Bobbinless?

[electrathon]

Hi Wiz,

Easy way to do it is to use the brake pad off a bicycle and shape it to fit into the belt groove on the band wheel. Make a bracket that can be held in place by the top right frame bolt (you may want to put an equivalent thickness spacer down the bottom bolt) and an arm that drops the brake pad into the belt groove at between 30 and 45 degrees. The arm needs to be on a hinge so it is free floating. When travelling in the correct direction the pad is pushed out of the groove slightly but when you go backwards it will lock in place.

Eventually I will crank out a commercial adjustable one to fit both old and new styles of domestic and industrial Singer frames.

Do you have a picture of this?

Aaron

[Anne Bonnys Locker]

Do you have a picture of this?

Aaron

Hi Aaron,

While I am happy to describe one way to do it I cannot really share my pics of the prototypes as they are of a more advanced design (actually simpler) and I do hope to make a dollar or two out of this.

[JoelR]

Neat idea Anne. Essentially a wedge when going backwards.

Back to the op topic: The reason it is not a simple retrofit is the thread fed by the needle must be fully wrapped around the bobbin. This would require a much longer travel for the takeup bar (or whatever the arm is called that pulls the needle thread tight after the bulk of it is pulled around the bobbin) to account for all the extra thread that would have to be fed to get around a full spool. The thread fed by the needle must move from one side of the bobbin thread to the other and the only way to get there is to make the trip around the bobbin.

A chain-stitch machine grabs the thread from the needle and holds onto it as the needle makes its up-stroke. During the next down-stroke the loop that is being held onto is positioned so that the needle falls within the loop and the next loop is grabbed from the needle before it makes its up-stroke creating a series of interlocking loops. This is a common way of stroring extension cords that are too short to need a spool but too long to have just lay around.

Edited April 26, 2011 by JoelR

[stanly]

Neat idea Anne. Essentially a wedge when going backwards.

Back to the op topic: The reason it is not a simple retrofit is the thread fed by the needle must be fully wrapped around the bobbin. This would require a much longer travel for the takeup bar (or whatever the arm is called that pulls the needle thread tight after the bulk of it is pulled around the bobbin) to account for all the extra thread that would have to be fed to get around a full spool. The thread fed by the needle must move from one side of the bobbin thread to the other and the only way to get there is to make the trip around the bobbin.

A chain-stitch machine grabs the thread from the needle and holds onto it as the needle makes its up-stroke. During the next down-stroke the loop that is being held onto is positioned so that the needle falls within the loop and the next loop is grabbed from the needle before it makes its up-stroke creating a series of interlocking loops. This is a common way of stroring extension cords that are too short to need a spool but too long to have just lay around.

Thanks for getting back to this:

para 1- I'm having a tough time visualizing this - don't suppose u have an illustration handy?

pars 2- U know the chainstitch I am talking about is 2 thread, NOT daisychain?

[Art]

I understand what you are talking about, it is a double chainstitch machine. I guess you can compare it to a serger where the bottom thread goes through a tube to the looper. In this type of stitch the looper thread is put through and around the upper loops by the looper, first outside the top loop and then inside the top loop forming the next outside loop (the needle and thread come down through the loop). Here again, there is an interaction of the loops, not an actual lockstitch where the top and bottom threads have to "dance" or go around each other to form the lock.

I don't know if I explained that too well, go look at a serger.

Art

Thanks for getting back to this:

para 1- I'm having a tough time visualizing this - don't suppose u have an illustration handy?

pars 2- U know the chainstitch I am talking about is 2 thread, NOT daisychain?

[simran]

I used to have a McKay stitcher for doing moccasin soles.

I always marveled at how that thing grabbed the thread and held onto it during the stitch process.

It was the single thread variety of course.

[simran]

here is the business end of a Champion 77 if anyone is curious.

This is the single thread variety.