I've ordered an MF18 finishing tap but short of buying both a roughing and a finishing tap, I'll need to rough out the thread on the Bantam. This will be my first internal threading operation.
Firstly, let's create a CAD model. This is a 1-1/4" hex body with a 17mm bore, 'cos that's what I've got. That's a little under 100% thread but it will be more than sufficient.
A section view, to sanity check:
Now I need to create a threading tool and set up the toolpath. The 16mm sized inserts I bought from Cutwel seem to by Vardex, so here's the relevant part of the datasheet:
Managed to get the tool set up:
And the toolpath. As the insert tip is 15mm from the back of the toolbar and the bore is only 17mm, I don't have much room for retract and clearance moves. Ideally I'd have some 11mm sized inserts but I'm not about to buy another boring bar and inserts.
Took a bit of buggering about to get there but I seem to have got there in the end. I'll need to drill out the stock and get it ready for threading but otherwise we seem to be ready to have a go. As ever, "what could possibly go wrong" etc. Watch this space.....
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