You may find that the drop in bobbin model machine causes tensions problems during FMQing for you and can be part of the thread breakage problem you're experiencing. I've put vintage machines on a frame, but I always used horizontal bobbin machines like a 301. It will also not be much fun to change out a bobbin with a quilt on top of it. The horizontal type are much easier to switch out bobbins. That's why long arm machines are engineered with horizontal bobbins. Better tension control and easier to change out the bobbins.

What a neat set up! You are one lucky quilter, in more than one way!! I hope these suggestions work for you, as I know nothing that might help, I just wanted to let you know that this is sure a neat idea!

Dina

One more thought to add to all the great suggestions ,I had the tension of the quilt its self too tight and that caused me to break threads alot so when you load your quilt you should be able to grab your finger through it. Hope these hints help you on your road to freearming.

I totally LOVE that machine, you've gotten good advice...so happy quilting!!!!