[How do I?] Chamfering large hole on manual machine

[schmidty13]

I received an RFQ for a part with a 2 17/32" hole that needs to be bored to size and then add a 3/16" X 45 deg. chamfer. This will be done on my Bridgeport (non-CNC). The bore is straight-forward, but the chanfer has me befuddled. I had thought I could just find a boring bar that held a square insert at 45 deg, but that has been a fruitless search, so far. If such a bar doesn't exist, one thought I had was to use a fly-cutter and make my own 45 deg. bit for it (not something I've ever done).

My inexperience is showing here and I guess I need advice (or a head-slap) as to the best way to do this. Does the boring bar I envision exist? Am I missing some far easier method?

 

[schmidty13]

Oh, and FYI: yes, I work in decimal, I was just being lazy and typed the customer's fractional print dimension's.

 

[mikey]

Can you mount the part on a rotary table and use a 45 degree chamfer end mill to cut it?

 

[markba633csi]

Or move the part to a lathe for the chamfer?
-M

 

[schmidty13]

Can you mount the part on a rotary table and use a 45 degree chamfer end mill to cut it?

I hadn't seriously considered that, mainly because I don't own one. While it might be a good excuse to buy one, the part is odd shaped and on the large side; overall is 14 3/16" X 8 1/2". Would have to be quite a large rotary I think?

 

[NC Rick]

Oh, and FYI: yes, I work in decimal, I was just being lazy and typed the customer's fractional print dimension's.

I like the RT idea, I'd use that to produce the hole in place of The boring head.

 

[schmidty13]

Here's the part

 

[MrWhoopee]

45° brazed carbide tool held vertically in one of the holes of the boring head or welded to a piece of stock held in horizontal hole. Chatter is going to be a problem with that much face contact. In desperation, bolt a piece of round slightly under the hole size (and shorter than part thickness) to the mill table, drop the part over it and use a 45° endmill, manually swinging the part. Might need a spring loaded retainer to hold the part down.

 

[Martin W]

Is this aluminum? How thick? If its aluminum and thick enough, just use a 45degree chamfer bit with a flush bearing in a hand held woodworking router. I have even done this, even with a piece of steel with a variable speed mechanism to get the routers speed down so you don't burn out the cutter.
Just a thought anyways
Cheers
Martin

 

[Liljoebrshooter]

How about something like this? I bought a set of 3 and I believe the largest is about 3 inches in diameter.
Joe