Choosing a Surface Plate Grade

Howdy All,

I'm shopping for my first reference surface. My nature is to buy the best grade I can afford. I'd like to be able to do some fairly precise measurements, and have an old Heidenhain electronic gage setup that can resolve to 0.5 micron. The question I have for the experts is "how good is good enough" considering that my workshop is not climate controlled most of the year. I live in Georgia USA and I only climate control on the very hottest and coldest days, so the plate would occasionally be subject to some considerable temperature fluctuations. That considered, am I wasting my money on an "A" grade plate? I also realize there are many factors to consider beyond temperature stability...

Your opinions are appreciated!

dgcope said:

Howdy All,

I'm shopping for my first reference surface. My nature is to buy the best grade I can afford. I'd like to be able to do some fairly precise measurements, and have an old Heidenhain electronic gage setup that can resolve to 0.5 micron. The question I have for the experts is "how good is good enough" considering that my workshop is not climate controlled most of the year. I live in Georgia USA and I only climate control on the very hottest and coldest days, so the plate would occasionally be subject to some considerable temperature fluctuations. That considered, am I wasting my money on an "A" grade plate? I also realize there are many factors to consider beyond temperature stability...

Your opinions are appreciated!

Click to expand...

I actually DO have the ability to hold standard temperature (68 F / 20 C ) if I need to do and not break the bank. Normally, I'm between 65 F and 75 F with no special care, ELSE not using the shop at all.

Size matters, too.

My 1960 Vintage Grade A Class 1 NBS traceable Do-All is only 6" X 12" and has only ever been used those long years to check measuring instruments.

There might be all you need?

The B&S 12" x18" was-once-upon-a-time Grade B bought used is imperfect, but more than good enough for layout and parts checking.

The 30" X 48" Grade A and seems-to-still-be Herman shudda been 36" wide for easier markup of the 4-foot B&S Camelback on the diagonal, but WTH, I Am Not A Scraper (nor Lawyer..) and at 30" wide I can far more easily wheel it through the 36" doorways where I cannot quite get a "straight shot".

"Take some fairly precise measurements" Guess that is about as specific as wanting your water wet, rather than dry.

...so ... what sort, with what, on what, and to what general goals?

Thank you.

The size I am considering is a 24" x 36". My primary interest at this moment is to teach myself to scrape. I recently acquired a surface grinder and have an interest in some machine tool rebuilding projects. Beyond that, for general layout and parts checking, I'm confident that a B plate is good enough for my purposes and skill level. I have an assortment of surface guages and tenths reading DTI's including a Millimess and a 50 millionths Bestest. Up to this point a cheap 9" x 12" has been working okay for me. It's just not big enough for the next steps I'd like to take.

a b plate is not worth the money. get the best plate you can get. if you count in transport and moving/setting up the price difference wont matter much. when scraping every micron becomes important and you will be glad not to have to question your plate, although even with aaa you eventually will. get a map of the plate too.