Stuck eccentric - how to remove?

[RWL2]

This is the continuing saga of my Consew 226 which top, bottom and head was completely frozen.  I've got most everything else apart, but the eccentric on the top shaft is stuck and has not responded to Kroil, paint thinner and Ed's Red and heat - so far, about a week and a half's time.  The eccentric hub is turning on the shaft.  It's possible that if I could get the hub to hold on the shaft that I could get the eccentric to turn in the crank and eventually get it loosened.  Thinking that I might be able to remove the eccentric and deal with it outside the machine, I was able to loosen one set screw on the eccentric's hub, but not the other.  It slides more easily on the shaft now.  I can push the handwheel end of the shaft toward the head fairly easily, but the toothed pulley is stuck, preventing further sliding of the shaft despite loosening the two set screws in the pulley.  I'm pondering what to do next and looking for ideas.  Is there a groove in the shaft in the area where the eccentric is located?  If so, I can turn the shaft a little at a time until the set screw finds its groove and then I can fix at least the one set screw in place.  After getting the hub secure, I could try rocking the handwheel back and forth to tap the eccentric's "arm".  Have any of you had to deal with this before?

[Gregg From Keystone Sewing]

Could be a needle bearing that Seiko started using here, not a bushing that Singer used and never gave one problem for the life of the machine.

The hole punched in the timing belt is from a set screw that was not recessed in the upper cog.  

[RWL2]

1 hour ago, Gregg From Keystone Sewing said:

The hole punched in the timing belt is from a set screw that was not recessed in the upper cog.  

Exactly.  It's the way it came to me.  It was one of the set screws on the lower pulley though that was the culprit so somebody was messing with that before it was taken out of service.  I've got the set screws loosened on the upper pulley hoping to slide the entire shaft to the right or left and remove the offending eccentric, but the upper cog's stuck on the shaft.  I've seen that odd belt appearance in occasional photos on the net and wondered why it had those punched out looking areas.  Now I know.

[DonInReno]

Rust responds well to impacts - not beating it to a pulp with a big hammer, but rapping on it with a brass hammer would be one of the things I’d try.   Don’t tap it twice and call it failed, but rap on it for a good 5 minutes.  
 

 

[RWL2]

I made progress today and got the eccentric and connecting arm out of the machine where I was able to free it up.

The first discovery was that one of the set screws in the toothed belt pulley has an extension that mates with a hole going through the shaft, locking it in place.  Once that was removed I could slide the pulley easily on the shaft.  An interesting aside is that although this a Japanese made machine, the screws are all SAE fasteners (inch sizes), albeit in a special fine thread pitch.  I was able to get a right angle screwdriver onto the 2nd set screw of the eccentric, freeing that from the shaft.  The metal of the shafts throughout this machine deforms easily, even when using a brass rod as the intermediary, so I tapped on an aluminum rod to push the upper arm shaft out.  I pushed it out from the pulley end because the needle crank at the opposite end is not easy to remove, plus there was a solid stop at the needle end of the casting for the eccentric to bear against, unlike the open casting going to the pulley end.  Once the eccentric and connecting arm were out I could see that the connecting arm was cocked on the eccentric.  After pushing them together so that the arm rode correctly on the  eccentric, the roller bearing would turn.  It eventually freed up enough that the eccentric and connecting arm could be easilly taken apart and cleaned.  Despite an initially gritty feel, with cleaning the bearing now turns freely without grittiness.  I lubricated it with Tri-Flow.  Since I had the arm shaft out it seemed like a good time to take the needle crank off and clean up that end.  Like the drive pulley, the needle crank has one set screw with an extension that fits into a hole in the arm shaft and fixes it / orients it in position.  Photos below.  Although this was for my Consew 226, it should apply equally to many Singer 111w class machines and possibly the Seiko STW-8b

 

Edited August 5, 2020 by RWL2
Reduce picture size to stay within 1.46 Mb limit.

[RWL2]

Picture of the eccentric and connecting arm with roller bearing.

43 minutes ago, DonInReno said:

Rust responds well to impacts - not beating it to a pulp with a big hammer, but rapping on it with a brass hammer would be one of the things I’d try.   Don’t tap it twice and call it failed, but rap on it for a good 5 minutes.  
 

 

I agree wholeheartedly.  Varnished dried oil often seems to responds to fresh lubricant / solvent, but not rust.  I needed to tap on the shafts to free seized components that I needed to remove for service / cleaning.  As I mentioned in my post above, I was impressed by how soft the steel is in these shafts.  Despite using a brass bar as an intermediary on the lower main shaft and an aluminum bar for the upper arm shaft, the ends of both shafts expanded slightly, making it difficult to slide components over the enlarged ends.  I measured this enlargement at about 0.001" on the lower shaft where I used the brass drift and a few tenths on the upper arm shaft where I used the aluminum rod as a drift.  I "stoned" the enlarged areas back to size with a fine beartex wheel on my polishing head.

[DonInReno]

I’ve been impressed that this has turned into a full tear down for you - by the time it’s back together and running correctly you’ll know it well!

 

[RWL2]

Just some minor follow up for anyone who might have to remove the upper arm shaft like I did.  When reassembling it, the lower set screw of the eccentric appears in the window in the rear of the casting when the needle crank points to about the 9:00 position as you look at the end of the machine.  The rotation of that eccentric on the shaft is what controls the presser feet and getting them timed took a lot of trial and error.  You may have to rotate eccentric a few degrees before or after 9:00 on the shaft to get the walking middle presser foot to touch the material at the same time that the needle touches the material.