Small Semi-Repair on South Bend Lathe

[682bear]

The gear cover on my old South Bend 14-½ lathe was cracked when I bought it. Over the last few years, the crack had grown until it was about to break completely in half...



I decided it was about time to do something about it.

I started by drilling a stop-crack hole at the end of the crack...



Then I cut off a piece of 1-¼ x ⅛ steel flat stock and drilled two holes in it... clearance for #8-32 screws. I transferred the holes to the cover, drilled the cover to match, and screwed the flat stock to the cover, bridging the crack...





My next step was going to be grinding the crack out in a 'v', then TIG brazing it up with silicon bronze... but I remembered the batteries in my welding helmet were dead...

I'll have to get some batteries and braze it up later... for now, it is reinforced enough to keep the crack from going any farther.

-Bear

 

[SLK001]

Is it cast iron or aluminum?

 

[682bear]

It's cast iron. I originally thought it was cast aluminum... but I took it off a couple of weeks ago and realized it was too heavy to be aluminum. I tested it with a magnet and found it to be cast iron.

-Bear

 

[COMachinist]

Why not use cast iron tig rod. I have been using it to actually Weld the brake or damage with cast iron. So far I have not had a single crack and no pre or post heating required. The stuff is great, for cast iron repair. I think it is called EZ-weld Tig wire, I think, will look tomorrow. I use it with argon, and well cleaned area.
CH

 

[ericc]

Cast iron filler puts a lot of heat into the material. I have successfully used it to gas weld with. It creates a huge pasty puddle, but it wets in well, and the repairs look nice. Silicon bronze puts less heat in, but occasionally I have had difficulties with it not sticking.

 

[woodchucker]

a tig braze should be good enough. this is not a high stress part.
But if you want to learn to weld cast iron....

BTW I repaired a handwheel with a flux wire weld. I was desperate, and it worked. who knew. I simply heated the part before welding, then covering it with a ceramic blanket when done.

Also I wish I had a tig rig... I was always pretty good with OA brazing.. I have been told by my local welding shop, that its not that different.

 

[SLK001]

BTW I repaired a handwheel with a flux wire weld. I was desperate, and it worked. who knew. I simply heated the part before welding, then covering it with a ceramic blanket when done.

Oh, you can weld cast iron like this. The weld pulls carbon out of the CI, making the joint weak and very brittle. If there isn't much stress on the part, you should be okay - just don't drop it!

 

[woodchucker]

Oh, you can weld cast iron like this. The weld pulls carbon out of the CI, making the joint weak and very brittle. If there isn't much stress on the part, you should be okay - just don't drop it!

ahhh, it's the wheel for my collet drawbar. with the old bar (I recently built a new one) the set screw pulled the boss apart. I stuck a copper or brass slug in the middle and welded and filled it.

I didn't know it pulls the carbon out. There is quite a bit of stress on it, when I crank down on it. Good to know it's brittle... If it lets go I'll report back here. I welded it 2 or so years ago.

 

[FOMOGO]

Been way busy lately, so decided to do a little fun project. The spindle bearing caps on the Niles lathe are taped 7/16-24, and the hit and miss oilers I got are 1/2" npt. Was tempted to pull the bearing caps and drill and tap them 1/2 npt to match, but decided not to go there, as I was concerned it might stress the caps, and possibly affect the spindle to bearing fit with the tapered thread. Got a 7/16-24 tap and drilled and taped the bases of the oilers, and used some brake line fittings to adapt to the bearing caps. Drilled out some copper washers to help seal the fitting, though not really necessary, as they are below the needle valve seat. Wanted to turn down the 1/2" thread on the oiler, but will wait to make sure the needle valve that controls the feed rate doesn't leak. Put one on the lathe and filled with ISO 68, and so far so good. Put a mark at the oil level and will check it in the morning. Mike

 

[682bear]

Why not use cast iron tig rod. I have been using it to actually Weld the brake or damage with cast iron. So far I have not had a single crack and no pre or post heating required. The stuff is great, for cast iron repair. I think it is called EZ-weld Tig wire, I think, will look tomorrow. I use it with argon, and well cleaned area.
CH

I don't have any experience with EZ-Weld... but I do have confidence in my abilities to successfully braze this cover.

The silicon bronze will be more than strong enough for this repair... it just has to support the bottom of the cover. The hinge and the screw that holds the cover closed are both above the crack.

-Bear