expanding an off center hole
 

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

AL

expanding an off center hole
 

Plunge cutting with a milling cutter *might* work. The best solution is to fit a
boring head to your DP spindle. It isn't as hard as you might think, there exist
a lot of 3MT to whatever arbors, 2MT also. Any el cheapo boring head with a
small boring tool would work OK for this.

But given the low price of 1/2" end mills I'd just chuck one of those up and
have at it. If you can get it to run slow enough (600-ish rpm) it should work.
The biggest problem with using milling cutters on a DP happens if you try to put
any side load on them. This tends to pop the chuck arbor out of the spindle.

GWE

Art wrote:

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

AL

expanding an off center hole
 

Art wrote:

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

AL


Unless ur drill press is really without slop in the bearings, runs
really true, and has a really tight fit to the taper - find a guy or
shop with a mill!

The local college almost always has a machine shop - the big ones have
"student" machine shops... gunsmiths tend to have mills... I have at
least 2 neighbors within 1 mi with mills (I have two myself now, but
that's not the point...)

Oh, unless the material is soft - plastic, aluminum, brass, then the
drill press stands a chance.

_-_-bear

expanding an off center hole
 

Is it possible to adapt something else to make the existing hole work?
IE think out of the box?

expanding an off center hole
 

Art wrote:

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

AL

Drill the existing hole to 5/8" and Loctite a flush plug of
5/8" shafting in it. Remark and drill your 1/2' hole.
Of course this way requires additionally a hacksaw & Loctite.

Tom

expanding an off center hole
 

Art wrote...
If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Plug the existing hole, punch the new center, and drill the new hole. Use
the same material to plug the hole. Size the plug for an interference
fit.

Jim

expanding an off center hole
 

I would redrill the hole to almost the desired size and then use a 1/2"
endmill with the table up as far as it would go so as to keep the spindle as
rigid as possible. Use lots of lubrication.

..040" might be difficult in a press.

expanding an off center hole
 

In article , Art says...

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

I'd use a milling machine.

Nuf' said?

Jim


--
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please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
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expanding an off center hole
 

"Art" wrote in message
...
Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

AL
Plug the existing hole with the same material, center punch, drill new hole.
Easy, works good.

Don Young

expanding an off center hole
 

Art wrote:

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

AL

Use a drill bushing and an end mill in the drill press is the cheap
fix. The drill bushing will (should?) keep the mill from wandering
sideways. I'd be inclined to use, say, a 7/16" mill to move the hole
over, then work up to size after comfirming that I was on my location.

Best solution would be a boring head in a mill, though.

Cheers
Trevor Jones

expanding an off center hole
 

jim rozen wrote...
In article , Art says...

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I'd use a milling machine.

Nuf' said?

Not quite. :-) How do you fit it in your drill press?

the other,

Jim

expanding an off center hole
 

Art wrote in message
...
Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

Don't even think of trying to do that. A twist drill will bend to some
extent to follow the original hole whether you use a drill bushing or not.
You must mill a new hole with a 2 flute milling cutter until it at least
clears all sides of the original hole and you can then enlarge that if
needed with a drill bit and/or reamer depending on the accuracy you require.
It's not recommended but at a pinch you can use a milling cutter in a drill
press chuck if you go easy.
--
Dave Baker

expanding an off center hole
 

What Don said.

Don Young wrote:
"Art" wrote in message
...

Hello RCM'rs.

If you have an existing 1/4" dia hole (1/2" deep), and want to drill
a new hole of 1/2" dia and offset it .040" from the center of the 1/4
hole but you only have a drill press how would you do it?

Right now I'm thinking of trying a drill bushing correctly oriented
over the part and just trying a twist drill but was hoping there is a
better way ( I would normally try plunge cut will mill).
TIA for any comments.

AL

Plug the existing hole with the same material, center punch, drill new hole.
Easy, works good.

Don Young