DIY SURFACE PLATE LAPPING PART 2

hello everyone welcome to my shop i'm robin and welcome back to the diy surface plate lapping video series this is part two i'm gonna carry on from where i left off on the previous video we're going to be showing uh using aluminum foil adhesive packed put onto surface plates to act as the abrasive surface and in general that can work but the heavier plates my 135 pound plates it turns out they're just too heavy period to be a good lap there's too much pressure on the charge on the plate and it just tends to rip the charge out so they're just a little bit too heavy uh they i did get the plate uh as you'll see to a acceptable level but um at the end of the video i'm gonna be showing you uh my ideas on making a lap for final finishing where i put a thicker aluminum surface on a lap a much lighter cast iron plate and i think that's going to work real well you also see that i decided that grooving was a good idea it turns out that grooves help a lot to get this wharf um give a place a place for the swarf to go and you'll see some scraping of me scraping the 18 inch square plates one of my ones that wasn't finished scraping it to be a lap and grooving it so lots of interesting stuff here and let's get to it so i'm starting to think that now the long aspect ratio plate that one is 10 by 30 i knew that wasn't necessarily the ideal proportions but i thought it'd be good for roughing and it's it's done well so far but um i just want to try another plate this is just a another plate that i have actually uses my welding table so i'm just going to stone that off and give that a try and see how that behaves give me a little more control of being able to focus on the areas i want without it being too too small if you get too small relative to the whole surface you're on then you're not getting any averaging effects of of straightness you can end up with more whoop to do this so you can picture if you did like a six inch diameter lap and tried to lap this plate you'd it'd be a mess you would just be you'd go berserk you need the averaging effect of the longer surface to bridge highs and lows and to smooth things out so let me try this other plate see what happens here i'm dusting on our uh our diamond powder and this aluminum should really really suck this up like crazy i have no idea this is going to work but it's not a big deal to give it a try and see what happens so i'm looking for something that's going to hold a charge for quite a while and really rough well because the everything is kind of slowed down now now that i've got the the hole out it seems like things have come into come to a halt and not like i'm not removing material but not nearly at the rate i'd like to so i'm going to try charging this thing up and roll it in okay now i'm going to try rolling this in see how this behaves on the aluminum get this where it's evenly distributed and then i'll get the stool out and actually get up going there where i can lean on it get my body weight on it so usually like on the iron plate if i did this here i'd be able to sweep up a huge pile that wasn't actually connected you can see there's almost no diamond and i put probably double the amount so this is really charging extremely well and i think i'm actually going to go back and put a little bit more on and try to get this really charged because this looks like this is this could be uh could be really great okay we're gonna flip this over and see what happens here nothing to lose i'm going to take a quick trip around the edge here so the things are falling out i get an even distribution of it around where i want to remove the material feels good it'll be interesting to see what the aluminum itself looks like benji looks pretty good on the plate remember you got to keep an eye on that and see what you're doing here so wow that is cutting nice that the iron plates would have been choking and getting sticky by now and this is just feeling very uniform got to be careful and not assume that this is removing material as slowly as before and end up going convex i know i'm pretty severely concave so i'm going to take another another pass around let's let's take a look at the lap before we go too far and see what it looks like what kind of conditions here's a look at the at the plate i think these parts are where it's puffy and the aluminum is actually floating up and down but it's cutting beautiful i mean it feels really smooth and like we're really removing material and the charges staying put the iron plate seemed like one lap and i was losing the charge and i just started to rub iron on well i don't know what i'm going to see when i measure here but i'm really impressed i'm like the cutting action difference between these two is like night and day really really nice just consistent and uh yeah it seems like this charge is actually staying put and just continuing to cut very very nicely get in here and see how how close this can see yeah that is really really doing a nice job so i'm going to take this off clean this off and do a check with the level and see where we are so i want to point out some some details here that can bite you uh i'm using the lap with the aluminum uh sheet foil bonded to it which is working nicely as a lap i've taken multiple passes around here and got tired of these corners still staying high and not really getting knocked down so i really focused on these corners getting the center of gravity of the plate you know pretty far out here and working in a circular arc here assuming that this thing's roughly spherical concave and worked in this zone all right uh now the 11 inch spacing that i'm using on the um on the uh level that you see here that's working wonderful as far as general contour and seeing what's going on in general but you got to be you have to remember that when you do that there are things that can happen within the spacing that you're not aware of and i just want to show you one of those things so focusing on this the plate now if i measure at these points is down to about three tenths overall bow on all all the perimeter just going on the perimeter doing each edge on there we're only talking about three tenths but if you look at this this is zero this is basically acting as a repeated meter it's got two feet well three feet and then this is three and a half spacing so this is three and a half inches out further silicon nitrate ball so right here this is running along this okay it's generally zero all right now watch what happens when i get here to where the zone where i'm measuring here that's dropped two tenths right there and that's because of me getting the center of gravity the plate over here i'm starting to roll this off where i i'm because i'm working with a small surface area that isn't bridging a lot of things i'm getting to a point where i'm i'm getting in trouble and if you didn't come back and check with this finer resolution meaning something in between here to see what these undulations are you wouldn't see this little drop off because i'm only measuring from here to here and then from here to here and i'm only looking at the general topography and missing the fact that i'm digging a hole here i'm okay this is this is going to come out all it means is that since this is technically three tenths high right here by the time i lap this down the rest of this down to where it meets this it's going to be fine but it points out that you need to do other checking and look for this type of thing and it's the same thing in the other direction i'll get my roughly zero and then it drops off it's not quite as as drastic in the uh short axis the three-foot axis of the plate i'm gonna do a run-through of the uh inspection procedure that i'm using on this i have my drywall square blade marked out with markings on it for the 36 inch direction i have markers at each end where i line the plate edge up so 36 inch plate edge then i have the foot locations at the 5.5 spacing that works out for the renzo meter and then this has the 11 inch foot spacing so that for quick overall assessment i can i can do that so first i put this centered because on this one there's only going to be three places here and then the foot location here and here this is my counterbalance we discussed before to offset the influence of the plate and the lap is still sitting on there because i'm using the lap to tweak my position and right now actually the lap is is just about the right spot so simply by moving the lap weight back and forth here over laterally to change the weighting of the plate i can tweak my reading so i get my bubble perfectly centered again right now we're just roughing so i'm zero here my bubbles perfectly centered now i'm going to move over to where this foot goes where the last one was that's the principle that we're using here that's what the way all of the measuring systems doesn't matter whether you're using an autocollimator a laser whatever you're still using a two-footed item to go from one reading and then from that to the next elevation from their elevation and then calculating what's going on now i have to move this to the corresponding place opposite to balance the weights these are the same weight so now i'm centering it so that the plates not tilting now i can come in and read this and that's probably about only about barely a tenth from here to their rise now in theory if this is a perfect curve there's if that's a tenth in that distance and this is a uniform curve there's some here we're not seeing because we're bridging the curve here this still if it's a curve it's still there's still the belly here if you picture this being uh concave which it was more severely before we got to this point so uh in general though we're only talking about a barely a tenth rise on that foot so if i come now shift the directions to the other side bring this left foot over here to where this was put this over here in its counterbalancing position and read what we've got here that'll tell us what's going on on this end i was previously had about six tenths high here this originally the pulp plate when they uh the people who started on this and quit when they were roughing this they roughed it pretty concave this was almost a full thousandth high on the corners relative to the center uh and i've got it down now i i really focused on the corners and got finally got it down to where it started to behave and now uh this is basically zero so in this direction this is below uh lab grade lab grade for this plate is is uh two tenths total band so this right here according to the level and actually this is relatively accurate um this is below lab grade already just in the roughing pass so that's the procedure on the four foot side do the exact same thing except i have markings for the forefoot side that are different because there we have the foot in the center we go here and here because we get four locations and do the same thing uh i have checked that and that's barely a tenth uh maybe a tenth and a half on each end high in that direction so we we actually are at lab grade already uh below lab grade just from this relative to using the level as a reference and actually um not that you'd want to certify a plate using this but for for in reality for shop purposes this is already way good remember a b grade plate at this size is six tenths is the tolerance so this thing was already a b grade plate before i even when i got to my six tenths location after my thousandth that was already in spec for b so we're just going to keep going and also the 40 micron that i'm using on this to rough does not leave a surface finish that is really uh ideal for a real high precision plate this will tend to first of all a little bit hard to clean um it's not like it's horrible and maybe a lot of plates probably are this finish as is but um i i definitely want to get the finish a lot better so i have the aluminum foil on the plate i have the uh what is it 1200 mesh or which is roughly 10 to 16 micron diamond powder rolled into the plate i sprinkled a layer of uh very light layer and brushed it out of the diamond powder and then set the plate down on it and i'm taking a lap around there i have no idea how this aluminum is going to hold up i'm surprised that the weight of this plate isn't a huge issue here it seems to be okay this is a very heavy plate it's like 130 pounds um so i'm taking the lap around here in a minute all this dark you see is the um i think the aluminum actually wearing from tumbling abrasion and i just trying to get a feel for how this whether this aluminum is charging or what's going on i know from past experience that i don't want to get too much smut going on here or it will smear and tear i just i'm just feeling something right there and that's what i was afraid of see how it's pivoting around there i'm gonna yank this off of there see what's going on um this is the general problem with with the aluminum i thought that with the finer grit diamond that it being as much smaller percentage of the thickness of the aluminum foil that the aluminum foil would have enough oomph but obviously that's not necessary see what's going on here without having to go all the way up and here's the typical problem with the aluminum you see what happened there where the adhesion just let loose and this just skidded and smeared the aluminum this is very soft aluminum this is 1100 series aluminum zero temper so right there that is what frequently happens okay now with the failure of the foil on the large lapping i think the oil obviously works fine on small lapping but it's just not going to work for this with the dead soft aluminum higher strength aluminum thicker would probably work just fine but even then for the final precision finishing i'm doing i think the glue variations would be an issue so here is the third plate of the three plates that i scraped uh this is a much coarser more pattern fine by most standards but much coarser than the other two that i did this is when i realized that oh duh two plates and a repeated meter is all you need you don't need three plates so i quit on this one so this one's not flat it's not you know radically off but it's not flat now i charged this with some six micron one time to uh lap some stuff and then that's when i remembered oh this one's not flat so what i'm gonna do the plan for making my finished surface plate lap is i'm going to groove this because of the success of grooving the other one just how much better that works uh in doing the granite because the place for the for the swarf to collect and not not make the plate rise up and uh then i'm going to scrape this using one of my other plates as a master and i'm intentionally grooving this first to see how difficult it is to scrape when it's grooved i think with the right techniques um and the right kind of scraping i think it won't be an issue but we'll find out but the first thing i'm going to do here is since this was charged uh even though six microns pretty small um it still will tend to wear my groove tool and it will also tend to to wear the scraper so i'm taking aluminum block i'm gonna put some wd-40 on here and i'm going to try to pull some of the charge out of here by having it go into the aluminum block probably not going to do a whole lot but it's it's the thought that counts so i'm missing with a little wd-40 here and we'll just see what what happens i don't know who's who's groovy who but or who's abrading who but it doesn't really matter one thing i can tell is i got a lot of hydrogen and hydrodynamic float going on so i'm probably going to go over to the band saw here momentarily and groove the daylights out of this thing so that it doesn't float like that so there's the groove block uh just a word of warning when you're working with abrasives you really have to think about what's happening as in i said i was going to go run the band saw and groove this well i just got done rubbing this on six micron diamond and my whole intent was that the diamond would embed in this so going over to the bandsaw blade and gently going in and putting these grooves in could seriously put a hamper on my brand new uh 70 dollar uh steroid band saw blade so i went over and used a cheap hand hacksaw to put these grooves in should have grooved it first before it ever touched the plate that i could have done on the bandsaw but you got to think about where your abrasives are charging and what they're going to do to your tools so so so sorry i've got my bar clamped on uh it's inch and three quarters from the edge of the router base to the center line i'm doing half inch spacing got the depth set with the single lip cutter i just ground and this is 35 000 rpm this is ultra fine grain ultra micro green carbide and here we go that router had no idea that it wasn't cutting wood that's how easy that cut so i'm going to do the pattern all the way across obviously i'll have to flip and do it the opposite direction on the last little bit where i clamp the straight edge and then i'll do it the cross direction very important you have a uniform layer that doesn't have any blobs or whatever because those blobs will turn into a bearing that is not really varying okay letting her down to get her first [Music] rub [Music] so [Music] here's what a pretty nice bearing looks like and a nice rub we've got a nice contrast between the orange background and the blue good identification of the high spots and over here we can uh we can see the same thing but it dwindles out and it's not touching here at the center at all so it is concave as we suspected i'm using my old friend here a inch and a quarter wide anderson style scraper i bought this when i first did these plates long ago and the inch and a quarter width is uh important for what we're doing here in bridging these uh grooves a good sharp scraper blade should just bite your nail instantly when you press down and push it should stop like a brick wall if it skids at all or if it does sh it really should just stop you dead in your tracks because it grabs so quickly if there's any any slide whatsoever it's dull it really needs to be super sharp and when you you feel this edge it almost feels like a knife edge when you slide across sideways it's so crisp and that's what gives you a nice easy cutting action and and not a lot of chatter using a very shallow angle here and just taking long full strokes because of the very large radius on there i'm having no problem at all going over these uh grooves from the from the grooving of the lap now i'm going at the 90 degrees to the first cuts and i'm just taking a pass you see how this super wide scraper takes very wide flat cut and keeps me out of trouble making sure these edges are good there you always want to never want to take a pass in the same direction twice because you're inviting chatter by crossing the long smooth edge of the scraper bridges the chatter from the other direction and uh there's no good reason for having chatter in your scraping okay so i have hit these corners remember this is probably basically spherical so the we should see a circle here in the center where we're not touching i've hit these two directions and same here two directions it really doesn't matter which way you go as long as you're crossed and obviously the magic of not having an issue with these uh squares is that i'm always going in this direction so i'm always bridging something if i try to do it this way nightmare okay you're just it's just going to be on the verge of impossible by going 9 or 45 degrees to the actual grooves uh no issue whatsoever with a nice wide scraper like this this large inch and a quarter wide scraper an inch would be enough i just happen to have an inch and a quarter wide i have an inch and a quarter and three quarter inch would be fine you could probably get away with three quarter the advantage of this the wider scraper is you can get a wide cut you know some of these cuts that i'm doing are almost like 5 8 of an inch wide well if that's on a three-quarter scraper gives you very little margin of error for starting that come up and hit the edge the the extra width of this scraper allows me to get a almost three-quarter wide cut when i get super shallow like this which is what i'm trying to do uh that that really helps i'm going to give this a good stoning with the coarse side of the precision ground flat stones i'm using the 8 inch pair here because that helps bridge and sort of flatten in the process so by using this vigorously meaning i'm actually bearing down trying to to remove things i'm inherently knocking down peaks that would cause just a point hit and i'm getting rid of those and what i'm doing here is i'm saving you know multiple passes of trying on here because the flat stone is so straight i can i can lean on this without fear of digging a hole or messing up the geometry and i'm intentionally sort of lapping with the precision ground flat stone i'm keeping a lot of a lot engaged so as an example this corner right here is hitting if i didn't do this if i didn't stone this good and hard with with this stone um that point would probably keep a lot of other stuff from hitting so i'm literally uh knocking things down until they start to bear significantly and that is going to save tons of passes of of checking with the plate so that's one of the beauties of the stones i know people probably think this guy's just trying to sell stones you ask the people that have made these themselves or have them and they'll tell you no it they're magic so uh it's not just sales pitch here uh yeah these really work good so then after i've done that now i'm just going to take a general sweep over here and make sure there's no dingleberries that are going to surprise me [Music] getting close now pretty good overall bearing we're a little bit light up in here we still got a few streaks in here from roughing that need to come out but uh we're going close so [Music] so here's a view of the master in the front here hanging on the straps and then the lap that i scraped with it the grooved lap and i've got this a little bit convex and i did that on purpose because the plates tend to wear uh concave because the center gets worked more from overhang so um this is all scraped oddly enough scraping on that groove pattern isn't that bad when you when you hit it at a 45 degree angle you know either direction 45 this way or 45 this way it just bridges right across the groove nicely so that wasn't really a big issue um that had about two tenths a little over two-tenths concavity of this plate from its original condition so it took a while to scrape all that off um but uh it's in good shape now so i'm gonna move on to charging this so i'm saying to myself how can i get this thing to the the situation where the uh diamond wants to fall down and puddle in the in the uh grooves what can i do about that well dummy turn the plate upside down brush it on inverted just sweep the brush this way which is what i did upside down and this is allowing the uh diamond to fall onto the face instead of falling down into the grooves so now the excess comes to the top back onto the brush instead of just disappearing down into the gullies so should be a more uniform you use less diamond uh that goes to waste in the grooves i'm not sure whether it actually falls out in process if it's dry enough and loose enough to actually fall out while it's upside down on the plate and get used up i'm not sure but this this is definitely a better way to do it i'm not sure i'm blocking the shot here but this way all the all that loose stuff comes right back onto the brush and we're onto the face of the brush to pick it up again and this is definitely the the hot setup here as you can see that really left a nice matte uh coating of diamond that diamond is just i don't know what's holding on there but um you breathe on it it falls off so you need to get this over to the plate um if you brush it with a dry brush it just brushes right off so you got to be careful with that and get it on the plate quickly foreign okay ready uh so i take a toothbrush here and scrub out the the granite swarf out of the out of the uh grooves right into the trash can i finally woke up and realized duh get the vacuum cleaner out and vacuum the plate off and the table [Music] as has been mentioned before a repeater meter cannot in itself measure the flatness of a plate it can only measure measure the repeat reading ability of the plate and that means relative to this these two feet the plane formed by those what's the rise and fall of this foot out here and that's representing the equivalent of a surface gauge or some kind of measuring instrument base relative to where it's measuring so as you drive around measure that same measurement different places on the plate you would get what that variation in reading that would be the repeat reading the same as what this measures as you go around the plate so they can't measure flatness they can only measure uniformity of sphericity so picture the plate being a sphere a very large radius a very good plate with uh you can have excellent repeat reading and yet be very out of flat so what if you had a super flat reference like something down in the two millionths of an inch over this 11 inch span then you could zero it on that then this would be able to measure flatness well thanks to my friend sam wagner i have just that this is a 14 inch diameter optical flat so i can take my repeater meter down here i've very carefully cleaned the feet and come down and sit very gently on this [Music] and turn on my meter and check this out make sure i'm sitting sitting well and zero this out i'll show you that here momentarily so we've got the plate down there and then we'll come back up here to the indicator and i'm on 10 millionths per division at the moment and i'm zeroing that and then seeing if my repeat reading if this stays uniform here as i change positions here yes that's repeating very nicely within 10 millionths there so that's my zero now i can bring this up to the plate sit down very gently on here to not disturb anything okay so there's my there's my reading now so i can cover up my optical flat thanks again sam that is a awesome awesome tool that will get used a lot here and as you see right here as we're looking at this um i'm going to reverse the repeat a meter here and see what we've got so that's plus 20 plus 70 60. and now to the end it starts to drop off so there's a little bit of shape in the plate but we're within about 60 70 million it's their repeat reading but that's nowhere near close enough to what we want where we want to be here's the general setup i have the profilometer the traverse unit sitting there in the front with the diamond uh stylus with the skid engaged with the plate the actual reading units in the back one of the tricky things on the plate is finding a spot where you've got homogeneous relatively poor free material that you don't have any inclusions or things that the granite plates have pores uh especially the pink granite will have more pores than this very dense black granite so finding a place where you've got a good smooth traverse without holes is important so you're not getting erratic readings here's the unit traversing and then we'll take a look here at what we're seeing on our division we're on the 30 micro inch scale on top and you can see there that roughly we're in the roughly a 10 micro inch finish ra so that's what i'm going to target for on the other plate uh to get in that general range uh because obviously to do a triple a plate starrett uh hermann whatever you want to call it plate company decided that they needed to go finer grit to get to that level so that violates the federal spec of net less than 16 going below 16 ra okay i'm shooting for a 10 micro inch ra finish on the granite this is 9 micron slurry that i used on a cast iron lap on a stand rich block here as a test to see what kind of surface finish i get it's a little high and my whole purpose here was i'm ordering some diamond powder and i need to know whether i need to get some six micron in the process it looks like the answer is obviously yes so it left this with some sick six micron and that's definitely uh that's definitely doing the job there we're down in the eight micro inch range there so i'd rather be a little bit on the shiny side than the uh coarse side plate should actually wear longer with the finer finish so definitely need to get some six micron powder on the way here we are on the big plate with uh being lapped with the 325 400 which is roughly 40 micron and now we take a look at the reading here and we're on the uh 100 micro inch range and you can see we're roughly in the 60 uh micro inch range so 60 ra so a long way to go um and we would expect to see this roughness i just want to get a comparison so we've got our autocollimator readings from our software demo software that we're using and you can see the concave shape of the entire plate and then we have this chart which is a little confusing because the plate axis is actually this way the way i've drawn a pencil not the aspect ratio that you see of the printout so that can really confuse you but according to this and according to my two-footed twist gauge these are my high corners and these are my low corners so this is twisted like this and like that high high so um excuse me high high low low and uh it's very important to make sure that you're making corrections in the right direction i've seen lapping people take a plate so far off from reading things wrong that they had to take the plate away and have it resurfaced at a factory so really important to make sure you know what you're doing double check i just just double checked again with the two footed twist gauge which doesn't lie and i had forgotten this orientation thing so if i would have just filed this paper i would have had it this way and i would have had the twist i would have been aggravating the twist that was there making it worse so that's a prime example of really really really be sure you know what you're doing and even then you make mistakes so be careful so i have a formula in here that converts the rise of the repeated meter foot into an angle relative to the other two feet in arc seconds and then it has to add it on top of that because the the um autocollimator reference never moves where on the repeated meter its new reference is where it just was so there's a hidden cell here that is taking the calculation to turn it into arc seconds and then it's adding the previous one to the current arc seconds to the previous one all the way across that doesn't make much sense but that's that's why i can use the repeated meter values and put them in here because it's converting these two um arc second values so here's our last map using the repeated meter zeroed on the optical flat and using the photo collimator software to print out now i've written these onto the plate just to get a visual of what's going on and i'll lap accordingly corners are high so so [Music] c [Music] so [Laughter] [Music] so [Music] [Laughter] [Music] these corners are still these opposite corners that are technically low relative to those are still high in overall concavity i just need to focus more on these uh the two opposite corners there i'm trying to stay away from the middle but not overhang too much but if you roll the edge over and you'll be a real unhappy camper so here i need to focus more because this is important not to let this swarf build up too much on the plates because it will start even with the grooves it will tend to start to smear and carry on so really a good thing to just keep after it and even though i'm not roller charging the plate currently it's got a pretty good charge on it and this shouldn't be causing a lot of problem there's all the swarf building up in the in the clearance grooves i personally really think the grooves are very effective data is now all entered and now i'm coming in and i'm going to go on the 3d graph and um looking at that and this is looking pretty good real good closure 12 millionths and 9 millionths that's very very good maximum height is 106 micro inches so just about a tenth uh well a little over 10th actually so um looking pretty good as you can see that plate turned out pretty nice it's in that particular measurement looks like it's a triple a plate we all know that vertical temperature gradient changes and things can move that around a bit but as measured um a triple-a plate my repeat reading is about 25 millionths which is not good enough for aaa triple a needs to be half of double a which would be 17 millionths and uh the plate that i'm going to show you next is what i plan to use to do some final tweaking and i'm also going to show you some of the procedures i used to make the plate and in the next video uh it will be me using that plate to do the final tweaking to get this thing to be much better repeat reading i'd really like it to be less than 10 millionths and um also keep it within aaa specs as far as below a tenth of of uh flatness and uh so this that's why i made this uh other plate it's the same plate that i was using with the aluminum strips glued on the lighter plate the 50-pound plate with aluminum bonded to it and uh but that'll be in the next video that you actually see me using this here i'm just going to show you the construction of it so let's go out and take a look uh what this plate looks like there it is that's the 50 pound plate i was using previously but with the aluminum bonded on and grooved and one of the things that's important here is i was concerned about the bi-metallic strip effect of having high expansion aluminum bonded to the iron so my thoughts were here if i groove this if i go clean through the aluminum it breaks this up and the acrylic adhesive has some uh ductility to it or some give and that means that in theory the shear forces that would occur between at the bond line between the two different coefficient coefficient of expansion will be absorbed a lot in the glue film all hypothetical and who knows how that will work but uh because this is so thin and that i've gone clean through the aluminum so it's not a continuous sheet in theory these can grow closer to each other or in a grow way and that gap is there to allow that to occur at the bottom of the groove so we'll see how that works but um next you'll see some excerpts of the manufacturing of this just for curiosity like i said before this will be used in the next video when i uh actually use this to try to take this plate from where it is now which is just just squeaking into aaa and the repeat's not good enough to get it well within that and get hopefully down in the 10 millionths repeat reading on the plate i'm making a precision groove trowel with seven thousandths deep teeth those little pips you see sticking up there are about seven thousands high and about fifteen thousandths wide i'm using a three sixteenths end mill with the 0.2 spacing on the bridgeport dial i'm using these parallels as stiffeners that spring steel piece is sitting down on the vise bottom so i'm just using my tallest parallels held them up to the right height to support that spring steel so it wasn't flapping in the breeze when i was machining it with that end mill why would i be making such a thing to spread this loctite 325 speed bonder over this 14 by 18 inch surface plate the volume i have there is going to end up about four thousands thick so it's important to get it spread evenly because i'm gonna be bonding this aluminum to the top i have the aluminum plate deburred well the edges have been filed both flat to get rid of any roll of the shear action on both sides to make sure that there's no distortion this side has been scrubbed with a sanding sponge and then degreased with alcohol i have a piece of film on the aaa surface plate to keep the goo or the glue ooze from coming out onto the plate and surface plate has been stoned well with a coarse stone lots of tumbling abrasion to get a good surface on there degreased and then this has a layer of loctite 325 speed bonder on there acrylic structural adhesive and i put that on with a trowel i made out of a piece of spring steel since you hold this the trowel at roughly 45 degrees you have to increase the depth of cut by the square root of two to get the film thickness that you're after all this is approximate anyhow but that film is on there right now i know it's hard to see but you can see the gleam on there and that's somewhat self-leveling now even after the um the trowel so i'm going to give that some time to actually self-level before i put the plate on to minimize any trapped air and then we'll flip it up over upside down onto the plate i also have to spray the 707 5 activator onto the aluminum and give it three to five minutes till it wets it's actually kind of uh unusual it kind of gleams up and gets a greasy look both these uh the activator and the 325 are excellent for oily surfaces very very tolerant of surfaces that aren't degreased well it's not the case here but with anything iron iron has a tendency to hold things in its porosity so it's a good choice of glue it's a good tough glue and it's resilient but still rigid and that's it and we have touchdown flipped the plate over lowered it onto the aluminum on the big plate decided to come out here and use the crane with the spreader to be able to carefully lower it down onto the acrylic adhesive and uh very very little exuded out so that film thickness and thick amount was was pretty close i'll let this cure until midday tomorrow and then i'll take it off trim the edges and see how flat it is and then we'll scrape it to get general overall bearing and groove it and then we're going to use natural diamond this time natural diamond is a sharper uh spikier kind of particle than the man-made diamond so it should charge better and cut a little bit coarser for the same micron size i'm grooving the plate with a d bit cutter 45 degrees with a flat i did a corner to corner line and i'm doing half inch spacing and i was marching way across just using a scale to or rule to measure and spaces across then i had to come over and do the other side and i realized duh if i could do both sides at the same time i almost got ready to use my inch and three quarter bar that i was using but that would have made the pitch of the ones cut on either side not be a multiple of this pitch and i would have been very unhappy when they met up but fortunately i realized it before i got there inch and a half plus three and a half is even evenly divided by 0.5 which is my pitch and it works but this allows me to take a pass up here on this side and still clear the clamps and come over here and cut on this side same time really cuts the time in half so there's the plate very usable as is but i want to get it further and we'll be doing that in the next video it might be a while before that video shows up as you guys will know but definitely intend on taking this thing a little further thanks for watching and i hope you found something useful or interesting in this video and i'll be back

Channel: ROBRENZ

Views: 74,594

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Id: k82T0T_4UHg

Length: 58min 45sec (3525 seconds)

Published: Tue Jan 05 2021