Lapping my Granite Surface Plate to AA Grade

all i'm doing here is really just taking a nice razor blade over the surface and um looking for any like embedded metal or anything that's in it that you know i might not be able to feel when i'm cleaning it and yeah i actually have found pieces of metal embedded in these and i believe all right so i think we've made it to the point where we're going to go ahead and lance is going to help me and we're going to start measuring my granite plate and we're going to do some measuring and eventually get to some lapping but i think lance wants to go ahead and talk about this a little bit so i'm going to let him take the lead right here yeah i asked him for a couple of minutes at the beginning of this video i can't help when we shoot a video but read some of the comments and when we were up at john's place uh recently for the scraping class i read through some of the comments on the video that where we were actually lapping his plates and measuring them and i i want to there's nothing that i'm about to say that's bragging it's just i want people to know my background because there are a number of people who commented on that video you know about some guy measuring the plates and the credibility of you know the results and all that and so i want everybody to understand that yeah i am a veterinarian and we talk about that and joke about it and i always joke about not being a machinist or whatnot but i've taken a deep interest in some of the more precision and metrology related stuff and yes i've only been doing this a little over a year but i have had a mentor and a guy that's been here a number of times we spend a lot of time on the phone i've spoken to two other people who do this for a living off and on you know i have a very strong physics background i've got a degree in chemistry and there's one thing that i'm really good at and that's learning stuff and so i want your viewers to know that we're not just halfway doing this like the results that we're getting i would put up against any certified group and i have uh all the confidence in the world that when we're done if adam wants to bring somebody in from an ale to a accredited lab and have it you know have them slap a sticker on it they're going to get the same results right and so um i wouldn't do it and i wouldn't let adam video it i didn't mean interrupt your buddy but i just wouldn't do it if i couldn't do it to that degree well and to bring up another comment that somebody had made was can you certify it and i had responded no you cannot certify it but we're still we're still measuring to the same results that anybody can certify will not that not that i need this if i was if my shop was in a position where i needed these standards you know because of the work i was doing because of contracts then we would have to get a certification we don't we don't need a certification right but we're showing the practice of it though right and rick geil the gentleman who's done this for the vast majority of his career has an al2a certification he was doing it back before alta even existed and um you know we've talked through all of that and i it's not even practical and reasonable for me to pay for that because i'm not doing this for a living i'm doing it it's a hobby for me it's a serious hobby and i do it for people that i really enjoy being with and hanging out and i do it because i'll probably i have a number of uh granite stones in here granite plates in here and i'll acquire them over the years and then i know i can put them in perfect condition and if somebody wants them i may sell them but i'm not doing it for a living it's something that i really enjoy doing it and it's it's a de-stressor for me for my normal life so i want everybody to understand that that we are doing this and i have no qualms about somebody that may send a tech out from an al2a lab or or certified group to check them i'm more than happy to hold my work up to that so anyway i didn't want to take up a lot of adam's video time for that but i wanted to let people know that we will be measuring this today we will be using essentially the moody method uh jc moody published a paper in i believe the mid 50s probably 55 about this particular procedure there was a lot of math involved things have evolved over the last 45 and 65 years the the the written certification program was first published by the federal government in like 73 and then it was revised in like 1977 it's in the federal register you can look that up it's the it's the calibration of granite surface plates and then i believe somebody will correct me if i'm wrong in 2006 asme took over that program and republished it and they have a little bit of what i think is a condensed version i've reviewed all of that literature including moody's original paper and all this work you know the basis for all this work falls under iso iso 9000 you know essentially so i want everybody to know that we're well versed in all of that here and that's how we're going to be doing this today so the equipment we're using you guys may have seen that at mr terry's place but it's over here on top of my big granite plate and for all you who can see that that large granite plate there has a cover on it this is a big uh steric pink granite got the wooden cover yeah just to protect it because unfortunately i have limited real estate here and i do use it a little bit as well i was like all of us like a little bit of a bench top so i want it protected so thanks adam for letting me do this it'll be a lot of fun so adam's got the camera setting on the reference side of the plate and this uh we have the read head set on here and we're getting ready to zero them um he should insert a clip that shows the eight lines that we measured they'll be on in graphite pencil because when we go to lap this it'll just come right off and again if anybody wants to look it up jc moody you can actually google it you'll find the paper explains exactly what we're doing here so the first thing we're going to do is um individually zero these heads so that we're within the working range of the pendulum inside the magnetic heads once that's done we'll zero them together and then we're going to take looks like we're going to have nine readings on each of these diagonals and then i haven't done the count but i believe we're going to do five on the short legs and eight on the long legs for readings so it'll be eight lines with those subsequent readings go ahead give it a second to go ahead i'm giving lance a hand we've got this little uh button right here and this is used to record the measurement and you're moving every four inches correct yeah the critical part about the electronic levels is the um back foot needs to reside in the same place that the front foot resided in in the prior measurement okay and that's the most critical thing because you want that that overlap that consistent overlap of four inches i haven't recorded it yeah we're gonna have to count now one two three four five the next one's six yes take that yeah cause i didn't hit it right now yeah that's the trouble with talking and trying to talk and film and then yeah i'm actually measure so you just tell me when go ahead and just for video purposes here you know i'm i'm going to try to just shoot some of this right here we're going to do diagonal and i'll show a couple more shots of doing this and then try not to bore everybody yeah we'll come back with the results after we get a few shots of this measurements okay this should be the last one on this room okay and one thing that we didn't um explain we're using a straight edge and that's for the level to follow to have a straight edge these angle plates here are simply just weights trying to hold it in place exactly and if this if if we were to actually rotate either the a or the b head on this plate at this time because we haven't perfectly leveled the granite the reading would go so far out of range it would it would invalidate the the process so all right so that one that one run is done so now we're going to move this around move everything and run the other diagonal okay go ahead yep that was a good run okay good all right so uh we're gonna move um so we've moved on to this direction here and we'll continue to map out those those lines accordingly and then flip it 90 degrees and then go this way yeah i have um the software set up so that we have to do the least amount of recalibration or re-zeroing on it so we did the diagonals now we're going to do the long runs and then we'll come back and do the short runs okay okay so yeah we just took the last reading and um you know basically this is like a um it's a b plate and it's not in that bad a condition adam and we we did i don't know if you're going to be able to see this on camera or not but we did get a really good reading our intercepts are all under 30 millionths so the overall fluctuation or the overall elevation difference on this plate is two ten thousands so two tenths so that's good so wow yeah that's better than i expected yeah and so i have i don't have all of the plate size and um grades memorized in my head so we'll go look up what a two foot by three foot plate grades at see what it'll take to get this better than an a okay so that'll be our next step and then yeah if you want to pan over here let's check it out over here and see and adam adam's got the camera on the reference side of this uh so you're looking at the plate just like right just like you were looking at it on the computer right now and i'm on the back side of the plate it's obvious that whoever was using this plate is using it fairly heavily in this area a little bit down here and then quite a bit back here so um that's how the plate was being used and so most of our wear low spots is going to be here here and here yeah it's really interesting because i would say just about every used plate i've seen got that very similar pattern my big uh granite there my big pink granite was exactly the same way the big hole was literally like right here yeah and then i had wear right in here now the difference was mine was like 2.2 thousandths it was it was a crater in in granite terms so so we actually have a pretty decent plate here this this would be usable as it is wow so yeah you you're you did good especially you know well that's fantastic because you know i i've done quite a few measurements on it on the channel sharing some things especially like those straight edges yeah you know and i mean i mentioned this is not verified so i don't know how i wanted this but i was measuring a half a thousandth variation in the straight edges yeah so you were you know the worst case scenario you had a you know basically a error of about two tenths depending on your measuring methods and all of that um if you did everything else correctly that's cool so yep i know whenever you go to start laughing now you'll you'll hit it a few licks and then you'll build we'll be able to see where those low spots are at we will right away and hopefully get those on camera and the other thing we need to do next is we need to put the um repeated meter on this because we need to look at local flatness so we just looked at you know overall flatness um over the full surface but we'll see what local flatness looks like as well because i would need that to grade it okay yeah but it's good okay so we just printed out the results for adam's plate and then we also went over to my reference book on um grading and um so this is a neat these are neat it's a 3d map of the moody plot um showing what we were just explaining and i don't know if y'all could see that on the computer screen or not closures are good they're under 30 millionths that tells me that the data is relatively accurate it's grading it as a b but if you look here it's 206 millionths or 2 tenths little over 2 tenths and actually the upper limit of an a plate is 200 so we're right on the upper limit for overall elevation again we have to do some repeat readings or local flatness evaluation and that needs to meet um 70 millionths local flatness total um high to low in order to hit that a spec as well that's good you're going to use the repeated meter for that correct correct yep and then this um little numeric map here um is good and we'll probably i'll probably have adam take the time to do this he's here and i'll have him do the work we'll actually go through and write these numbers on each of the corresponding lines and then when we start lapping it um we'll watch the lapping pattern and you know right there's your high point on the plate which is literally right under my finger here we should be able to the the dusting pattern from the lap will match this numeric pattern here so we'll see virtually no cutting back in this area virtually initially no cutting here at the front of the reference part of the plate and a lot of it will happen in the middle and um i believe this yeah this one corner appears high but that's actually only at 100 millionths so but this is kind of verified to what you're saying right there yeah we're high here a little high over there but there's your low spot there and low over here as well right and it's my understanding that you [Music] really do want to finish them a bit high in the middle they talk about loading a plate and and granite will move when you put weight on it and so traditionally i think it's as i've been taught it's a little better to have it high in the middle and perhaps sloping off of that but either way i mean we're not very far away from an a plate and then if we find any holes that's the that's the unknown right now if we find a hole we could go from having to lap at say maybe a half a tenth or even if we got aggressive a tenth to something way bigger than that if and and because there's large areas in the moody plot that aren't covered in our repeat uh repeat a meter checking local flatness are going to check these areas so back at you in a little bit so we are we have the repeated meter out now and um adam and i are just going over the plate to look at local flatness so um i've already taken a quick peek at the plate so there's a nice size hole right there at the corner which we actually could see on the large plot and um there's some other wear on the side that adam's standing on over there but overall local flatness isn't bad but we have a lot of work to do you're finding a lot of uh a lot of variations a lot of variations and local flatness there yeah i mean if i had to give you a reading now the local flatness is worse than the overall flatness it's probably i'd have to grade it at three tenths because of that one hole okay and there's a crown in the middle and since they use this plate around the edges it's it we're getting a much worse local flatness reading than it really is and i say that because it won't take much to hit it with a lap and get it much better than it is so we're going to shoot for we're going to shoot for 70 millions trying to trying to give you all a cool shot here yeah we're giving you guys a bird's eye view of what we're actually looking at you can see that big wear on the far side of the plate that we showed you on the elevation map and off camera adam and i were talking about this repeated meter people it's not as simple to use as you might think because we're constantly going over um areas that we've traversed with the base or with the tip and it's simultaneously reading referencing all three contact points so you have to be very mindful of a 3d image in your head when you're using this because you can mistake a high spot as you're traversing on the far side as you're traversing over a low spot in the middle of the meter and so hopefully you guys will find this interesting get to ride along the ride-along shots are always pretty cool all righty we're gonna start a lapping campaign here i'm going to charge the the larger of my two laps larger via surface area not weight but this is a cast iron surface plate that lance has already hand scraped and this is what he uses to lap the granite for those that are unfamiliar i've showed him doing this in a couple of previous videos not too long ago yes but just for those that are not aware i also showed that roller we made that up at john's and he's going to be using that to charge the charge the diamond so yeah this plate has had i don't know how many hours of use um this plate did the entire um all the work on the three foot by six foot pink grain that's a lot of lapping too yeah when you if you look at the top of this plate you can see that pretty much half or more of my scraping is gone yeah it's almost i've almost lapped all of the hand scraping out of it one of the things i was going to ask you is there as you continue to use this and it continues to wear is there a reason to have to hand scrape it again in fact the more i use it on different plates the flatter this will become okay and so you know likely uh scraping it would potentially take it backwards in terms of flatness okay and then they can't see it but out of the camera view is my is another plate that i recently i got hand scraped and that was matched to my a double a plate here i mean it's an a plate because i don't keep it temperature and humidity control but a double a plate um and i used that i've used that just for one small started one small project with it and we may end up using it primarily on this plate but i want to sort of use my lap that i know is known on here just to get a feel for what the top of this looks like okay on these here we go yeah we're gonna have to block this thing up yeah we're gonna have to we're gonna have to get this so that it's not rolling around this this stand is exactly how it came minus the mods that i've done right and um i've just never had a reason to do it but we're gonna modify this stand later so that i can actually you know screw some jacks down right and uh get this thing where it's solid wherever it sits yeah we're going to be doing a lot of um stopping and starting so we'll do we'll get it fixed up my uh this robin renvette is watching he can hear my uh lap is already fully charged [Music] all those real bright white spots must be little holes and valleys just that that's um that's plate abuse yeah and that's how it was when i bought it it was uh yeah it was a well-abused plate matter of fact when i got it for whatever reason when i came in there to pick it up it had dirt all over it right like people had picking things up out of the dirt and set it up on here yep that's crazy okay perfect well you get the um that numeric grid so over there that we printed to print out that top one right here that one yeah bring that over here and if you would set it set it next to me and uh what we're talking about right here yeah so you're gonna reference this just so i can remind now this this is much softer granite than what the bulk of the work i've done versus that paint grant it's got a lot of quartz in it okay yeah so i got to be careful because clean this again we're likely going to check this more frequently than we normally would you know just because it's going to cut this very aggressively the low spots are really starting to be highlighted now with this third [Music] of course we got a low spot right on that edge there too and i know this wasn't even part of the measurement there that's correct and like um and hopefully i repeat this stuff correctly i mean i spent so many hours talking to my buddy rick about all this and um but i think rand r-a-h-n was a company that touted finishing their plate to the edge in other words you know most i call it setback but i don't i don't be honest with you i don't know the official term but you know you know how we measured it in from the edge yeah so we have basically a border you were telling us before some of them will measure all the way to the edge yeah rand was the only i think the only company maybe that basically when they sold a plate they finished it to the edge and they guaranteed everything right to the edge which is i don't think that's how the industry does it now too many people do it that way now because usually there's an accepted area where you're putting things on and off the granite um that you you you just don't include that in the calibration measurement [Laughter] is it better all right perfect already perfect already come here it's better than my uh better my big plate so your minus um 10 milliamps there you know that's good we're gonna call that our zero and rotate it 90 degrees and we are maybe plus five that was two tenths before yeah before we start flexing with this okay look at this come here remember that before it was intense yeah i was jumping up and down 10 millions now that's 80. mine's right there may be done with this today i'm not kidding okay so that's one of those times when you're like well there must be a hole there well i don't know if there's a hole there it could be a high spot right here but i won't be able to pull this back far enough to see right so you know so let me go this way and see okay so there we're so in that dark spot and we're kind of out of our two inch border but it doesn't matter we're a tenth there because that corner okay yeah i mean over uh eighty percent of this plate were already 20 million local flatness which is amazing the whole thing we went from 2.2 tenths to a little over a tenth and it's only because of these spots right here you can see that didn't even take for what well we did that in maybe 15 minutes 15 minutes i mean that's what cleaning it and everything yep so a couple of licks yeah so we'll i'm gonna um gingerly go back over the plate again with the lab and uh and we'll wash up real good and we'll let it dry overnight and then we'll come back and read it again in the morning i'm gonna try to take it down even and get these couple little low spots and um you know i think we can try to do whatever you want to do but i think if we get this down to 150 it's a tenth and a half or less um with the we i know i can get the repeatability under 50 millions you'll have an a a good solid a plate if you want to try to achieve those double a numbers we can but we'll see i'm gonna let you run the show man yeah we can chase our tail too if we're not careful right i know i know that's to take consideration also just like he was explaining to me it's really easy where we had a little high in the middle there it's really easy to overlap this quickly and then you have a bowl shape instead and then you're and then that's when you're chasing your tail because you're having to go back and lap it even more to bring it down yeah it's um it can be an exercise in patience but less can be a lot more yeah i kind of was missing this he's talking to me as he's working lances but so he's clean he cleans it in between laughing sessions and just like he was he was just telling me this he goes as rick told him taught him you got to get your hands in there and get dirty and i completely understand there's a lot of things that will not substitute the human touch you got to get in there and work it you can feel it you can feel the diamond and the in the dust and um break it up and get it clean so uh just use simple window cleaner right here any kind of window cleaner windex and get you you know have you plenty of towels handy don't try to be cheap and just have a few just have your old towels and then clean it i know everybody has a different opinion you know i like to use on my plates i like to use fantastic and i know like you know cash masters up at kinetic he did a live stream on instagram not long ago he likes to use gojo and cleaner without the hummus i think that's the name of the brand but and and he likes to clean his place with that you know which i think is a great degree sir so everybody has their recipe but rick rick kind of screams at me about putting anything on a plate that um that's being a little dramatic but gives me crap about putting anything on a plate that can leave a residue right so he likes window cleaner plain old plain simple winter cleaner i will not the man's been in the business for 30 to 40 years yeah so he's he's got experience he knows what he's talking about he doesn't like anything on a plate that could leave a residue that will then cause you to collect particulates and then that just turns into a laughing compound on the base of anything you put on it okay and so you know it makes sense it makes good sense i still do like my fantastic but it does leave a little tiny bit of a residue it's a degreaser so this plate is beautiful now i mean we just have a couple small areas here and it cut way faster and like i was telling adam i don't have a most of my experience which is still limited is on pink on the granite the pink ground here and it's it's hard it's got so much quartz in it and um this is cutting very quickly it's soft it's very yeah and me being around it here for just a couple of times now i can see just for those that are uh wondering see that's just pink granite that's the cover over it but here's another stair pink granite right here okay so this is what we're keep referring to this is a harder granite than the gray that i have so this is the softer material here that's looking good yeah it is it's really it really is looking excellent all right we're going to give you guys our another ride along but i'm having to lance is having to reset zero because just the weight of the noga and the camera on the repeated meters throwing it off and this is this isn't the way that you should use it for a few meters a camera hanging off the back of it but yeah he just did an initial inspection and he is extremely pleased with the results he's got off this already i think we're right on the borderline of double a on local repeatability yeah guys and i'm having to reach around the camera to try to adjust this and i'm not going to get it exactly on zero and it doesn't matter that it's on zero one of the first checks we do is you put the repeater meter in the center and then you rotate it 90 degrees to see what variation and you guys can see better than me it's probably 10 millionths maybe 15 millions um in the 290 degree axes there which is excellent i mean you'd like it to be zero it's pretty close to zero and then just with a little bit of lapping on my seasoned lap i'm not going to do the whole plate but you guys can see that is it is it repeating the way it did earlier or is the camera messing with it well it's tough because i have to go slower with the camera on there but um but you guys can see we're like 20 maybe 30 millionths um in local repeatability you know hopefully you all remember when you saw this we were too tense before so just you know we've been out here about a half an hour and um like i said to adam off camera you know my lap has got a lot of time on it and so um it it's it's flat flat flat flat so lance was extremely pleased at how quickly this thing is flattening out and getting good results compared to the pink granites that he's been working on yeah that is just substantially different and i'm going to call this 50 millions total um and so you can see right over here where he was well you bring him right over here yeah see this is that low spot but you really can't even see much of a difference when you i was asking lance maybe it's the diameter of the little carbide pad is you know gapping that little dark spot right in there yeah there appears to be some linear almost like grooves almost like rub marks through there exactly and so um and and you're right it's probably bridging those little variations and there's a there's a little spot like right there yeah you see a little bit more left and then of course across the edge of it there as well so that's pretty cool yeah so we're going to let this set overnight now let it dry out completely in this ac room and um and then we'll check we'll check the overall elevation differences in the morning and okay i think we'll try to shoot for you know a tenth or less since this worked so quickly we can get more aggressive with the time we have maybe get you a double a by the time we're done okay all right we're gonna let it sit overnight we'll be we'll be right back though all right so it's the next day the next morning and we just finished measuring the granite surface plate again i'm going to let lance explain to you what he found and what he's determining where we're at right now i think it's good news but i think there's still a slight amount of work left to do on the on the plate so what'd you find so we um we measured this morning and we're at a hundred and i think 145 or 146 million so 1.46 tenths um overall flatness which makes it an a plate but as we were measuring it i told adam i thought based on the numbers there was going to be kind of a hole in the middle which is how i started lapping it is from the center and then i was working out and i was being very careful the edges because i didn't want to roll them over so basically what we have right now is something that looks like this the whole way across it's pretty symmetrical i haven't looked at the number graph yet but um so now what i'm going to do is just come in and i'll lap these two sides and and bring it together because if anything we want a little bit of a a crown on the center you know if we can achieve that it's not that critical because you're only talking about 20 to 40 millionths so um and so you're going to do the sides a little bit heavier and and you may even get some of these i think low spots all this will come out okay and so the whole surface will be uh very homogeneous so right um but yeah it's an a right now we know that the repeatability is under at or under 50 millionths which is just sort of right at the upper limit of double a and so we'd have to get it to a hundred millionths or a tenth to get into double a range on overall flatness okay when you should be able to get it close to double a before you leave without a problem okay cool so here here's a here's a little look at the computer screen i know it's hard to see but that's sort of a you know map of what the surface is looking like within the computer system it doesn't really look like that unless you're measuring in millions millionths of an inch that's what it looks like right there that's pretty cool so you can see we got a little a little bit of a dip which will be sort of right in here in this side exactly all right so uh you know we'll do another update later whenever we uh make some more progress on it all right all right well we're on to a well lance is on to another uh light lapping session here we've already measured it again and uh found out that you actually were actually a little bit low here and a little bit low right there overall flatness was 1.6 tenths yeah right 160 million 160 million so it's a grade a right now but i wanted to try to capture this before you got too far into it you can see because it's darker there and there he's you know he's already run the lap on it so you can see the high spot so he's just trying to do a very careful very light lap focus more in this area and try to stay off the corners and see if we can drop it down a little bit more well and then also this um a little learning on my part because this this uh dark gray granite is a lot softer than the paint it cuts in a lot faster than the paint a little more assertive than i needed to be which we finally went we went kind of two ways i laughed it to begin with and it got a little hollow in the center so i went back and i did the i did the edges which brought it back to a nice dome shape but i over did it on the high spots so it's all about learning hey you know you're learning and you're practicing i mean it's still an a grade plate it's phenomenal already we're just picking over yeah and and you're um you use the repeta meter and that was really good here in the center anyway too yeah everywhere except for when i got the back of the repeated meter down in this area here was 40 millionths over the whole plate which is a double a repeat local repeat reading it it just put it back out into an a out here so since we're so close i'd like to get this to 100 millionths which is a tenth overall flatness yeah and then keep it down around that 40 45 million so technically it's in the double a range yeah that's what i want to do for you that would be sweet yeah we're baby laughing right now see and my buddy rick my mentor told me that these these gray or dark plates really you've got to be careful with excuses bless you that they're extremely soft so i had no idea how soft but i've only ever done a couple of small ones like this so anyway we'll bring you back for the next update and uh let you know maybe we'll hit that double a grade pretty soon making another measurement on the plate here i've been giving lance a hand recording the measurements that's what this little guy is right here watching the monitor for it to settle that's that that's that low corner that's that little corner over there but uh yeah so i'll just give it an update you know he's he continues to do some lapping here and um lapping and measuring it it's definitely takes some time doing this because we have a total of eight eight run eight lines that we have to to measure so we'll bring you back whenever we get our results look at that zero all right last measurement we're gonna get lance's reaction to this it's either gonna be good or bad that run was like three tenths of an arc second like that's how flat that one line is yeah i don't know if i want my reaction on camera let's let's see it ah oh my god oh my god yeah that's phenomenal 70 millions overall flatness so seven tenths of a tenth really you got it down that close huh so that's double a right it's double a oh yeah double a graded double a yet until i check it with uh you gotta check local flatness with the repeated meter and i see two little spots in here i'm gonna hit with the lap yet so we'll probably get her closer to 50 or 60. millions overall flatness i'm definitely seeing this still low here yeah here and in here still being low and then you got a low spot sort of right in here yeah i told you the middle was going to have a little cup in it which and that's because of the the way we're lapping it but um there's still a little bit of a ridiculous ridge here like i say ridiculous probably 30 minutes or something right here where my hand is um but yeah at this point if we keep chasing it we can make it a lot worse yeah well i know that's the big word but this is the one i was hoping to get on video because this is the first time that we actually hit double a on overall flatness of the plate yeah i could have done one or two less lapping sessions if we hadn't charged the lap before we started we talked about that off camera george the ver it should have been the beginning of the video where i showed you charging it and he said i'm gonna need to charge it and i saw a lot of diamond on that too whenever yeah i mean it was still like charged and this is so soft this plate is so soft but it's all right it's a lot of fun i still enjoy doing it and um you see the reflection yeah it's just it's it's it's awesome yeah all right so i think this is our last lapping session that we're going to be doing i know it's going to be the last one that i'm going to be here for because uh i'm getting ready to leave i'm going to leave this with lance for the next week but he's extremely happy i think he's extremely happy of where he's got this measurement now on overall flatness and local flatness so where are we at it's it's well into double a so it's uh overall flatness 65 millions so that's for uh 24x36 and then repeatability local flatness is no worse than 40 million it's actually a little better than 40 millions and the spec on a double a is 45 million for this size but when you say that though we'll show you so you're measuring that you were within 20 millionths on most everything but you're talking about that corner the only reason i'm calling it 40 millionths rather than 20 between 20 and 30 millions is this corner here it's got a little it's right in there and again we're talking 10 to 15 millionths of variance over the rest of the plate yeah over the variance of the rest of the plate so it's a double a plate so even if adam takes it home and it settles out a little bit different in his place with temperature and humidity there's absolutely no way it's not an a plate but it'll probably remain within a double a standard yeah because we're 100 100 million star 10th overall flatness would be a double a we're 65. that is awesome really really happy hope you're happy um i know he was really happy with his intercepts uh intercepts yep 1.5 millionths and 7.8 millions which is where they cross the difference between where they cross there yeah i mean truthfully if we keep mucking around with this plate we'll just make it worse yeah because because then you could start going low in some places there's a lot of work that we've already done but uh let's let's uh we're going to slap my iphone on there and take one more video of the dials just so they can see that and i think that's going to be it yeah we don't want to bore him to death okay so adam um set this up on the repeater meter and we will get a little bit more fluctuation whenever i change direction on the repeating meter with this weight on the back because it's not balancing it perfectly yeah but um you guys can see that there's very little within um plus or minus 20 millionths and when i put a side load on this it changes as well with the camera weight but um that's just the only way i can get a camera mounted on here the noga holder with the camera so it's a little heavy so it's actually fluctuating just to smidge more because of the back and forth movement with the weight on the back of it but i think you guys can see we're plus or minus 20 milliamps on the plate it's fantastic absolutely fantastic can you show them this corner over here just the the low corner well from this angle it's no longer a low corner so on the sides i will have to see if i can find a way to make that corner look worse so well that is the low corner there we jumped down to 40 millions but i'm past our actual lapping area so if we go right to our lapping areas and it's still close to 40 million but anyway phenomenal all right well we've completed the lapping on my 24 by 36 granite surface plate here and lance finally has it to where he is happy with it and we are at an overall flatness from end to end at 65 millionths and our local flatness using the repeated meter is within 35 millionths is that correct within 35 millionths and it is it is good now this is considered a double a where we've got it correct it is a double a grade this is a little bit kind of like a before and after so this is this is what the map looked like when we first measured it right there all right and then this is where we're at currently right there and these papers right here just represent a numerical version of this right here okay but it is it is extremely flat and it's beautiful it's got a nice polished finish whenever you actually look across it like that well it's hard to see it but you might be able to see lance's reflection right there and i know that i have a very flat and true granite surface plate that i can now take home and use for measuring and inspecting so thanks a lot buddy i really appreciate the help on this you're welcome you have a really nice plank now i think i do thanks to you yeah all right [Music] you

Channel: Abom79

Views: 183,634

Rating: 4.9149055 out of 5

Keywords: granite surface plate, surface plate, lapping, hand lapping, cast iron lap, lapping plate, differential levels, precision measuring, precision metrology, granite plate

Id: -CM3VWKXasY

Length: 49min 55sec (2995 seconds)

Published: Thu Mar 11 2021