You can give it a shot with JB weld. It looks like the break may be in a spot where the belt won't actually stress those pieces.

You can also get some Aluminum brazing rods and a propane torch and probably braze that back together.

 

Aluminum is usually welded in an inert gas such as argon, but I would question whether the pulley is pure aluminum.

 

I don't think that is repairable for what you would be willing to spend. I would look for a replacement, or skip the high speed. If someone did weld it, it would need to be trued on a lathe. I have used the aluminum solder and it is very strong, but a fine line between soldering and a pile of molten aluminum. Not knowing the alloy the sheave is made from could make it complicated.

Wish I had a better answer.

 

Just buy a new step pulley. That is the best repair.

 

https://www.ereplacementparts.com/four-step-lathe-pulley-p-3851925.html

That part isn't available at eReplacement.

Personally I'd leave it alone, it may chew up your green belt a little, make sure your cover is closed just in case.

 

There's a BOYD section on OWWM.org that folks offer and ask for specific machine parts as well as whole machines. There's a plethora of knowledge within the community revolving specifically around old woodworking machines and what it takes to get them running like new. The only word of caution I'd offer is many of these Ole boys are about 1.9 steps into the grave and any facts you might have mean nothing if it's not an opinion they share, logic is absent with a shocking number of the regulars.

 

I wish I could help you, I have a similar problem with my lathe as well. While there are a lot of step pulleys available, I found it impossible to find one that will fit the large shaft diameter.

 

Yeah I was hoping to be able to find a replacement somewhere, but checked McMaster Carr, grainger, etc and no luck. I guess the 1" shaft is pretty rare. There's a replacement on eBay for $70 but considering the lathe itself cost $50 it's tough to spend that on my budget.

Sounds like brazing isn't a great idea with the material being unknown.

Maybe I'll try jb weld and just stand clear when it's spinning or make a cover.

 

Even if the pieces are bonded on, that sheave is bent and should be trued. Not doing so will probably eat up your link-belt.

 

As an alternative provided there is clearance for it, you could cut off the broken side of the pulley and replace it with one side of an adjustable pulley that are in common use with evaporative coolers.

I'd have to measure one up, but they have a large diameter hole where they install on the motor arbor.

To cinch it all up, you could clean up that nut and reuse it or find a standard hardware item to replace it.

 

Highly doubt it is pure aluminum.
Most likely a cast Zamak alloy. Will not braze, or weld. Only way I know to repair Zamak is using PbSn or SnAg solder. The zinc in the alloy oxidizes quickly and easily, making it hard to solder and creates poor adhesion for polymers due easy water permeation into ZnO2. Soldering works better if you plate some copper on interface first. It's not a strong repair, mostly used for decorative parts, so YMMV.

The DDL-121 lathe pulley is unique animal. Backside as recessed bore, and it includes indexing marks/holes. Doubt you ever find a generic replacement.

+1 OWWM.org BYOD forum section or fleabay is your best option for replacement.

Restoring ARN is never cheap, we do for Fun!

 

Have a machine shop mill one for you.

Or turn one from well seasoned ironwood. A great uncle of mine made pulleys, eccentric cams, and gears from ironwood. They held up to years of hard use.

 

As a follow up, here is a photo of an old rusty adjustable pulley from my cooler

What you get is a two piece pulley where the outer flange (top in photo) can be screwed in/out then locked down. This changes the effective diameter of the pulley to adjust the ratio for speed adjustment.

If the top flange is removed, you have a flange with an inside diameter of 1-1/8" (fine thread). My thought is if your shaft is 1", you could use a piece of 1/16" wall, 1" ID tube as a shim so this flange could fit over your shaft.

If the damaged flange is cut off (preserving the nut), you might be able to slide this flange on, then use the nut to clamp it all together.

They are cheap and come in steel or aluminum.

Anyway, just spitting out an idea! 8^)

 

I have an extra one in my hand right now..

 

If you can't replace it, just grind off what is left on the pulley and don't use that speed.

 

As CaptainKlutz said, It's not aluminum but what they call pot metal. Put a torch on it and it will dissolve to almost nothing in almost an instant. Keep searching the internet. I bought a step pully from someone a while back that had almost every size, shape, and description. Sorry I can't remember the site name. Just do searches for pulley, sheave, etc.

 

I've got one for sale right now. I have a small selection as well