I bought another new granite surface plate, with this one being 12″ x 18″ x 3″ and with 2 ledges.
It’s a Grade A plate with 0.0001″ surface accuracy and 0.000060″ repeat gage reading.
Generally, B is toolroom grade, A is inspection grade, and AA is laboratory grade. The higher the grade, the higher the accuracy – and price.
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Granite surface plates provide a flat reference surface.
In total, I have a Starrett 12″ x 8″ x 2″ “toolmaker flat” for portable or office use (also a recent purchase), a new Precision Granite-branded 12″ x 18″ x 3″ surface plate (shown above), and an older B-grade surface plate that I bought 15 years ago from Enco for $15.
While I was hoping to buy a larger Starrett surface plate, they’ve been backordered at every supplier for many months. If I ordered one last spring, I likely still wouldn’t have one. I luckily managed to find another USA supplier.
I upgraded more of my metrology equipment as well, such as splurging on a digital height gauge to replace a much cheaper one with a dial readout. I bought the dial height gauge more than 10 years ago, and never liked using it.
I also bought a cylindrical square for use with the plates, and the cost was painful. I went with a USA-brand there too, and regret it a bit, as it’s hard to move around. Import squares come with handles.
There are measuring tasks where all of this comes in handy, but there are also some checks that can only be done with a flat reference surface.
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Imported toolroom B-grade surface plates can be found for less than $100, and they’re still decent. My older one will continue to be used in other ways, such as a sandpaper lapping plate for polishing or sharpening tasks.
If you’re interested in more detailed posts about precision measurement tools and the like, please let me know!
In the meantime, I’m going to have to find a cover for the surface plate to protect it from dust and debris. Any ideas?
Bruce
Just build a plywood box to set over the surface plate. If you want to get fancy, have the ‘lid’ of the box with some kind of sturdy fasteners under the surface plate so you can set the box over it, latch it, and then move it with the handle you built on to the box. That said, I try never to move my plate.
MM
That’s what I use for mine. I built a plywood box that fits over the plate, I made the bottom of the box double-thickness so I can use it as a general purpose work surface when I don’t need the precision. The plate is on a welded stand with heavy duty casters so it can be moved around as needed.
Jim
Agree on a box to cover the plate. That’s what was used in any dept. where I worked
I would like to hear more about precision measuring tools especially the digital height gauges you looked at during your search.
Also, I miss Enco.
Nathan
I’m intrigued by the measuring tools also. Why a cylindrical square?
Last flat reference I used had nice adjuster feet on it. And are their some that aren’t granite?
Shane
I would love to hear more about precision measurement tools! I worked at a machine tool manufacturer for a few years and even I had to google what a cylindrical square was. Thank you for the information.
Troy
Awesome purchase! I hope you don’t come to take it for granite.
/dad
Skye A Cohen
Tool news you might want to post about:
Festool domino joiner, the smaller one[500] apparently had a huge fire in a parts supplier factory and is now on a months long wait. The tools are backordered everywhere and impossible to get with a several month due date but I’m told that the due date is a guess as their process got pretty scrambled.
Apologies posting this here, i couldn’t find a more appropriate email link or something like that.
D3t
https://discuss.toolguyd.com/ The forum or I’ve messaged the Facebook page before also.
eddie sky
I had no idea there was a forum! And shame, can’t sign up. And Stuart wants to shut it down. 🙁
Should have Forum link at top. And link in each article/review/tip.
Oh well.
grokew
To be fair, even though the link is shown on every page, it is way down after the comments, making it easy to miss.
Stuart
The forum’s been around for 8 years. It was never popular enough to give up top-menu real estate for.
The shift to mobile also went hand-in-hand with the rise of social media and decline of topic-specific forums.
It’s due to be decommissioned due to disuse and the increased frequency of bad actors with specific agendas.
I can gate-keep trolls and bad actors out of blog comments, but that’s not possible in a forum.
When I have a chance, the forum will be decoupled from ToolGuyd and then either transferred or decommissioned.
Right now it’s set to private mode with no new registrations permitted.
MM
@Stuart
Regarding the forum, I know this is something of beating a dead horse since you’ve already decided to shut it down. But I see your comment about It was never popular enough to give up top-menu real estate for being something of a catch-22. Every time the forum is mentioned here on the main site there are people who mention they’ve been on the site for ages but weren’t even aware of the forum. I can’t help but wonder, perhaps if the forum did have “top-menu real estate” perhaps it would be popular enough to justify it?
Stuart
No. Maybe it was up there are some point, I don’t remember. I had posts about it in the earlier years. Keep in mind that the desktop view was the majority view until just a few years ago, and so it was highly visible.
Even with menu placements, consumption habits are different today.
There’s also the fact that the forum outlived most of the purposes it was created for.
Stuart
It’s not ideal to hijack a discussion thread, but if one has to, posts like this one are a good place for it.
There’s an email link at the top of Desktop and bottom of Mobile pages, an email address in my Instagram profile, and various other social media direct messaging methods. Responses to the email newsletter get to me as well.
It’s difficult for me to get back to everyone about everything, but I see everything.
Facebook messages have tended to be buried, but the app has been better about sending me notifications about this.
And yes, the forum is likely to be decommissioned.
Stuart
I checked multiple dealers, and they all have March delivery ETAs.
I’ll ask Festool USA if there’s anything they can communicate about the matter at this time, but I don’t really expect them to.
Rcward
What are your uses for these?
MM
Their main intended purpose is a precision reference surface to measure things off of, usually in combination with a height gauge. Those are a lot like calipers but oriented vertically and taking measurements off its base which sits on the surface plate. Like calipers those are made in vernier, dial, and digital versions. But they can be used for many other things too. More complex measurements can be done using the surface in conjunction with other tools like V-blocks, a sine bar, dial indicator, depth micrometer, etc. You can use it to check parts for flatness by placing them on the surface and sticking feeler gauges in any gaps. You can check cylindrical parts for straightness in a similar manner: try and roll them on the surface and if they don’t roll perfectly feeler gauges can be used to identify and measure any bending. They are also useful when you want to create a very flat, smooth, surface on a part: put a little water on the surface plate, then put a sheet of wet/dry sandpaper on top. The water makes the paper stick by capillary action. Now you can use that as a lapping surface.
Stuart
It varies.
I wanted the larger one for squareness checks that my smaller plates are far from, ideal for.
With a vertical reference on a horizontal reference, I now have a perfect square reference to check whether squares are perfectly square.
Or, let’s say I need to mark a metal block exactly 1/2″ from a surface. A height gauge or scribe can do that far quicker than other means.
Ryan A. Brown
Precision Tools, YES PLEASE!
Jared
You reminded me that I wanted to get a surface plate!
In my brief search I spotted one in Canada from Busy Bee Tools that is 12″x18″x3″ with an accuracy rating of plus or minus .0001” on sale for $70 – which seems remarkably cheap for that size compared to what I saw elsewhere.
I think that will work for me. I don’t expect to need more than “shop grade” for my projects.
Saulac
I used to use a very large one at work to check weldmans for straightness. Huge time saver. I wonder if cheap lasers have replaced some of the need for these. Talking about old school precision measurements, few years ago I ran into a very old gent with a very large equipment (?) where he projected what being measured onto a large screen…he said it is more accurate than anything. Still have no idea what it was, but I believe him!
MM
Sounds like an “optical comparator”. The larger ones were indeed extremely precise.
Saulac
That’s it. Thanks. He must have one of the larger one. Larger than anything Google shows.
James+C
I don’t normally watch this show, but if you youtube search for “Rick and Morty true level” I think it’s applicable here.
Greg
For a “budget” option, countertop stores that cut stone slabs for people’s kitchens, often have remnant cuts they’re happy to get rid of for cheap, in some cases they might even be free, depends on the shop. Some of the remnant cuts, can be pretty big too.
Another option, float glass is very flat too. Something like the thick glass used in glass table tops. Of course, glass being glass, you need to be careful, and opting for tempered might be the saner choice. These will not be remnants, but in often cases still significantly cheaper than proper granite surface plates.
While I wouldn’t consider these reference grade by any means, if you just want a known flat assembly area you can tuck away, it works pretty well.
Matt
Table top glass isnt going to be flat. A easy way to prove this is to look at how distorted a reflection is in one, versus the reflection in a camera lens filter.
IronWood
A stone sink cutout is what I use for sandpaper sharpening. We used to live down the road from a countertop place and they’d just lean remnants up outside the fence for people to grab. Score!
Mark M.
Dumb question amnesty, I guess, but what are you using it for? Lots of good descriptive information but it seems like we’re missing the “why?”.
Stuart
As a flat reference for measurements and squareness check.
Let’s say I have a straightedge and want to check the flatness of a circular saw shoe. Is the straightedge straight and flat? Grab a surface plate and feeler gauges and check.
This is one of those tools that everyone uses differently.
Travis
If you plan on doing any spotting using machinist blue, I highly reccomend springing for Canode water based machinist blue (or red or yellow). Dykem blue is far more readily available, but tends to get everywhere and sticks to everything. Canode, being water based cleans up easily and works just as well.
Drew M
I’ve heard rumors from machine rebuilders that Canode yellow is no longer made.
Steve
Stuart – where did you buy your granite surface plate?
Steve
Stuart
MSC for the Precision Granite surface plate under SPI branding.
Steve
I’m afraid the link doesn’t redirect for me past the google ads. Do you have a direct link?
John Newell
https://www.mscdirect.com/product/details/01941103
Roy
More metrology posts please
Big Richard
Metrologist here, please no more metrology posts. I don’t want to be reading about work stuff while I am at work trying to kill time reading about tool stuff.
Stuart
Are you being serious, or making a joke about meteorology?
Shawn Yuan
No talks about meteorology! The weather man said sunny and blue skies last week while it started drizzling. Every time they’re super wrong, I surmise that they just stick their head out the window before the weather forecast.
JR Ramos
Wow, you sprang for a Starrett!
Y’know, one question I have about plates in general is why the different thicknesses for the smaller sizes like this. 2″ is pretty solid. Why step up to 3″…? The 6″+ seems plausible for the large and very large plates. Will granite actually bend/sag a little under it’s own weight if not adequately supported? Thermal considerations? Surely not to hedge bets on safe shipping/arrival.
The price of cylinder squares has always made my eyes water. I understand why, but wow. The…advanced details?…of high accuracy metrology are just incredible really. For many years I never really understood the need for grips on mic standards and such – thought they seemed like unwieldy items for comfort or convenience before I learned that they were for thermal insulation when used for long periods at a time. Had no idea that steels could actually change dimensions just from body heat (let alone ten degrees of room temperature variation…).
Stuart
No?
I have a tiny Starrett toolmaker, ALL of their other sizes and styles have been unavailable.
The SPI at MSC turned out to be “Precision Granite,” which I am thus far happy with.
I think the thickness is proportionate to the footprint for strength or stability.
There are definitely thermal considerations, I’m not sure if that makes a difference between say 3″ and 4″ for smaller plates.
Regarding micrometers, oh definitely. When dealing with high precision, repeatability is key; you don’t want measurements to change over say 30 minutes because you’re holding it. Features like ratcheting thimbles and such help with repeatability too.
IronWood
I love that in this day and age the gold standard for precision is still a piece of rock! I just find that satisfying. And if anyone else is interested in this kind of stuff, Simon Winchester’s “The Perfectionists” is a really great read.
Wayne R.
On YouTube, in Keith Rucker – VintageMachinery.org’s channel, he’s got a good video called “Surface Plates: Granite vs Cast Iron”, it’s pretty good, I think adds a lot about this topic.