Members Dufresne Posted March 5, 2020 Members Report Posted March 5, 2020 What do you clean the needle bar with before applying JB weld? I have to fix a couple. Not sure how deep of wear is to deep. It makes sense to fix it while the head is apart. Quote
Members jimi Posted March 5, 2020 Members Report Posted March 5, 2020 I don´t think Brazing would be a good idea? The heat could bend the needle bar?? and there is a small channel for the thread to pass which has a small wall where the groove is closed with a thin strip of metal, that could come loose maybe?? Quote
Members Snakeoil Posted March 5, 2020 Author Members Report Posted March 5, 2020 I'd have to look more closely at the needle bar to see what you are talking about Jimi. I'll give JB Weld a try. I can always do it over with braze. Cleaning should be done with acetone or lacquer thinner. You need to cut the grease/oil and alcohol will not do that. Mineral spirits will work, but can leave a residue behind. If you use min spirits, and this would work with zero solvents used, wash the bar with Dawn dish detergent and very hot water. Make the JB Weld fix and then once cured, oil the bar inside and out. The small amount of flash rust you will get between washing/drying and oiling will be of little consequence. regards, Rob Quote
Members Constabulary Posted March 5, 2020 Members Report Posted March 5, 2020 I know JB weld very well but I would not use epoxy on such a small "blemish". Not sure if it really would "stick" in place for a long time or how fast it will wear off again. How deep is it 0.2 mm? File it down - done. Really not a big deal. Quote ~ Keep "OLD CAST IRON" alive - it´s worth it ~ Machines in use: - Singer 111G156 - Singer 307G2 - Singer 29K71 - Singer 212G141 - Singer 45D91 - Singer 132K6 - Singer 108W20 - Singer 51WSV2 - Singer 143W2
Members Snakeoil Posted March 5, 2020 Author Members Report Posted March 5, 2020 Slightly of topic, but let me tell you about using epoxies for stuff like this. I have repaired pitted front fork tubes for vintage British bike when replacements were not available. The bikes are still leak free. My cousin has an ancient Caterpillar dozer. The two hydraulic rams for the front blade were severely pitted. New cylinders were going to cost more than that relic of a dozer was worth. We fixed them with epoxy and that was probably 25 years ago and they are still leak free. The front sights on Colt Govt model .45ACP pistols are staked in place. The slide recoiling tends to make them loosen over time. I install them with JB Weld and have never had one loosen after 1000's of rounds. If you prep the surface correctly, the epoxy will stay put. Quote
Members Snakeoil Posted March 5, 2020 Author Members Report Posted March 5, 2020 Okay, I was fresh out of important things to do and thought I'd play with the needle arm. Pulled the needle arm out and took a closer look at the thread erosion. Here is what I found. This is the needle arm surface under the little thread tension spring. What I had not noticed before or simply forgot about (damn gray hair) was the wear on the thread tension spring. So the combination of the wear on these two mating parts may have contributed to my skipped stitch issue. I decided to use JB Weld on the needle arm wear. Here is the repaired (filled) wear area on the needle arm. I did not fill the wear in the spring as being hardened and polished, I did not expect it to stick. So, I stoned the surface a bit and then polished on the buffing wheel with a little white jeweler's rouge. The wear is not gone, but greatly reduced. I think I need to put on of these on my list of parts I need to get. So we'll see how the epoxy holds up. When I get around to ordering a few parts and they arrive, hopefully, I've have used the machine a bit and can see if the thread gnawed thru the JB Weld. As a side note, I think my 9 year old laptop is dying. I need to get a new laptop and should it die before I do, please excuse any lack of response in the interim. I have my phone so it probably will not happen. But just in case... regards, Rob Quote
Members Constabulary Posted March 6, 2020 Members Report Posted March 6, 2020 As I said, I know JB weld very well and I´m using it A LOT (just as you do) - but keep in mind that you are threading the needle bar with a metal wire and the edges of the threading wire will wear off the epoxy sooner or later because it is "rubbing" exactly where the thread is running. So the groves in spring and needle bar are the result of the thread but also a result of the rubbing threading wire. I don´t think this tiny amount of epoxy will last for a long time. Just my 2 cents. Quote ~ Keep "OLD CAST IRON" alive - it´s worth it ~ Machines in use: - Singer 111G156 - Singer 307G2 - Singer 29K71 - Singer 212G141 - Singer 45D91 - Singer 132K6 - Singer 108W20 - Singer 51WSV2 - Singer 143W2
Members Snakeoil Posted March 6, 2020 Author Members Report Posted March 6, 2020 Great point. I had completely forgotten about the threading wire. Yes, I can see that chewing thru the epoxy. On my wire, shortly after getting the machine, I did not like how that wire felt as it passed down and out the end of the needle bar. The wire, which is a high carbon steel, was certainly "biting" into surfaces on its way down the needle bar. So, I stoned the end and then polished it. Made quite a difference to how the wire travels down and out the end of the needle bar. So, although your point is well taken, my particular wire might not be as damaging as say a new one. It's an experiment for sure. We'll see what happens. Appreciate the insight. A bit embarrassed that the effect of the wire never occurred to me. Homer Simpson moment for sure. Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.