# Boring bar fly cutter



## Larry$ (Jul 27, 2021)

I've never liked the look of multiple passes with my biggest fly cutter. Was inspired by a video using a boring head as a fly cutter. 3/4" shafting, face ends, chamfer, drill & tap for M6 on the lathe. Drill & ream for 1/4" carbide tool on the mill. Old, dull 1/4" laminate trim bit, grind to shape of a cutting tool. This took several tries & tests to get an semi-acceptable solution using my Shars D bit grinder. 

Set up my 3" Chinese boring head on the Jet mill with the bar in the side opening, moved closest to the head. Chunk of unknown 3" wide steel in the vice. Interrupted cut! After multiple tries with different tool geometries I still got an only fair finish. .... Extend bar to cover a different piece of 6" wide steel. I didn't change rpm or feed rate but got a pretty nice finish. SF/M was much faster. No problems with chatter or vibration, cut smoothly. 

I'm going to grind a tool specifically for aluminum and see how that goes.


----------



## brino (Jul 27, 2021)

Some people here would say "Pictures or it didn't happen!"

You're lucky I'm not one of those guys.......  

-brino


----------



## mmcmdl (Jul 27, 2021)

brino said:


> Some people here would say "Pictures or it didn't happen!"
> 
> You're lucky I'm not one of those guys.......
> 
> -brino


Too bad I am ! 

*PICS or it didn't happen ! *


----------



## Larry$ (Jul 28, 2021)

brino said:


> Some people here would say "Pictures or it didn't happen!"
> 
> You're lucky I'm not one of those guys.......
> 
> -brino


1. Fly cut steel after many tries of grinding the carbide router bit that I made for the boring bar. It cut this unknown steel plate nicely but another piece of steel would not cut well. It just wanted to sort of smear. 
2. The boring head with the bar, 1/4" reamed hole for bit and a set screw, simple! A flat was ground on the bit for the set screw. 
3.  9" diameter cast aluminum, fly cut in full width passes. Old router bit I ground to cut aluminum giving decent finish. I'm surprised that the boring head with a 3/4" bar sticking out that far would cut nicely. No chatter. 420rpm. The aluminum was poured in to a pie pan as left over during a casting. You can see all the hydrogen bubbles from not properly controlling the melt.


----------

