Reddit mentions: The best dimensional calibration products
We found 25 Reddit comments discussing the best dimensional calibration products. We ran sentiment analysis on each of these comments to determine how redditors feel about different products. We found 19 products and ranked them based on the amount of positive reactions they received. Here are the top 20.
1. Grizzly G9649 9-Inch by 12-Inch by 2-Inch Granite Surface Plate, No Ledge
- Bilateral accuracy of plus or minus .0001" total instrument runout
- Package dimensions: 10.6" x 13.1" x 2.7"
- Approximate weight: 26.3 lbs
Features:
Specs:
Height | 2.7 Inches |
Length | 10.6 Inches |
Weight | 25.14 Pounds |
Width | 13.1 Inches |
Number of items | 1 |
2. HAWK PRECISION 1-2-3 BLOCKS - TM39123
- 2 Identical Blocks, Set With Box Weighs 2 Lbs., 8.7 Oz
- Each Block Measures 3"x 2"x1"
Features:
Specs:
Weight | 2 Pounds |
3. LEE PRECISION 90689, Quick Trim Die.300 AAC Blackout
- Product Type: Sporting Goods
- Item Package Dimensions: 10.16 L X 3.302 W X 0.762 H (Cm)
- Country Of Origin: United States
- Item Package Weight: 0.200 Pounds
Features:
Specs:
Color | Silver |
Height | 2 Inches |
Length | 5 Inches |
Weight | 0.36 Pounds |
Width | 2 Inches |
Size | Small |
Number of items | 2 |
4. HHIP 4401-2418 Black Granite Surface Plate, Grade A, Ledge 0, 24" Length x 18" Width x 3" Height, +/000075" Accuracy, 150 lb. Weight
Surface Plate is checked by an auto-collimator for Overall accuracy assuranceGranite surface plates meet or exceed federal specifications ggg-p-463cIncludes a Certificate of inspectionAccuracy is +/-.000075 inchMeasures 24" Length by 18" width by 3" height
Specs:
Height | 2.99999999694 Inches |
Length | 23.99999997552 Inches |
Weight | 150 Pounds |
Width | 17.99999998164 Inches |
Size | 24 x 18 x 3" Size, 150 lbs Weight |
Number of items | 1 |
5. BL-123NH Pair of 1" x 2" x 3" Blocks without holes
- Our part # ALL-55525
- Heat treated and case hardened to HRC 57-62
- Made of precision-grade tool steel hardened and ground on all 6 sides of block
- Accuracy and squareness on all sides within .0001"-.0002"
Features:
Specs:
Number of items | 1 |
6. Mitutoyo 64AAA590 Calibration Set for Shore A Scales with Nominal 20, 40, and 80 Blocks Included, with Mahogany Case
- Mpn: 64AAA590
- Country of manufacture: United States
- Manufacturer: Mitutoyo
- Supplied in mahogany case
Features:
Specs:
Height | 1.5 Inches |
Length | 7.9 Inches |
Weight | 0.55 Pounds |
Width | 3.8 Inches |
Number of items | 1 |
7. Anytime Tools Angle Block Set 30-60-90 & 45-45-90 Precision +/- 20 Seconds, Machinist Tool, 2 Piece Set
- High Precision: +/- 20 Seconds, 0.0001" per inch
- Set contains two angle blocks: one 30°-60°-90° degree block and one 45°-45°-90° degree block
- Precision Ground Solid Hardened Steel
- Thickness 0.25"
Features:
Specs:
Number of items | 1 |
8. Grizzly G9648 9-Inch by 12-Inch by 3-Inch Granite Surface Plate, No Ledge
- Bilateral accuracy of plus or minus .0001" total instrument runout
- Package dimensions: 10.7" x 13" x 3.5"
- Approximate weight: 36.45 lbs
Features:
Specs:
Height | 3.5 Inches |
Length | 10.7 Inches |
Weight | 36.55 Pounds |
Width | 13 Inches |
Number of items | 1 |
9. Anytime Tools 1-2-3 Blocks Matched Pair Hardened Steel 23 Holes (1"x2"x3") 123 Set Precision Machinist Milling
MATCHED PAIR, Professional Quality ToolPrecision ground Steel and Case Hardened on all six sidesSquareness on all sides within 0.0001"Surface finish from 6 to 16 microinches23 through holes (5 tapped 3/8"-16 TPI and 18 plain)
Specs:
Weight | 1.92 Pounds |
Size | 1 Pair (2) |
10. HFS (R) 1 Pair 123 Blocks 1-2-3 Ultra Precision .0002 Hardened 23 Holes 0.0002"
- [Ultra Precision]: 0.0002" height accuracy precision matched blocks for mounting work for precision.
- [Application]: This steel blocks can be used for set-up, layout and inspection jobs. Suitable for all kinds of machine tool.
- [Durable Material]: Made of hardened tool steel and precision ground on all six sides
- [23 Holes Design]: The unique design makes your work smoothly, great performance. precision steel blocks Has 23 holes with 5 holes tap to 3/8-16 threads for clamping and 18 untapped holes.
Features:
Specs:
Number of items | 1 |
11. Starrett 81802 Impala Black Granite Toolmakers Flat, 12" Length, 8" Width, 2" Thickness, 0.0001" Overall Tolerance
These handy flats are small precision surface plates that are ideal for many inspection and checking uses throughout the plantThey are especially well suited for layout work and offer an easy, portable reference for gaging small partsThe shipping weight is 9kg
Specs:
Weight | 32 Pounds |
12. Flir C3 – Compact Thermal Camera with Wi-Fi
- Portability Pocket Portable Thermal Camera with Msx Enhanced Thermal Images providing stunning detail to help you identify problem areas easier
- FLIR One displays live thermal infrared imagery using the FLIR one iPhone app so you can see the world from a thermal perspective
- Wireless connectivity Wi-Fi Connectivity transfers images wirelessly to mobile platforms. Standard is 802.11 b/g/n. Operating temperature range is minus 10 to 50 degree Celsius. Digital camera is 640 x 480 pixel
- Measurement Modes – Center Spot or Area Min/Max allowing you to quickly measure within a defined area box
- Image Modes: “MSX” adds key details from the on board digital light camera to the IR image adding detail and clarity; "Picture in picture" overlays a fixed Section of a thermal image onto a digital photo to clarify problem locations and enhance documentation. Spectral Range: 7.5 - 14.0 µm. Storage Temperature Range:–40°C to 70°C ( 40°F to 158°F)
- Includes: Infrared camera, lanyard, pouch, power supply/charger, tripod mount, USB cable, printed documentation
- Brilliant 3" intuitive touch screen with auto orientation for easy viewing
Features:
Specs:
Color | C3 |
Height | 4.9 Inches |
Length | 3.1 Inches |
Weight | 0.3 Pounds |
Width | 1 Inches |
Release date | March 2017 |
Size | C3 |
Number of items | 1 |
13. Accusize Industrial Tools 81 Pcs Steel Gauge Block Set, Grade B, P900-S581
- 81 pc Grade B Steel Gage Block Set with MFG'S certificate
- Manufactured under carefully controlled conditions allowing for the highest degrees of accuracy when used at a temperature of 68 degrees F. (20 C).
- All gage block sets are assigned serial numbers and accompanied with a certificate of inspection listing the deviation for each block
- Each gage block set meets or exceeds federal specification ASME B89.1.9-2002.
- Hardened to HRC 64 / All gage block sets are made to special standard to resist corrosion and defacement
Features:
Specs:
Height | 8.661417314 Inches |
Length | 13.385826758 Inches |
Weight | 2.8 Kilograms |
Width | 2.755905509 Inches |
14. 81 PCS Precision GAGE Block Set W. Certificate, Grade A(-)/3#702-G3-NC - New
81 PCS PRECISION GAGE BLOCK SET W. certificate, GRADE A(-)/3 #702-G3-NC - new
Specs:
Height | 8 Inches |
Length | 30 Inches |
Weight | 11 Pounds |
Width | 25 Inches |
Number of items | 1 |
15. TTC 9" x 12" x 2" Thick Grade B No Ledge Black Granite Surface Plate
- For general inspection work throughout the shop.
- Meets or exceeds Federal Specification GGG-P-463C.
- Harder than steel.
- Retains accuracy for years.
- Overall accuracy: ±.0003"
Features:
Specs:
Weight | 26 Pounds |
Number of items | 1 |
16. Mitutoyo Steel Rectangular Gage Block, ASME Grade AS-1, 1.0" Length
Grade AS-1 gage block supplied with a Mitutoyo certificate of inspection that the block meets American Society of Mechanical Engineers (ASME) B89.1.9-2002 standard for flatness, length, parallelism, and surface finishHigh-carbon, high-chrome steel provides high hardness and wear-resistanceRectangula...
Specs:
Height | 3.1 Inches |
Length | 2.1 Inches |
Width | 0.8 Inches |
Number of items | 1 |
17. HHIP 3600-0042 Machinists' Bench Block (Holes 1/8~5/8 Inch)
- 3" Diameter x 1-1/2" H; Made from steel-hardened and Ground
- The knurled side provides a good gripping surface; V-groove across the face accommodates round and odd shaped stock
- Made from steel-hardened and Ground Holes from 1/8 to 5/8 (3-16mm) diameter
- A handy tool for holding work when driving pins, drilling, etc.; 3" 1-1/2" H
- Holes from 1/8 to 5/8 (3-16mm) diameter
Features:
Specs:
Height | 1.49999999847 Inches |
Length | 3.99999999592 Inches |
Width | 1.49999999847 Inches |
Number of items | 1 |
18. Granite Surface Plate 12" x 18" x 3" A Grade
- Stable, ultra flat surface
- Flat to .00005
- Moisture and corrosion free
- Easy to clean -
- WoodRiver is proudly made by Woodcraft, America’s leading supplier of saws, planes, power tools, hand tools, wood stain and paint, routers, sanding, wood, kits, dust collection and more. Our award winning family of brands includes WoodRiver, Highpoint, Woodcraft and Woodcraft Magazine as well as the greatest selection of woodworking books, videos, and plans.
Features:
Specs:
Height | 4.5 Inches |
Length | 20.63 Inches |
Weight | 80.2 Pounds |
Width | 15.5 Inches |
Size | 12" x 18" x 3" |
19. Mitutoyo Ceramic Rectangular Gage Block, ASME Grade 0, Metric
Grade 0 gage block supplied with a Mitutoyo certificate of inspection that the block meets American Society of Mechanical Engineers (ASME) B89.1.9-2002 standard for flatness, length, parallelism, and surface finishCeramic block for dimensional stability and thermal expansion resistanceRectangular ba...
🎓 Reddit experts on dimensional calibration products
The comments and opinions expressed on this page are written exclusively by redditors. To provide you with the most relevant data, we sourced opinions from the most knowledgeable Reddit users based the total number of upvotes and downvotes received across comments on subreddits where dimensional calibration products are discussed. For your reference and for the sake of transparency, here are the specialists whose opinions mattered the most in our ranking.
Studio can become a second home for you, especially towards the tail end of each semester as everyone is rushing to wrap up final projects. Like others have said, there may be nights where you may be better off sleeping in studio or need to pull an all-nighter. Studio culture is definitely fun, though; folks tend to find some interesting ways to reduce stress.
For 2D software, use AutoCAD. You can get a free educational license for all Autodesk software and they are the industry standard. I used Adobe Illustrator and Photoshop to set up final plot sheets and to pretty up 2D drawings / renderings.
For 3D software, SketchUp is free and stupidly simple. I used Kerkythea as my render engine (it's free but is a little outdated). Once you move on to more complex projects, I'd recommend Rhinoceros3D with V-Ray. Familiarizing yourself with Revit is also great for future employment.
Some model-making tips that I wish I'd known in my first year: 123 Blocks are a gift from the gods, spray accelerant for super glue is amazing, and hot glue is great if you can hide it from your professor / critics.
So this is a month old but I have some insight if you haven't already started a certain path.
I just bought a 300blk upper for my pistol. I have a lot of 223 brass I've saved to and decided to reload for 223 to save some money. Well I'm pretty well into reloading for 223 and decided i would start for 300blk as well. The equipment isn't too expensive (relatively) if you get some Cabela's sales and buy some discounted gift cards. Full equipment with necessary parts will run about $250 after everything (can be cheaper if you buy a bundle pack).
This kit
Digital caliper
Initial 300blk dies
Trimming die
Trimmer
Case lube
That's pretty much it for the equipment side. Then you'll need bullets, powders, and primers.
If you're starting out with 223 brass you may want to cut the case before trimming, but you'll need something to cut it with. If you buy some ammo to shoot and collect the casings you can't use them too.
I have everything I need for 300blk except powder pretty much. I just need to find something to use.
So $250 for equipment and 1k round of 223 reloading will cost me about $175. That's $425 for the first 1k round of just 223. Once I buy stuff for 308, 300blk, and 9mm I'll start saving in much higher quantities per round. I think I'll probably actually start saving money through reloading in a couple months if I shoot as regularly as I'd like. I still buy ammo on sales and all, so I typically don't count brass into my cost for a reloaded round. On average it's about $.18/round (for .223) if I don't find good deals.
Edit: so I just went through and did some calculating. .178cpr for 223, .285cpr for 300blk, and .362cpr for 308 of I get good sales and free shipping.
Very cool and informative video. Really neat use of salvaged parts and the guy is intelligent and skilled. However I think he kind of down plays and under estimates the cost of the product and tools he was using and he also mentions the fact that you can buy a lathe (that would almost certainly work better) for a similar price. The big kicker is the other tools. The tools to use and or build this lathe would cost more than the machine itself. I'm going to link you some of the tools you'd want to be able to use this machine effectively (and make it).
This granite block will be the basis for all of your measurements it is extremely flat. You'd probably want to make a stand for it and it is very heavy as well. The 933$ version would be ideal for bigger stuff but maybe you could just make small stuff it's a small lathe anyways so lets say the 235$ version
https://www.amazon.com/HHIP-4401-1812-Granite-Surface-Accuracy/dp/B01LTHIHCK/ref=mp_s_a_1_3?keywords=granite%2Bblock&qid=1569402248&s=gateway&sr=8-3&th=1&psc=1
Mitutoyo Digital Caliper 120$ The waterproof version is better if you intend to use coolant. I think you could use cheaper no name ones for the ones that he built into the machine but you would need one good one.
https://www.amazon.com/Mitutoyo-500-196-30-Advanced-Measuring-Resolution/dp/B00IG46NL2/ref=mp_s_a_1_3?keywords=mitutoyo+digital+calipers&qid=1569402063&s=gateway&sprefix=mitutoyo+digital&sr=8-3
Range dial indicator (runout gauge). He used one in the video and you'd be using one a lot. 219$
https://www.amazon.com/Mitutoyo-64PKA075-Indicator-Magnetic-Plastic/dp/B007XZIT5I/ref=mp_s_a_1_4?keywords=runout+gauge+mitutoyo&qid=1569402528&s=gateway&sr=8-4
Micrometer set with standards. 354$
https://www.amazon.com/Mitutoyo-103-922-Micrometer-Standards-Graduation/dp/B0006J42OA/ref=mp_s_a_1_5?keywords=mitutoyo+micrometer&qid=1569403065&s=gateway&sr=8-5
That's just getting started. Now you might be able to find some of this stuff used but I'm not sure if I would trust it. You wouldn't believe how careless people treat tools that cost several hundred dollars. If you did go used I'd try to find someone getting rid of their personal tools, not shop tools.
This isn't to discourage you though. I just want people to realize it's not easy or cheap. I'd start out with a lathe for wood and make stuff on it that doesn't need the tight tolerances.
Check out this guy. https://youtu.be/yCaGW9z4blM
You are doing everything right from what I can see, just needs more!
That handle part of the square is probably machined perfectly flat and can't flex right? I'd use that. It took me well over an hour to get the finish i wanted with 400 grit. Just keep rotating the cooler 90 degrees every 5 minutes or so so you are working it evenly. Sand in a figure 8 motion and if it starts catching too much to be smooth, add a little more water. I'd cut the sand paper in to small pieces just large enough to use comfortable around the block and change them every 5-10min depending on how it was feeling.
The amount of paste in the first one was a bit much, I recommend people over apply because its easy to smear off the paste during re-assembly or just not have enough to fill in a bad job and the HBM gaps. You can't hurt it, it just takes more clean up time, too little paste and its cooked. Now you have a feel for it the second application is looking good, I'd put a little excess over the HBM and go thin in the middle (when its flat!) now you have the hang of it.
Looking forward to your results! I see that SC mouse pad :)
If you are looking for a good block to sand with, I'd grab these: https://www.amazon.com/BL-123NH-Pair-Blocks-without-holes/dp/B000P496VU/ref=sr_1_8?ie=UTF8&qid=1550778570&sr=8-8&keywords=machinist+block
Judging by how the Shore scales overlap, you probably want to be using D anyway: http://www.imperialrubber.com/images/03-numerical-comparison-of-shore-scales-for-measuring-hardness.jpg You can always convert into another scale if you really want.
Here is the same meter that you found for less money and ships from Amazon: https://www.amazon.com/Digital-Durometer-Rubber-Hardness-Display/dp/B01ET0E2UA/
I would just buy that and try it out. The reviews you posted seemed mostly positive aside from one asshole who left one star because he's an idiot, one guy that got a defective unit, and another guy who said it isn't accurate (no idea what he was actually doing with it).
Buy it from Amazon and return it if it isn't working.
You aren't going to get exceedingly accurate readings with a device that isn't a piece of actual lab equipment. This is serious business. We're talking very precise tip geometries, forces/springs and measuring equipment (think micrometer or dial indicator). https://en.wikipedia.org/wiki/Shore_durometer
I would buy the cheap meter and then a calibration set: https://www.amazon.com/Mitutoyo-64AAA590-Calibration-Included-Mahogany/dp/B007FFTUGI
You can determine a correlation between your readings and known values. Plot the three points in excel to generate a best fit line and equation, plug the values from the cheap meter in and bingo. You will still be under $250 and you can buy a the right used shore tester when it pops up on ebay.
Craftsman Table Saw Model # $150
Shop Fox model #G8826 fence system $275
Freud P410 Premier Fusion 10-Inch 40 Tooth Hi-ATB General Purpose Saw Blade $80
Wilton 15” drill press $100
Parks 12” planer $600 This requires a little road trip
Atlas 6” jointer $150 Model #
Delta 10” bandsaw, Powerkraft radial arm saw and Rockwell contractor table saw $200
I would resell one of the tablesaws Just pick the nicest one and sell the other.
Oneway Multi Gauge $97 This is for setting the jointer perfectly and the dial indicator can be removed to make planer setting jig as described by Bob Vaughan (see youtube) or fine woodworking 107.
Angle block set for machine setup $30
Bessey Bar Clamps $14x3 plus maybe $10x3 for bars Say $75 total
Stanley sweetheart chisel set of 4 $80
This leaves $243 left for misc things like drill bits, planer/jointer knives or sharpening F style clamps a cordless drill, random orbit sander, sand paper ect.
I got a 12" square by 2" thick surface plate on Amazon for about 30 bucks with shipping. Best shop purchase in awhile.
EDIT: Can't seem to find the particular one I had, but here's something close. Not quite as accurate as the one I got (came with a cert and everything!). It's extremely useful for sanding things flat, polishing, and measuring accurately. I use it the most for sanding; just throw a bit of water on there and a sheet of wet/dry sandpaper on top. The water sucks the sandpaper down flat. The thinner the paper (usually higher grit), the better it sticks to the plate and the flatter it gets. Can get an almost mirror shine with 2000 grit and just a very very light buffing on aluminum.
Good question, and it pains me a bit that I have a small box of unused tools that were purchased when I began. I'm sure I missed a few things, but here you go:
If links weren't provided then I already had the item.
Yeah, first aid supplies would be good.
FLIR C3 - COMPACT THERMAL CAMERA WITH WI-FI https://www.amazon.com/dp/B01MS85Q85/ref=cm_sw_r_cp_api_i_Nzg4DbHGN81Q7
For anybody looking. It’s about the size of an iPhone and has a decent detector. We give them to our crews that work in confined spaces and with energized equipment.
is a grizzly like http://www.amazon.com/Grizzly-G9649-12-Inch-Granite-Surface/dp/B0000DD0KE/ref=sr_1_1?ie=UTF8&qid=1451237818&sr=8-1&keywords=surface+plate good?
and alright. I just read that some people say you shouldnt use "precision tools" for sanding. Whats treating it right? would that just mean not using it as an anvil or throwing it, or do i need to do something to condition it?
Here's a small gift (~$15), 123 Blocks, they are precision machined metal blocks, they have been incredibly useful for building physical models, which he will do A LOT of during his school time. I have had my set borrowed by fellow students more times than I can count. Everyone always says they are very handy and versatile, which i can attest to as well.
An Amazon link for ya!
A 12"x18"x4" one is north of $200, can't imagine what this is:
https://www.amazon.com/Starrett-Granite-Toolmakers-Thickness-Tolerance/dp/B003XU77XC
0.0001" or 0.00005" tolerance is par for the course for these.
they're typically used for metrology and the like as reference
In that case I'd say these are more like gage blocks, then, although there's no reason feeler gauges can't be used as models and not just measuring tools. Still, nice idea.
I have one of these and it's really useful for that purpose, and for quick measurements for 1", 2" and 3"
I like keeping a pair of these around for tool setup and other things.
TIL!
And not very expensive.
Things that'll always be useful/consumable regardless of what kind of maker they are:
http://www.amazon.com/gp/aw/d/B003U9W8BM/ref=mp_s_a_1_2/182-1573071-3110618?qid=1408820061&sr=1-2
http://www.amazon.com/Set-Up-Blocks-Precision-Machinists/dp/B00134DPM2
Those are what I bought.
As for their uses, I found some YouTube videos about it while trying to figure out how to make a certain cut.
eighty bucks on amazon (no that's not a referral link), but apparently they can go into the thousands for a set.
Now you have.
I've only used these little ones for lapping, but I'm probably going to get one to build a test stand with, and maybe even make a height gage.
New ones Flir ONE PRO Android USB-C £450 or FLIR C3 £560 The FLIR one pro being better resolution (they use the phone which cuts down costs)
It's if you're going up to say the T6XX (640x360 vs 160x120) then the price jumps. For a survey, looking for major heat loses and an additional to add, do you need that level?
Its a machinists bench block:
https://www.amazon.com/HHIP-3600-0042-Machinists-Bench-Block/dp/B00N4115UG
No problem, what your basically doing is getting a cheap version of this
Requirements for gauge block wringing: Average surface roughness of at least 25 nm and flatness of at least 130 nm. The blocks do not need to be metal. It works even with clean blocks or under a vacuum. There is no or virtually no pressure required to wring blocks together. The strength from wringing two blocks can be as high as dozens of atmospheres.
Things this is not:
Van Der Waals Force/Gecko feet: Technically london dispersion forces. Between two flat planes with 10nm separation in a vacuum, the van der Waals-induced pressure is around .05 atm. This is two or three orders of magnitude too low. Its an additional order of magnitude lower under atmosphere. Additionally, the force is repulsive before its attractive.
Cold Welding: Cold welding only works with metals. Wringing works with any flat, smooth, hard surface. It also requires pressure, zero contamination, and no atmosphere. Also, cold welding would result in galling.
Magnetism/dielectric/electrostatic: Works with ceramic blocks, is independent of resistivity or electronegativity.
Some other kind of metal attraction/molecular attraction: These bond lengths occur over hundreds of picometers, and would be blocked by a film of any thickness or composition in between the blocks. Also beyond half a nanometer the force will be repulsive. In fact the longer the bond length, the more repulsive it will be initially. These bonds drop off with the sixth power of distance. (edit: straight from the mouth of the wiki: bodies have to be conformal to 1 nm or less to exhibit this.)
Casimir effect: Operates on a longer distance than van der Waals, and can cause pressures of 1 atm. at 10 nm. Still a little low to be the culprit. Also, as someone who worked in a nanotechnology lab, making devices that can fit in the space between gauge blocks- the Casimir effect is witchcraft and not to be trusted. By most formulations it would not describe what we see in gauge blocks. Among other things it should work MUCH more strongly for metals.
Surface tension: Maybe. But it doesn't work in vacuum or with clean blocks, so no.
Trapping a vacuum: No. If anything this should push them apart because you'll tend to trap air underneath the thing rather than trap vacuum. Also, the maximum force would be 1 atm, which is 50x lower than reality.
Trapped liquids: The idea here is that any amount of trapped liquid would try to vaporize if you pull the blocks apart, and since it doesn't want to do that the blocks stay together. This wouldn't keep the blocks together, just resist pulling them apart momentarily.
Personally I don't think we can say nearly anything about wringing without actual data, which I haven't seen. I suspect that it is mostly surface tension that does the high force stuff, and the effect is way weaker with clean surfaces, and that it probably has something to do with the casamir effect, and nobody is totally sure on that shit because it has confounded nearly every nontrivial experiment done with it. Primarily though- I'm not sure anyone has ever done an experiment with TRULY clean gauge blocks, which is way harder than you'd think. Dropping a block in acetone isn't good enough.