Home made insert flycutter

[DaveH]

Here are some pics showing my home made fly cutter with replaceable insert cutter.



The major problem I had was holding the Morse taper 3 suitable for milling. However John (Blogs) came up with a solution “screw it together”. So I made it that way, however it can be made by a “force fit” or loctite it together.

Started with a Morse taper 3 with a blank end.



Ready to start the threading. The thread was cut about 60% and finished with a die.



Finished threading. ½’ UNF



I used a piece of EN8 50mm dia for the part to hold the insert. This was basically a disc (17mm thick) with a threaded hole in the centre.
Here it is worth mentioning whether screwed or fitted together another way, take it back to the lathe to make sure it runs true.

Here the whole assembly after some milling, was screwed together and mounted in the lathe


The thickness is reduced to allow the insert to protrude about 1mm (0.040”), at the bottom.



It is unscrewed and further milling is carried out. Although only one insert is used keeping it symmetrical helps with the overall balance.




The finished fly cutter.





Some aluminium ‘faced’






Just to note these round inserts come in different sizes 8, 10, 12, 16, 20 mm dia. I used 12 so a smaller or larger fly cutter is possible.

DaveH