Sharon Mallory Report post Posted January 29, 2015 I am finally trying to use my machine to make a new leather bag, I had the tensions both moved as light as possible for a couple of duffelbags I made for presents and was sewing the light canvas exterior to inside linings at the zipper. Now I am trying to top stitch through 2 layeres of leather. I have to keep fiddling with the tensions because I see the bottom thread on the top of the leather, after I've already adjusted it and sewn some of the same thickness. The book I got with the machine only shows you adjust the one top tension but here and online with you tube they show two tensions that have to be adjusted at the same time with the same amount of turn and to only do a little at a time. Could someone please clarify for me. Does anyone else have to adjust the tensions so much. My other flat bed is not that picky I just adjust a little and it stays put. i know this machine wants more thickness and larger needles with it. Thanks for the help. Sharon Quote Share this post Link to post Share on other sites
DoubleC Report post Posted January 29, 2015 If you look in your bobbin case you'll see a screw. Turn it 1/4th turn to the right and try that. That will make the bobbin thread harder to pull through the leather. Also about middle of the face plate of your machine there are tension discs there you can loosen by a 1/4th turn to the right. Then at the top of your machine on the side away from you you can also turn to the right 1/4 turn. See if these help and modify as needed. Quote Share this post Link to post Share on other sites
Samalan Report post Posted January 30, 2015 On that bobbin screw don't forget the lock screw first and the best news on this machine is you can call Steve! . Quote Share this post Link to post Share on other sites
JLSleather Report post Posted January 30, 2015 What size thread are you using? LOTS of people set these machines for ONE type of stitch in ONE type of material - usually with the same needle/thread combination. The rest of us may need to make an adjustment occasionally it's not difficult. The picture shows the bobbin IN the machine, though you may find it easier to adjust by tilting it out, or even removing it. Each his own. I don't use it for thread under 207, though I think you could get away with using 138. Loosen the clamp screw, make your adjustment (clockwise is tighter), and then snug the clamp screw back down. Quote Share this post Link to post Share on other sites
Sharon Mallory Report post Posted February 8, 2015 thank you so much. i didn't see the other screw, i will try again. Quote Share this post Link to post Share on other sites
Sharon Mallory Report post Posted February 8, 2015 i'm sorry i'm using 138 and sewing purses. 69 and 92 on my smaller machine, the 618 can't handle the seams and marks the leather. i have only just finished the one completely leather exterior due totension trouble as i dont like wasting the leather. Quote Share this post Link to post Share on other sites
Docado Report post Posted March 2, 2015 Make sure thread is not getting wrapped around little screw and thread guide on it's way down to needle from take up lever. It happens when you are repositioning or removing a piece of material. If you pull extra slack in thread with left hand it sometimes loops around the guide. If unnoticed it will cause excess pressure on top thread causing bottom thread to be pulled up through material. Good Luck. Quote Share this post Link to post Share on other sites
CowboyBob Report post Posted March 2, 2015 This should help you. Quote Share this post Link to post Share on other sites
catskin Report post Posted March 3, 2015 Are you using the same size thread top and bottom? If not you will have a LOT more trouble getting tensions right when you change thread size. I have a CB 4500 and almost never have to adjust thread tensions regardless of thread size. You should NOT have to be messing with bottom tension unless something really bad happened. It also sounds like the top thread is not coming smoothly, It could be the way you have it wrapped through the holes in the top peg, I have quit using it and run it trough the bobbin winder discs, they are adjustable and the thread comes at a steady tension. Coming through the peg it can get catchy and do what you are seeing. The reason I use the bobbin winder discs is I use a bobbin winder not attached to this machine Quote Share this post Link to post Share on other sites
silverwingit Report post Posted March 22, 2015 Like catskin I rarely have to adjust the tension on my Cobra 4. I use 138 to 346 thread on leather ranging from garment leather through multiple layers of 7-8 oz. veg tan. No problemo. Sounds like a return to basics is in order with revisiting threading, trying different needle/thread combo's, starting from scratch adjusting tensions etc. If you do need to adjust your bobbin tension, forum member Al Bane has an excellent Youtube video on that subject, amongst his others on the Cobra 4. (For whatever reason I am unable to post a direct link here; search for Al Bane on Youtube.) Good Luck, Michelle Quote Share this post Link to post Share on other sites
