kgg

The main advantages as I see it: i) they are cheaper for the manufacturer to manufacturer as it will require less parts. ii) may provide a less machine vibration over a belt driven machine. iii) may provide a small amount of increase in response for startup and slow down since the motor is bolted directly to the drive shaft. The main disadvantages as I see it: i) motor replacement is probably going be specific and limited to fitting that manufacturers machine. ii) speed reduction / torque / motor wattage will be limited to what the manufacturer determines is best suited (cheapest) for that machine. iii) more electronics to fail. iv) probably going to be harder and limited in finding replacement parts later down the road as the machine ages. My concerns are: i) repair / replacement costs. ii) long term dependability of the motor and other internal parts iii) are these going to be like our vehicles where it just as well they welded the hood shut since you will need special tools to figure out what is defective. What I find misleading is some of the advertising say they are more efficient at saving 40 - 60 percent of electrical costs. Is that number as compared to clutch motors or existing servo motors of the same wattage??? To me they make it sound like it is over the belt driven servo motors. kgg

The reason I asked is that the Sailrite Workhorse ($225 US) and the Reliable SewQuiet ($199 US) even though they are only 550 watts are 12 coil construction versus the typical 6 and 9 coils of lesser cost brushless motors. As a side note a inexpensive and maybe questionable quality Chinese 12 coil 750 watt off aliexpress is about $190 US. My thought is the more coils should help provide a smoother low speed torque range. kgg

How many coils does this motor have? kgg

Whether either of those brackets are going to fit and work properly will depend on whether the Global WF 1575 is a clone of the Juki LS-1341 or the older Juki LS 341 or if it is a closer cousin to the Juki LS 1342. The bracket in the second sketch configures so the machines feed dog is the driver for synchronizing. To get that bracket to work the machine may also require a new feed dog as well as other parts. I would check with the dealer of the Global WF 1575 and see if the bracket, which is made for the Juki LS 1341, would fit and if so what else would be required like the feed dog, needle plate etc. My take on this type of binding setup is that: i) they use the much more expense 90 degree binder/folder attachments rather then those typically used on flatbed machines. ii) the setup may not provide as quick access for bobbin changes, ii) may have to change parts (feed dog, needle plate) back and forth when you don't want to use it as a binding machine iii) it is also going to be expensive. There are other less expensive alternatives that may provide similar results using the flatbed binder / folder attachments. I use the same binder attachments (1/2" to 2" single and double fold) on my clone of the Juki LS 1341 that I use on my other flatbed machines without having to make any changes to the feed dog, presser foot or needle plate. That way I don't have to have a dedicated and more expensive set of binding / folding attachments for the cylinder bed then the flatbeds. With unison feed machines I do question whether for most needs a synchronized binding / folding setup offers better results over a non synchronized setup to justify the cost difference????? Others with experience using both systems and styles of binding / folding attachments would be better able to answer that. kgg

Nice job. It will be a lot more convenient and functional mounted in the table. A couple of other options would be a better stitch length indicator and belt drive bobbin winder. If you find you are having problems with the thread move your spool of thread down under the table top. You may also find that if you want to install a binder / folder attachment or straight edge guide the two bolt holes to the right of needle that are drilled into the bed may have to be tapped to accept the hold down screws for the attachments. kgg

Some questions to consider: i) What style of binding attachment you are looking to use? A 90 degree binder or the less expensive inline binder attachment more typically used on flatbed machines. The cost difference between the two styles can be considerable. ii) Do you have different styles of machines (cylinder bed / flatbed ) that you would like to be able to transfer the binding attachment to rather then then buying different styles of binder attachments for different machines? iii) How thick is the piece of material you are planning on trying to slide through the mouth of the binding attachment? iv) How thick is the binding material? kgg

Depending on how thick / type of leather you are planning on using and if the portable walking foot will work I would still first choose the the Worker B motor. If you find the speed control isn't where you need / want it then you could add a speed reducer and a servo motor at a later date. The LSZ-1 clone I showed is consistently run at max thickness or just above using the tiny 90 watt standard domestic motor. The advantage of having the zig zag besides the zig zag is you can sew closer or farther from the normal center needle position simply by setting the needle to either the left or right and selecting zero on the zig zag setting. That way it works as a straight stitch machine just with the needle left or right of the normal center position. As a note all the feet / feed dogs available for the LS-1 Leatherworker are readily available for the LSZ-1 from either Sailrite or Chinese suppliers. Before investing in a portable walking foot Sailrite have you tried to get a more capable industrial flatbed or cylinder bed machine shipped directly from China or Taiwan? kgg

The portable walking foot machines were designed for sewing canvas while at sea. That said the Sailrite machines seem to be better made with good customer service and video's then a lot of the other similar portable walking foot machines. The LSZ-1 with the zig zag is a nice option to have while the Leatherworker is a LS-1 (painted green) straight stitch machine and mounted into a short table with a good industrial servo motor driving it. If I were importing one I would go with the LSZ-1 with a hard metal case for safe storage and their Worker B motor if it could be used on the electrical system of your country. Otherwise I would get a LSZ-1, mount it in a table and strap an industrial servo motor to it that would work on your electrical system. The short tables like that of the Leatherworker are I think to short and you would windup putting a table extension leaf on it. The attached photo is of a table I constructed for a LSZ-1clone mounted in a table with an extension leaf. This little machine has one job, edge binding. It has been modified to do this as efficiently as possible in the less amount of space with the necessary attachments.

Like the old saying " Someone's trash is another's treasure." kgg

The quality of thread can play an important part in any stitch as well as the needle. You didn't mention what size of needle you are using. If the your needle is poor quality / damaged or incorrect size for the thread and or the thickness of material you are going have problems. If the quality of the thread is poor then you are going to have problems. I would check the following chart as a starting point in selecting a needle for a particular thread size. Example: V138 needs a #22 or 23 needle but in thick / sticky material you may have to move up to a #24 needle. I think your Class 26 is a clone of the older Juki LS-341 who rated their machine for a #24 needle for V138 in thick materials not what size of thread can fit through the eye of the needle. www.tolindsewmach.com/thread-chart.html I would replace the needle and replace the spool of thread with a brand name products like Schmetz needles and A&E thread both of which can be had from companies like wawak.com. Also note that there have been a lot of problems associated with the 8 ounces size spools of no name brand sewing thread. kgg

If I'm not mistaken: i) Techsew 4800 is a clone of the Juki LS-1342 costing about $ 2300 takes a #18 to #24 needle ii) Juki 1341 costs about $ 5000 takes a #18 to #24 needle manufacturer rated for V138 iii) I am assuming you meant Juki DSC-246 not Juki DS-246 costs about $ (unknown) takes an #18 to #23 needle manufacturer rated for V92 thread iv) Alder 669 costs about $ 5000 sewing thread manufacturer rated for up to V138 v) Parts and accessories for Juki and Juki clones are more available and less expensive then those for Alder machines. Please note the price I have shown doesn't factor in the cost of shipping or anything else. Since this is going to be an expensive purchase find a dealer, even if it means doing a road trip, and do a sewing test run with your items using the thread you want to use. Remember two things: 1) no one machine will do everything 2) BY ONCE, CRY ONCE kgg

The article dikman has suggested is an excellent starting point to help you narrow down your needs. If you need a walking foot with zigzag and your budget doesn't stretch to the portable walking foot Sailrite LSZ-1 then the only options that I know of are i) the used market market for either a used portable walking foot Sailrite LSZ-1, ii) used market for an industrial machine similar to the Consew 146 or iii) a new portable LSZ-1as there are a number of options like the Reliable Barracuda, Consew, Kobe, Rex, to name a few. Be aware that the portable walking foot machines are rated for V92 thread and were made to do repairs to sails. The zigzag feature is a nice add on but you could really open up your buying and machine options if this wasn't a must have for your type of sewing needs. kgg

The price maybe right but getting parts well that maybe questionable / expensive. If you can stretch your budget a bit I would look at the Tippman Boss for $1000 US. If you need parts they are readily available and if decide you need to later on move to a motorized machine you should be able to get most of your money back. kgg

I would suggest trying to add a secondary reservoir air tank alongside your skiver setup to extend the time interval that your air compressor kicks in. How big is your existing compressor tank, size of compressor motor and how long before you empty the tank before the compressor kicks in?? kgg

The Techsew 2750 is a clone of the older Juki LS-341 machine. The following link is to the page which shows "Adjusting the relationship between the feed dog and the needle bar" at the every bottom of the page. https://www.manualslib.com/manual/917750/Juki-Ls-341n.html?page=10#manual kgg

A couple of quick notes for when you decide to order and the your machine arrives. 1. Have a second person to help you pickup, unpack, move, lift and place the machine. 2. Industrial sewing machines are heavy and clumsy to handle by oneself whether they are brand name or clone. Example: i) Juki DU-1181N head alone weights in at ------- 31 kg (~68.3 lbs ) ii) Juki DNU-1541 S head alone weights in at ---- 36.5 kg (~80.5 lbs ) iii) Juki LS-1341 head alone weights in at ---------- 37.5 kg (~82.7 lbs ) iv) Juki TSC-441 head alone weights in at --------- 56 kg (~114.6 lbs ) 3. They probably are going to have packing oil over their surfaces so they are also going to be slippery also. Clean all oil off before trying to move or lift them once they are out of the shipping box. 4. Cylinder bed machine and patchers are nose heavy and always wants to tip over until you get a couple of mounting bolts into the rear of the base and table. 5. Since shipping to your location is so outrageous I would suggest either building a table or getting a used industrial table locally. A industrial sewing table is going to be 1.2 m L x 0.5 m W (48"L x 20"W ) and with the weight of a motor weight in probably around the 35 kg mark. kgg

The prices they have quoted are nuts. Portable Walking Foot Machines: The Reliable Barracuda 200ZW sells for $579 US in North America and the Consew CP206RL sells for $549. These portable zig zag walking foot machines can be had from from China (without the name tag) for even cheaper off of places like Aliexpress. Those sellers would probably quote shipping to Dubia. Of the machines that you were quoted on what I think would work for your small items would be the portable walking foot machines. They may need some small modifications to the pressor foot and feed dog to do thin linings. The Sailrite portable walking foot is a better quality machine but comes at a much higher price tag. Those portable walking foot machines originally were made to repair sailboat sails while at sea. The other three you were quoted on are drop feed machines that would be best suited for your linings and the Juki TL-2000Qi is not a walking foot machine. For your linings you would be better off getting a used vintage Singer 99k type / style machine. A lot of these domestic manual sewing machines can be purchase from India if you can't find one locally. Remember no one machine will do everything. That is why a lot of us have a few different types (flatbed / cylinder bed / patchers / portable walking foot / etc) of machines with varying capabilities. I would suggest starting out with either a domestic sewing machine or a walking foot machine like the Juki DU- 1181N to do your linings and to learn on would be a wise move before jumping into the more capable machines. kgg

The first one you listed is a cylinder bed machine while the other two are flatbed machines. If you can afford a Juki and need / want a cylinder bed then seriously consider a Juki 1341 or a used 341. If a flatbed is what you need / want then buy the Juki 1541 but you should be looking at the Juki 1541"S" model which has a safety clutch. The cost difference is probably less then $100 but could save you an expensive repair if you jam up the machine. The 4-5mm thickness in leather would be approximately 12 - 13 oz and your 10mm would be equal to approximately 24 oz. I think if you want the ability to sew at 10mm or above consistently you probably should consider looking at cylinder bed machines in the Juki 441 ($10K) class and clones ($4k) and for flatbed machines in the Juki 1508 or better. Those machines are going to well exceed you $2,000 budget so that really only leaves the one arm bandits (Cowboy Outlaw ($1400), Tippman Boss ($1000), Master Tool Cub($2000)). kgg

You never mentioned the size of the thread or the size of needle you are using. You may have to move up a size larger needle. I would replace the needle anyway first. kgg

A couple of quick notes: i) the top thread should be thread through the top hole in the top guide pin where you thread through the top hole and around so the thread comes out the bottom hole in the top thread guide pin ii) the spool of top thread should be placed so you have 2 1/2 times the height of the spool from the base of the spool to the thread stand guide arm hole. This will allow for better unwinding of thread from the thread spool. iii) Avoid having the thread stand guide arm hole too high so not to create a steep angle to the thread guide pin. The closer you can get it to being on a horizontal line to the thread guide pin the better. iv) If I'm not mistaken your machine is rated for a max needle size 100 (#16). A #16 needle is good for V69 thread. Using needles and larger sized thread may cause problems depending on the thickness / type of material being sewn and the hook to needle clearance. kgg

That is a really nice useful item. Excellent work. kgg

My first check would be to remove the needle and see if it then allows a smooth revolution by hand-wheeling. If so the needle is rubbing up against something. Have you: oiled the machine, removed the bobbin and checked to see there is no old thread wrapped around under the basket or noticed any signs of parts rubbing? A couple of photo's maybe helpful. kgg

From your sketch I would say it is a British Standard 3870 class 2 lapped seam. Look at the 2.05.02 in the Coats Reference Guide to Different Seam Types under Numerical Designations of Seam Types ( www.coats.com/en/information-hub/Seam-Types ) or ( www.coats.com/-/media/Coats/Information-Hub/Seam-Types_tcm35-155172.pdf?rev=ab977c6d9977486f8312d07387f20bf3 ) for a better / clearer view of the seam types. I would suggest changing to a 2.02.01 or for more strength a 2.04.01 that way you should be able to get an attachment to do the seam in one pass. I agree but not surprised at what the seller is suggesting. Speed reducer either by replacing the hand-wheel or an intermediate speeder reducer between the motor and the existing hand-wheel probably costs less then $200 or put an EFKA servo motor on for $1000 plus. I agree with Wiz that a good start would be to replace the existing servo motor with a good old fashion analog brush motor with the speed rheostat for about $150. My opinion is follow the KISS way, analog servo motor, drive belt, sewing machine. Once you put electronic controls in for the drive motor and needle positioning there are more things to go wrong. I don't use speed reducers, needle positioner's or electronically controlled servo motors on any of my machines. If I needed to lower the sewing speed I would seriously consider installing an intermediate speeder reducer but if I needed to add a speed reducer to get extra punching torque I would say I am using the wrong machine for the job. kgg

I normally use the same size thread on the top and in the bobbin. Sometimes you want to highlight your top seam but don't need the additional strength that will be provided by the same size thread in the bobbin. The main thing to remember is the strength of the seam will only be as strong as that provided by the smaller thread. I would turn off the needle positioning then add a speed reducer pulley between your servo motor and the machines hand-wheel or change the size of the machines hand-wheel pulley. There are pulley size calculators out there that would help with sizing the hand-wheel for a given motor and pulley speed. Are you binding the edges of the material?? If you were doing a lot of felled seams I would invest in a flat felled seam attachment. kgg

Thread Sizing standards can drive you down the rabbit hole that is for sure. For the less commonly used thread sizing the easiest way to determine what the machine can handle is by the range of needle sizes a machine can accommodate and from there work backwards. A rule of thumb with Juki specifications is their machines are able to handle sewing thread of the same size in both the bobbin and the needle for sewing thick materials less one thread size of the max needle size. The needle specification for the Juki PLC 1690 is for a SCHMETZ 134×35R Nm100～Nm140 (Standard Nm120) with a 120 (#19) needle recommended and probably supplied. I used the spec from the Juki site for this machine ( www.juki.co.jp/industrial_e/products_e/lether_e/postbed_e/detail.php?cd=PLC-1690_PLC-1691_E). That relates to a needle range of a #16 to a # 22 needle so from that I conclude it will sew thick materials using V46 (T45) to V92 (T90) thread. For thinner materials the range would be V69 (T70) to V138 (T135). With it's sweet spot thread being V92 (T90). I guess it will depend on the toughness and thickness of what you want to sew. kgg