Making Flat lapping plates 4

[Music] [Laughter] here's our feed stock for our penny labs so I went and separated all my pocket change and you need pennies that are US pennies I should say that are older than 1982 okay and so here's the difference here's what they look like when you scuff the back of them this is just to get the glue to adhere better but you can see there's a colored actually maybe that's not a good here's one that has it better yeah there we go those are better you can see here this is these are pennies that are I think these are eighty to see how 82 is you may have dink in them and we really don't want that we want as much copper as possible so these are older than 82 so 81 and an older so what's that one 70 75 yeah anyway I'm scuffing the backs and then we're going to gloom down so no zinc those are it go away all right so we're prepping these pennies to glue them down to these platen sear now I did I want to do to penny laps and then one with the copper washer had it's more of an experiment on my part the copper washers are actually kind of nice they're really uniform and they have a hole in them which is kind of cool this gives us a little more surface area when they're machined up but yeah I'm just trying this kind of a side experiment so I've seen to the backs and kind of roughed them up in preparation to glue them but what I want to do now is take off some of this carnage you know this the patina that's on these penny and what I'm going to use here is I got some copper cleaner here and what this is is a white vinegar and salt so there's a couple of three tablespoons of salt and then some white vinegar and what we're going to do will just drop these my little tough here now you can see you can see the tarnish on them now okay it's kind of cool actually works then we'll just put some of this in there just enough to kind of cover them up and you can already see it I'll bring in closer you can already see the effect it's pretty immediate and you can see they're already brightening up all as barrages is kind of coming off anyway that's a nice trick the white vinegar is sold if you have to clean copper in the home shop works really good now it doesn't give it a bright finish like bright dip which is a commercial process that uses a well you know what I don't know what they use actual kind of chromate something or rather anyway this works pretty good so let's we're going to rinse these off and then dry them off and then we'll come on just clean the the lap a prior to bonding these down and then I'm going to put this this is just basically a fence to keep me honest around the edge at least for most of it as I'm gluing these down you know I was trying to use tweezers on the you know on this one here and the fingers are the best this is a Loctite 380 and it cleans up with acetone so it's not too bad to get it off so it's pretty pretty straightforward this particular industrial size here has a pretty good that's pretty good dispenser tip so you know to have to screw around too much so you want to give it a little a little swirl I get a big blob of it there so better put another one right there and so so it goes glue your fingers together to and snow you know trying to be super neat with this is a probably exercise in futility here so just make sure you get the the prep side down [Applause] last couple the last couple are going to they're going to hang over so but we're not going to we're not going to stress that about it because we'll just trim those off you know I suppose you could try to get it perfect but I'll think is any particular advantage to that all right it's probably good so those will just clip those off all right so let's let that sit and we'll do the other one see you later Abe Abe's gotta go alright looks like we get a nice full cleanup there and they're all copper those zinc ringers in there alright put a little chamfer on then I'll do the other one alright so we got them all finished the pennies faced actually really easily and as you guys notice that I ended up a couple leaves fell off and I think the washers are smoother and they probably needed a little more prep than when I gave them ultimately you know I got to pay stuff but these are this was a no-brainer they just went really easily and I was able to champ from so the shape on the back made contributed to it or I don't know what but they're also have a little more surface area than these do too but a couple of these popped off and I had to put them back on and go back and redo it so a little bit of a nuisance but I can't blame myself a little bit because I could have prepped the aluminum a little bit better than I did it was just a smooth turn finish and I didn't scuff it up with with any paper so these are actually ready to start lapping together I'm going to label them and mark them with the the some increments you know eight increments on them and then we'll start lapping these with the time saver but the yellow time saver for brasses and coppers and bronzes and things like that so as we go [Applause] okay so there was some actually some really good questions that came through on lapping plates three video and I thought I'd just address some of those now let's go ahead and do it so it's a little bit of talking so you don't want to listen to talk and you can fast forward from here so the first one was about the wavelength of this particular like this weird light here so this is what we call a monochromatic light source so it's light of a particular wavelength and and in this case here it's a it's helium light which has a wavelength and if you guys remember from your physics class you know a wavelength is basically that right okay so from there to there is a wavelength well light that's actually a measurement that's a distance from there to there okay and we can measure things with light which is really cool right and in this particular light on this this light here is let me turn in here this is five hundred and eighty seven point six nanometers okay that's the wavelength of this particular light okay and by the way that's pretty small nanometers our dinky okay so that's about twenty two millionths of an inch 587 nanometers is about twenty two millionths of an inch okay so without getting into you know heavy duty nerd nerd Ville there okay what what we're trying to do with these lapping plates is we want to get them to some fraction flat within some fraction of this particular wavelength okay you know and personally my my target has been a quarter wave of this particular light okay and what that translates into is that's that is point let's see I wrote it down over here because I couldn't remember 0.15 microns okay so about three millionths of an inch all right and point one five micrometers okay and that's pretty small now it's totally achievable and with our optical flats we can actually inspect and evaluate that surface okay for how flat it is compared to in using this as a reference okay so this is our reference standard here it's a known wavelength so it doesn't need to be calibrated it's a kind of the part of the electromagnetic spectrum right so it's it's kind of it's our standard in this case length standard edition see now you know when we as we flatten these and we get them flatter and flatter and flatter right somebody somebody brought up you know you know why is that one particular plate not in that these guys here the cast iron ones why does it have that hollow in the middle well that's just a natural process of the lapping they're actually they're alternating and hopefully you can see this ruler here they're alternating between concave and convex right okay now this is a great exaggeration right so the flatter you get that a little bit of lapping and it takes a concave a little bit and if you flip it on top and you lap it a little bit more it goes the other way and make those convex right so optical flats are actually marked whether they're concave or convex okay and which is pretty cool right now here's a really neat part this is the part I thought it's really neat right is so if you think about that you know you can never have something that's just absolutely pure dead flat now you can have things that are flat but not absolutely in the theoretical sense flat right so they're always going to be a little bit concave are they're going to be a little bit convex okay now we could be talking very very tiny amounts but there always be that way so if we actually achieve this quarter wave that that I'm looking for on these plates just any that's just a personal goal okay and so it should be totally achievable with these techniques okay what that means is is that radius that we're talking about and this is this is really cool right that radius that we're talking about is something like almost twenty four miles the radius is twenty four miles or thirty eight kilometers for our metric friends right so if you took that curve and you and you went and you walk to where the center of that curve was it'd be 38 kilometers away so now the optical metrology guys where I work they talk in 100 kilometer radius so these are incredibly flat things that they're fiddling around with they're at work so anyway I just thought you guys would like that and a little bit of background we're going to we're going to dig in deep to this because this is really interesting stuff and for all of the fellow nerds out there we'll dig into this and the optical flats a little bit better and but I want to do the lapping plates and kind of focus on those and then here's a blade that I got just kind of you know I struggled with that carbide carbide tip blade for cutting grooves right well this one's got a diamond edge on it and this would probably work really well I haven't tried it yet but I was at Lowe's and they had these and it was I was fifteen bucks or something like that so I figured I'd get one and give it a try for cut and cast iron okay okay so look we're looking at these the cast iron plates now and and I've done a little bit more lapping on these too to try to get rid of that little that little pesky ring that I was a annoyed by and there's still some halo of it so I get a little bit more to do so I put another hour into it or something so we're going to continue on and then we'll we'll repolish the plates and then we'll check them with the the light in the optical flat okay now a couple people I guess they didn't hear me in the first video uh you know hey what's that material right well these are discs that came from mcmaster-carr and i put the part number in the description so you can look them up and buy them they have them at different sizes you know I think you can get them up to twelve inch or something like that and they're not particularly expensive so if you want to try making a set of three lapping plates you know you can buy the material fairly cheap now don't skimp on the thickness because this thickness it translates into stiffness okay so what you don't want is you don't want something that that you know as you're putting a little bit of load on it or whatever it's deflecting and changing too much okay so these are fairly rigid in the you know over this diameter and thickness here okay so in another person say well gee why didn't you surface grind those first well yeah you could do that but my surface grinder only has five inches of transverse travel right so I would had to turn the plate around and putz around with that right and as you guys saw you know from a lathe turn finish I put three hours into it to get them you know down to I don't know it was about one band or something like that or one and a half bands right which is pretty damn flat right in the scheme of things right so yeah surface grinding it might have sped it up a little bit okay but you know I would have spent I would have spent an hour to you know grind in these all flat right so you know you're doing tool once when you're when you're lapping yeah okay if you got a grinder fine grind and you'll save some time probably all right but that's the reason I didn't do that because I really wanted to do this with with no tools or no particular fancy tools right so guys that maybe just have a lathe or maybe you don't have a lathe right I mean you frankly you could start with these plates looking like this and and start rubbing them together and it would take you longer but you would end up with flat plains okay so what basically you know if you're building a pyramid and you had rocks right you could rub these rocks together and end up with a bunch of surface plates okay so in no measuring tools right so that to me that was kind of the attraction of doing this the hard way so to speak all right and then yeah everybody's a smart guy out there or smart person all right and they said well gee you're using that time saver right you know you could go really fast if you just switch the diamond well you know sometimes that's it it's not about fast it's about the journey right this stuff's cheap and what I really wanted was I wanted something that wasn't embedding right so diamond tends to charge into the softer surface because it's so damn hard right and we're going to we're going to show that with those copper laps but I wanted something that didn't that didn't embed embrace of it abrasive into the surface so that's kind of why I chose this and yeah diamonds faster hands-down right you know you want to go fast youth diamond okay but remember that whatever grit diamond that you are using you know some of that's going to be stuck in this plate and you'll it may come out or it may cause you problems when you least want it to cause you a problem okay when you have a 30 micron scratch in a one hit you know in a 1 micron surface finish okay that's when it really annoys you when something like that happen so so we're trying to keep these pure and you know as far as we can take them before we get crazy with diamond on them ultimately there will be diamond on these but one will be you know maybe 10 Mike 9 micron 6 3 or you know I don't know 6 3 1 something like that I don't know that's probably how they'll end up and you can recondition them and get rid of the diamond ok so don't worry about that but I just wanted to do it without diamond initially okay okay so the last thing I wanted to address you know with the lapping procedure here is I got a foam pad underneath this okay so this has the ability to to to rock basically in all directions so that it it can kind of follow my my non machine like motion okay and you know what we're doing here is and that's what these marks are about and maybe you guys didn't pick up on it is yeah I'm doing this linear stroke okay but I'm also moving sideways okay I look you know about the same amount off this way and about the same amount off this way okay as well as that and that okay so it's kind of a you know I guess with zig zag motion you would call it right but it's it's limiting the you know the overhang and then I do that for a while and then I o'clock at 45 degrees so between the red mark and the yellow mark and I do the same thing so I'm rotating this relative to that somebody said oh you get it you need to rotate that plate you don't need to rotate that plate okay and I proven it because these plates are pretty flat right so the trick is this foam under here right so if this was on a solid surface I might agree with you okay that you need to clock this a little bit too but effectively we're clocking this relative to that and then this takes a turn on top of that one - so we're averaging all this stuff out and that's how this process works is it's just magic of averaging okay so we're averaging the highs against the highs on this one while it's on the bottom then we average it the other way and then our strokes are averaged out because we're rotating this so there's all this averaging going on right and the result of that averaging is that it gets closer and closer and closer to a flat plane okay so that's my mic rebuttal or my answer to to the rotation of the lower plate okay and okay [Applause] [Music] [Music] [Music] [Laughter] you [Music] [Music]

Channel: oxtoolco

Views: 162,525

Rating: 4.8249907 out of 5

Keywords: Lapping, Optical flat, Optical metrology, Monchromatic light, Helium wavelength, Nanometer, Toolmaking, Gage, Gauge, Metrology, Loctite 380, Copper lap, Three plate method, Joseph Whitworth, Cast iron lap, Diamond lap

Id: zwrTGVSxzJI

Length: 23min 53sec (1433 seconds)

Published: Fri Apr 14 2017