What kind of accuracy can one expect from older Starrett tools?

[C-Bag]

LOL! If not for you TM51 I never even would have known what I had was something special! I do really appreciate the simplicity and bulletproof nature of the old tools, especially that height gage. It was interesting to note wherever the old gage was being used was where they had to be checked. The B&S BestTest has a last tested sticker but the height gage has a sticker that proclaimed it exempt. That's pretty bulletproof IMHO.

 

[mcostello]

What is this thing called a mechanical pencil? Does it do the writing by itself? I only use the ones that use a wall mounted sharpener.

 

[mikey]

What is this thing called a mechanical pencil? Does it do the writing by itself? I only use the ones that use a wall mounted sharpener.

From the days when Mechanical Drawing was taught in high school and when draftsmen actually drew plans and prints on paper. Now that I think of it, the good old days are, in some ways, not that good.

 

[Boswell]

From the days when Mechanical Drawing was taught in high school

Hold on, when I took drafting in highschool I used a piece of wood with graphite in the middle. I had a piece of wood with sandpaper on it to sharpen to the right type of point for what I was drawing. No mechanical pencil until I was out on my own. Now even my mechanical lead holders are in a box for my son to ponder over one day. All serious drawing is now in AutoCad.

 

[mikey]

Yeah, well, I don't think mechanical drawing is taught in school anymore. So many kids don't even know which way to turn a screw to tighten or loosen it, much less what a ratchet is or is for. Sad.

 

[pontiac428]

A height gauge isn't a calibration item. It measures the distances between two points along a factory etched vernier scale that cannot change (at room temperature, at a given latitude, and only under an orange sun). I bought a Helios height gauge this year, and am happy with it's elegant simplicity.

 

[P. Waller]

The vernier should be properly zeroed when the jaws are closed. As to proper calibration with a set of gage blocks, I wouldn't worry about that. I haven't seen a set of gage blocks that can calibrate the full range of a 24" caliper anyway. People seem to forget that this is a hobby machinist site.

A hobby site yes, however many members want tenths accuracy at all times, this is not hobby work and will require some standards such as gauge blocks.
There is no reason other then cost that you will not buy a 20" long gauge block and stack from there for a 24" caliper.

Have you never browsed the Metrology forum here? It is fascinating.

 

[C-Bag]

I've been using the same Staedtler mars/80 pencil since highschool. Almost 50ys, wow. Not only is it bulletproof, the lead retracts so it doesn't break in the chest pocket of my shop apron. I also have an ancient cast iron rotary sharpener I don't long I've had. Both never let me down.

 

[francist]

Seeing as how this has gone seriously off-topic already, this was my grandfather's mechanical pencil. Circa 1930.
He was not a draughtsman but rather an officer of a political party. There's still a bit of lead in it -- good Bohemian graphite 0.045" diameter -- although my grandfather died in the 1950's already.

-frank

 

[RJSakowski]

A hobby site yes, however many members want tenths accuracy at all times, this is not hobby work and will require some standards such as gauge blocks.
There is no reason other then cost that you will not buy a 20" long gauge block and stack from there for a 24" caliper.

Have you never browsed the Metrology forum here? It is fascinating.

Cost is precisely the reason.

There are a very few fortunate individuals who can say money is no object. Spending nearly $1,000 on a 20" gage block to calibrate a 24" vernier caliper that is used once every couple of years is a poor use of funds, IMO. I would much rather put that money towards something like a TIG welder or a surface grinder. My wish list is nearly infinite. In fact, if someone told me that they would give me a million dollars on the condition that I had to spend it all on my shop within 24 hours, I am confident that I could.

If I were really concerned about that caliper, I would send it to a metrology lab for certification. I have that same caliper and the fact is that I'm not. Every comparison that I have made with it against my micrometers have shown it to be reading right on. Now I haven't compared to anything past 12" but I am confident that Starrett built their caliper correctly.

If you have browsed the metrology forum, you will have seen that I am a regular contributor. I know of few members of this forum that work to tenths of thousandths unless it is fitting a bearing or similar. In fact, common advice is unless you're working for NASA, don't sweat it. One only has to look at some of the magnificent work by members of this forum to realize that is true.

BTW, if you are going to do a proper calibration, you better plan on buying a 10" gage block as well.