Singer 7- prone to cracking ?

[DonInReno]

12 hours ago, Gunnarsson said:

One method to deal with cracks in spoked cast iron wheels (and many other places) is to preheat the spokes next to the broken one, or similar places. This makes the surrounding structure cool down and shrink along with the repair, avoiding causing tension and new cracks. 

I agree preheating is very important.  I like to evenly heat the entire piece to 1000 degrees F, do the repair, and cover with multiple layers of fiberglass welding blankets to slow down cooling.  

[Silky]

12 hours ago, DonInReno said:

I agree preheating is very important.  I like to evenly heat the entire piece to 1000 degrees F, do the repair, and cover with multiple layers of fiberglass welding blankets to slow down cooling.  

This works well for smaller parts when practical, especially with something like a spoked wheel.  Submerging the part in a tub of dry wood ashes is also an excellent medium to slow the cooling.

[councilman24]

I've never heard of one cracking. See post on 7-33 needles for very good manuals.