What metal drill bit for putting a Piranha on?

[tomfifield]

You could rent a mag drill, I say this after seeing the broken hand!
As far as the calipers reading goes take a close look, at the hash marks, you can see it is just over .8. look at the calipers you see the numbers start at 0 and the numbers indicate the the line above them. The dial is off so don't even take it's reading into affect. I have worked with this kind of tool for 35 years at Boeing making parts for the big jets.

 

[Baby Grand]

Count hash marks, starting with the zero hash mark ...
Anyone who has worked a lot with mics and vernier calipers will understand a resistance to accepting anything a dial indicator reads without double checking it.

 

[RoyJackson]

Count hash marks, starting with the zero hash mark ...
Anyone who has worked a lot with mics and vernier calipers will understand a resistance to accepting anything a dial indicator reads without double checking it.

I have worked with mics, vernier calipers (height gauges too, BTW) and have done metrology for many many years...no "resistance" as you wrote, but it's .890 plus a few thousandths.
Again, visualize where the movable jaw would be if you had a .095" gage block stack...pretty closely aligned with the .100 mark...you may or may not see the .1 numeral.

I don't care for dial calipers....much prefer the digital type. The gear drive or "string" drive (on the cheaper calipers) tend to jump a tooth or break the string, rendering the caliper useless unless you want to tear it down and rebuild it. The gear drives are a pain...the string drives are a major pain...

 

[oosik]

RoyJackson,
The dial caliper reads 0.895. Digital is so much easier - After hours & hours of reading dial calipers I have found errors can creep in. Digital is right there for you - unless you have fallen asleep.

 

[RoyJackson]

RoyJackson,
The dial caliper reads 0.895. Digital is so much easier - After hours & hours of reading dial calipers I have found errors can creep in. Digital is right there for you - unless you have fallen asleep.

Yeah, but dial calipers were a major improvement over the older vernier scales...with the caveats I listed in post #33.
Dial and digital calipers weren't around when I first got into QA/QC (yes, I'm a dinosaur). All calipers require the operator to develop a "feel", but with vernier calipers, one also had to determine the best alignment of the marks on the scales. A 5x or 10x loupe was frequently required.

Digital calipers are great (my favorite are the Mitutoyos), but you still need to develop the "feel".

 

[tomfifield]

Look some more at the calipers. Count the spaces and you will see the numbers indicate the line above them. When they are closed it is at 0. The number 1 is in the first space so it has to open to the line above the number 1
to be at .1.
I can not understand how you can not see what it reads, it is just a bit over.8. As you can see the last number you see is .8, then the caliper is open to just over the .8 mark. This makes it about .81 or less.
The dial has nothing to do with any thing as it is not zeroed. Count the spaces and you will see the what the numbers indicate.

 

[Leejohn]

My god what are a few .001 when drilling something like he is doing.

 

[tomfifield]

Not much, and he will be going through a hrd spot. The informationm that I presented was simply to clear up how to read a caliper.

 

[bnhawkins]

The .100 thou vertical mark is to the right of the 1 so the .800 thou vertical mark must be to the right of the 8 - calipers are reading .795

 

[tomfifield]

Look close it is to the right of the hash mark, you can clearly see the hash mark above the 8, click on the photo and enlarge it.