Finally Got Some Spotting Drills

[MrWhoopee]

I had never heard of them before the internet informed me that I'd been doing it wrong all along. Harry taught us to use center drills, Fred did the same. When I looked around for some spotting drills, they were crazy expensive (for what they are). Found these a few days ago and ordered an assortment.

Carbide Spotting Drills

 

[mmcmdl]

We ( old timers ) were not taught wrong . Spotting drills were made for CNC production machines . Z depths were cut 75% and tool setting was simple to achieve the required chamfer angle and diameter . Just another tool to cut production costs .

 

[Leslie]

I'd like to make a Spot/Chamfer Drill Tool suggestion (used on CNC or Manual, Mills and Lathes)
I've been using these for about 20 years, they're Carbide (I prefer uncoated) double end and can Spot and Chamfer Mill part edges.
They also have a bit of a chisel edge @ the Point which helps the point live longer (particularly when used in harder materials).
I find them reasonably priced ($38.66/ea for the linked size example), they offer various sizes, angles, coated or uncoated versions.

https://www.travers.com/product/promax-132-01520-spotting-drill-20-726-250

 

[rabler]

I had never heard of them before the internet informed me that I'd been doing it wrong all along. Harry taught us to use center drills, Fred did the same. When I looked around for some spotting drills, they were crazy expensive (for what they are). Found these a few days ago and ordered an assortment.

Carbide Spotting Drills

Let me know after using them if you think it makes a difference over using center drills.

 

[mmcmdl]

One of my most favorite shop memories . 1984 I started a position at Ward Manufacturing who made paper machines . I ran 2 G&L HMCs with dual rotary tables and tombstones . All programming and tooling offsets were done in the tool crib . One night I was proving out a set-up and the supervisor came running up asking why I was not running the pot at 100% . I told him I was proving it out . ( the machines had lights on top that flashed if set under 100% ) He grabs the router sheets and says the program is proven and to crank it up . Cool , crank it up ! All went well until a tool change that pulled an 8" 1" diameter spot drill instead of a 2" 1/2" diameter center drill . Jammed the tool change arm on top of the tombstone and more lights flashing than a firetruck . I called him on the radio and asked how he liked THESE lights . I then packed my box and gave him and the company my one finger resignation .

 

[woodchucker]

I have been using spotting drills over center in the mill and the thing I like is no risk of breaking off the tip. I have broken the tips on the smallest centering drill on the lathe. I don't understand it, it's usually well buried when it breaks.

At any rate, I don't see much of a difference, but will continue to use the spotting drill on the mill.

btw, mine are hss and cobalt. Not carbide.

 

[mmcmdl]

I don't understand it, it's usually well buried when it breaks.

The reason they break is the surface speed is to low on the tips . It pushes rather than cuts .

 

[woodchucker]

The reason they break is the surface speed is to low on the tips . It pushes rather than cuts .

I thought I was using the fastest rpm. I guess I don't have enough rpm for the smallest center.

 

[SouthernChap]

We ( old timers ) were not taught wrong . Spotting drills were made for CNC production machines . Z depths were cut 75% and tool setting was simple to achieve the required chamfer angle and diameter . Just another tool to cut production costs .

I think the advantage of a spot drill for making that initial chamfered hollow over a centre drill is that the angle of the tip of a spotting drill is greater than that of a centre drill and also an average twist drill.

So, an average twist drill's tip would be more likely to make contact with the bottom of the cone made by a spotting drill before hitting the sides, than it would be to make contact with the bottom of the cone made by a centre drill.

I doubt that difference for our purposes is particularly meaningful.

That said, for no other reason than the fact that I like drills oops:), I do have spot drills for use on my bench drill plus some stub drills too (I love those); mostly Swisstech (which seem reasonably well made) with a couple of Dormer chappies because one of the Swisstech spot drills and one of the Swisstech stub drills were out of stock in the sizes I wanted.

Eh, use whatever drill makes you happy and gets you where you want to be, I say.

 

[mmcmdl]

Eh, use whatever drill makes you happy and gets you where you want to be, I say.

Absolutely . Makes no difference to us , but to large production shops where time is money it does . One other bonus .................the spot drills fit normal size collets , CDs do not .