On Thu, 14 Feb 2019 17:50:38 -0800 (PST), wrote:

On Thursday, February 14, 2019 at 2:17:31 PM UTC-5, wrote:
Finally last night I was able to sit down and figure out the probe
adjustment.
I have 5 probes. One 10x Tek probe, one 20x Tek probe, one
Probemaster 1x & 10x probe, and two other 1x & 10x probes from China.
The 10x Tek and the Probemaster probes are 100 MHz rated and made in
the USA. The Tek 20x probe is 200Mhz rated and USA made. The Chinese
probes are 100MHz rated.
I realized the probes need to be adjusted only in the 10x mode. I
didn't know that. That for sure was part of the problem.
Looking at signals from my function generator it seemed that the
voltage was off. Then I realized that my meter displays the RMS value
of the AC signal and the 'scope displays the peak values.
I got all the probes to display a nice square wave in the 10x
setting. I don't know why I got really weird results before but it may
be because I was in my machine shop with CNC machines running. At home
with everything quiet all the probes behaved like they were supposed
to. At the 10x setting.
But with the probes set at 1x the square wave isn't quite square.
The 3 probes that have the 1x setting all act the same, with the
square wave being slightly distorted.
It didn't seem to matter if the 'scope was set to AC or DC
coupling. It also didn't matter if the signal being measured came from
the 'scope or from the function generator.
Is this normal, for the square wave displayed to be perfect in the
10X setting and slightly distorted in the 1X setting?

The 'scope is a Tek465B.
The 20X probe is a TEK model P5120
The 10X probe is a Tek model P6053B
The Probmaster is model 3901-2
The Chinese probes only have a model number-P6100

So, as near as I can tell, the probes are all right, at least they
all act the same. But what causes the distorted square wave at the 1x
setting?
Thanks,
Eric

Cool. Hey Eric, I just want to say that one reason I enjoy
sharing whatever small amount of knowledge I have with you,
is that you'll always follow up and tell me how it turned out.

I wish I had more customers like that. They send me
a problem... I send them off a few potential solutions,
and then ~1/2 the time I don't hear back. I assume something
worked... but I don't which of the three solutions it was,
or they made some bone head mistake and are embarrassed.

Oh, here's a machinist question for you. When tapping
holes in an easy metal, Al 6061 say, with a through hole
I've got these 'gun'* taps that shoot the chip out the
bottom of the hole. If I'm doing a blind hole is there
a tap that shoots the chip back up the tap.
(chip may not be the right word.)
I tap mostly small stuff
4-40, 6-32, 2-56... in approximate order of usage

George H.
*gun taps is what I call them, there is a GN on the
stem.
The taps that direct the chips back out of the hole are called high
spiral taps. Spiral point taps, AKA gun taps, eject the chips ahead
of the tap. I use high spiral taps a lot but I don't like them. They
are weaker than spiral point taps. I know, the terminology is
confusing, especially since the high spiral taps are actually high
helix taps.
For blind holes in ductile materials, such as wrought aluminum and
mild steel, I like to use roll form taps, AKA form taps, AKA roll
taps. In fact, I use roll taps whenever I can because of the stronger
thread and because no chips are generated. These taps require a larger
hole and hole size must be controlled well because the tap just
displaces the metal. With a roll tap you can tap right down to the
bottom of a hole because there are no chips generated.
Because form taps displace the material the thread is stronger than
a cut thread. Virtually all the fasteners you will find in your local
hardware store will have formed threads.
Materials that can be roll or form tapped include all the wrought
aluminum alloys, such as 6061, 6063, 5052, etc. Mild steel, 1144
steel (stressproof), 12L14 steel (leadloy) and 303 stainless steel
also tap well with form taps. 304 and 316 can be form tapped but great
care must be taken to avoid broken taps. Tap life will also be short
in 304 and 316. But if you need threads all the way to the bottom and
want to do it in one pass roll taps can work.
Materials that should not be formed tapped are the cast aluminum
alloys, half hard brass, cast iron, and the like. This is because the
material is not ductile and the resulting thread will have tiny
fractures, resulting in a weak thread.
I have tapped thousands of holes with 2-56 form taps.
Always use cutting oil when drilling and tapping holes, never motor
oil. Using motor oil leads to broken taps and bad finishes and poor
tool life.
Hope that helped.
Eric