monkfinch

Consew 206 RB-2.

I pretty sure I solved the problem with my inconsistent stitches. As some of you may already know, the Cobra Class 4 comes with a bunch of accessories including different plates and presser feet. As I mentioned in a previous post, I had been using my Cobra to sew 10 oz harness straps to a waxed canvas folded seam consisting of three layers of 18 oz duck. To do so I had been using my right toe presser foot with the "blanket set" plate and notched feed dog. This setup "walked" over the canvas and leather nicely. However, my rolled leather handles DO NOT like this setup and the subtle lift of the feed dog seems to be what is causing the nasty bobbin thread loop. This is why adjusting of the tension disks did not help my issue. It also explains how I could have knots on the top and loops on the bottom at times. That puzzle literally melted my brain. When I reconfigured my Cobra with the right toe presser foot and slotted plate (for strapped goods), the machine now produces a beautiful lock stitch on my handles. I had never tried this setup prior because I did not favor the idea of disabling the feed dog thinking the more things feeding my workpiece through the machine the better. Shame on me for not spending more time with the accessories to see what they can and cannot do. Live and learn... ---Chris

I am definitely going to check this out. I have an oil pot for Singer Class 7 in a parts drawer. It may work on my Cobra. ---Chris

Wizcrafts, My black thread is noticeably stiffer, but I get the same looping bottom thread with my white thread too. I've been curious about lube pots but suspect they may be messy. Does anyone use one with their 441 or 441 clone? The pre lubricated thread is definitely something to consider. Trox, You make an interesting point regarding the threaded bobbin. Admittedly, I've been letting the thread wind on there with little order. I will try winding one in perfect rows and see what happens. What really puzzles me is I can stitch a piece of leather and get knots on the top as well as loops on the bottom, which does not make a lot of sense to me. Another observation - I reread the manual that came with my Cobra and there was a section that mentions how the top tension disk is the main tensioner and the lower one is for fine tuning and will determine the "height of the stitch". I had been following other instructions and making simultaneous adjustments to both disks. Today, I am going to try dialing in reasonable tension with the top disk then see if I can bury my knot using separate adjustments to the lower disk. Anyone have experience with this approach? Thanks for everyone's help so far! ---Chris

Here is what I am taking about regarding the looping bits of bobbin thread on the underside of the leather. This example was much worse because I tried a smaller needle and was sewing into preexisting stitch holes from a previous failed attempt. Generally, I get approximately two smaller loops when I try to sew a straight run on a 15 inch handle. ---Chris

Kevin, I've been using Organ 7x4 - 180/24 with my A&E nylon 277 left twist thread. I just tried going down to a 160/23 needle and it doubled the amount of bobbin thread loops on the underside of my leather. ---Chris

CTG, The stitch is a straight run which is why I do not understand why this is happening. I am much better at resolving black and white scenarios (like every stitch is bad), but to have several inches of nice tight stitch then get a stitch with a little loop of loose thread on the bottom... --Chris

I've read all the Cobra 4 related thread tension posts on this forum and was unable to find one that addresses the specific issue I am having. First off, I've had my Cobra 4 for about 2 months now and it is a great machine. I had been using it to sew 10 oz. veg tan straps to a waxed canvas hem consisting of three layers of 18 oz canvas w/ nylon 277 thread on top and bottom. Everything is great - consistent, tight stitches. I started a new project where I am sewing wrapped leather handles using three layers of 5-6 oz chrome tan or stiff latigo (depending on the color way). I set my tension using scrap leather and everything looks good. When I proceed to sew I will get a few dozen stitches in then "pop" - a knot has risen to the surface on that one stitch. I recognize that leather is organic and not consistent in regard to density, but I've done a fair amount of sewing on Singer Class 7's, etc and never encountered this issue. Sometimes, I will get through stitching the entire handle and everything looks good on top. When I flip it over, I see 1 or 2 stray loose stitches with little curled loops of bobbin thread. Adjusting my tension does not seem to correct this. I've tried: 1. New needles 2. Adjusting the 2 top tension disks in sync 3. Letting the tension out of the two disks and incrementally tightening them 1/2 turn at a time 3. Adjusting bobbin tension 4. Calling Cobra Steve (He said to try turning the top tension disks 1 complete rotation clockwise) 5. Increasing my presser foot tension (this seemed to help a bit) 6. Sewing glued vs non glued handles Any help would be greatly appreciated. Thanks! ---Chris

I reversed the retainer ring, tried adding thinner shims, raised and lowered the needle bar dozens of times, tried different sized needles. When I hand crank the wheel everything appears fine - the hook finds the loop and completes the lock stitch. When I start sewing leather it stitches ok on a straight pass, but when I drop the needle and turn 90 degrees then commence stitching, after two or so stitches... a skipped stitch. I think the 45K is tired. I know I am tired! My business depends on a reliable machine, so after doing my homework, I called Steve Tayrien and purchased a Cobra Class 4 package w/ the accessories. http://www.leathermachineco.com/catalog.php?item=57 As most of you already know, Steve is extremely helpful and passionate about his Cobra machines. Initially, I was tempted to go for an Adler 205, but numerous sources told me Adler is now making this machine in China and I could not personally justify paying double the money vs. the Cobra (Juki 441 clone). Juki parts are also reasonably priced in comparison to Adler. The Cobra should be delivered late next week. Thanks to everyone who tried to help me resuscitate my 45K. I still love my other vintage machines, but I am curious to see how a brand new machine handles in my shop. ---Chris

I downloaded a GA5-1 parts list and it does not have a retainer ring like the 45K does. Let me know what you think of the GA5-1. I may be in the market for a cylinder bed to replace my 45K... ---Chris

Anyone know where I can get a replacement retainer ring (Singer / Simanco part # 91430)? My sources do not have one... OR I see there are new stitchers that appear to be copies of the Singer 45K like the Tech-SEW GA5-1R. Does any one know if parts on these machines are interchangeable with the Singer 45K? http://shop.raphaelsewing.com/index.php?main_page=product_info&products_id=274 ---Chris

Amuckart, As far as needles, I've been using: - Organ brand needles size 328LR 214x2RTW DDx2LR 180/24 (for leather) - Leo Lammertz brand size 328Ch 180/7 (for canvas) I have 214x2RTW 230/26 (for leather) but I did not like them with the 207 thread because they left a larger stitch hole that I would like. Anne Bonnys Locker, The race has been cleaned. I thought the groove on the retainer ring was factory machined, but after your comment it's looking like it's a wear pattern. Good eye! Also, at some point the ring was reversed and an identical groove is beginning to appear on that side too. The groove on the correct side is noticeably deeper near the ring opening. That may be where I am getting my extra lateral movement. That's an interesting point you made about backing the timing off for heavier leather. Not sure if that applies to what I am doing - sewing 10-12 oz harness or bridle leather through canvas webbing and two layers of 18 oz. waxed duck canvas. ---Chris

Amuckart, Thanks for your response. It makes sense to have a little "slop" in the shuttle race. I also have a Singer 7-34 that uses a similar bullet shuttle type. The 7-34 sews perfectly and its shuttle/race has way less wiggle than my 45K. I am going to try a brand new shuttle for my 45K and see how that goes. As far as thread, I've tried 207 and 277 nylon with matching thread for the bobbin. I've also tried 207 with 138 in the bobbin, but that produced even more skipped stitches. I've tried a few different needles for canvas and leather. I'll get the needle sizes when I go to the shop on Monday. ---Chris

My Singer 45K cylinder machine is no longer reliable in that it continually skips stitches. The timing appears to be fine and the shuttle hook is in good shape with a polished tip and no burrs. The only issue I can find is lateral play in the race/shuttle causing a gap between the hook and the needle kerf to occasionally exceed the recommended width of 2mm. My service manual says to insert a paper shim to correct this. I now have 4 card stock shims and adding more obstructs rotation. My questions is whether anyone has experience with this issue? A replacement race assembly will not be cheap and I would love to hear opinions before I throw money at this machine. Lastly, any recommendations for vendors that have 45K race assembly's? Thanks! One last thing - notice how my shuttle driver has been ground. Has anyone seen this before? I guess that is one way to keep the driver from slipping... ---Chris

Art, Are you using burnishing ink on wearables? I've been trying various things to get a decent finished edge on 10 oz. english bridle and harness leather. Hand burnishing produces the best result, but I cannot scale that. When I bought my finishing machine, I was told the irons were for sole leather and admittedly I never tried them. I will test them out with some Yankee wax today. Lately, I've been finishing my straps with Fiebings oil based dye, letting it dry then rubbing the edge with a stick of bees wax. I then burnish on an industrial felt wheel. The result is acceptable, but I am eager to improve this process. ---Chris