch.

Anyways, I've wanted to get into gear making for awhile but never had the time. I got laid off because of the pandemic and found myself in a weird place. I'm attending law school in the fall so going through the hassle of searching for a new job for just a few months of employment doesn't seem worth it. Unemployment happens to give me a ton of free time though, so I'm pursuing some stuff that I wouldn't normally be able to.

My first project was hand stitching a Firstspear Tubes conversion for plate carrier. Had a blast designing it but it took like a week to do all the stitching. Picked up an old Singer 1050 c for $20 to see if I'd still like sewing. Wasn't sure it'd be able to handle sewing webbing and everything but it has performed surprisingly well. Has made it through several layers of webbing and cordura, single layer of scuba webbing. I need to use the handwheel sometimes though.

Cut my teeth on some grocery bags for the wife to learn the basics (and make the beginnger mistakes like not sewing the right sides together!!). Made a few pouches with molle and velcro. Working on a backpack kit from Sailrite now. Would love to design and build my own in the future.

Looking for to talking with everyone here and hopefully learning a thing or two!