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

[EdK]

Nice job on the fly cutter Dave.
Very nice tool.

Ed

[ETC57]

Nice job Dave,

Look's great and seams to work great too

Jerry,

[Wongster]

Nice... On to the To-Do list...

Regards,
Wong

[Highpower]

Very clean lines, and looks to be quite stout. Another beautiful job.

[Mayhem]

Dave - I'm curious to why you used a threading insert to only cut 60% of the thread and then finished it with a die?

Nice work on the cutter. Have you tried it in steel?

[DaveH]

(04-09-2012, 12:48 AM)Mayhem Wrote: Dave - I'm curious to why you used a threading insert to only cut 60% of the thread and then finished it with a die?

Nice work on the cutter. Have you tried it in steel?

Mayhem,
60% thread (depth) it may have been only 50%, my arm was getting tired.

Because the thread length is short I decided to turn the chuck by hand. Under power by the time I have started it would have been time to stop and not having a brake to stop it very quickly and not much of undercut/run out a little risky.
I think the lowest speed is about 80rpm, without changing to the slower pulley sizes. I'm far too lazy to change to the slower pulleys for just one thread.
So my left arm/hand provided the power. Once it is at 50% I know there is little chance of the thread wandering whist using the die. Also I don't have to measure the thread, the die will take care of that.

The main reason I start the thread is to make sure the finished thread doesn't wander.

If I have to cut a 6mm thread by 40mm long I will use this method again to keep the finished thread straight.

I have used it on steel, it worked fine - it is an carbide insert so one would expect it to work. I just reduced the depth of cut.


DaveH

[Mayhem]

Where is your sense of adventure Dave?

With such a large radius on the insert, I was curious as to whether you had experienced any chatter issues in steel. I guess not.

[doubleboost]

Nice Job Dave
Well shown
Those form tips give a amazing finish in the lathe as well
John

[Dave J]

Hi Dave,
Nice work, I just have one question about the last picture. I looks like the fly cutter is on an angle to the work, was your mill not trammed?

Dave