Singer 31k48

[Tastech]

@hugh123 I have both machines you mention .The 48 has a roller foot while the 15 has a flat foot .  The roller/foot shaft is also different in both machines as in the needle clamps . The fundamental difference is that the bobbins and bobbin carriage are different . I use my machines for stitching shoe uppers up to 3.5mm overall thickness . Not sure what that is in ounces

[hugh123]

@Tastech I would be running a layer of 3.5 mm and a layer of 1.5 mm so 5mm total. Do you think it could do that? 
Thanks for the reply

[Tastech]

@hugh123 I think 5mm would be about the limit using chrome tan. with the right needle and tension . The only thing i can see going wrong is if the needle cant punch through it may allow the needle shaft to slip from its timing setting . Open the side cover and make sure the needle shaft screw is tight before you start . Do a practice run using 3mm then 4 mm then 5mm which will give you a good indication of what to expect and to just get the feel of things . If you motor doesn't have enough torque to get through at a slower speed then a reduction wheel might be necessary. not for a lower speed but for higher torque. 

What sort of motor are you running ? Old school induction clutch motor or the new DC variable speed ?

[hugh123]

@Tastech not my machine as of yet just one available on fb marketplace. I’d be running veg tan rather than chrome tan not sure if that makes a difference. I assume it has the old clutch motor rather than a servo motor. How do you find wheel feed vs walking feed for this kind of work? I’m on the fence about getting a machine but if it will work for what I want then maybe I can get him to drop the price and pick it up to start with. 

[Tastech]

With industrial machines its a horses for courses sort of deal . The machines are very specific when it comes to intended use . Walking foot versus roller foot is all about intended use . I mainly used a post bed machine for sewing shoe uppers because i can do the concave / convex parts with easy access . I prefer a roller foot because i can do tight curves and see what going on when i am making brogues. I also use a cylinder arm walking foot for other bits but mainly making bags. I use a flat bed roller foot for stitching the padding to shoe tongues and attaching that to the vamp. I even hand sew some features  like apron and spit toes because i don't know of a machine that can do it  You can cross over with machines but generally i use a specific machine for a specific task and even leather thicknesses . 

Ask yourself what specific task do you want the machine to do ? there will be a good machine out there that is perfect for the job . Even consider a new Chinese machine. they are generally clones of existing tried and true machines and to my surprise are really good and relatively cheap . I love the old legacy machine but most are obsolete and very hard if not impossible to get parts for .My preference is a treadle powered machine but after half an hour i get cramps and my hips hurt so i use a servo motor on all my main machines.However I just love the precision of a treadle when doing a wingtip brogue 2 mm off the edge around a tight curve . One really good advantage of a new machine with a servo motor is the reverse feature . No more turning the job around and having the roller where you don't want it and missing the same stitch hole. No one will ever notice it but i know its there and a little piece of me dies each time it happens . 

[hugh123]

@Tastech back again. The 31k48 sat on marketplace for another couple months so I talked the price down a bit and went and tried it. It stitched 5 mm thick like it was nothing and even up to about 7-8 mm. So I went ahead and bought it. Now my question is what needles do you use and up to what size can I run? I received some shmetz 18s with it which I understand could run M40(69) or maybe M36 thread, however if at all possible I would like to run M20(138) with a 22 needle, just wondering whether you've tried anything like that. What size thread can I run in the bobbin? If I could run M36/Tkt92 I would be happy. Also it is extremely fast- what servo motor do you run and could you maybe give me a link? thinking that may be quite helpful in the near future.

Thank you.

Hugh

[Tastech]

@hugh123 My machine uses a 16-257 needle . I dont remember if this is standard or if i tweeked the needle bar to line up  so i can use the same needle on all my machines .I use the 16 for tkt 70 thread . For tkt 90 an 18 might do it but a 20 would be ideal  a 22 might leave too big a hole . You may have to adjust the bobbin tension to suit .

I use a 750 watt servo motor  i got from ebay . I got the slowest one i could find . I believe there are 2 versions with different speeds . I also have one on a treadle which is a modified 29K patcher treadle . As i mentioned earlier the bobbins and bobbin case is different to the 31k-15 so get the right one . I got some spares on Ebay from china ( after making a mistake and getting the wrong size) .When i set one of the machines up with the new servo i also bought some bearings and pulleys to make a speed reducer but i don't need it so i have not installed it .

I forgot to mention in an earlier post the the difference between the 31k-15 and the 31k-48 . The 48 has a roller feed dog not the standard up , back and down feed dog.

look after the machine because parts are very hard to find and you will have to resort to buying a spare so you can rob bits off it .

 

[hugh123]

@Tastechthank you. Im having trouble finding a servo motor that looks like it will work. Could you point me in the right direction?

[Tastech]

@hugh123 this is the one i got 

https://www.ebay.com.au/itm/203842070658

If you search sewing machine servo motor on ebay you will see this type come up everywhere .  There is a difference between them such as watts and top end speed . I looked for the lowest speed and highest wattage . Note that the speed range i chose is 500-4500 rpm and wattage is 600W . Some state that their range is 0- 4500 rpm but i think they don't quite understand what they are talking about . I am happy with both the power and speed . I hardly ever run it above minimum speed which is fine for me . To run it even slower i just pulse the foot pedal and it gives me a stitch at a time .One thing to note with it is that you can bolt it straight on where the existing one was but the pulley did not line up so i moved it about 20 mm left or right . To get the right position i put the motor upside down on top of the table bed and inline with the slot and marked and drilled the holes from the top and then bolted the motor underneath . I didn't use a set length fan belt but this silicone rubber stuff that you cut to length and insert an aluminium joiner to connect the 2 ends . I have no idea what the product is actually called but my local industrial supplier has it in stock . Which reminds me i need to get a few meters for some machines i have restored . The diameter is about 7 mm but comes in 3 sizes .

In case you were wondering i have fitted an after market roller on the foot but had to lift the foot up so it would fit . Pretty easy to do but if your original roller is fine then just leave it .Because it would be of much higher quality than a new one .

From memory  i got some spare bobbins and bobbin case on ebay and they were listed as a singer 31K20 . The 31K15 looks the same but the bobbins are not as deep .Both machines are built on the same basic body but have a few differences the bobbins and bobbin case being one of them .

If you have any problems sourcing them let me know and i will go through my purchase history and take some measurements and see what i can find for you 

Regards 

Tas