Comments
ExHempKnight OP t1_j91sxsw wrote
Thank you! I need to bring the standards to an instrument calibration place, and have them checked. I'm sure they're fine for my little hobby shop, but I'm kinda particular about that stuff.
tlove01 t1_j926wwg wrote
Metrology is cool
ExHempKnight OP t1_j92o92l wrote
It really is. Since I've started this journey of precision work, I've really gained an appreciation for how important the tiniest of distances really are. And that everything is rubber.
agnarxrist t1_j939305 wrote
What do you mean by “everything is rubber”?
ExHempKnight OP t1_j93adnm wrote
Everything is flexible, to some degree. Drop a feather onto a pool table, and the weight of that feather will bend the slate of the pool table. It's a tiny, tiny, TINY amount, but given appropriately sensitive equipment, you will find that there's a deflection.
When you're measuring down to 3, 4, or especially 5 decimal places, even the heat of your breath can distort a part a measureable amount.
Robin Renzetti has a great demonstration of this, if you're curious. Skip to 31:00 for the relevant part.
phuntism t1_j93g2qp wrote
For those who watch the video: If you skip to 31:00, you need to watch to 35:49, to see why he's doing this testing on his carpet? :)
zyzzogeton t1_j93of6q wrote
Adam Savage has some interesting discussions about his journey towards precision. Pask has a similar kind of arc as well on his channel. The hallmark of craftsmen is that their tastes become more and more exacting over time. The tools needed to accomplish that become more and more specialized and beautiful too.
ExHempKnight OP t1_j93wnid wrote
I've enjoyed Adam Savage's journey. Wild to see someone I admire so much, have the same kinds of struggles and learning experiences that I have.
Occhrome t1_j92af4m wrote
I’m sure they will be fine. We calibrate our sensitive torque wrenches all the time and they hardly ever need adjustment.
ExHempKnight OP t1_j92m00q wrote
I'm sure they will, as well. But as old as they are, I'm sure they're a bit worn. I don't need them to be exact, I mostly need to know exactly how off they are, so I can compensate when I calibrate the mics.
THE_CENTURION t1_j92q9rn wrote
I mean... That's a completely different kind of tool I don't know why you think that's applicable.
These kinds of standards can corrode and change or need to be re-lapped, or just wear. That doesn't ruin them, but you need to know how long they actually are so you can zero the micrometer correctly.
avidblinker t1_j9335mn wrote
Nah they’re right. I calibrate the color on my computer’s LCD display at home every few months and typically don’t need to change much
Lampshader t1_j93bdpu wrote
Nah that can't be right, because I have to reset the clock on my microwave every month
The_Best_Dakota t1_j93hrak wrote
That’s just the power company being shit
Lampshader t1_j93ijx3 wrote
It almost certainly has its own internal clock rather than using the mains frequency, but that's beside the point
The_Best_Dakota t1_j93irt9 wrote
I was making a joke about the power going out and needing to reset it bc I find myself having to do that at a frequency that’s probably more consistent than that of the power itself
Lampshader t1_j94b0an wrote
Ah oh right, yeah that's annoying too
Fat_Head_Carl t1_j93m644 wrote
With all that work you put in, why the fuck not!
I have inherited a box of machinist tools... I'm not sure what they're good for, but they seem all new. They're starett
Esset_89 t1_j92f3p1 wrote
Bring the gauges as well, they also need to be checked
ExHempKnight OP t1_j92ktrj wrote
Nah, once the standards are known, I can calibrate the mics myself. I'm not looking for NIST traceability.
nicaldrogo t1_j92ymiy wrote
Depending on usage, you might need to get them tested for flatness and linearity. Parallelism for a 0 to 1 inch mic as well
ExHempKnight OP t1_j938jxk wrote
I'd love to have them all lapped, but that's beyond any equipment I have, and prohibitively expensive to have done.
There aren't a lot of places that can do it, anyway.
nicaldrogo t1_j93lqd1 wrote
I think you misunderstood me. You mentioned that you could use the end standards to calibrate the mics. All that does is set the zero on the mic itself. Calibrating a mic consists of checking for linearity, flatness, and parallelism. Like you mentioned, it won't matter for your use.
ExHempKnight OP t1_j942yaa wrote
Fair points. If I understand correctly, the measuring faces are checked using a set of optical flats, each a slightly different length, to check for parallelism at different rotational positions of the spindle, right?
Tawmcruize t1_j95t1i1 wrote
As a quality tech who calibrates micrometers often, if you have any that seem to not center very well ( you get a measurement but a little more force changes it by a tenth or so) you more than likely have a burr or foreign material on edge of the faces and a really smooth stone should be able to take it off, this is what I think I used for a v mic that had rust on the carbide faces and it checks gauge pins to tenths still.
boonepii t1_j95p3uq wrote
I got to see a huge metrology operation last week. Over 150 calibration and repair technicians. Was very very cool.
Metrology is a very cool job. Tons of demand.
HOARDING_STACKING t1_j91iqam wrote
You should cross post this on tool porn if you already haven't. Those are absolutely gorgeous!
user_none t1_j921hvc wrote
Hold up. There's a tool porn sub? Awww, damn.
GullibleDetective t1_j93j7dc wrote
Yeah its mostly just half naked pics of Maynard James Keenan :P /s
SteakFries t1_j94kqfo wrote
Lmaoooo
GullibleDetective t1_j94l59h wrote
Reddit is so weirdly oddly trolly and specific I could see that
I once ran across a sub called Bolton tits where all the boobs had Michael Bolton on them, it's no longer a thing
ExHempKnight OP t1_j91ivqt wrote
Thanks! And yeah, I posted it there, too
[deleted] t1_j94eie9 wrote
[deleted]
shadowsong42 t1_j92fbc9 wrote
I keep forgetting that a micrometer is a measuring tool, and not a subdivided meter. Add in that I missed the "lived", and the first thing I thought was "how can one 0.1mm be longer than another?"
Lampshader t1_j93bwfk wrote
If you use English spelling, the terms are distinct:
Micrometre: one millionth of a metre
Micrometer: tool to accurately measure small distances
Americans spell the unit of measurement as "meter" though, presumably as part of their quest to sabotage the metric system (or should that be meteric system?)
Optimistic__Elephant t1_j93jvp8 wrote
The English language and all it’s bizarre rules is a strange pairing with the metric system.
Lampshader t1_j94b65m wrote
> it’s bizarre rules
Not sure if deliberate...
[deleted] t1_j93nues wrote
[deleted]
Optimistic__Elephant t1_j93uhln wrote
I just meant in general English has lots of weird rules like:
> I before e, except after c Or when sounded as 'a' as in 'neighbor' and 'weigh' Unless the 'c' is part of a 'sh' sound as in 'glacier' Or it appears in comparatives and superlatives like 'fancier' And also except when the vowels are sounded as 'e' as in 'seize' Or 'i' as in 'height' Or also in '-ing' inflections ending in '-e' as in 'cueing' Or in compound words as in 'albeit' Or occasionally in technical words with strong etymological links to their parent languages as in 'cuneiform' Or in other numerous and random exceptions such as 'science', 'forfeit', and 'weird'.
Which is funny because metric system is all about logical and consistent rules. So metric + English language is a funny pairing to me.
[deleted] t1_j93z7rn wrote
[deleted]
ExHempKnight OP t1_j92o0xk wrote
Depends on how many decimals you go to, and rounding. 0.12mm is longer 0.11mm, yet both round to 0.1mm.
Sorry, couldn't resist lol
shadowsong42 t1_j92ywbp wrote
No, no, you have a point.
mechy84 t1_j957hch wrote
Just don't say 'micron'.
VisualKeiKei t1_j91x3ah wrote
As someone who has a retired $20k+ box full of Etalon, Tesa, Compac, and Interapid Swiss tools among other machining and metrology tools that are BIFL, I would want this awesome restored set with display rack instead.
ExHempKnight OP t1_j92ovww wrote
Lol I dunno about all that. These mics are good, but they're not Etalon good.
I do wish I had the equipment to lap the anvil/spindle faces. That's really the only thing stopping these from being truly good as new.
But, I suppose I need to be realistic. The mics only read to thousandths, and the tolerances required in my little hobby shop aren't aerospace-grade. Pretty sure they'll be perfectly fine as-is.
Doesn't stop me from wanting to, though...
HipsterGalt t1_j932nzn wrote
I swear we'll machine our way to accidentally splitting an atom one day, purely out of that desire to chase 0. Gorgeous mics though and I'm with the original commentor, I'd pay heaps for a set like this. Though I've yet to do so for those Tesa indexable calipers. One day.
ExHempKnight OP t1_j9393g3 wrote
They're honestly not hard to restore... Disassemble, clean, strip paint, re-enamel the engravings, mask, paint, reassemble with a drop of appropriate oil, calibrate. Just takes patience and attention to detail.
There's probably around $500 in all this. Plus a couple hundred of hours of my own work.
HipsterGalt t1_j93f81j wrote
I'm just not even sure I'd be able to find a set to start with. Though I am definitely making a rack like that one way or another.
ExHempKnight OP t1_j93ftgn wrote
I got these one at a time, mostly. Just cruised ebay.
VisualKeiKei t1_j94k8ac wrote
Your effort and care in the resto definitely shows and the display rack is just awesome. It's way more impressive than all my gear stuffed into a boring brown Kennedy roller. Even a person not familiar with these tools would have the impression they're something special and they're more than sufficient for the home gamer.
I see century-old Starrett and B&S micrometers all the time on eBay and it would be neat to collect and restore a set one day.
johanvondoogiedorf t1_j93n0uk wrote
Whats a micrometer
ExHempKnight OP t1_j93xjbe wrote
It's an instrument used to measure very precisely, down to 3, or even 4 decimal places of accuracy. Used mostly in machining and/or metal work.
Each micrometer only has one inch of range, 0-1", 1-2", etc.. The set I've posted measures to 12", so there's 11 mics total.
Hollywood0967 t1_j94f4cn wrote
What are all those bits on the bottom for?
ExHempKnight OP t1_j94fhq3 wrote
Those are standards. They're rods of a calibrated length, used to adjust each mic to zero. Each micrometer has a corresponding standard rod. The black plastic sleeves on each one serve to insulate them from the heat of your hand, which can cause the standard to expand, thus no longer be exact.
Hollywood0967 t1_j94ga16 wrote
Neat!
Zestyclose_Plenty_49 t1_j91p7xj wrote
I work in CNC and my god this is beautiful
ExHempKnight OP t1_j91q8uy wrote
Thanks a lot! I'm just a basement-shop hobbyist... So I appreciate the compliment from someone who does machine work professionally.
The only thing I'm unable to do with these is properly lap the spindle and anvil faces. If I could do that, they'd be as good as, if not better than, new. But for my purposes, they work great as-is.
GanderAtMyGoose t1_j91rfic wrote
What are the things stored at the bottom of the stand?
ExHempKnight OP t1_j91tim3 wrote
Those are micrometer standards. They are used to calibrate the mics, to ensure accurate readings. Each mic has a corresponding standard... The 3" standard calibrates the 3-4" mic, and so on (the 0-1" mic calibrates on 0, so it doesn't have/need a standard) The plastic sleeves on each rod are to insulate them from the heat of your hand, which can throw off the calibration.
GanderAtMyGoose t1_j91ubgv wrote
Ahh got it, makes sense!
TocsRetsek t1_j93xj7m wrote
They are used to standardize your mic. We use gage blocks to calibrate mic's. We use a labmaster to calibrate the the end rods as compared to the gage blocks.
OneFingerIn t1_j91ldvs wrote
I have no need for this, but I desperately want it.
FLTDI t1_j91pxbm wrote
What are the jaw sizes? Those are amazing
ExHempKnight OP t1_j91qkn2 wrote
Thanks! The set goes from 0-1" to 11-12", in one-inch increments. I've actually almost got a full set to 24", just don't have the stands for the larger ones. Hopefully one day...
A_Light_Spark t1_j92p8d4 wrote
Of course they are buy it for life.
They:
- are made of metal
- don't go under stress, i.e. heat/torque/compression
- are not used outside
- have no moving mechanism
- have no electrical components
ExHempKnight OP t1_j92qn5d wrote
Mostly true. The threads, spindle and spindle bushing, and (most importantly) the measuring faces, are all subject to wear and corrosion. This brand in particular compensates for thread wear in a unique (and in my opinion, superior) way, compared to Starrett or Mitutoyo. The bushings are also replaceable, which I'm not sure is an option with the other brands.
And as old as these mics are, and as much work as I've put into them... They can almost certainly benefit from having the faces lapped. That's really the only thing keeping them from being good as (or better than) new. But I don't have the equipment to do that, and having it done is not cheap (especially for as large a set as I have).
TheMooJuice t1_j9302el wrote
How specifically does this brand compensate for thread wear?
Also what kind of hobbies do you have which utilise these? I have read all your other replies however am unfamiliar with much of the terminology unfortunately
ExHempKnight OP t1_j936wep wrote
Mostly, measuring instruments like this are used in precision machining. Metalworking lathes, milling machines... Stuff like that. I have a small hobby shop in my basement with a lathe, a mill, and a couple of other machines.
Machining in and of itself is a big part of my hobby, but it also supports basically all the other things I'm interested in. I've designed and machined a custom hotend for my 3d printer. I've machined mounts and pulleys to mount a supercharger on my mid-90s Saturn. Brackets for valves on my beer brewing rig. Custom feet for my bed, which house scales, which I use to tell my home automation system when I'm in bed. I could go on.
As for the thread wear compensation... I'll preface this by saying that Starrett and Mitutoyo are fine instruments, have been around for a long time, and are basically industry standard as far as I know. Thread wear in a micrometer is not a huge issue, and plenty of those mics are still kicking, and still accurate, with decades on the clock.
So, quick and dirty micrometer terminology:
- Thimble: the part you actually turn with your fingers.
- Spindle: rod that sticks out of the of the thimble. Has external threads on the end inside the thimble, the other end is a very flat face, which is one half of the measuring surfaces
- Barrel: cylindrical part of the micrometer frame, has internal threads that the spindle screws into
- Frame: the main body of the instrument.
- Anvil: sits in the frame, directly opposite the spindle. This is the other half of the flad measuring surfaces.
Starrett and Mitutoyo compensate for thread wear using a tapered, threaded collar at the far end of the barrel. There's slits in the end where the anvil screws in, and the tapered thread is on the outside. As you tighten the collar, it squeezes those slits smaller, which tightens the internal threads.
The problem with that, is it's only those first couple of threads that are taking up the slack.
The Slocomb micrometers use a 2-piece threaded portion. The 2 pieces have serrations that mesh. If the thread wears, you simply tighten the outer collar one or two serrations, and all the slack is gone. The difference here is that by clocking the threads differently, it causes all the threads to be engaged, rather than just a few at the very end.
This distributes the wear over more surface area, which will make it wear slower. Plus, you can clock the threads infinitely, whereas you can only tighten a tapered collar so much.
Lampshader t1_j93cof0 wrote
>- have no moving mechanism
Uh, have you used a micrometer before? They have moving parts, that's kinda their defining feature, the use of a threaded mechanism to get higher precision
A_Light_Spark t1_j944lr9 wrote
By moving I mean parts that are constantly getting wear and tear during operation or even standby. Like a cog in a clock or a piston in an engine.
Dominick555 t1_j91mtow wrote
Nice use of the flat head screws!
ExHempKnight OP t1_j91ngk0 wrote
All the hardware for the stand is original, as far as I know. The wood slats are new, as the stand arrived to me in pretty sad shape. I stripped and repainted the cast iron frames, and polished the nameplate. The rubber bumpers between each mic were dried out and painted over, so I replaced them with pieces of rubber fuel hose.
miataturbo99 t1_j91lks3 wrote
This needs an NSFW tag for sure. Beautiful 🤌
ExHempKnight OP t1_j91mxfw wrote
Thanks a lot!
Igoogledyourass t1_j92e1oq wrote
That set is incredibly nice. Good lord I've never even touched any nearly as big as some of those (that's what she never said).
ExHempKnight OP t1_j92kzs0 wrote
Thanks!
Thats just the first half of my set. Biggest I've got is 22-23". I'm trying to build a full set to 24", I'm only 4 mics shy.
thewander t1_j92fd8w wrote
Just started a machining class. This comes at a great time where I understand more than I did. thank you
ExHempKnight OP t1_j92m86d wrote
You're welcome!
I've thought about taking some classes in my spare time, fill in the gaps that the (probably thousands of) hours of machining YouTube I've watched have left in my knowledge.
thewander t1_j92z52p wrote
Thousanths of hours….
ExHempKnight OP t1_j938bao wrote
Been into machining a long time. Subscribed to a couple dozen different machining channels.
Check out Clickspring. His clock-making series is amazing, even if you're not into machining.
alittlebitaspie t1_j93gdlc wrote
Hopefully those will pass calibration and inspection. they look to be in flawless condition, so hopefully they will and will be more than a pretty display.
ExHempKnight OP t1_j943eb6 wrote
I'm just a home-shop hobbyist, so they pass muster as far as I'm concerned. And they definitely see use!
alittlebitaspie t1_j945hkt wrote
It wouldn't hurt to have them checked and calibrated, even for home use. I'm guessing that you don't do much that would require that kind of precision but it's good to know where they're at.
ExHempKnight OP t1_j9463mh wrote
Agreed. At the very least, I intend to have the standards checked.
hlvd t1_j92et16 wrote
Nice work 👌
ExHempKnight OP t1_j92o2k9 wrote
Thanks a lot!
councilface t1_j92gtah wrote
Beautiful
ExHempKnight OP t1_j92nsat wrote
Thanks!
pgcooldad t1_j92l66u wrote
Bellissimo 👏👏👏!
Seriously, this is a very nice looking set.
ExHempKnight OP t1_j92nre1 wrote
Thank you!
I hope all the work I've put in, means that they will continue to be useful tools to someone, long after I've shuffled off this mortal coil.
surfaholic15 t1_j92qht6 wrote
They are works of art. I have serious mic envy going on here.
ExHempKnight OP t1_j92qtmd wrote
Thanks! There's a lot of work in this set, and this is only a small portion of my collection. I may have a problem lol
surfaholic15 t1_j92t6c6 wrote
Well if you get tired of your problem I will gladly shoulder the burden, free lol.
Frankly as far as I am concerned you would have a problem if you were tossing those in a drawer or leaving them out to rust rather than giving them the respect and care they merit.
ExHempKnight OP t1_j92tgkf wrote
Some of these were definitely rescues. Previous owners did not show much love to them, which I did my best to make up for.
surfaholic15 t1_j92uc1p wrote
I can't fathom folks that own precision instruments or truly beautiful tools and don't treat them well. Then again, I learned what woodworking skills I have using hundred years old tools, so that may bias my opinion.
It's like in our work. The disposable stuff from harbor freight gets cared for and not abused, but no extraordinary measures so to speak. Our precision tools get far more care.
You do beautiful work.
ExHempKnight OP t1_j92v6uc wrote
Yeah, it doesn't take much effort to keep things in good shape. But even that seems a tall order for some people. Especially if they're communal-use tools. There's a reason I have my own personal torque wrenches and other assorted calibrated tooling at my job (aircraft mechanic).
surfaholic15 t1_j92z2wk wrote
Yep, whenever hubby is working with anyone I look at how they keep their tools. If I see precision things mishandled I give him a heads up so he knows to keep an eye on his good tools if he has to use them lol.
He recently helped a friend rebuild a CAT excavator engine. That buddy of his is really professional. Tables laid out, tools and parts organized at all times, everything carefully cleaned and repainted before reassembly. It was a joy to see them doing the job right :-). Winter is equipment maintenance season.
weaselbird t1_j92urky wrote
That is some sexy shit right there
ExHempKnight OP t1_j92uvin wrote
Brown chicken brown cow
Also, thanks!
muckluckcluck t1_j935x66 wrote
A beautiful set of clamps!
ExHempKnight OP t1_j9385mh wrote
Good range on them, too!
luedriver t1_j93bh50 wrote
I got confused and wanted to know what kind of mic rophones these were
0JesseJStacks0 t1_j93ddit wrote
Beautiful
ExHempKnight OP t1_j93efpv wrote
Thanks!
Agariculture t1_j93h0nb wrote
Nice display as well!
mmoolloo t1_j93uelu wrote
Have you seen Adam Savage's restoration video of his set of micrometers and case? I'm no machinist, but I'd love to have a set like that just to admire the craftsmanship.
ExHempKnight OP t1_j93wjub wrote
I haven't! I shall seek that out as soon as possible.
mmoolloo t1_j944p13 wrote
Oh, and is that oak?
ExHempKnight OP t1_j946abb wrote
It is, yes. As it arrived to me, the slats were made from ratty-ass plywood. A coworker kindly donated some scrap oak he had.
mmoolloo t1_j948zvx wrote
I can't think of a better choice tbh. The contrast with the steel and the gloss black looks stunning. Cheers for the great gob man!
ExHempKnight OP t1_j94an9t wrote
Thanks a lot!
I've got a Slocomb catalog from the early 1900s, and it actually says oak. Thankfully, my coworker had some scrap pieces that fit the bill perfectly. Couple of coats of polyurethane, and done!
mmoolloo t1_j94bqbi wrote
I thought I was done with this thread, but the fact that the material is spec deserves another hats-off. That was lucky, especially with lumber prices right now.
RDandersen t1_j9442ro wrote
I don't know why, but somehow it looks like the stand and tools were about 6 foot tall and standing on the floor. Something about the angle maybe?
Nice megameters, if that is the case.
snowysongs t1_j94jqk5 wrote
What is this thing?
ExHempKnight OP t1_j94k2hc wrote
It's a rack of micrometers, which are measuring tools used to measure very small distances (0.001"). Required tools for machinists, and many others.
Karimura12 t1_j94k2iw wrote
Vernier mics? Give me digital or give me death, nobody got time to read all those tiny lines lol. Cool collection! Can’t imagine having to use those larger ones, thank god for CMMs and vision systems
ExHempKnight OP t1_j94kb43 wrote
I've got a couple of digital mics, as well as some digital calipers, which see use in my basement shop.
Yeah, even simply zeroing the big boys using the standard rods is challenging. Especially the 22-23" I've got.
Karimura12 t1_j94kyoj wrote
That’s awesome! I’d love to have some home tools, would come in handy pretty often. I actually work in metrology, not a word I come across in the wild very often
Robobvious t1_j94mjc4 wrote
Neat! What do you build that needs such exacting measurements?
ExHempKnight OP t1_j94na3q wrote
Things. And also, stuff.
In all seriousness, I make all kinds of things. Brackets and idler pullies to install a supercharger in my mid-90s Saturn. Valve brackets for my beer brewing rig. A replacement part for a very expensive pen (<-- shameless plug for my YT channel).
I'm currently building a 3D printer, and I'm using some of the larger mics to make sure the frame is parallel and perpendicular where it needs to be. I've also designed and machined my own custom hotend.
Sometimes it feels like I'm mostly using my machines to make parts to modify/improve each other. But it's still a lot of fun.
EvilPandaGMan t1_j94pnz5 wrote
You should bring this over to r/skookum
pastafaz t1_j94qolk wrote
Man you have to post this on r/machining or machinists if you haven’t already.
SheepdogApproved t1_j94qp7k wrote
Are these the same ones Adam savage restored a case for? Looks great!
ExHempKnight OP t1_j94ueqq wrote
Same size range, different brand. The set he built the case for are Mitutoyo, while mine are J.T. Slocomb.
omw_to_valhalla t1_j94wqis wrote
Absolutely gorgeous set and work!
stlblues310 t1_j94x9dw wrote
Should make all your screws align straight up and down (or horizontal, dealers choice) to fit the precision theme
mechy84 t1_j957ppw wrote
OP should consider joining the American Society for Precision Engineering (ASPE). They would be in company of people with very similar appreciations.
Trewarin t1_j95bxes wrote
The skookum Subreddit would like this too.
rockerscott t1_j95qmw8 wrote
At what point should they be called MACROmeters
girl_incognito t1_j99e0k5 wrote
That stand is brilliant!
ExHempKnight OP t1_j99ju71 wrote
Thank you! I was pretty excited to find it. I've seen the stand in the Slocomb catalog I've got from the 1920s, but I never expected to actually see one.
It was pretty ratty when I got it, but I'm pretty chuffed with how it turned out.
bumgut t1_j92mnw1 wrote
Can i measure my penis with this?
ExHempKnight OP t1_j92nfsm wrote
The 0-1" mic measures down to ten-thousandths (0.0001"), so yea, I think you're covered. Every decimal counts, right?
doogle_126 t1_j92n32p wrote
No these are for macroscopic size measuring.
[deleted] t1_j93564r wrote
[deleted]
ExHempKnight OP t1_j9384jw wrote
Lol relax! This is my basement shop. The walls don't need to be pretty.
As for the granite... That's the most important thing in my shop. It's called a surface plate, and it's flat. Very, very flat. The difference between the highest and lowest points, over the entire 12"x18" surface, is less than 0.0002".
A surface plate is the reference for the entire shop. Using various instruments, I can use the plate to tell if a part I made is flat, if opposite faces are parallel, or if perpendicular faces are, in fact, perfectly square. I can measure the height of objects relative to one another. I can use it to make other things flat, and then use those things to check the flatness of other things, such as the sliding surfaces between different moving parts of a machine.
Mine is a relatively small surface plate. They can get downright huge. 10, 20 feet long, and 1-2 feet thick. And bigger.
[deleted] t1_j938deh wrote
[deleted]
ExHempKnight OP t1_j93998l wrote
Lol! It's a workshop. Always gonna be a mixed bag. Pretty tools, ugly work surfaces.
CR123CR123CR t1_j91s8d1 wrote
Original calibration gauges below as well? Those are very pretty tools