Spotting Drill

[Hilmar]

To all.

What makes a Spotting Drill a Spotting Drill?
How different is it from a regular Drill.
Can you make your own?
Why not to use a center Drill.
Are there any tricks to this thing?

OK Mcgyver this is all Your fault,ha ha ha .
Hilmar

 

[Mcgyver]

OK Mcgyver this is all Your fault,ha ha ha .

hey - what else is new


this is a spotting drill

its the correct tool for starting a hole - people often press a centre drill into service for this but centre drills really are for drilling conical centres for lathe centres.

Spotting drills are

- very rigid
- the cone the form is 118 so a drill will locate properly into it - the cone on centre drill is 60 so the drill starts contact on the edge not the conical plane - this means the drill might not start as accurately but more importantly it won't chatter when starting as they sometimes are prone to do when starting in centre drilled hole
- ever bust the pip of a centre drill? who hasn't' right. well you are unlikely to bust the pip off a centre drill when you're using a spot drill

 

[rake60]

A spotting drill is for spotting a pilot for to accurately guide the placement
of the drill bit that will be drilling the hole.

A center drill can do the same thing, but it can also cut the 60 degree
included angle for a machine center to engage.

If your not drilling for a center a spotting drill is a better choice in most applications.

Rick

 

[rake60]

Oh I see Mcgyver beat me to it! LOL

Rick

 

[BobWarfield]

Nice one, guys.

Don't overlook the screw machine length bit either. Being shorter, it is considerably more rigid and can often be used without a spotting (or center) drill.

The other perverse thing about screw machine length bits is since they're less common, I tend to be forced to buy higher quality bits, which also helps.

Cheers,

BW

 

[Bogstandard]

In the UK we would call that a stub drill.

You will also find now, almost all manufaturers of drills are going for the four facet ground drills. This supposedly allows you to be able to drill the hole without the use of a primary starter hole.

John

 

[Hilmar]

Hi Rick,
is the top doohickey a spotting drill ?
I have one of those and taught it was a reamer.
Thanks guys for the info.
Now I have to break off some of my drill bits to make such a thing.

Mcgyver, I am still working on the triple.
Hilmar

 

[rake60]

Hi Rick,
is the top doohickey a spotting drill ?
I have one of those and taught it was a reamer.
Thanks guys for the info.
Now I have to break off some of my drill bits to make such a thing.

Mcgyver, I am still working on the triple.
Hilmar

LOL
Thats a solid carbide spotting drill.
It can be used to drill deeper holes but for it's cost I wouldn't try it.

Rick

 

[Hilmar]

Hi Rick,
is there such a thing as a Tap Blank? This what it looks like to me. At first site it might be a reamer but after looking at it for a while I think it may be a blank of some kind.It has three sharp flutes which look like a tap. No markings as such. At the square end is a LH engraved. To be a center drill this thing is dead dull at the tip.
Hilmar

 

[Mcgyver]

its' just a tap with a very fine thread

 

[Hilmar]

Aha, that is what the invisible tread looks like.

 

[rake60]

I have no idea what that is.

I do know that a carbide spot drill has a well defined chisel point and
relief.

Rick

 

[zeusrekning]

Also not there is no side relief on a spot drill for increased rigidity.

 

[wareagle]

is there such a thing as a Tap Blank? This what it looks like to me. ......... To be a center drill this thing is dead dull at the tip.
Hilmar

This is what a tap looks like when it is produced at 5:00pm on a Friday afternoon.

 

[rake60]

LOL
And I'd still find a way to bind and break it!

Rick