kgg

The problem with buying used is like buying a used car, you have to be careful. My rules of thumb when buying a used machine for myself: i) is it has to be in impeccable condition or as close to new condition, ii) not have been used in an industrial setting iii) the price is 70 percent, max. of what a new one lists for. Example: The Boss you mentioned for $850. A new Boss is $999 x .70% = $699.30. The max price I would pay would be $700. Yes those machines use the 794 needles. A typical 135 x16 needle used in the Juki LS-341 has a shank diameter of 2.0 mm while the 794 has a diameter of 2.5 mm. As a note a 2 1/2 " finishing nail has a shank diameter of 0.099" or 2.51 mm. kgg

A few photo's would be helpful in showing the overall condition of the machine, asking price and most importantly what you want to sew. My main concern is the parts and accessories for the PFAFF machines can be expensive. Unless you are use to using a sewing machine with a clutch motor you need to add to the selling price somewhere between $150 and $200 for a servo motor to get controllable speed control. kgg

It would be if nothing else the little road trip to see if the machine would work for your needs and the owner my drop her price once you arrive. I still would wonder whether the cost saving of $150 USD would be worth the no warranty and no extras versus a new machine with warranty???? kgg

A new Boss is $999 USD plus shipping plus any accessories. Does the machine come with anything extras? The 341 has probably been used and abused in a factory setting and is old. There are no photo's showing the drive belt or the internal head parts or what parts were replaced. Also there has been a lot of machines imported from overseas. IMO I would stay away from the 341 and would consider the Boss but that may not be the machine for your purses as the hole the needle will make is going to be very large. Think of the size a 2 1/2" finishing nail will make. I would take a sample of your stuff and test out the Boss. Keep in mind the Boss will be better suited more for doing sheaths and holsters then purses. kgg

It really doesn't matter on how long the rivet shank is. The shanks are all the same diameter for a given rivet size whether they are 1/4" or 1 1/2" long. Procedure normally in a nut shell is punch the appropriate size hole in the leather, put rivet through, put burr over the shank and with a the correct size rivet setter set the burr down over the shank to the leather, cut the rivet off slightly above the burr and then dome the rivet shank with the rivet setter doming part. kgg

Just to add to @AlZilla comments. when you stop to do a 90 degree turn: i) bury the needle to the bottom and then raise the needle about 1/4" ii) raise the presser foot up slight to take the tension off the material and the turn the leather. iii) drop the presser foot back down and continue. Some of your problems are probably being cause by not holding the threads for the first three stitches and then back stitching to your starting stitch that will lock the so the threads don't get pulled. I am going to assume you meant 135 x 16 needle not 136 x 16. For V138 thread the range is #22 to 24 depending on the thickness and type of leather. Veg tan I find grabs the thread more then chrome tan. Here is a link to a good thread size vs needle size chart ( https://www.tolindsewmach.com/thread-chart.html ) Looking at your photos the leather looks very thin which means there is very little thickness to constantly bury / hide the bottom knot in. I would suggest: i) you try again with either thicker leather or a few layers of thin leather to give the needed space to burying the knot. ii) you lock the starting stitches. kgg

Just watched this youtube video about you make those fancy very expensive ladies bags and thought it might be of some interest. Is it true or misinformation I don't know but it does make one wonder. kgg

Basically sanding the edges of leather sorta like those various shapes of sanding / honing cones used on dremel machines but on a lot larger scale. kgg

Nicely done on the 3D printed template forms. My suggestions: On the 3D printed templates. 1) Increase the nozzle end temperature and filament compression. 2) At your direction changes in the template "Cutting" and "Marking" templates at the four corners do a 0.25 mm fillet so the filament is laid down as a radial turn rather then a 90 degree turn. That way the head speed doesn't have to slow down as much to make the turn which will decrease your print time. 3) I would change the "Cutting" and "Marking" from being indented to being raised markings which would decrease your print time. 4) If the bed of the 3D printer is to small to allow you to print say the "Cutting" and "Marking" template as one unit change you design slightly by putting in joining slots or shapes. I would try: 1) cutting the ends of the sandpaper so they join together at say a 45 degree angle. 2) Then super gluing some thin 1" nylon binding tape to the back side of the sand paper so 1/2" is glued to each end. Then the other end is butt ended to the first part and supper glued to the other side of the 1/2" binding tape. That should eliminate the overlap ridge / bump and as it rotates you don't have the whole joining edge of the joint striking the leather at the same time. It may or may not work but maybe worth a try. kgg

Probably because China is such a large market. I know they make the Juki DU-1181n walking foot machine in China. I have one and it is NOT of the same quality as my Juki DNU-1541S made in Japan. kgg

The Juki DSC-246 is made in Japan. Also if you zoom in the nameplate indicates it was made in Japan. kgg

You also might want to check wawak.com for needles 135x16 x size 16 needles ( https://www.wawak.com/sewing/sewing-needles/industrial-sewing-machine-needles/schmetz-leather-industrial-machine-needles-135x16-tri-dpx16-d-10pack/#sku=smnl135116 ). I would not advise you to use a thread larger then V69 with #16 needle. My personal option on the Vinymo thread is yes it can be used in sewing machines but really is meant for those with Class 441 machines like the Juki TSC441 as well as the clones like the Cobra Class 4 and the Cowboy 4500 or the one arm bandits like the Cowboy Outlaw or Tippman Boss to name a few. kgg

What I would do is vacuum the machine with a throated down (1/2") shop vac, wipe the exterior of the machine of with a damp cloth, inspect the internals and if you think there is sand in the internals I would then do a couple of complete flushes of the machine with diesel and then with synthetic transmission oil then wipe dry and oil everything. kgg

From their website ( https://artisansew.com/cylinderarmandpostbedmachine.html ) " Fabrics: 135 x 17 Size(14 to 23). Leather: 135 x 16 TRI Size(14 to 23) " Using undersized needles for your thread my cause problems depending on the thickness and toughness of the leather as the hole the needle makes has to allow for not only the top thread but the twice the thickness of the bobbin thread. If the material is sticky or the needle hole is to small you can get skipped stitches. Here is a good cross reference of recommended needle sizes for various thread sizes. ( https://www.tolindsewmach.com/thread-chart.html ). According to this website ( https://districtleathersupply.com/products/vinymo-mbt-size-5-0-6mm-polyester-thread-full-spool ): Sizing Size 8: Comparable to machine thread size 92 Size 5: Slightly thicker than machine thread size 138 Size 1: Slightly thinner than machine thread size 207 #8 - 0.5mm #5 - 0.6mm #1 - .75mm #0 - 1.00mm When you compare those thread generally accepted thread dimensions to the chart I referenced something is way off. I would strongly suggest contacting both Artisan as the 246 appears to be rated for up to V138 thread and the manufacturer of the thread ( https://nagai--yoriito-com.translate.goog/eng/pages/13/?_x_tr_sl=ja&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc ) or the US distributor ( www.districtleathersupply.com ) V92 - 0.337mm V138 - 0.414mm V207 - 0.508mm V277 - 0.586mm Also here is a pretty good review of the Vinymo thread from a previous discussion in 2022. kgg

The Consew is just another clone variation of the Singer. Some of the clones use a small needle like thing that you tie the thread to and drop it down the threading hole. If they copied the thread from the Singer, Singer had their own thread pitch and finding them is going to be difficult / impossible. So you can either re-drill / re-tap the holes or use a smaller bolt that will fit through the hole. kgg

I see they added a bobbin winder to the top of the casing rather then off the belt. Great price at $2000 CAD or about $1440 USD. kgg

How good a copy, clone or whatever you want to call them depends on the quality of the casing and internal parts. kgg

Download the Singer 29k-72 manual. Here is a pdf version: kgg Singer 29K71, 72, 73-1.pdf

Two basic methods depending on your interest: 1) Hand stitching, relatively inexpensive. 2) Machine sewing, relatively expensive. Basic New hand operated sewing machine from $1000 USD up and New motorized sewing machine from $2800 USD and up. kgg

Assuming the machines are in good operating condition. As a note the ls-341 is basically an older version of LS-1341. There is a topic that should answer your questions. kgg

I don't think you will ever get a good stitch when the material is .4mm thick and the bobbin thread is .292 thick and the top thread is .292 thick for a total thickness at the knot of .584. I think you would have to down to something like V33 thread. I think the stitch line in the paper versus the fabric has to do with the paper being rigid and the fibers fabric move as the needle enters. The lack of fabric friction, the fabric weave, the thinness of the material and the V69 being UNbonded probably is causing the thread to twist/curl. Try a seam with 3 layers and see what happens. kgg

I wouldn't bother with the belt cover, I find it harder to grip the handwheel and like @dikman said I never install them for that reason. If you really want / need one find someone with a 3D printer and have them print one. I would suggest: i) getting some 1 1/2" plywood, maybe difficult / expensive to get or two pieces of 3/4" plywood and gluing them together. Then gluing a nice laminate to the top of the plywood. ii) dump the clutch style servo motor for either a brushed or brushless servo motor. It will improve your sewing experience particularly with that 3:1 speed reducer you have. kgg

The correct size of needle for Tex 70 (V69) is a size 100 (#16) in thin, a size 110 (#18) in thicker possibly a 120 (#19) in real thick. The correct size of needle for Tex 90 (V92) is a size 120 (#19) in thin, a size 140 (#22) in thicker. Here is a good chart for needle size versus thread size: ( https://www.tolindsewmach.com/thread-chart.html ) I could be mistaken but the PFAFF 545 H4 uses 190R needles to allow for the addition sewing capacity height wise of the H4. Thin materials will always pose a problem as there really isn't enough material to hide the knot sort of like trying to sew a sheet of paper. That combine with an oversized needle for the thread size and you can get funky stitches. kgg

As @dikman said. I think you will be wasting your money on anything with 335 in the model number for your needs. kgg

If I'm not mistaken the sewing capacity of the machines you are looking at is roughly 12mm and you want to sew 15mm. The machines so far are what I would consider similar machines to the Juki LS-1341 or Juki LS-341 sewing capabilities with a max thread size on top and in the bobbin of V138 ( .4mm ) in max sewing thickness. You may sew 15mm occasionally depending on the needle thread combination, the type material and the toughness of material but consistently probably not. To sew 15mm which is touch less then 5/8" really you are into a class 441 machine similar to a Juki TSC-441 or clone. Since you are hand stitching you are probably using .8mm thread which is roughly V554 / T600 / Tkt 5. That thread size will exceed even the Juki TSC441 or clones which can handle V415 (.7mm). Another option maybe a one arm bandit in the Class 441. In that class you have three options Tippman Boss, Cowboy Outlaw and the Weaver Cub but will still be limited to V415 thread. kgg