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I have a stirrer welded on to a hollow shaft its Astaloy can you thread the hollow shaft.

Do you mean Hastelloy? If so it is going to be difficult....

Yes hastelloy is not easy to machine. It gums up tools and makes it difficult to cut and then it work hardens and wont cut at all.... Use a slow feed rate and keep a close eye on your cutting tool. And make sure everything is very rigid, work piece mounting, tool mounting etc...

Pippin89 - I would say tapping an internal thread on a hobby lathe is going to be fun, personally I would opt for thread milling if at all possible. I treat it like hostile stainless and flood it with coolant and as you say, cautious feeds. I would sooner machine Inconel every time.

Probably not going to work. Back to the drawing board I guess.

Does it have to be Hastelloy or is this a repair for someone else. What thread and depth?

Ovenpaa wrote:Does it have to be Hastelloy or is this a repair for someone else. What thread and depth?

Its an exsisting piece of kit we need to mount the stirrer shaft. The shaft is hollow the thread would be some thing like M5.

M5 is a perfect size to crack off. Use a solid carbide 4,5mm spot drill and take care with the tapping operation. I only use Guhring taps thee days and if this was a lathe job I would hand tap with the wrench aligned to a pin in the tailstock chuck. It should go with care.

I have decided to let some one else worry about it if we really need to get it mounted we either make a new one or modify this one but it will be a local engineering machine shop that does it.
Unfortunately we don,t have any in house machining facility any more we sold off all of the lathes mills etc. All the staff either retired or left to join other companies.Which makes things a bit difficult has we are a research facility and most of the stuff is novel and can be unusual in construction or materials used. But its not my call and they charge us a fortune.