Why do machines "like" threads?
I have been using 100% cotton in my new Singer Quantum. I sent it back for repair as the LCD screen went out and pulled out my old favorite Singer 2010 (28 years old!) and did some piece work and it was so nice! The pressure foot is exactly 1/4 inch from needle to right outer edge..no guide, no special foot like the new one needs. So I decided to use the 2010 for piece work and the 9960 for top quilting and other larger straight assembly.
However... I did this one day with the 100% cotton, knowing that in the past cotton covered poly is all I used on that machine to minimize fluff...worked perfectly. But in quilting, hearing 100% cotton is so good, I decided to use that. Worked fine the first day. Few days later read that cotton in the bobbin and poly in the top was a good match for softness. Well, the machine didn't like that at all as it "bird nested" on the bottom and no change in the tension would fix it. I then put cotton/cotton back on it, and still bird nesting. I put poly/poly and still...those stupid birds!!! I tried the cotton covered poly in both and still..nesting. I went back to cotton/cotton and it is better, but I was so frustrated I stopped and havenn't gone back since my grand daughter was here this weekend...but this is my question
I know that machines "like" different threads...but come on...its a machine for heaven sake...how much can it "like"?!?!?! It all goes through the same threading system no matter the thread content..and I know some thread is thiicker, stronger etc. But still... how tempremental can a metal machine be? And why? I figure the weight of the thread could be the biggest advisary...but I was using the same weight threads of each...30 wt just cotton or poly or both. I can see where the bobbin and the top being different, the threads might not stitch together right due to slipping or holding based on one being a slicker thread than the other (so to speak)...but still...why do machines like different threads? And if you have an all time fav of thread or combo there of...let me know that to! I use only 100% cotton fabrics (Keepsake Calico, Kona, Quilters Legacy etc) so the fabric is always the same...so ...any thoughts/suggestions?