keithski122 Report post Posted April 9, 2020 (edited) I have a typical tw1 -899 which I use for auto upholstery, not a common machine so I'll post a pic of it. Thread I use is UK size 20 (poss. tkt size), I don't know what the US equivalent size is but is big enough for a decorative top stitch though probably not as big as belt or holster size.Needle size is 135/17 hole size 21. Generally the machine sews great however when I sew car hooding which is a cloth base, rubber center and vinyl topping the lower thread is loose.I've tried tightening the top thread but it feels too tight and starts to fray and snap.Shortening the stitch length helps but is not the right way to correct the problem and is still not tight enough. My thoughts are that the lower thread needs tightening however its at its tightest. I cannot get near the machine at the moment due to corona virus however when I get back to work I would like to be armed with some ideas to try. Having huge problems uploading corrct sized photos so only included a picure of the lower face of the hooding material with the fault, lower grey line is with 6mm stitch, upper grey line is with stitch shortened to 4mm. Stitching on vinyl is fine.I'll upload more pics if I can work out how to do it. Edited April 9, 2020 by keithski122 Quote Share this post Link to post Share on other sites
chrisash Report post Posted April 9, 2020 Its very easy to get a bit of fluff between the bobbin spring and causing the spring to not be tight against the thread so worth a good clean out Tex 20 = 138 Quote Share this post Link to post Share on other sites
keithski122 Report post Posted April 9, 2020 Thank you, good to know what the sizes are. Unfortunately its not fluff as I've since had the shuttle apart when I had some thread jam it up. Picture of vinyl lower face. Quote Share this post Link to post Share on other sites
Wizcrafts Report post Posted April 9, 2020 A #21 needle doesn't poke a wide enough hole to easily clear the knots from Tkt 20/#138 bonded thread. Move up to a #22/140, or #23/160 needle. The larger hole will allow the bottom thread to be pulled up with less resistance (resistance is futile!). With less resistance, you can back off the top tension and even increase the bobbin tension a bit, to get rid of the loose bottom stitches. Quote Share this post Link to post Share on other sites
keithski122 Report post Posted April 9, 2020 Great idea, I did go smaller in size with needle but as we didn't have bigger I couldn't try.I will order some bigger to try. I did forget to mention but with the previous machine I used, a juki 563, and the same sized needle and thread this material sewed fine. Quote Share this post Link to post Share on other sites
Wizcrafts Report post Posted April 9, 2020 1 hour ago, keithski122 said: I did forget to mention but with the previous machine I used, a juki 563, and the same sized needle and thread this material sewed fine. Different machines, different hooks, different feet, different springs, tensioners, guides, take-up levers, etc. Each machine has its own quirks. Quote Share this post Link to post Share on other sites
