dikman Report post Posted August 11, 2015 (edited) Pondering this, I decided that steel is really the best way to go, so to keep it simple I basically clamped each bearing between plates. Lots of hole drilling, but it's worked out very well. The machine is now very slow (compared to what it was) although it still has a slight problem if the leather is dense/hard/too thick - but I'm working on it. I figure an even larger pulley on the handwheel will not only slow it down to a crawl, but give me even more torque. The belts are round cross-section neoprene rubber. This stuff is oil-resistant, has some stretch but best of all to make a belt it's just a matter of cutting to length and super-gluing the ends together. A couple of photos for those who are interested, showing pretty much the finished product, there's not much left to do now but work out what size needles and thread it can handle. (It came with a cone of thread with a faint 40 on it, which appears to be Metric 40/T70/#69). All been good fun..... Edited August 11, 2015 by dikman Quote Share this post Link to post Share on other sites
dikman Report post Posted August 17, 2015 The final piece of the puzzle - Wiz mentioned a tension release, and I said it didn't have one, which is quite true seeing that I don't have the original tensioner. Anyhow, it got me thinking that it would have had one (once), being an industrial machine. But I couldn't figure out how it would work (certainly not the same as the domestic tensioner that I fitted). The parts listing didn't show anything that was obvious, so I pulled the needle end of the machine apart to try and figure it out - like most things, it was pretty obvious once I worked it out!!! I bought a Singer 478 for $10 (!) so that I could get another tensioner assembly and should be able to modify it to work like the original. Only problem is that they started using plastic gears in these machines and that included the part in the tensioner that is used to adjust the thread controller spring - and, of course, it's split. I should be able to fabricate one from aluminium, as there's no real stress on this part, and with a bit of luck should be able to get the tension release working. I haven't done any stitching yet, but used it on the holsters I'm making to pre-punch the stitch holes. I was quite impressed, as I could get it to chug along quite slowly and get a nice even set of holes. It was rather nice watching it go down, up, feed, down, up, feed....all at a very civilised pace! Quote Share this post Link to post Share on other sites
dikman Report post Posted August 31, 2015 At the risk of boring everyone, I decided to experiment with thread/needle size. It came with #16 needles and #69 thread, which is what was used to make shoes with, I guess. I bought some #138 thread (on special for $14 for a cone, so I couldn't help myself). The thread actually fitted the #16 needle quite well (no sign of dragging), so I gave it a go on a piece of old stiff 4-5 oz leather. It actually went through it ok, but wasn't pulling the bottom thread into the hole. I put this down to the needle hole being too small for the four strands of thread going through it. Or maybe the leather was too stiff? The only bigger needle I have is a #21, so I tried that. It worked fine if I turned the wheel by hand, but as soon as I tried using the motor (very slow speed) I started getting runs of dropped stitches, looks like the hook on the shuttle isn't grabbing the thread. Strange how it worked with the smaller needle, but not the bigger one. I'll get some #18 needles next week (out of stock at the moment) and give that a try. I was pleasantly surprised that it worked at all with the thicker thread. Quote Share this post Link to post Share on other sites
Northmount Report post Posted August 31, 2015 Is your presser foot lifting with the leather when running with the motor? That will result in skipped stitches. Try tightening the presser foot spring down some. Tom Quote Share this post Link to post Share on other sites
dikman Report post Posted August 31, 2015 Yes, it is lifting with the bigger needle. Good point. More experimenting today. Quote Share this post Link to post Share on other sites
Wizcrafts Report post Posted September 1, 2015 Try some #22 leather point needles for your #138 bonded thread. That is the recommended small size. Also, see if titanium coated needles are available for it, in sizes up to 22. They sew hard, or glued, or taped leather better. Quote Share this post Link to post Share on other sites
dikman Report post Posted September 1, 2015 Titanium needles? Good grief, I consider myself lucky just being able to get the right size in "plain" needles! I increased the rolling wheel pressure, and that definitely helped (I forgot that I'd backed off the pressure last time I was messing around). I think 138 thread is do-able, although I think that a #22 needle may be a little too heavy. I experimented with a #16, with 138 thread, and got it sewing pretty well - until I tried two layers of 3-4 oz and one layer of 6-7 oz. I got a couple of stitches and then the needle snapped most convincingly! I'd obviously pushed that combo a wee bit too far. The problem with the breakage appears to be in the design of the roller and feed dog. The feed dog mounting plate is actually raised just a little above the adjacent area of the needle plate, so in effect the leather where the needle pushes through is unsupported. If the leather isn't too thick then the needle can push through ok, but if it's too thick (for the size of the needle) then the leather deflects downward slightly and allows the needle to bend just enough to miss the hole in the needle plate, resulting in either a bent point or a snapped needle. I may try and build up that area to give more support to the leather. This is all good, as I need to find the limitations of this machine. (I've just made yet another pulley - larger - for the stepdown that I made, to try and slow it even more). Quote Share this post Link to post Share on other sites
Wizcrafts Report post Posted September 1, 2015 Dikman; I believe you are trying to run the old post machine beyond its design parameters. I would keep the thread size at or under #92, which happily runs through a #19 or 20 needle. Just my .02 Quote Share this post Link to post Share on other sites
dikman Report post Posted September 1, 2015 Wiz, I have no doubt that you're correct, as I assume that the needle/thread combo it came with (#16/69 thread) is the optimum for what it's designed for. I'm sure that at it's original speed it couldn't handle anything heavier. I've slowed it down significantly, however, which is giving me greater control, and while it will never handle what a good walking foot can do I reckon I can get it to go past its original design parameters - within reason. Like I said, it's all good fun, and your assistance has been invaluable. Quote Share this post Link to post Share on other sites
dikman Report post Posted September 7, 2015 I had a bad day a couple of days ago, courtesy of this machine! I thought I had it sorted and was happily running a line of stitches when I broke a needle - size 21 - and everything locked up! I eventually tracked it down to one of the bevel gears that drive the hook/shuttle shaft, it had been knocked along it's shaft just enough to get out of mesh (I'm just glad they used metal gears). I reset the hook timing, but then found that something was catching a strand of the thread occasionally, breaking it and causing all sorts of threading problems. I stripped and polished all the parts where the thread ran (found a few grooves in one of the thread guides, so smoothed them out) but it didn't help. Eventually I noticed that the hook was the culprit, catching the odd strand, breaking it and then the strand was unravelling back along the thread, making it appear that the problem was elsewhere!!! I couldn't see anything wrong, but I polished the hook with some metal polish just in case but to no avail. The timing appeared right, so at this point I gave up for the day. Next day I searched the 'net for hook problems but couldn't find anything that I hadn't already checked. I figured it had to be a hook timing issue, so redid it, starting from scratch. Previously, I'd used my "calibrated" eye to get the required 3/32" adjustment on the needle bar, this time I used a 3/32" drill bit as the gauge. So much for my "calibrated" eye, it wasn't even close to 3/32"!!!!! After I adjusted it correctly, the hook position was way too advanced, no wonder I was having problems. I reset the hook again, and that was it, the hook picked up the thread perfectly every time. In the meantime, my size 18 needles had come in, so I tried the #138 thread and found it slid through the eye without any drag. I fitted a needle, loaded the thread and, with some trepidation, started the machine. Eureka! A perfect row of stitches! I tried different stitch lengths and different thicknesses of leather and it didn't miss a beat until I got to 1/4" thick. It worked if I turned it by hand, but the motor didn't like it too much, although I discovered later that it depends on how hard/dense the leather is as it will (just) do soft 1/4" stuff. It will actually punch through 1/4" fine, using the motor, if there's no thread in the needle, but adding thread appears to load it down a bit more. Doesn't matter, it'll be fine for most of my needs. Wiz, the manual states that it will use up to size 24 needles and the only criteria on thread size is that it must pass through the eye of the needle with no drag. This means that theoretically I should be able to use up to #207 thread, although the thickness of the material is likely to be more critical (should be ok for thinner stuff). The only real problem is that I would need to open up the hole in the needle plate, but I'm not sure that I really want to do that. I think I'll stick with the 18/#138 combo as the max size used, as it appears to work fine. I found an old belt, about 3/16" thick and a bit on the hard side, and ran several rows of stitches down its full length without missing a beat, so I'm feeling pretty happy with it. Hallelujah! Quote Share this post Link to post Share on other sites
Constabulary Report post Posted September 7, 2015 I just have read a manual of the Singer 31-19 / 31-47. They say that the needles for this machine are MADE in these size, they do not specifically say that the machine can use this size of needles. You know what I mean? I think it´s like reading between the lines and it leaves room for interpretations. So what is the poet trying to tell us? I honestly don´t think that 23 or 24 size needles can successfully be used in machines of these classes. I guess its about the same text that you found in your manual. Just my 2 cents Quote Share this post Link to post Share on other sites
dikman Report post Posted September 7, 2015 (edited) The wording is pretty much the same in my manual. I agree that while a 24 needle seems a bit much, particularly for anything but thin leather, I don't believe they would list them if they wouldn't work. These are industrial machines, and if they didn't work as claimed industry simply wouldn't have bought them. Not that I can see much use in such a large needle and thread if it will only go through thin stuff! I suppose it sounds good, being able to list bigger needles, even if the practical applications are limited!! (I must admit I was momentarily excited at the thought of using 207 thread, until I stopped and thought about the possible problems of using such a large needle in this machine. I'm happy enough at being able to use 138 thread, as it puts me way ahead of my other little domestic Singer). I used it today to pre-punch the holes on another gunbelt, I used a broken size 21 needle, which I ground to a point, and simply turned the wheel by hand while feeding the belt in. Worked very well, and gave me nice even holes. I did try using the motor, but even though I've fitted a speed reducer it still doesn't have the real low speed control I need and can run away very easily, particularly when doing a pattern. Edited September 7, 2015 by dikman Quote Share this post Link to post Share on other sites
cdthayer Report post Posted September 8, 2015 [Ouote: I honestly don´t think that 23 or 24 size needles can successfully be used in machines of these classes.]Don’t forget that these machines were used for other materials than just leather. Woven fabrics like burlap and duck sometimes needed a large thread for some applications, so the larger needle could work just fine for them.A smaller thread may have been required in the bobbin, but the upper thread could be large enough to require the large needle sizes.Just my 2 cents.CD in Oklahoma Quote Share this post Link to post Share on other sites
dikman Report post Posted September 9, 2015 Thanks cd, that makes sense (we tend to think in terms of leather on here and it's easy to overlook other materials, I guess). Looking at your list of classic machines, I see that I've got one that you haven't . Quote Share this post Link to post Share on other sites