Making a dead center hole in a round part

[doc]

Recently had occasion to drill out a busted stud in an SU carb float bowl on which the float rides up and down. How to get the old broken stud drilled out and a new stud put in on dead center? A friend of mine came up with this idea. Pretty sharp, i thought, and might have lots of applications.

Thread is metric M6 X 1.0. I have metric tap and die set,
I have 2 1/8 diameter hole bit which fits bore of carb bowl exactly.

Steps:

clamp block of wood to drill press(with 5/8 clearance hole predrilled)

Bore 2 /18 dia hole aboout 3/8 deep in wood.

Flip hole bit over, so it forms a 2 1/8 pilot locator dead nuts
centered to spindle.

Locate carb bowl on hole bit pilot (now central ID of bowl is dead
nuts concentric to spindle).

Drill tap drill hole, tap by hand, works perfectly.

Only someone with both woodworking and toolmaker experience would know
this trick.

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doc

[Ol'fogasaurus]

Hmmm, it should stop the drill bit from walking on you too.

Lee

[fusername]

I can see where you would need that. good pointer!
olfoggy, got these but cheaper a while back, life saver in a few places

use em to start holes all the time, go dull kinda quick but getting my moneis work, used em to countersink maybe 5 holes, start about 499

[rubbachicken]

that's pretty neat

[Ol'fogasaurus]

Fuser, you brought up countersinking (CSK) as far as I know there are 4 standard CSKs: 82°, 90° (probably the most common), 100° and 120°s. Using the right kind of tool holder (a chuck) in a mill or when doing horizontal drilling, you can shorten up the grip on a standard drill bit to the point to where there is almost no deflection of the drill itself (not sure what the affect it is on the drill bits flutes) and you can do that to a pretty small drill bit.

I’ve seen the ones you have and have been tempted but so far I have been able to withstand the temptation. Good to know that they seem to wear fast though.

Lee

[fusername]

lee, it could be my imagination on the dulling tho, using them again. Since I only had a drill press, I can't slip a bit in deep, so these things have been a life saver. Even when they finally do go dull, I will buy another set. Sorry buddy, but they are worth the money

"I will not give into temptation, unless she's really hot"

[hugging corners]

great idea
and wood and chatter comment makes sense
ill add pic of different type of cutter
would a groove in wood only be enoung? it would proably regiure little clamping to prevent rotation- but its adjustable
double ended one is a chaeap harbor freight
others are vintage craftsman
same principal should apply

[doc]

It's a matter of cutting the hole the right size and big enough for your workpiece to just fit. Take advantage of already centered drill column. Seems like same principle applies. And your cutters are adjustable for size. Need to wear eye protection, maybe more.

doc

[Ol'fogasaurus]

In the past, for larger round rod I have used a piece of Angle Iron in lieu of a Vee Block (http://www.bing.com/images/search?q=vee ... ORM=IQFRBA for example) and held it in place with a clamp. I dropped the drill down into the Vee Block to center it in the tool (angle iron) an clamped the tube in place. I also put a flat spot where I had to drill and tried to punch a location for the drill to hit but not always with the accuracy I would have liked. The Vee Blocks do work though.


Lee

[rubbachicken]

works great if you can drill a hole the exact size as the piece with the hole that needs drilling
i'd like to find a 100% good way to drill out exhaust studs on VW heads, air cooled and wbx

[Ol'fogasaurus]

Is there any of the stud sticking out?

[rubbachicken]

Is there any of the stud sticking out?

not always, i had hoped to have enough time one day to make a jig, something that would sit in the exhaust out port, that would guide a small drill dead center through a stud poking out, and or a stud that's snapped off flush or below the surface.

it's not something i'm in a hurry to do, i have a pile of heads in my workshop in the UK, that could do with some stud action when i finally get them here

[Ol'fogasaurus]

If there is enough stud to slide a nut over that sometimes works. I keep the nut very tight on the stud (fit wise and tight to the flat surface and use the nut to stop the wandering of the drill or center punch. It doesn't always work especially if the top of the stud is not flat but a close fitting drill or center punch may be able to work this way.

Lee

[fusername]

+1 on what lee said. thread M8 nut on whatever is left, or wedge it on tehre, and use a really big drill bit that centers on the nut to drill into the b stud.