The cheapest motorized Chinese Cobbler?

[SmartShop]

About the belts:

MXL has a tooth pitch of 1/12.5" or 2/25" or 0.0800".

GT2 has a tooth pitch of 2mm or 2/25.4" or 0.0787"

The difference might be enough to mess things up with a belt wrapped around a sprocket but with only one tooth engaged on an inverted belt, I am pretty sure that it will work fine, maybe better than an inverted MXL belt because inverting will spread out the teeth a bit. 

[SmartShop]

OK, it's out of the box, almost all of the Styrofoam is removed and my room is destroyed.

After a second look, the chrome on the hand crank side lever has it's plating bubbling and peeling off.  It looks like I'm going to have to sand and paint more than the frame.  Additionally the little sheet metal piece that holds the spring loaded arm for the thread is bent and pretty ugly.

I had hoped for better but for $70, this is pretty much what I expected cosmetically.

I think some of the hardware might be missing, specifically for the stand, probably not a big deal but annoying.

Once I get it on the stand, I'll try to assemble the rest and see if it works.

[SmartShop]

Well, the stand sucks.  I almost tipped it over twice, it is clearly a poor balance job and I may be missing one of the screws that retain the legs but I will be replacing all three because they are too short, the two are "hanging by a thread".

The big problem I have is the shaft the hand crank bolts to got smashed in to the bearing and that deformed the pin key.  After a few taps with a sledge, the shaft slid out of the inner race of the bearing.  The good news is the hand crank is a tight fit on the shaft.  I had to give it a few taps before the nut would engage the thread and snug it up.

Once the hand crank was on, I turned it and met stiff resistance because the needle shaft was clamped too low to the linkage.  After a few turns of a screwdriver to loosen, adjust and tighten, the crank turns but with a scraping noise at certain points.  It seems like rubbing, not binding.

I think this design just needs a few washers to keep the pieces from rubbing against each other.

Compared to the Cobbler of Turbo Conquering Mega Eagle, mine has a shielded bearing, that might not need replacing and my shaft is a tight fit so I probably don't have to make a new one.  The key will probably need replacing and the hand crank keyway is quite oversized I'm not sure how I'll fix that, I may make a key with two diameters and a step.

I'm going to have to watch more videos on the operation to see how to tune it up.  I think I want to start with the rotating needle and foot assembly to clean and lubricate the inside.  Next, I'll probably go after the bobbin assembly and arm.

For kicks, I held up the motor and I think I might be able to make a platform to hold my spool of thread and mount the motor underneath.  The good thing about that spot is it could make mounting and moving the machine simpler.

Eventually im going to have T-slots in the top of my workbench, I plan to make a base that will allow me to clamp it to them for a sturdy support that does not extend beneath the arm.

[kgg]

This is my Chinese Cobbler be readied for strip down to add a longer drive shaft and pulley which will be connected to a motor. The pictures may give you some ideas on adding some attachments.

 

[kgg]

I forgot to add that I added a removable table top (Black thing), main mounting plate, adjustable / removable nose support, 1 lb thread spool holder, a two light swivel lighting holder, scissors holder, better stitch length adjuster knob, a needle position indicator, higher top thread guide, relocated the main tensioner, repurposed the second tensioner as a bobbin tensioner and added a edge guide. This truly is a tinkers machine.

Stay Safe,

kgg

[dikman]

I didn't realise that you had one of these beasties too, Keith. You really like your 3D printer don't you! The small table is a great idea for one of these machines and yours looks very neat.

Smartshop, those legs it comes with are probably great for a street-side repairman in Shanghai, but in general are pretty useless. Most users make up a wooden base to attach it to.

[SmartShop]

For now I need the stand.  Once I have my workbench with the T-slots, I'll be able to make accessories that attach to the workbench instead of the sewing machine itself.  This will make it very modular and flexible and easier to store the parts.  I'm only going to use the machine occasionally so storage matters.

The motor is going to stay with the machine so that mount will be fairly permanent and hopefully as minimal as possible. 

I think I am going to make a mount that uses a toggle clamp style linkage so I can disengage the motor to make it a bobbin winder too.

On YouTube there are cobbler videos by K S Lam.  One is really good and uses a clear cover on the arm to show how the machine loops the top thread around the bobbin to make the stitch.  Another shows a thread holder with an arm that prevents thread twists.  I think I want to do that and also incorporate my motor mount in the same piece.  That's my plan so far.

The motor I have is held together and bolted to the standard mount with two long threaded rods parallel to the output shaft, with nuts on both sides.  Its also about 3.5" long so I'm going to take the motor to the hardware store to see if I can find some kind of 2x4 hanger to use as the pivot point for my motor mount, then a modified toggle clamp to have an over center mechanism to hold it engaged with the hand wheel ring.

My belts should arrive tonight and that Walmart MXL sprocket is coming from LA so it shouldn't be delayed like the sprockets I ordered from China.

I want to bush my arms but I don't (yet) have the lathe and mill I would want to do that job right so I'm looking at ways to do a temporary fix that doesn't prevent me from doing it right later.  I'm not sure if I can do a good temporary fix on the hand crank shaft but I can just keep that well lubed.

[kgg]

16 hours ago, dikman said:

I didn't realise that you had one of these beasties too, Keith. You really like your 3D printer don't you! The small table is a great idea for one of these machines and yours looks very neat.

Thanks dikman, I actually really like the little "Tinker" and the 3d printing helps me solve problems inexpensively on all my machines as well as my other interests.

kgg

[SmartShop]

I did some shopping today and I think I have figured out how to do a cheap tune up that will us an inexpensive material to bush the 8mm shaft without much machine work.

I'm going to leave the 6mm bolt alone for now.  The good news is if that joint wears, it will all get cleaned up when I ream it out for a real bushing.

I got an acorn nut and a toothed lock washer for the 12mm shaft to make it pretty.

One of my belts came in.  It is a looser fit than I had hoped for.  I will probably need two layers of foam double stick tape to take up the slack.

I got a piece of 2x4 and some sort of Simpson 4x4 anchor.  I have decided that my first motor mount attempt will use this.  It will allow me to mount the motor at the back, the sewing machine in the middle and then the base in a more balanced position.  Home Depot didn't have toggle clamps so I might have to order one.

Now the 8mm shaft bushing idea is this: I was looking for plastic tophat bushings but I wasn't finding workable sizes unless they were $2+ at McMaster Carr.  Since I'm going to need at least 2 and I'm not sure how they will last, I decided against that.  What I found that is cheap is polyethylene spiral sleeving.  3/16" with 1/32" wall should do it.  The idea is ill replace the 8mm shaft with a 1/4" bolt that has a nice finish and wrapping it with the spiral sleeve will make it 5/16", very close to 8mm.  With some nylon washers, it should slick things up and the slit in the spiral can even hold some grease.

I think a 1/4" bolt will be strong enough as a temporary fix but eventually ill add better bushings and full size shafts.

[SmartShop]

Well, that was a bit silly, I assumed that the shafts and threads would be common between Chinese Cobbler machines.  Turbo Conquering Mega Eagle had a 12mm hand crank shaft, mine is 10mm.  Also, looking through McMaster Carr, they actually have a good selection of very thin sleeve bearings so I ordered enough to do my 1/4" shaft tune up that won't need machining and enough to do a full size 8mm shaft fix and the 6mm bolt.  I also got a 10mm shoulder bolt to make a new hand crank shaft with and on eBay i found the 16100 size bearings, 10mm pillow block bearings, acorn nuts to cap off all the threads and a couple reamers for installing the full size shaft bushing fix (3/8" adjustable plus 8mm).

By the time those orders were in it was very late and looking at toggle clamps, I couldn't decide which would work for my motor tensioner so I slept on it and after I woke up, the answer was there.  Now I ordered the type I need in two sizes.  Hopefully the little tiny one will be enough.

My belts are still a little issue, they are 6mm wide but my foam tape is 1/2".  I think I'm going to try to slit my tape in half on the roll with a razor blade.  This going to be a double edge razor held in a vise, held in a bigger vise so I can hold the blade 1/4" off a flat, lay the roll on the flat and spin it against the blade to make the slit.

Any way, last night and this morning I figured out a lot of what I'm going to do.  The key for the hand crank shaft is one question that still remains.  I'll measure the keyway in the hand crank and order a pin.