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Shars Surface Plate - 'certificate' Not Inspiring Confidence...

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whiskylogic

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#1
My Shars 9x12x3 "Grade A" surface plate arrived today. "Accuracy" good to .0001", according to the specs. I was hoping to use this as a general surface for measurements, and I'm toying with the idea of using it to scrape-in some of the smaller surfaces on my import mini-lathe (it's not like I could really make it any worse...).

Now, I've heard good things about Shars stuff in general, but I couldn't find much specific to these ultra-budget surface plates (this was under $30 before shipping) - and this "calibration certificate" reeeeeeaaaallllyyy doesn't inspire much confidence.

WP_20161013_008.jpg

Horrific typos aside, there is no indication on here whatsoever that anything was measured. Most fields that would indicate such are blank.

Now, seeing as I bought a $27 surface plate to do some *relatively* accurate measurements in the first place, I obviously have no way of interrogating this surface for flatness.

Thoughts? Experiences? Opinions? I'd love to hear 'em.
 

John Hasler

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#2
My Shars 9x12x3 "Grade A" surface plate arrived today. "Accuracy" good to .0001", according to the specs. I was hoping to use this as a general surface for measurements, and I'm toying with the idea of using it to scrape-in some of the smaller surfaces on my import mini-lathe (it's not like I could really make it any worse...).

Now, I've heard good things about Shars stuff in general, but I couldn't find much specific to these ultra-budget surface plates (this was under $30 before shipping) - and this "calibration certificate" reeeeeeaaaallllyyy doesn't inspire much confidence.

View attachment 137568

Horrific typos aside, there is no indication on here whatsoever that anything was measured. Most fields that would indicate such are blank.

Now, seeing as I bought a $27 surface plate to do some *relatively* accurate measurements in the first place, I obviously have no way of interrogating this surface for flatness.

Thoughts? Experiences? Opinions? I'd love to hear 'em.
Buy two more and check the three against each other.
 

Dan_S

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#3
Now, seeing as I bought a $27 surface plate to do some *relatively* accurate measurements in the first place, I obviously have no way of interrogating this surface for flatness.

Thoughts? Experiences? Opinions? I'd love to hear 'em.
Send it back, something that's properly inspected is going to cost more.
 

brino

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#4
Hi Whisky,

First, Welcome to the site!

What? You don't trust that "Ladoratory Superviser"?!

Jeez, I can't even decode the manufacture and calibration dates.......is that the sixth month and 58th day or the the 58th week?!?!?

I hafta agree with @Dan_S, perhaps a few more dollars can get you something you can trust.

One I have been looking at is:
http://www.leevalley.com/en/wood/page.aspx?p=32526&cat=1,43513,51657

-brino
 

Dan_S

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#5
These are what came with the 18x24 I got from Grizzly. Note that certificate is just like yours, but I got a report with it.

It was $70-80 new, but by no means would I trust the "report" if I really needed to rely on the plate being accurate.

P1040413.JPG P1040414.JPG

If i wanted a nice plate but didn't want to be ripped off by some of the well known brands I's get a Standridge.
http://www.standridgegranite.com/images/stories/docs/forms/sg_pricelist.pdf
 

Bob Korves

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#6
When we had Standridge Granite come to calibrate and certify surface plates for four of us, we asked about Chinese import surface plates, and the foreman told us that most of them are very good, and occasionally there are ones that are not even close to the advertised accuracy. I was not surprised. Quality control is an expensive cost for manufacturers, and eliminating it or only checking a small percentage of the finished product allows them to sell the plates cheap while making money, even after shipping them across the ocean. I understand that concept.

The problem is that, as you have pointed out, we are looking for a trusted reference to calibrate our tools and test our parts. We have no way in our home shops to test the reference standards. Our references need to be something we can rely on to be correct. So, for me, a plate I cannot trust to be accurate to a known tolerance is worthless. If you want something for layout work with a scribe and Dykem, they are probably just fine. For precision work, you will be rolling the dice every time you use the plate. For me, that is not acceptable.
 

whiskylogic

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#7
Thanks everyone for the replies!

Honestly, I'm just looking for something 'flat enough' for some newbie hobby-level work. I more-or-less just wanted to share the ridiculous 'certificate' my plate came with (I honestly would have been *more* comfortable not receiving any paperwork at all).

I guess part of me was hoping some people could maybe chime in with personal experience regarding these plates, or maybe some reassuring words about Shars being a more quality-conscious importer, but its ultimately academic.

My 'shop' space is less than 50 square feet, in a fourth floor apartment in the city (gotta do what you gotta do), else I probably would have looked for a larger, surplus plate of known provenance. As it stands, this was the smallest 'useful' size I could find - at a really good price ...if it meets its advertised specs, that is.

Like I said, I just want to do some basic height/flatness/squareness checking, layout, and maybe some crude introductory scraping (even an out-of-spec surface plate is waaaay flatter than the stuff I'd be looking to scrape).

Regardless of my disquiet as to its accuracy, it's certainly flatter than my MDF workbench...

Thanks again for the input!
 

RJSakowski

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#8
I have had excellent service from Lee Valley in the past.

Having said that, remember that they are a supplier of woodworking tools. What is dead flat for a woodworker can look like the foothills to a machinist.

The Lee Valley plate spec of +/- .0001" (assumed unilateral measurement) is equivalent to the grade B spec. of .0002" TIR. No mention of a certificate of compliance, for whatever that's worth.

Here is an informative paper on surface plates. http://www.qualitydigest.com/aug03/articles/03_article.shtml
 

francist

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#10
I have the Lee Valley one, I'm happy with it. And, as I recall, the certificate was even less comprehensive than the OP's.
But it does what I want it to do, and that is general layout and part referencing for the average quality of stuff I fool around with. It's miles flatter than any other material I could reliably keep on hand.

The one deficiency I note right from the get-go though is the size. Nine by twelve gets small real fast as soon as you have an instrument plus a part of any substance. But then again, it works for most things and didn't cost an arm and a leg.

-frank
 

Bob Korves

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#11
You are not any better off if you buy a nice looking used USA surface plate instead of an import plate. Both are equally unknown quantities, even if one is a used Starrett or other highly regarded brand plate. You have no idea how it was used and treated. Any plate you are using as a reference for calibrating your tools or testing parts to meet stated tolerances must be a known quantity. The used 18x24" plate I bought, a well known American product, was .003" out when I got it. In the surface plate world, .003" is a bowl, not a plate. I did not have any way of actually testing it, and knew it was well used, but bought it anyway for a core price and had it calibrated and certified. Now I am happy. Do not spend a lot of money for a used surface plate, make sure you know what it takes to get one calibrated and certified where you live, and add that to the total cost.
 

Ulma Doctor

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#12
if you are using this surface plate to master your mini lathe, you would be improving it's accuracy regardless of the calibration of your plate.
you will in effect be mastering one part, then transferring that flatness (or lack thereof) to the next part.
you will be scraping the parts to a matching plane
it would be ok for you to use this plate on your mini lathe that may never send parts to Saturn.
is it book of Hoyle correct?- absolutely not!!!
but you are a hobbyist.
i saw your pictures of the mini lathes' machined surfaces :eek:
if the plate turned out to be only .001" on the mark, your precision will undoubtedly be better, i assure you.
 
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astjp2

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#13
I paid $400 for a 4'x6' plate, I had a friend check mine and it was within 50 millionths high to low. I had to build a stand and I would like to get it lapped in but its not really necessary for what I use it for. Tim
 
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