Has this ever been done?

[catskin]

10 hours ago, CowboyBob said:

With the way the servo & speed reducer work & how lightweight they are compared to this setup would be overkill on a sewing machine(esp with all the extra parts on it).BTW we had a variable speed like that on our old Massey Harris self-propelled combine that I used to run on our farm & it would eat a belt every couple of yrs,as long as your were moving you could slide the lever up & down pretty easy though.

I am not thinking of using that kind of setup. Unless they already were out there.  Was just curious if it had even been done before servos and all this more modern tech became available.  And Bob  I ran an old Massey combine many hours too.  That was one of the things that made me wonder if it had been done on a small enough scale for a sewing machine.  With the controlled pulley on the motor shaft and the spring loaded one on the machine or mounted on like speed reducers are now.

[CowboyBob]

2 hours ago, catskin said:

I am not thinking of using that kind of setup. Unless they already were out there.  Was just curious if it had even been done before servos and all this more modern tech became available.  And Bob  I ran an old Massey combine many hours too.  That was one of the things that made me wonder if it had been done on a small enough scale for a sewing machine.  With the controlled pulley on the motor shaft and the spring loaded one on the machine or mounted on like speed reducers are now.

Oh,Ok,to answer your question then,I've never seen it done on a sewing machine.

[Cascabel]

I think what you are asking about is called a Reeves Drive.   My metal lathe has one.   It works quite well, but I'm not sure it would be suitable for a sewing machine.