GerryR

Many of the three phase motors produced today are "inverter" rated and are spec'd to run from 10 to 90 Hz (175-2295 rpm) and are usually attached to a gearbox. In my particular case, a 5:1 gearbox giving 35 to459 rpm final output. Further reduction from the motor pulley to the sewing machine pulley keeps you well above the 10 Hz minimum with plenty of low speed control. Couple that with the VFD setup which allows the top speed to be programmed so that the full range of the pot, in this case foot pedal, is from 0 to programmed top rpm and you have very fine speed control. (The DCservos operate the same way as far as programmed top speed is concerned.)

If you want to control the VFD with a foot pedal rather than from the control panel of the VFD, you can get an inexpensive TIG welder pedal (Ebay) that contains the potentiometer (pot) needed by the VFD for external speed control. I mentioned this in another thread. (Not all TIG pedals have the pot included, some just contain a switch, so you have to be careful when ordering.) Just lock the clutch on the 3-phase clutch-motor and use the foot pedal to regulate speed. The one I'm using on my machine is called a "HITBOX" (www.unitweld.com) and I got it off Ebay. It contains two pots, one the foot pedal operates and another that can be used to limit top speed that is mounted on the box and has a control knob. Just my $.02 @Tigweldor Very neat solution!!

Welcome aboard! Very Nice work!! Interesting wood; type?

I've had mine for years, red handle (fine) and purple handle (medium). I also have their pen style (roundish) that I use for odd shaped cutters; for example I used it for getting into the curved end of my farrier knife and to touch up coarse serrated blades. Very handy, long lasting Items.

I don't know anything about your Seiko but would recommend you look at some AC drives (VFDs - Variable Frequency Drive) and AC-3 phase gearmotors. The VFD will convert a single phase input (like regular household power) to 3-phase power that the motor requires. AC gearmotors can be bought with different ratios; I use one that is a 5:1 reduction. The gearmotors are much more compact than speed reducers made with pulleys and belts. The VFD requires a potentiometer input to vary speed. I found a TIG welder footpedal, new, for $35.00, which had the included pot I needed to control the VFD. Just another option. CowboyBob, on this forum, I believe offers DC servo systems and good support from the comments I have seen.

I never end up on the good side of making money on my ideas. Seems the lawyers are who make the coin. Besides I'm too old to care; I just do these projects to stay busy and keep out of trouble (most of the time anyway!)

Yes - When trying to sew 20 oz. leather, the 135x16 needle's shoulder would enter the leather, distorting the entry hole, due to the added stroke associated with using the M-bobbins. CowboyBob recommended the 190 needles which were approximately 5+ mm longer. By cutting a few mm off the shank, the shoulder is now above the 20 oz. leather at full down stroke on the machine because of the longer 190 blade.. It worked out well. Added the Photo of the Needles: Needle on left is 136x16, center standard 190, right is shortened 190. Notice the extra length in the blade compared to the 135x16.

As I seldom use 207 thread, I left the tension on the bobbin alone; it works as is for 69 thru 138 (I don't use 69 much either). The 207/207 in the picture above had too much bobbin tension, but I didn't fool with it much. I just wanted to make sure it functioned with the three thread sizes (92,138 and 207). Once I get it motorized, i'll do some long runs with the proper adjustments for all the thread sizes. There is enough range in tension setting for the upper thread, I think, to compensate for the 207 in the bobbin. On the Chinese patchers there are two upper thread tension setups (Some people say one is for bobbin winding, but I can't see how that works for bobbins the way it is set up). I always use both (actaully 1-1/2) for upper tension adjustment and have had no problems. On my unmodified patcher, I changed the needle system to 135x16/17 because of all the leather options, but because of the added stroke of the modified unit above, I'm using a shortened 190 needle system. Projects like this one keep me in the shop and out of trouble, mostly!

Just to finish up and make some final comments: Here is a picture of the different size threads run on the machine. Everything ran pretty well except when running the 207 thread in the bobbin. I need to increase the upper thread tension or lower the bobbin tension to get the knot to pull further into the leather. I did the stitching one-handed with the machine clamped to a table, hence the crooked stitch paths. Once I get it motorized, I can use two hands and guide the leather better. Like I stated earlier, it is no longer a true "patcher" due to the size of the arm however, the dimensions of the new arm are 1.5" wide by 1" deep, so it can still be used in fairly tight places. It was a fun project and with the larger M-style bobbins, I can do "longer" projects between bobbin changes. Also, being able to use 207 top and bottom makes for more sewing options; 207 in the original patcher bobbins wouldn't get you very far.

Is that not a DC servo controller/motor that is driving your machine? If so, why not just change the parameters in the controller to get better low speed control. Most of the DC servo systems can "crawl" and have ample torque for the machine. Just curious.

I don't know how your machine is assembled but my lathe has oil level windows that pop out of the front of the machine and you just replace an O-ring to stop a leak from the window. I use a thin blade to work around the window to get it out. I dont know of any "repair" sealer that will work once the oil starts leaking; maybe someone else does.

@CowboyBob The 190 system works perfectly. I trimmed 5mm off the top of the shank and can now do 20 oz. leather (machine limit) without the shoulder hitting the leather and widening the top of the hole. Thank you for your input!

I was told it could be done, just have never seen it done. From the article linked, it is very involved; unless you are running some large motors with very expensive VFDs (for which Rockwell Automation is noted for) I think it would be cheaper and safer to use one VFD per motor. But, thanks for the link; never to old to learn something new!

I'm working on a project, just for my amusement, where I changed the needle stroke (I'm presently using the 135x16 needles) of the machine. Because of this the added stroke causes the shoulder of the needle to just enter the leather on 16 oz and and above, widening the hole at the needle entry point. I read that the 328 needles have a 1.98mm shank diameter up to size 140 and a larger shank(s) after that. the 135x16 needles have a 1.98mm shank. If the 328 needles have a slightly longer blade, I could cut the shank to get the same total needle length (~45mm) and keep the shoulder away from the leather. This is part of my conversion project of a Chinese patcher to using M-style bobbins. If the total length of the 328 is near 60mm, as Tigwelder indicated, then maybe I chose the wrong system to modify. Like I said, just amusing myself.

Looking for the actual length of the shank, shoulder and blade of the 328 needles sizes 19/120 and 22/ 140. I found the overall length of 5.2cm and shank diameter of 1.98mm by searching but can't find the other info. Any help will be appreciated! Thanks in advance.