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Why center drills in a lathe and not a drillpress

I use a method that works better than using a edge finder to locate a hole in the center of a piece of metal. Just requires a caliper and a 0,5 MM Pentel P205 pencil.
A sharp line from a point or an Exacto knife is better.

1. Mark two lines on the X axis slightly off center.
2. Do the same for the Y axis.
3. Peen a hole in the center using a 5X or greater lens. I work the peen so the circle is centered in the bullseye.
4. Now in the drilling position. Use a pointed shaft and locate the hole with a 5x lens.
5. Now chuck up the center drill and make a light cut.
6. Do any final X-Y movements/center drill cuts until perfect alignment.

I have my flame retardant suit ready.
 
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NO DRILL PRESS HAS A QUILL THAT WILL HOLD .001"

NONE!

It's not a matter of runout. Run out will still center, SLOP won't!

Maybe true for your typical drill press, but I'll bet my Cameron and my Dumore have less than 0.001 runout.

The Cameron can drill a 0.002 hole, and the spindle runout is specified as less than 0.0002"

For drilling, I like to use a spot drill - someone here was selling them a while back, so I bought a supply of them.

Steve
 
Maybe true for your typical drill press, but I'll bet my Cameron and my Dumore have less than 0.001 runout.

The Cameron can drill a 0.002 hole, and the spindle runout is specified as less than 0.0002"

For drilling, I like to use a spot drill - someone here was selling them a while back, so I bought a supply of them.

Steve

Dyammm! Can "Practical Machinists" not know the difference between RUN OUT and deflection!

YELL, Ran't, slap forehead, stomp foot.
 
I use a method that works better than using a edge finder to locate a hole in the center of a piece of metal. Just requires a caliper and a 0,5 MM Pentel P205 pencil.
A sharp line from a point or an Exacto knife is better.

1. Mark two lines on the X axis slightly off center.
2. Do the same for the Y axis.
3. Peen a hole in the center using a 5X or greater lens. I work the peen so the circle is centered in the bullseye.
4. Now in the drilling position. Use a pointed shaft and locate the hole with a 5x lens.
5. Now chuck up the center drill and make a light cut.
6. Do any final X-Y movements/center drill cuts until perfect alignment.

I have my flame retardant suit ready.


And if you would employ some flexible twist drill (3mm or less) to SPOT the prick punch, the results would be fine indeed!
 
OT but I use 82 degree spot drills so if making flat head csink just go to depth and then drill. Eliminate a step, at least for small csink sizes. Not very efficient for large holes you can push a drill harder. If you don't have a controlled angle on the hole chamfer 82 degrees is a good way to go.

Unless you’re working with metric flat heads, which are 90degrees.. I found that out the hard way after years of only using 82 degrees spot drills and counter sinks.
 
I have a few different diameter drill blanks with a point ground on them. In a radial drill simply drop into your center punch with the drill blank and lock the location. I will then punch the pointed drill blank into the center punch location making it slightly larger. Throw in the drill and go for it.

Sent from my SM-G960U using Tapatalk
 
Small diameter drills will tend to wobble and break in general and walk too. Larger drills may also move around a bit effecting the diameter of a hole also they do it less depending.

The later is very often caused because the larger drill very often will have the web chisel edge dulled up or the drill itself. It does effect things quite a bit.

It depends on type of material, whether the top surface is straight or angled, and the cutting edge and proper grind of the drill. It must be right to even drill a hole on size.

I have done it both ways. I like to stack the deck most of the time. Yet also if I am in a hurry I know enough to look at a drill or notice how it is cutting to know that it is cutting round and true.

A center drill will help in that it will take the brunt of the outside skin of the material keeping your drill points in better condition and less worn and chipped.

On a lathe the stouter a drill the less inclined I am to use a center drill on either lathe , mill, or drill press. I just drill it appropriately with proper force and pecks.

Most shops will ignore keeping their tooling of any kind properly maintained and replaced. All drills are in now way made equal. Some drills should at some point be thrown away. All it takes it to inspect any tooling after completing a job and returning the tools to storage.
 








 
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