Deburring the inside of a side hole approach, workable?

[bikemutt]

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.

 

[Rob F.]

Maybe I missed it but is there some reason you can not drill the small hole first?

 

[MaxPrairie]

Might work. Otherwise flex hone. A deburr blade may also get in there depending on what shape you have.

 

[Thunderjet]

Free machining brass is the answer.

Drill cross hole, then rotate both directions and remove.

Easy peasy.

 

[guythatbrews]

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]

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]

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]

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.

 

[bikemutt]

Free machining brass is the answer.

Drill cross hole, then rotate both directions and remove.

Easy peasy.

I should've mentioned, the radial hole does not go all the way through, just one side.

 

[Thunderjet]

I should've mentioned, the radial hole does not go all the way through, just one side.

It will still work just fine

You want to rotate in both directions for a Better result.