tap threads into cast iron?

Question

I have a cast iron table saw base with threads that need to be re-tapped if possible. Can a tap cut threads in cast iron or will it break?

Answer 1

Yes you can. Especially if you are tapping out a hole with bad threads. Us plenty of tap oil and only turn a 1/4 turn and then use your compressor to blow out the chips. Do it slowly and feel how your tap is reacting. Back off the tap twice before you stop to blow out the chips. (at 1/8 turn and at 1/4 turn)
It may say cast iron but it very likely is a low carbon steel as cast iron will rust to fast to be used for anything.
We used to drill and tap old tractor blocks when the threads stripped out. That is where my Dad taught me about tapping.

Answer 2

Re Tapping Threads

Answer 3

You can do it. Use oil on the tap,be care full when you start. Make shore the tap is going in straight and is following the old threads. There are 3 types of taps 1,starter tap 2 plug tap3 bottoming tap. If it is a blind hole use a 3. otherwise any # tap will work.

Answer 4

tap threads cast iron

Answer 5

You are working with wrought iron which is a high grade cast iron. make sure you have the proper tap pitch (threads per inch). If possible run the tap through the hole , don't back it out.

Answer 6

Yeah, you definitely can. A lot of engine blocks are made of cast iron, and threads need to be retapped all the time.

Answer 7

Iron is pretty soft. The tap bits are made of high-carbon steel. Just use lots of machine oil and go slowly.