beefy

Ah, is that so. Thanks for letting me know. It makes me feel a lot better because I didn't know the K6 was not a unison feed. Put that together with no reverse and it looks a lot less attractive. So that "loss" turned out to be a blessing in disguise.

Cheers AIZilla, I do a little boat fishing and there's these things called sea anchors or drones. They are a conical tube, and I was wondering how the hell would I stitch one on a flat bed machine. The post bed machine seems like the perfect machine for that type of thing too. Also looks like it would be easy to add a platform around it if I needed a temporary flat bed machine.

Thanks Dikman, come to think of it I've never seen a used really heavy duty machine for sale, except through a dealer.

Thanks very much guys. Really appreciate the detailed responses. I don't yet have a maximum thickness I expect to sew of anything. It's more a case of I've acquired an extra machine so just wondered if one could be set up for heavier work, rather than having 2 machines that can only do the same work. I'm really still at the beginning of this industrial sewing machine game. It started with my wanting to make a bimini and side covers for my boat but I'm finding I'm falling in love with these industrial machines, especially the walking foot ones, and I find I'm looking for extra things to make LOL. I think it's just a matter of time before I start playing with leather too. Based on what you have explained to me it seems I'd be pushing the machine beyond it's design limitations. I may be better off getting one of the extra machines in a nice working condition with a servo, speed reducer, and needle positioner, and selling it at a profit and putting the money away for a more appropriate machine for leather. I've been absolutely kicking myself for a while now. Seen a Singer 132K6 going for a steal not far from me, but shrugged my shoulders because it didn't have a reverse. Never realised the value of these machines at the time. Needless to say it went very quickly and 2 days later I see the same model machine advertised for A$1000 more. I bet it was that one. I wouldn't have sold it though. Regarding the bobbin conversion I've read/viewed every resource I can on the conversion and understand what's involved. I don't expect this will increase the thread size capability, just want the extra bobbin size. The existing bobbin case seems to wobble a lot so I thought it might be worn out and instead of just doing a direct replacement I decided to jump in the deep end and do the modification. I'm a mechanical fitter and have a lathe and milling machine, as well as access to a CNC mill, so I'm lucky enough in that regard. Regarding the extra torque with a pulley reduction system I've retrofitted my machines with 4 pulley reduction systems and servos, and wow, the torque will smash things. Before I got my Seiko STW-8B I was using my basic lightweight Mitsubishi DB-189 with V138 thread (that's not a typo LOL) and got some needle deflection with the thick stuff I was sewing, and the needle hit the plate. Wow, what a solid crunch as the needle buckled and snapped, I was sure something must have broken or at least went out of adjustment. Nope, just continued sewing OK. That's when I started looking harder for a triple feed walking foot machine.

Something I've only heard mentioned once is the use of a VFD (variable frequency drive) for a 3 phase synchronous motor. The guy claimed the control with this setup totally outshines any servo motor. You can get these drives with single phase input and variable frequency 3 phase output, so you don't need a 3 phase supply to run a 3 phase motor. These drives are often used in industry and have many adjustable settings. Some that may be of interest are: Current limit - this will limit the torque of the motor and could be used as an electronic safety clutch. No need for a mechanical clutch. Max speed - these drives go from 0 hz to a frequency you would not want to run your machine at LOL. However, the max frequency can be set. External braking resistor option to reduce stopping time. This is a guess but I bet they also have a ramp up option which will be adjustable. Likewise my guess is they will have a ramp down option although this may not be wanted/needed. Probably some other settings that would be useful. Google and find a user manual and you'll get an idea. Something I should add is that I've heard running at very low rpm can cause motor heating as the internal fan of the motor is not doing anything useful. I'll leave anyone interested to do further research on that one. However, if the current limit is turned down and thus the current is low relative to the normal operating current of the motor, perhaps this heating effect will not be of any concern.

I can't believe I've now got two medium/heavy walking foot sewing machines. Came across a good price on the Singer so just grabbed it. Would anyone say one machine would be better suited than the other to thread heavier than V138. I'm waiting for parts to convert the Seiko to a large U size hook (the one used in the Juki LU-563), but I also realise that Juki lists an optional U sized hook for "extremely heavy" thread. So I'm toying with the idea of having one machine set up for V138 thread, and the other one for larger thread >>IF<< it would be OK to do that. Just don't know if one machine is better suited to the heavier thread than the other.

Thanks for explaining that AIZilla. Had a little laugh with what you said, "Simple to do, but apparently takes a lot of words to explain..." That's just like the programming of my needle positioner. Seems such a simple task yet the coding takes a lot of time and focus, and keeps getting longer.

Hi Toxo, Thanks for posting that picture. I might actually use the design method of that one to make my own but with magnetic hall sensors instead. Only problem I can foresee is a hall sensor on on disk may pick up the magnet field from a magnet on a neighboring disk. No I've never seen your old type, as I am very new to this industrial sewing machine stuff. I've only seen the ones all over Ebay, Aliexpress, etc. My guess is the sensors on your old one are infra red receiver/transmitter types. What I like about that physical design is it's easy to build (I've got a lathe). Downside is it's a bit more bulky as more position disks are added. Did dust ever cause the optical sensors to work correctly ? Yep, seems many Chinese sellers think the need for instructions is just plain silly. The instructions that came with mine are just completely wrong, and probably based on some other controller. And when you hassle them enough to give you some instructions it's still terrible and not complete. That's what has made me give up on them and play with this idea instead.

Cheers AIZilla, interesting suggestion. I'm just a beginner at this sewing gig and all the videos I've watched start of sewing forward then backstitch then forward again and continue. Would you only start off backstitching with leather but not fabrics, vinyl, etc.

Thanks for the suggestions Nejcek74, yes, using an Arduino Uno or Nano for this one. I normally use these boards but program in straight C using Atmel Studio, but for this simpler project will just use the Arduino IDE and "Arduino C". Also adding an external mix of operational amplifier circuits basically because I'm unsure of how the "analogue" output from the microcontroller would affect the servo. Op-amps will give nice smooth variable DC signals. The basic principle is my system will simply "go between" the foot pedal output and the servo speed command input, and "take over". It will monitor the foot pedal output as well as the heel switch, monitor the outputs from the needle positioner, and command the servo to do things accordingly. So basically the servo is nothing but a driver for the motor and it's not even aware a needle positioner is installed. The servo simply does what it's told by my controller, pretty simple really. The most difficult bit is getting the programming correct and foreseeing all the situations that COULD happen. It's so easy to find things afterwards where you say, "Oh yeah, I didn't think of that condition existing at some point" LOL. I've pondered the idea of a DIY needle positioner disk, where I can have more than 2 sensors IF there's any benefit to having more than just a needle UP and a needle DOWN position. The rotating disk itself would have just one magnet glued in a hole in the edge. Hall sensors around this disk can be moved to any position to have the needle stop in exactly the desired position. For now though I just want to get the basic design working with an off the shelf positioner. Got one arriving mid January. Never thought of the idea of automatic back stitch control, good suggestion. I like that one and it could be my next quest. Will have to work out an electrical way to operate the reverse mechanism.

Thanks Dikman, yes this design will be specific to my setup, but my setup is a typical Chinese servo drive, so any time I get a new cheapy servo, if the connections are not identical, I will be able to easily modify them to suit. You are right, I don't need this so much for very slow sewing but it will be great for other things when I'm going faster. I'm also finding as I'm learning to handle say tarp material or a canvas cover, not having to concentrate on the needle position will make life much easier. I'm also going to make my backstitch foot control so my hands will be completely free nearly all the time. To be honest this is more a labour of interest rather than a huge necessity. I get very engrossed in the design and programming and the hours tick away quite quickly. And when the design is completed (and works LOL) I enjoy it every time I use it.

Thanks Fibresport, the servo IS what normally does the control when it receives the signals from the synchroniser, but my design will command the servo drive based on the needles position. I've already paid for 2 motors and drives so don't want to buy 2 more LOL. Plus I enjoy this design work and it will be very cheap.

In keeping with my growing love of my newly acquired industrial sewing machines, I'm now getting myself absorbed in designing an electronic circuit and programming a microcontroller to make my own needle positioner. I've given up trying to get any sensible instructions for my cheap Chinese servo from the seller. I know it also doesn't have any heel press functionality. So far this is the functionality I'm programming for it: Single revolution/stitch from EITHER the needle UP position or needle DOWN position. This is done by a quick tap on the pedal, either forward (for needle DOWN) or heel tap (needle UP). Stop in needle DOWN position when foot pedal released. Go to needle UP position when heel tapped. Adjustable "coasting" speed when searching for either needle UP or needle down position. This is to have control over overshoot if servo cannot stop motor fast enough. Search for needle position is cancelled if operator presses foot pedal while motor is coasting and waiting for needle UP or DOWN signal. Safety feature - adjustable timeout for motor coasting and looking for needle UP or DOWN position. Coasting stops if signal not received within timeframe. This prevents the machine going on forever if some fault occurs like a broken wire, or faulty needle positioner. Are there any other useful features a needle positioner could have ?

No I don't have a needle positioner installed. The first thing I was wanting to do was check I can actually access the settings for the needle positioner, hence me starting this thread. However, yesterday I order a needle positioner because even if my servo supplier cannot give me the instructions I can still design my own interface for needle positioning (using the off-the-shelf needle positioner) and it will have better functionality than what my servo drive has. Example my foot pedal controller does not have any switch for when you press back on the heel of the foot pedal, and I check the wires from the foot pedal controller and there's only 3 which will be +5v, 0v, and the variable signal from a potentiometer. No wire for a signal from a pedal heel switch. So looks like my servo is very basic and doesn't have this functionality built in.

Well the seller did respond. This is what he said: Needle positioner setting is adjustable without connecting the needle positioner, but an E8 or E9 error code will be displayed once adjusted. The code will disappear once the needle positioner is connected. They sent me a video but it's in Chinese, so I've messaged them back to ask for English instructions LOL. Here's the video in case anyone can make use of it. NEEDLE POSITIONER PROGRAMMING.mp4