60° chamfering in bore, CNC lathe

Hi guys,
We've some shaft type jobs which have their 1st setup done, 2nd setup requires part to be faced, put a chamfer in bore to help tailstock revolving centre support.

Problem is, I don't have programmable tailstock body on all lathes. Need some tool which can quickly chamfer the bore before tailstock quill can actuate ... Can't let a boring bar do it since tailstock is quite near and usually quill stroke is short.

Maybe a tcmt style tool ? To be clamped in 25x25 OD turning tool spot ?

Chamfers are usually small, upto 2x60° max. Bore dia 14mm & upwards.

Sent from my XT1033 using Tapatalk

What's wrong with a centre drill?

Sent from my D6603 using Tapatalk

I'll have to clamp centre drill in Collet, which in turn will sit in boring bar block. There isn't much space for block. Else I would have done it by just a small boring bar.
Moreover, there's already bored hole in centre.

Sent from my XT1033 using Tapatalk

Cut yourself a length of 1 1/2 square stock same length as a turning tool. I used 1" stock and welded on some material to the end for meat where the center drill goes.
Machine down an area to 1" square leave about 3/4 or so of the end of it at 1 1/4.
Drill and ream for a #5 center drill on center line of the top of the 1" shank in the 1 1/2 area.
Drill and tap two set screws to hold the center drill in place.

This makes a 1" shank center drill holder that when installed in a turning tool block it puts the center drill on the same center line as the tip of a turning tool, you just have to set the geometry in for X center line. If you push the shank of this tool up against the tool holder all you have to do to set it is record the X geometry and input that number next time you use that tool and your ready to go.

For chamfering this job I would grab an old center drill, grind off the tip and align one of the cutting edges to the X axis.
The tip of the tool will only need to stick out past your tool block an half inch or so.

You can use same tool with a good center drill for future jobs that you need to center drill, just put proper geometry in so tool goes to X axis center line of spindle.

These 1" shank center drill holders can be bought that come with bushings for different center drills if you can find it.
There was a long lead time and I didn't have time to wait so I just made one.

Bring this tool down and manually machine the bevel you desire.
Set the operator position to X 0, send tool to X home. Lets say from "0" on the position screen the tool moved 12.3623" to home...go to your X geometry
and manually input that number.
If you MDI that tool
T0404
G00 X 0. it should go right back to the position you needed to cut that chamfer. (note: this works with HAAS, assume would work with any Fanuc, I not sure)

I was wondering if I can employ a Vnmg tool ( lying idle), (Evqn 117.5°) and ground off the bottom part at tool tip, even the bottom corner of insert.... Use G1 X....Z... to put 60° chamfer.

Sent from my XT1033 using Tapatalk

Vishrut said:

I was wondering if I can employ a Vnmg tool ( lying idle), (Evqn 117.5°) and ground off the bottom part at tool tip, even the bottom corner of insert.... Use G1 X....Z... to put 60° chamfer.

Sent from my XT1033 using Tapatalk

Click to expand...

That's the beauty of Gcode, you can do anything you damn well please.
If you can get that tool in there and get it to cut rather than rub it will work.

If you have to do a lot of Fing around with it to get it to work it is not advisable though.
You would want a tool that any average operator could look at a setup sheet and load said tool and go.

Centre drill doesn't have to go in a collet head, simple bushing would do? Which would make it pretty ffing stumpy.
Sometimes I feel some people will make a meal out of anything.

Sent from my D6603 using Tapatalk

Also why was this cham not done at same time as the bore?

Sent from my D6603 using Tapatalk

EnglishJules said:

Also why was this cham not done at same time as the bore?

Sent from my D6603 using Tapatalk

Click to expand...

Didn't got the exact 60°....bore was done from the other side is quite long...dia 14 mm & 70mm long...

Sent from my XT1033 using Tapatalk