Parott1 Report post Posted August 1, 2016 I bought the cb4500 mainly to sew biothane beta. I swapped out the stock feed dog with a slotted plate, but after some advice from forum members, I put the stock feed dog back in yesterday. After I installed the feed dog I was getting nice stitches, but the knot was in the bottom side of the beta. I tried loosening and tightening the bobbin tension, but as you can see in the pics below, I keep getting loops on the bottom. The thread did get stuck in the shuttle a few times. Every once in a while the top thread breaks by the needle. I'm running size 138 black bonded nylon thread with a #24 794s needle along with a lube pot. The primary thread tensioner (on the side) is as tight as it can get and the secondary (at the top) still has room for adjustment. The top thread tension is already very tight, so I didn't want to keep cramming down on the secondary tensioner. What adjustments would I be able to make on my own without voiding the warranty? . . Quote Share this post Link to post Share on other sites
dirtclod Report post Posted August 1, 2016 (edited) I think you should back both top tensions, back off and start over adjusting the tension. If you have another color thread i would use that ( some people have a lot of trouble with black thread ) when i got my machine i was told to set the tension for the lightest things i would be sewing and that it should be good to go on anything else. That advice has worked pretty good for the last 20 plus years. When i go from 277 to 138 i do have to tighten the top tension just a little. Most of the time when i'm sewing both the top tension and the side tension have maybe one turn. On the bobbin tension i just do it by feel. But i have read on here that some folks use a weight gauge like what you use to weigh a fish with and set the bobbin tension at one pound pull. Edited August 1, 2016 by dirtclod Quote Share this post Link to post Share on other sites
CowboyBob Report post Posted August 1, 2016 Loose threads on the bottom like that is one of 2-things #1 threaded incorrectly,make sure you go around the 2nd tension on the side 1&1/2x when threading. #2 too loose top tension,you also need to be sure & hold on to the needle thread for the first 3-4 stitches when you start sewing.So if it's threaded correctly tighten you top tension 1/2 turn @ a time. Quote Share this post Link to post Share on other sites
Parott1 Report post Posted August 1, 2016 (edited) It was sewing beautifully, but the knot wasn't burried in the center. So I made a few more adjustments to the top and bobbin tension. After the adjustments it would sew 4-5 nice stitches then I would get 1-2 with loose loops on the bottom. The top tension is almost too tight in my opinion. Ill double check to make sure it's threaded correctly. Edited August 1, 2016 by Parott1 Quote Share this post Link to post Share on other sites
LumpenDoodle2 Report post Posted August 1, 2016 From personal experience, I would double check that the thread is actually sitting properly between the tension disks. Also make sure your thread isn't getting hung up on anything at the spool. Finally, rethread the machine, and back off the tension. Then adjust one thing at a time, and see if there is any improvement. Quote Share this post Link to post Share on other sites
Parott1 Report post Posted August 2, 2016 I backed off both tensions and started from square one. I cleaned the hook and race then added a few drops of oil. The bottom tension was very loose, so I started there until I got the loop in the center. Switched over to the beta and just made adjustments to the top tension. The stitches are nice and tight and the backstitching is working flawlessly! Quote Share this post Link to post Share on other sites
