Surface Plate & Gage Blocks

I have a 400mm square granite surface plate and an old set of imperial Matrix slip gauges which I use a lot in conjunction with a digital vernier height gauge. I know you can get by using other more basic kit but I would not be without these three items which I use daily. - Rik
 
Bob Korves said:
I absolutely cannot get along without a surface plate and gage blocks any more. If you do not have known accurate references, you are guessing at everything you do.
. [snippety snip]
If you have a very accurate flat, a very accurate 90 degrees, and very accurate length references, you become your own reference standard in a home shop.
The precision I need is almost always way (WAY!) lower than what I can test, and that is a very good thing...
But to answer your question, no, a beginner does not _need_ those things.
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Exactly what I'd say! At the other end on the spectrum, I grabbed a steel rule in a cheapo shop (Wilkinsons for the others in the UK), only when trying to use it did I notice the 12 tenths to the inch... I hang it by my PC at work, where we do metrology as a speciality, for when someone doesn't get the point!

If you don't have accurate references, nothing else will be accurate: what if every part you made had a 0.3" dimension measured with that 12-tenths rule?

As an aside, what I do all day is build networks (not very mechanical, sorry, but kind of explains a couple of useful principles of metrology) that deliver timing to banks, stock exchanges etc - they're having to meet new rules that mean they have to timestamp every deal to 100 microseconds (0.000100), lots of penalties if they don't - and it has to be "traceable" to an international standard (UTC, administered by the BIPM, same people who define very exactly what the Metre, Kilo, Inch etc. are).

Before a system gets used for timing, they have to look at the increase in error every time a measurement's "handed down" to the next stage - we supply the bank with time certified and guaranteed (yep, penalty clauses for us too!) to be 100 times better (1 microsecond, 0.000001 sec.) to allow for that loss of precision once we let go of it. Before we hand it over, it's actually running at 50 - 100 nanoseconds (0.000000050 - 0.000000100) because WE need to allow for OUR loss of accuracy too - and when traced back to source, we finally run into the laws of physics at about the 5 - 10 nanosecond level (where moving the clock from the floor to the bench changes the gravitational pull and means adjusting the clock...) - and long term it's appalling accuracy, a second in 158 million years, the shiny-domed scientists are working on the next improvement, when it shouldn't gain or lose more than a second in the lifetime of the universe (so far...)

I guess I care about Precision Measurement :)

Back on topic!

As Bob, I get a lot of use from surface plate, precision squares etc. qualifying other tools and made parts, and use measurements to get to what I want to make (my lathe even has gauge trays and a micrometer built in for when the +/- 0.001" of the Trav-A-Dial doesn't cut it) - and correct measurements mean that what I've made fits, no faffing about adjusting parts as long as the accuracy I require in making it isn't as good as I can achieve in measuring it!

Sorry for the ramble, but perhaps it gets a principle across?

Dave H. (the other one)
 
I agree with Toolroom. I got along fine with a thick granite floor tile, a home-made height scriber, and (don't laugh) a home-made machinist's jack for layout work. I'd set the length of the jack with a hygrometer, then use that on the tile to set the scribes height. Transfer my layout marks to the workpiece, then verify with calipers. Usually got within a thou or two, which is plenty for when cutting to a line. But now I have a proper granite surface plate, Jo blocks, height gauge, etc. Makes it a lot easier for layout work, and tons easier for inspection work. I recommend at Jo blocks at least, and a sheet of tempered glass or granite sink cutout to get by. When enco has a sale on, and you have the spare cash, nab a surface plate. Once you start using one, you'll probably either use it all teh time, or hardly ever.
 
I actually think a surface plate and height gauge is most useful. I use mine to scribe measured lines. I got the idea from watching Tubalcain videos. I don't have gauge blocks but would like to have some to check my measuring tools if nothing else.
 
The last time I used a proper cast iron surface plate was when I came out of my time and that was 62 years ago. During my
service.Best as an Engineer in the Merchant Marine I used a large piece of porthole glass. These days in my shop I regularly use
a piece of plate glass when marking out with my height gauge and sine bar. I also use a glass plate when grinding in flat
surfaces with grinding paste. I would say Save your money for a start and buy something more useful.
Best wishes and many happy hours in your shop Mike Jones
 
Agreed, a good surface plate, height gage, and set of gage blocks are must haves. Once you use them you'll use them a lot. Check Craigslist often in your area for surface plates. Or get a import from Enco cheap when they have the specials. Either way will be light years ahead of using a substitute. I use my height gage and surface plate for scribing layout lines all the time. I have a nice Mitutoyo A grade set of gage blocks for testing but I use a cheap import B grade gage blocks for setting up on the lathe and mill. On the lathe the shop grade blocks work great for setting your hard stops for a specific length of cut or depth for boring.
 
abrace said:
All,

How essential is a surface plate in a beginner's shop? Is it something I can wait on, or is it something that I should have immediately?

Same question goes for gage blocks.
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I have a cast iron surface plate /marking table and hight gauge that I use a lot. I have made several tools that are featured in Harold Hall books and it is so easy to do the marking accurately when using these tools. The gage blocks I don't have and never had a need for them.
 
ogberi said:
I agree with Toolroom. I got along fine with a thick granite floor tile, a home-made height scriber, and (don't laugh) a home-made machinist's jack for layout work. I'd set the length of the jack with a hygrometer, then use that on the tile to set the scribes height. Transfer my layout marks to the workpiece, then verify with calipers. Usually got within a thou or two, which is plenty for when cutting to a line. But now I have a proper granite surface plate, Jo blocks, height gauge, etc. Makes it a lot easier for layout work, and tons easier for inspection work. I recommend at Jo blocks at least, and a sheet of tempered glass or granite sink cutout to get by. When enco has a sale on, and you have the spare cash, nab a surface plate. Once you start using one, you'll probably either use it all teh time, or hardly ever.
Click to expand...

a hygrometer???
 
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