How to set up a surface plate

something that is really important to do in your shop is set up your granite surface plate correctly and that's what I want to talk about today hi my name is Dale and welcome back to metal tips and tricks I am going to set up a granite surface plate now I bought this surface plate about six months ago it's three foot by four foot and about I don't know five or six inches thick six inches thick and I never finished the stand for it because I didn't know how to set up the points that it's going to set on and that's why I want to talk about today what I've learned and we're going to talk about every points Bissell points at let's now take a look at a beam and how we can support it in different ways so if we take our beam and we know that if we put two points on it it's going to seg one way or another if we put them in too close what's going to happen is these ends are going to drop down and we're going to end up having an arc in our material so let's look at it the other way is if we put them out here well we're going to get a SAG and our energy our gravitational forces are going to pull more on the center it's going to eventually Bend in the center well when we talk about Airy points and Bissell points that's how we're going to counteract it but we have to decide which way to go so let's talk about Airy points first airy points is going to control how the ends stay flat and also parallel and doesn't allow the material to lengthen at all so what it would look like if we set up on Airy points and of course I'm exaggerating when I put our points there what our goal here is to keep this end and this end as flat as possible and square we want that at 90 degrees and what that happens what allows us to do is it keeps this distance equal so it doesn't change over time the next way of figuring out the points is Bissell points our best selves points excuse me I know I pronounced it wrong I sometimes well you guys know me I screw up all the time bessel points so bessel points what happens with them is they equal I equal everything out so they look more in this shape but what changes here is the deflection here isn't as much but there's a little deflection here the thing that also changes is these ends tilt out and our length changes it becomes more of a plus and a negative at the bottom and that's things we have to decide what we want to do is how we want this to average out so the surface stays as flat as possible well Bessel points are the way we actually want to do that for this particular table because I don't care what happens on the ends I want to make sure this stays as consistent as possible through the whole length of this I don't want the end to be lower like it would be on an area on the area points this Center will end up being lower and sacrifice these corners staying square where here the corners are sacrificed by going out and lengthen the material but the range this falls off is not as much how do we calculate it well I promise to keep it very very simple we just have a multiplier that we take our length and multiply it by that so I'm going to do an experiment right now we're going to take and just do a piece of paper and set up airy points I mean Bessel points on this so you can see what's going to happen so our multiplier that we get to deal with is 0.2 to 0-3 way overkill for what we're talking about but we're just going to keep it there it's kind of like rounding off by 3.14 blah blah blah blah blah we only need 3.14 that gets us close enough and what we're going to do is multiply this number by the length of what we're working with so we got a piece of paper that is 11 inches so we're going to go point 2 2 0 3 times 11 equals 2 point 4 2 3 actually 3 to be scientific so nobody gets mad at me the next one is we're going to times it by eight point five point two two zero three times eight point five equals one point eight seven two five blah blah blah so what we'll do is we'll just measure this out two point four two three and that's going to give us the points where we want to line up and I'm going to borrow a couple 5c Kaulitz here and I'm going to set these up so we can see the effects on a piece of paper so there we go now we are dealing with arches here which strengthens the paper but you can see right here we have our s shape going now if we wanted to correct that and go to our area points well we stretch this out a little bit and you start to see how our Airy points are applied to this where this starts to stay more level and square and this Center starts to fall more now we're talking about a piece of granite here that's 2 billion years old or whatever and it's 6 inches thick it's not going to change that much but we do want to prevent it now here is the other challenge is trying to get four points pressed against the granite surface plate so it doesn't warp because there will always be more pressure on one than the other so we have to be aware of that so a lot of you would say when and you can do this on a smaller surface plate is we can just go into three points get these two on the Bessel points back here and this one on the Bessel point across there but on a larger surface that we're kind of messed up here hold on you can see what's going to happen here is we may get a good SKS shape through the center but these corners are falling off and we don't want that so how are we going to fix that well I think you guys are going to like this we're going to actually leave the third one in there and we're going to make a beam come across with two points coming up where these Bessel points are and that's going to actually pivot so if I decide to move this table from one end of the shop to the other the floor is uneven well this is going to twist a little bit but the pressure all the pressures here the table is going to be allowed to stay lush since I was going to say stay level it's going to allow the table to stay flat no matter where I put this so that is the key to Bessel points and aeri points and this does apply to also smaller things like if you have a straight edge or a level that you're putting into box let's say you have an 18-inch level well if you want to put that level in a box you need to set this up so it's only on two points so what a lot of you'll say well I'm going to put on three well you can't do three because no matter how accurate I set this up there will always be two points higher than the other so you're going to get sag or something so you need to attend to that and be careful that you don't damage a really nice expensive level now I'm going to continue an entire series on building the ultimate metrology table because what I want to do with this I want to get all of my measuring equipment in one area not just one area but a clean area that I can work within so I'm going to finish building the stand I'm going to put a series of drawers in it we're going to put metal panels on the side but I don't want to just put in metal panels I want to take advantage of my bead roller and we're going to add some artwork into those panels I'm not sure if we'll do an art deco design we may just go a very simple raised panel sort of look like you would see for kitchen cabinets I'm not exactly sure what's going to happen I might just do some experiments so we're going to do some bead roller work on sheet metal we're all they're going to talk about other engineering and building the stand up so it's a lot stronger than what it is I'm going to talk about casters because I have of course you know me I have a theory on everything including how you set up casters on something especially this heavy and then the final episode I'm going to build a set of drawers for this for all of my equipment to go into and that's a real challenge because you get into different measuring devices that are twenty four I think my tallest measuring device is 24 inches tall and I want to be able to put it in a drawer or cabinet under here and I want to talk about that well I hope you guys like this kind of go into the math and the engineering of this stuff I try to keep it as simple as I can because I'm not an engineer by trade as you guys know but I do try to study everything I can and learn as much about engineering as I can so if you do like this kind of stuff give me a thumbs up if I made any mistake give me some comments if you like what I'm doing also give me some comments alright guys until next time go out in your shop build something cool thanks you you

Channel: Build Something Cool

Views: 49,580

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Id: YZgpdMtN-AM

Length: 11min 39sec (699 seconds)

Published: Fri Oct 07 2016