M-Style Bobbin Chinese Patcher Mod

[GerryR]

I've had a little more time on my hands than usual and decided to mod a Chinese Patcher to handle M-style bobbins to get the added thread capacity.  One of the goals was/is "no modifications to the existing machine" so I can get back to the original patcher just by swapping parts.  Well, I got everything done "except" I need to either make a different swapable hand / cam wheel or make a different needle bar connection to get the additional needle down stroke, about 0.3".  The cam for the bobbin rotation works as is, as the angles of motion are proportional.  I don't know if in the end I will get it all working, but at least I can easily put it back to original.  I think these patchers get a bad wrap, but mine has worked flawlessly.  It's definitely a educational project.  Comments and suggestions are welcomed.

[chuck123wapati]

I'm wishing you all the best and can't wait to see the outcome. I love mine too a little cleanup and a few tweaks and they run like a clock.

[GerryR]

Well, because I didn't have an easy way to make a new hand / cam wheel to get the added needle stroke that I needed, a machine mod was going to be needed.  I had a second machine and chose to modify it to be sure the mods would work before messing with my good machine.   To get the added needle stroke, I moved the pivot point of the arm by 0.75 inches toward the hand wheel.  I had to machine the frame in order to relocate the pivot point, but it worked out pretty well.  I have one small issue that I will address Monday and that will finish it.  It is no longer a true "patcher" but after running it for awhile with different threads I will swap the parts over to my good machine which is motorized.  Here's a few pictures of what I ended up with.

[GerryR]

First Stitches!  (Still doing some "tweeking," but looks promising.)  These are a single layer of 8 oz. veg tan and a double layer.

[GerryR]

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. 

[TomE]

That's quite a project.  Well done!  Did you adjust the bobbin case spring tension to cover all those thread sizes? I haven't tried #207 thread in my Cobra Class 29 patcher.

[GerryR]

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!

[Tigweldor]

Is that why you wanted to know the size of 328LR needles - thought about using them in your patcher at an earlier time ?

 

Greetings

Hans

[GerryR]

39 minutes ago, Tigweldor said:

Is that why you wanted to know the size of 328LR needles - thought about using them in your patcher at an earlier time ?

 

Greetings

Hans

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.

Edited Monday at 08:22 PM by GerryR
Added needle photo.

[Tigweldor]

well, I´m glad it worked out for you.

Get a "utility model protection" on that (your mods) for China and have them manufacture the needles in your chosen length- you can make some coin from/for your tinkering

 

Edited Monday at 08:09 PM by Tigweldor

[GerryR]

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!)