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Deburring the inside of a side hole approach, workable?

bikemutt

Aluminum
Joined
Mar 5, 2022
I'm going to turn and center bore a 1/2" diameter aluminum rod to 3/4" depth, inside diameter 3/8". The inside diameter needs to be a tight fit for a 3/8" insert. To finish, I need to drill a #22 radial side hole into what's now a tube. I've been having a hard time figuring out how to debur the inside of the side hole without spending a bunch on specialized tools; this may be a one-off part.

So I thought, why not turn a tight fit piece of aluminum rod to 3/8" and use it as a "backer" for the side hole operation. I'm thinking the drill won't see any daylight when it moves from the work piece to the backer, should make a nice, clean hole as if I'd drill into rod instead of tube.

Destined to fail, or has potential?

Thank you.
 

Thunderjet

Hot Rolled
Joined
Jun 24, 2019
Free machining brass is the answer.

Drill cross hole, then rotate both directions and remove.

Easy peasy.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
If it's just one part stick it in the lathe and polish it or use a triangular scraper.

If it's many parts spring for the tooling, Cogsdill or Cofa have various choices, cogsdill tool cheaper. That is unless you've more time than money.
 

Mtndew

Diamond
Joined
Jun 7, 2012
Location
Michigan
So I thought, why not turn a tight fit piece of aluminum rod to 3/8" and use it as a "backer" for the side hole operation. I'm thinking the drill won't see any daylight when it moves from the work piece to the backer, should make a nice, clean hole as if I'd drill into rod instead of tube.

Destined to fail, or has potential?

Thank you.

Aluminum on Aluminum is destined to fail, as it has a high chance of galling up on you.
Someone above mentioned brass, that's what I would use for a plug.
 

Big B

Diamond
Joined
Jun 26, 2009
Location
Michigan, USA
If you are just looking to deburr and not chamfer the holes you can alternate between the large drill and the small one after the holes are drilled to take the burrs out. I've usually just used the drill bits by hand to take the burrs out. It would be easier if you can drill the small hole first so the burrs aren't as large.

If you need to chamfer it I don't have any suggestions.

I do think that your idea of putting a close fitting piece of stock in the hole when you drill the small hole would work fine too. Kind of like putting a sacrificial piece of wood under another piece of wood in a drill press when you don't want the hole to chip out when the drill bit passes through.
 

bikemutt

Aluminum
Joined
Mar 5, 2022
Maybe I missed it but is there some reason you can not drill the small hole first?
I thought about that Rob F., but, based on the last time I tried that, as soon as the axial hole's bit came into the void, it turned ugly. The bit wondered towards the void and chattered noticeably.

I think it may work if the axial hole is deep and the radial hole is far into the axial hole, that way the bit would have more support.
 

barbter2

Aluminum
Joined
Nov 25, 2019
Location
On Tour....
Might work. Otherwise flex hone. A deburr blade may also get in there depending on what shape you have.
^^^^This.
Turn complete.
Drill cross hole.
You have a #22 (.157) hole going through .062" wall section.
Use a small deburr blade through from the outside, to internally deburr.
Gravy!
 








 
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