Author Topic: Gauge block  (Read 167 times)

Carpenter84

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Gauge block
« on: October 04, 2018, 10:54:05 PM »
I put a b grade box of guage blocks on my Christmas list, but I needed one now. I was watching the Stefan Gotteswinters videos on rebuilding the Schaublin lathe compound, he used a guage block to span the dovetail flats to indicate so as to not get drunk from the needle bouncing all over.

So, i made one. A2 tool steel, hardened and ground. I ground this thing down to the last few passes were .0001 each. Beautiful finish. The needle doesn't move under my tenths indicator on a properly cleaned surface plate... I had to clean the plate twice before I got rid of some errors.
Turns out my scraping on this part is flat to a tenth over the span inside outside and 2 tenths from end to end. Not too freaking bad...
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

4GSR

Re: Gauge block
« Reply #1 on: October 05, 2018, 06:57:43 AM »
Did you calibrate your new dial indicator before use? :o

Just picking on you.  Your doing fine there and that is a good way of getting an average measurement across a surface.

Good work there!

Ken
Ken

Carpenter84

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Re: Gauge block
« Reply #2 on: October 05, 2018, 12:11:15 PM »
I will calibrate it when someone tells me how. Lol. Or pays to send it out. I'd be thrilled to get my two test dial indicators calibrated. I've kept up with my mitutoyo mic. Had it repaired twice now. Likely paid more than it's worth, But, what are ya gonna do?
Those three precision measurement instruments are the only brand name things I own.

Well, that's not true. My telescoping gage set is mitutoyo. But I think that's it... And I bought it all together when  i bought a retired machinists toolbox for $250. Everything else is cheap Chinese.
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

Ulma Doctor

Re: Gauge block
« Reply #3 on: October 05, 2018, 10:22:09 PM »
a point of information-

as the name implies they are indicators.
they do not take direct readings of measurement, they only indicate geared interface needle movement against a background of lines on the dial.
they can be very precise instruments, when used in the laboratory under ridiculously controlled environments to the ten millionths of an inch-
BUT AS SOON AS YOU RISE ABOVE 68°F YOU MAY LOSE ALL YOUR .0001" REPEATABILITY
9 Lathes, 5 Milling Machines, 6 Welders, 2 Surface Grinders, Shop Smith & woodworking stuff too !!!

MIKE WALTON

Carpenter84

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Re: Gauge block
« Reply #4 on: October 06, 2018, 05:46:40 AM »
Why above 68°? And not below freezing? Or would freezing also be true? I understand climate effects metals, and the racks inside indicators are no exception.
Is there more info there?
And also, why repeatability? Wouldn't the rise in tempurature and the expansion of metals create a consistent result as long as the expansion has halted? So then technically, it could be consistent and predictable?
Or are you suggesting that once above 68° each reading I take in a momentary period of time could potentially be different?
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

Carpenter84

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Re: Gauge block
« Reply #5 on: October 06, 2018, 05:51:40 AM »
And then I suppose the same would be true for my gauge blocks. My garage is heated, but not cooled. So in the summer it gets pretty brutal, in the winter I keep it about 7°c then rise to 19 when I work.
I had already been thinking about my cast iron straight edge and the winter cold. I was considering making a small wooden case and keeping it in the house. Probably the same if I get the gauge block set for Christmas.
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

4GSR

Re: Gauge block
« Reply #6 on: October 06, 2018, 09:50:12 AM »
The cold won't hurt your cast iron straight edge.  The cold will keep it very stabilized.  Just don't hit it or drop it. Be like a piece of glass,  probably will shatter all over the place.  If you intend to use it, yeah, keep it some what warm, or at least at the temperature the work piece is at.

Funny, you mention the cold, I work with some down hole oilfield equipment that can't handle the really cold environment.  At -10 degrees F, the cast iron will fracture just from bumping it against a hard surface.  Also the sealing rubber elements becomes very brittle and will get damage from handling.  We have to spec special rubber compounds and harnesses for the lower temperatures they encounter.  and the temperatures down hole at 5,000 feet down up there in the arctic are only in the upper 60's most of the time.  Totally the opposite down here in south Texas where down hole tempatures on the same day get up to over 275 degrees F!

Ken 
Ken

chips and more

Re: Gauge block
« Reply #7 on: October 06, 2018, 08:46:23 PM »
The only uncertainty that I’m aware of when using an indicator is cosine error. Depending on what angle the pointer is in relation to the indicator body when in use can and will affect quantitative measurement. In most cases it doesn’t mean much or who cares…Dave

Ulma Doctor

Re: Gauge block
« Reply #8 on: October 06, 2018, 09:20:54 PM »
my point is that if you breathe on a half millionths indicator, you can induce an error

accuracy is a goal,
at our level a thousandth resolution is more than sufficient for 99% of the work
9 Lathes, 5 Milling Machines, 6 Welders, 2 Surface Grinders, Shop Smith & woodworking stuff too !!!

MIKE WALTON