Broken Singer 31K32

[LumpenDoodle2]

As a mere wimmin, and a bodge expert, If it were me, I'd drill 2 holes through the broken bit.   Line it up in place, mark through the holes, then drill two holes in machine.  I'd then thread the holes, screw the whole thing down, with maybe a smear of jb weld, and some loktite on the threads.   Finish by filing the screw heads as smooth as keeps one happy.

Might work, might not.   

 

[Evo160K]

So this is perhaps a bit off topic, but it's so unusual...at least for me....I thought some of you might appreciate it.  This is courtesy of my friend with the broken vintage fan, he repaired it with the pins and Loctite method mentioned above.

He went on to say, and I quote, " on my suzuki TS-125 I had the head bolts pull out of the cylinder, so I just drilled a small hole through the casting and pinned the head studs in place, it held and was able to torque down the head.  I used steel brads for that repair.  saved me having to get helicoils or some other drill and retap method."

Now I thought that was trick.

 

[mikesc]

Problem with any ideas of drilling two holes ( one either side of the shaft ) tapping them and pinning them on the OPs machine..is that only one side ( the upper side as we look at the photo ) has enough metal to be able to drill a hole..The shaft goes through the metal "off centre"..look carefully at the lower part of the break, and there is less than 5mm of metal available to drill there..and the break is holding the shaft in place, so there is really maybe only 3mm of metal "drillable" without hitting the shaft..If the drill bit has to be centred ( it does ) that means only 1mm of metal will be left to either side of the hole..Into this 1mm "wall" you'd have to tap a thread..I have ( as do no doubt many of you ) tiny tap and die sets..( right down to watch makers sizes ) measure the diameter of the smallest practical tap that would hold in cast iron..that will be the 2mm one..and you'll realise that although there is enough metal to work with and drill into at the ( as we look at it ) "top" of the break.. There is not enough metal to drill and tap into at the bottom of the break.

Cast iron is fairly rough crystalline structure..large crystals..requires coarse taps..which is why Singer etc used coarse taps..coarse taps need larger diameter holes in order for bolts and screws to hold..The "thread" part cannot be a lager proportion of the diameter than either the shaft of the screw or bolt, of the hole that the screw or bolt is going into.

How many 1mm or 2mm diameter screws or bolts do you find screwed into any cast iron parts on your Singers ?

There is also the matter of holding a part steadily enough to be able to drill it with small diameter drills and using small diameter taps..both of which are very brittle and will snap easily..Singers were drilled and machined after casting in cradles to hold them steady..( as can be seen in the Singer film in the Scottish archives ) ..they were not using Dremels and bench drills on a sewing machine head casting which would have to be turned upside down..and locked rigidly "on it's back" before drilling with highly brittle fragile tiny diameter drill bits and taps..and if the drill bit so much as glances off the shaft while it's making the hole in that very restricted less than 3mm wide area..it will break due to the differences in the density and hardness of the two metal across the shaft of the drill bit.

ps ..if JBweld was actually called JBglue ( which is truly what it is..it does not weld anything, no resin glue does ) then people would not think that it can do "magic"..epoxies do not "fuse" metal together..they stick it..

Marketing does not actually triumph over physics or chemistry..only in peoples expectations and beliefs..

Pins and loctite ( another brand name for an epoxy resin ) will work in many situations..it is actually how most restoration and repair of antique statues is done..and there are variants of the technique used in surgery ( and much research currently being done on the possible "glues" ) but there must be enough "whatever" available to be able to drill into..and a two second glance at the OP photo shows that is not the case on the lower part of the break..I presume Eric and Bob noticed that immediately too.

Edited March 31, 2017 by mikesc

[mikesc]

There is of course also the problem that if the OP tries to drill and pin with JBweld ( or any other epoxy resin that they can get in what is apparently "darkest furthest reaches of Scotland ) and the drill bit snaps off, the tap breaks, or the drilling makes more of the cast iron break off.

Then they are screwed..

True welding will then be out, as welding two substantial parts together is possible..welding three ( or more ) parts some of which would then be tiny would not be possible without very very expensive and specialised equipment.

[LumpenDoodle2]

2 hours ago, mikesc said:

There is of course also the problem that if the OP tries to drill and pin with JBweld ( or any other epoxy resin that they can get in what is apparently "darkest furthest reaches of Scotland ) and the drill bit snaps off, the tap breaks, or the drilling makes more of the cast iron break off.

Then they are screwed..

True welding will then be out, as welding two substantial parts together is possible..welding three ( or more ) parts some of which would then be tiny would not be possible without very very expensive and specialised equipment.

Bummer........

[suzelle]

Nice machine there! Sorry it was damaged. I have gotten them that way before! Had one sent to me that was bouncing around in a box with styrofoam peanuts. An old 201k with it's dome shaped wooden carrier. Smashed to smitherines.

[torrbuidhe]

Hoy, this isn't darkest Scotland, that's down near Moffat. This is the treeless northern plain where wolves and musk ox roam

No JB Weld locally but I could get it delivered here, you can even get sewing machines delivered here

Somebody has recommended a local steelworking firm so I'll try them next week

Neil

 

[gottaknow]

As a side note, I use cobalt drill bits with a 135 degree tip on cast iron. I always use cutting oil as well. When I'm using my cordless, I take it off the drill setting and use the clutch set on a fairly low setting. It prevents broken bits. When tapping, I cut no more than two threads before backing the tap out to clean it. I've broken bits for sure. Usually they become a permanent part of the machine. 

Honestly, I'm really opinionated when it comes to metal working as it relates to sewing machines. I was fortunate to have two old timers train me. You'll find no JB Weld in my factory. I did use it during my years as a locksmith and safe technician though. 

Regards, Eric. 

[dikman]

Mike, thanks for a most interesting discourse. While I'm in no way in your league (some would say I'm one level above bodgery!) I do know that old cast iron is a bugger to work with. It's hard to drill, I've broken the odd tap or two when attempting to work with it and as Eric said they usually then become part of the metal!! I once repaired a piece with an ordinary arc welder (it was all I had handy) and more by luck than anything else it worked.

LumpenDoodle, you've got the term "mere wimmin" wrong (besides your shocking spelling ). The correct usage is "mere male", I've never heard it applied to the female persuasion. After all, we all know women can multi-task whereas men often struggle if attempting more than one thing at a time.

[George1520]

The best way to weld cast iron is to heat it red hot first and then braze it with bronze roads. The heating part is important  and it it will destroy the paint around the weld.

Unless you have other cracks, leave it the way it is. There is still plenty of tread and and material for to nut to tighten. Also, look for bend shafts too.