Help! Wanted Techsew Stitching Nirvana, Got The Blahs Instead

[JLSleather]

Checking in a bit - couple things I need to pop out so they can be drying .. According to this book (which does not say techsew) 21 is a "roller follower" and 7 is a presser bar guide bracket. I'll get you the part numbers (at least what they were when this 'edition' was printed) in a bit. $8 says that part number is valid whether it says techsew, cobra, cowboy, blahblah, and prolly some others too.

[YinTx]

Update on the BGMC 2700 Variant (similar to Techsew 2700)!

The more I looked at the machine in operation, the more I became convinced there was something wrong with the tensioner spring in the bobbin case, (photo, with screwdriver pointing it out) so I removed it and tried to flex it.

Not really a spring steel metal as you might expect, since it bent easily. So I gave it a bit more of a curve, and reinstalled it. Voila, there was a bit of resistance on the bobbin thread once again, and I could adjust the tension by tightening/ loosening the screw. Success there! I feel the tension is still uneven as the knots don’t alway sit correctly on a single run of 2 foot stitching, but it is much improved. If I can find a new one to replace it, I will. Any ideas on further improving tension consistency would be appreciated.

I also observed the shaft in the end of the handwheel while the machine was running and not piercing the leather. The handwheel was slipping on the shaft, and not at the safety clutch as I had originally presumed. So I removed the hand wheel, and noted the screws that secure it to the shaft (again, photo with screwdriver pointing it out) were not even aligned with the flat spot on the shaft.

Realigned, tightened screws very well, and once again, voila, success! Punching through hard veg tan once again, no problem.

I have also lowered the needle to change timing between the hook and the needle. So I seem to have the smaller machine running stitches with larger thread (135 is the only one I have tried so far). Will change out to a lighter thread tomorrow and see how that works, hopefully I have discovered most of the issues and can get back to work with this machine.

Will try to take a video of the Techsew 4100 later as well, to illustrate where the binding seems to be occurring in there and update on that when I have done it.

YinTx

[JLSleather]

Ooops.. sorry -- I thought I had mentioned the hand wheel slipping possibility. Good idea when things aren't what they should be.. drop the belt off the machine. If you can turn it by hand and still have the same problem, you have eliminated the motor as part of the problem. Plus, if the hand wheel is loose on the shaft, you'll probably catch that then.

[YinTx]

Update just to show video of binding on the Techsew 4100. There are two videos since I had to make a second take to get the additional information in.

I have also been able to get the smaller machine to handle the 69 thread, but not very well. Still looking for a replacement bobbin spring for a BGMC, a close variant to the Techsew 2700, so if anyone knows where I can get that part, please let me know.

First Video of Techsew 4100 binding problems:

Second Video of Techsew 4100 binding problems:

YinTx

[Wizcrafts]

Before doing anything I mention below, try rotating the outer foot pressure adjuster on top of the machine. Sometimes they get drilled off center and the presser bar can hang, until you lift and release to feet. It happened on my machine and I drilled out the bore slightly to clean it up.

Check the forward alignment of the inner and outer feet, to ensure they don't make contact and bind against each other.

You may have to remove the (4) C-clamps from the crank arms controlling the feet, including the one on the back, and pull off the entire crank assembly. It will be hell to get it all back on, but it is doable. I just went through that process, for other reasons. Remove the needle first. At this point the inside foot will be rotatable slightly. Make sure is doesn't bind going all the way up and down (disconnected.

With the cranks off you can plainly see what is going on with the lifter block. You also have unfettered access to the screws that lock the presser bar in position. It may need to be lifted, lowered, or rotated slightly (if the inner and outer feet hit each other). Unscrew the adjuster and see if you can fully raise the outside presser bar, then have it drop on its own when you let go.

The block with the big roller rides against a flat steel bar with oversize holes. They allow you to move the top and bottom as needed for the smoothest up and down flow and lease forward/backward free motion needed. You can actually remove the presser bar from the top, with the outer foot and screw off. Then you can plainly see what is deflecting the big coil spring and shifting the lift block.

Oil everything left in the head, which will be so much easier with half the parts out. Oil the four shafts before trying to reinstall the crank assembly.

A magnetic pickup tool is your friend. Make sure that parts that fall down cannot fall through to China! I save clips and screws on magnets, or in magnetic bowls.

If you find that the casing has been gouged by the binding lifter, try to smooth out the sharp edges.

It's hard to troubleshoot these machines over forum posts. But, once you figure out what caused all this, you will have lots more experience in case something similar ever occurs.

Edited January 28, 2015 by Wizcrafts

[YinTx]

Wizcrafts,

Thank you for the detailed suggestions. I did take it apart further, and took some video along the way. When I can get it uploaded, I'll post it. Suffice to say, I did remove the cover, the shuttle and race, and removed the link crank arms by removing the snap ring "c-clips", and lowered the block some (about 1/4") just to see what it would do. That only managed to keep it from feeding leather when in service, so I think I can rule that out as an issue. Nothing seemed to be out of alignment (the rods on the needle and presser feet never were contacting each other). The main issue I saw was the rear presser foot (with the spring) would not move freely. I loosened the set screw slightly on the bushing that is at the bottom of the casing as the presser foot bar exits the head, which seemed to help some. It appears that this bushing is causing most of the binding. I'll be looking for that part along with the shuttle and race so I can replace it if possible. The issue is not yet solved, but I am hoping this is narrowing it down!

When I can get a video of the dissection uploaded, I'll post the link.

YinTx

[JLSleather]

Is that the bushing you said it didn't have?

Wondering from what you said, coupled with what Wiz said, if a fella couldn't rotate that shaft a half turn (since so much is loose already) and eliminate the possibility of a bent shaft. Much more likely I would think that a worn bushing is causing it to 'one -side', particularly since it rotates the roller into the casting

[YinTx]

I'll let the video speak for itself. Sorry about the volume, I'll work on speaking louder in the future. But if you turn it up, you can hear it pretty well.

You can see I took it apart, tried to make adjustments, checked for free play, tried to find the binding area, etc. In the end, I think I have a general idea of what to do, but please take a look and make any inferences and suggestions based on what you see. JLS, I am thinking maybe if I can not rotate the shaft, maybe I can rotate the bushing. Next time I open it up I'll try that. Thanks to everyone helping me out here, it'll get fixed eventually!

YinTx

[YinTx]

So a quick update on the Bogle-Greenwell 2700 (BGMC 2700, or Techsew 2700 variant). I ordered a new tension spring to install in the bobbin basket to deal with the bobbin tension spring problem. It unfortunately did not have the same size holes for the screws to hold it in place. I was informed I needed a new bobbin basket, so I purchased one. On arrival, it did not fit cleanly, and caught the thread as it came around the top, causing a birds nest on the bottom of the leather as it stitched. So I removed it, and modified one of the springs I had previously purchased to accept the screws of the original basket. It is now sewing flawlessly, so I used it to make my new laptop bag mock up from vinyl, using 135 thread. I was also able to use it with 69 thread to make repairs to a leather bag, and it stitched just fine. The operator (i.e., me) however did not stitch flawlessly, so I can see I need much more practice with the machine to make acceptable stitches. Here is a photo of the completed mock up:

YinTx