Scraping basics - Scraping flat - Part 1

[Music] welcome back let's talk scraping today I'll just start at basics this time I have shown scraping a few times in the past on my channel but in the comments there always pop up some questions that I want to address in this video and also I want to show the minimal basics of scraping so let's begin what is scraping scraping it basically a way to create a flat surface with hand tools just like filing or chiseling or even sawing by hand scraping is a chip removing process with the goal of creating a true flat surface why are we scraping there are a few reasons one the part doesn't fit on a machine tool if you if you're working on a big machine part and you cannot fit it on a bigger machine to to get surfaces flat you have to rely on scraping also a scraped surface generally if done right really flat surface grinding is pretty darn good but scraping can be better surface grinding can be better than scraping it always depends a little bit on who does what but generally scraping produces a dead flat surface if done right there are two kinds of surfaces you want to scrape one or flogging surfaces like machine ways on those the scraping is beneficial because the scraping victim gives not a uniform even surfaces create a of high and low areas and that's beneficial to carry the oil between the two sliding surfaces which prevents galling and premature wear on the other hand there are surfaces that you scraped because we have no other way to create a flat surface maybe for let's say an angle plate let's say this angle plate here you could surface grinders if you had a surface grinder big enough but I don't have so I machined it and then I scraped it on those parts you don't want heavy deep valleys for for oil because they are not sliding part you just want the part to be flat so this shows an ideally surface ground part which is perfectly flat and this part is scraped part all from size you of course imagine those two parts moving against each other these points up here are the points contacting between both of the parts and those carry all the load so the load spreads out over all these points and the area between between the high spots which is low there is space for oil so you have uncountable number of small wellies that have space to carry the oil when the two parts move against each other because on the high spots where the parts touch each other there is no space for oil it will get scraped off and moved out by the by the two parts rubbing against each other so that's very beneficial in and modern CNC machines wood box waves you find this often you have one side hard mem ground and the other side is scraped but hey couldn't you just surface grind both parts and let them run against each other yes you could and it is done but the problem is as you have a incredible high area of contact between the two parts the oil film gets very thin over time if you don't have a pressure Lube system and eventually gets even pushed out completely and then the surface is where and Gaul so they they score up the surfaces imagine 2 gauge blocks these are standard gauge blocks of course and they have a very good surface finish and when you rub them together it should the end if you rub them long enough they will gall between each other and tear up the surface so and you have also this you move them against each other this they call it stick slip effect they stick together until you overcome the friction and then they move stick slip it's called that's a real problem on CNC machines with slide ways or even a manual machine with slide wave so ground the ground ground it can be done but you have to take precautions like machining in oil grooves proper all grooves proper defined ones what do we need for scraping and easy just about a thousand bucks worth and tools now I'm just joking you can start out pretty basic okay what do we need but let's go over these there are some advanced tools in the selection some that you need in the beginning so the most basic thing you need is a scraper I will go into detail on that later you need a way to sharpen it preferable a diamond wheel there are other ways you could use a balanced file diamonds stones or even a green carbide wheel silicon carbide wheel for your bench grinder but those are pretty awful so try to get a very fine grit diamond wheel and mounted on a bench grinder like this I will show this is my ghetto car by grinder I will show that later then you need some some high spot blue either the old oil-based pression blue or dye chem or this is the diamond brand the old base stuff is a horrible mess at the end of the day you look look like a smurf or you get the waterfall you can note bloom and preferable if you can get it the yellow - you need a brayer is very useful this is to spread up the paint on your master surface for example surface plate you need stones for deeper in a medium grit India stone like this one works quite well this is all this is stone that Richard King hands out at his classes and works quite well and I happen to like a fine aluminum oxide stone that I surf a strong on one side perfectly flat this works for finishing very good this is a piece of plate glass I used this to spread out the paint because my surface place is not as big and I'm inbuilt in the lucky position to have an power scraper this is a ramps power scraper and of course there is the well-known by Axel a power scraper this makes works so much faster it's point-and-shoot with this you have to do all the works yourself with this you just aim and let the Machine remove the material and you need a nasty surface a surface plate you can get a cast iron surface plate or which i think is preferable a granite the the Chinese import grade zero zero and it's quite good you can get you can for example buy an old coordinate measuring machine on eBay with a granite table and strip the Machine down and just keep the table this will make you end up with a press for a rather cheap and very big surface plate you can buy the Chinese ones which are reasonable cheap and quite okay or you can buy something like a plan elite from Germany or Standridge granite or starett granite surface plate they're all there are really a lot of manufacturers that make hard stone surface plating expecting equipment so you need that too and of course if you want to give machine ways like duck tail or prismatic ways you need a straight edge profess the straight and flat straight edge you can make them yourself out of cast iron scrape them then you're good to go okay let's talk about the most basic tool the hand scraper there's a shop mate it's modeled after the Vioxx hand scraper it takes a takes a carbide blade in the front which which is clamped by Midas upper piece and and this four millimeter screw here just like this the scraper itself has a step cut in and Gurda blade can rest and the clamping pieces will relieved in the center and has a pad in front and back so it it actually clamps the carbide blade you can buy the carbide blades for example from by ax or sandwich and this scraper is endless the blade to end us to handle 470 knowledge of law that's for me that's a good size I convert this with this quite well there is also a pad and I can screw on the end when I want to push with my with the belly or with my body it's just a rubber pad from an angle grinder for sandwich handing wheels and I tapped I drilled and tapped the end of the handle up scraper for an m8 screwin screws directly into the roof so the errata basic scraper and you don't want to make the this portion here too stiff otherwise an attempt to chatter and don't work as well this one has four millimeter thick and 20 millimeter wide and it's quite flexible that's what you want you want don't want to make it any thicker like sandwich cells a scraper too but it's something like 30 millimeters wide and 5 millimeters thick and it fits like hell it really kills you when you have to use a question time so that's basic hand scraper I did all the scraping on my life for example with this prick back in the day before carbide was widely used people used carbon steel or tool steel blades harmed them and stoned them sharp but they get down so fast they work but you're pretty much sharpening all the time even the carbide needs address after a few passes scraping cast iron anyway so whatever you do try to get a carbide blade they are not cheap but you can make him out of your way around it and by for example a carbide planer blade which are rather cheap and use that but the grade of carbide on those is not perfect for scraping but there you can also silver Staller an old lathe invert indexable inserts to a piece of steel and shorten data there are many ways to do it but this is a hand scraper like this is a nice easy project for a rainy Sunday afternoon and you will have a tool that lasts you or you buy the buy X hand scraper which looks pretty much like this so for the geometry of the scraper blade if you look down on it like this there are ground with a radius a good general purpose radius is a 16 millimeter radius can do pretty pretty much most of your work with a 60 radius you can do roughing kinda and you can do almost finishing with it and when you look at the side of the blade like this you want it to be five degree negative so you turn this and this is this is the work you grind your tool negative five degrees this would be if we have a right angle in here this would be neutrals zero Degree cutting angle and if we have 95 degree in here this is five degree negative because we were beyond 90 degrees if she grinded like this this is positive for example if you grinded 85 degrees in here this is five degree positive this will appear is five degree negative and there's zero degree neutral one important thing is the surface finish on the grind of these blades and as you can see this is crowned on a 3,000 grit diamond wheel and surface finish is really darn good I don't even do lapping or something like that to the scraper blade off the 3000 grit diamond do it perfectly good enough and as you can see it's ground five degree negative like this the other side is has its grant to 5 degree negative two times so it makes it's like a roof shape it's like this and I do that or pretty much everybody does this so they have two cutting edges when one side gets still they'll flip it around and you can go on before you have to go to the grinder you can even do this to all four sides scraper blade then you have eight cutting edges before you have to go back to the grinder if you can't see I also hit flat surface here against the grinding wheel and I will show that later until I get a mirror finish up to the cutting edge this improves surface quality on the scraping end decreases shadow so as a surface finish you're looking for roughly there is one little tool I didn't show this is a radius gauge it has a this laser cut out of stainless steel has a forty sixty ninety and hundred fifteen millimeter radius on it and you use it to check your grind just like this and in between in here this is 25.4 by twenty five point four millimeters so one inch by one inch you use this for checking your the quality of your scraped surface i can show that later too how is it done I'm glad you asked I will show you okay let's do some actual scraping let's say we have this random block of cast iron and you want to make it flat on this surface obviously somebody had already a go at this and we don't know anything about it yet only that a hack already scraped around on it so in order to check the flatness we need to break up the surface otherwise it would just stick to the surface plate and be a blatant mess so we take our scraper with a sixty radius blade and we just go at it we just scrape once over the whole surface to break it up and when you do that you want to make actual chips you don't want like this you really want to lean into you want to take a proper proper chip so you produce actually a small scraped Valley so you see that I went roughly 45 degrees across the surface and we do that because we will alternate now 90 degrees to it and go for it fast the other direction otherwise if you don't alternate your direction you will get horrible chatter the the chatter it you always get a little bit of chattering and when you don't alternate the direction the chattering gets worse the the scraper blade moves into the old chatter marks and makes them worse so alternate your directions so now we have surface scraped ones over pretty much and we take our India stone medium coke medium grit and we remove all the birds from scraping on each scraper pass on the end we create a very tiny bird we need to remove that work stone before we go to a surface plate there are techniques that eliminate the burr at the end like pulling out at the end like this this leaves basically no burl but it's very it takes a lot of practice and it's a little bit slower now we want to take this over to a circus place and check it for flatness before we go on otherwise we're just scratching up the surface and we have no clue what we're doing so throw at the surface plate and ask some [Music] glass cleaner here and I like to use that for the surface plate to prepare it and we have our blue can note ice ball blue water soluble and we just get a small dab of it on the surface plate it doesn't need much of it and you take a prayer or foam roller or something like that and you spread it out in one space somewhat even it's almost feel a bit too much then you roll out the surface where you want this is just a paint spreading area you spread out a bit of paint roll out get your brayer coated with the color tube then you want to prepare the actual surface that you're working on just try to get a an even coat of the fluid on it after that you take your work piece and you rub it on on the paint and you transfer the blue from the surface plate to the high spot of your part it feels a bit I'm adding a little bit more of the bluing it feels a bit faint for roughing and you always want to make sure that your part is cleaned you don't get that dust into the surface or something like that now you rub it and important thing is to hinge the part as possible you take one hand end of the part and swing it around a little bit and you you try to find the spot around which part rotates and it looks like it's about here so that means we have the part is high here and it looks like here so these are two high spots you can also identify them with a plastic face tammer we identified this and this corner is hi can you hear the difference on the high spot it sounds more solid and when we slip it around and we look at the bluing when we look at the bluing now we have high spot here and high spot here and we get blue here in this area and found here in this area but we also get blue here and here and that's dangerous we don't know if this is a real actual reading the caustic part could have tipped over the access between the two high spots that means it rocks back and forth so we ignore this and this for right now and concentrate on the cornice here just like this we're only going to scrape these corners here until the hinge the hinging point moves in about here and here rule of thumb biz 33% of the overall length to the inside and center if you want to have your hinge point about sides then you can't be pretty sure that your properties slap other ways to check it for example with a large knife edge straight edge against light or with an indicator and check if the part is weeble wobble in them perfectly but the hinging is actually very fast ways and I was surprised how how accurate it is before the class was Richard King I didn't know or I read about the hinging but I didn't gave it any consideration I was thinking that it's optional but it's not you have to do something to check if your part is actually bold and then you have to confirm if you're blue your area you you have your high spot is actually a real high spot or or just part just tipped over and on an extreme case you could have a part that's like this it's super super convex and when you take your print your bluing then you rub it on the surface plate you could get bearing points all over the surface because it's rocking back and forth like a rocking chair but it's not flattened in any way and that can cause you to chase your tail for hours and hours will drive you completely not so do do something to find to identify your the partes high not only by robbing but with a second method like hinging it so we're just going to scrape these two areas now at this point you don't care about the appearance of your scraping at all you just want to get material off and you want to get the part where you roughly flat when you get to the edge to the edge that faces towards you is to be really careful otherwise you you catch the edge and tear up the surface either you're super careful which means you're lazy or you take your part and actually flip it around which is the safer method of course then you go yes like this and I prefer to use a shop vac to remove the cast iron dust or chips when you use compressed air you will end up with the small carbide small cast iron wheels everywhere in the shop [Music]

Channel: Stefan Gotteswinter

Views: 392,121

Keywords: scraping, schaben, flachschaben, handscraping, biax, renz, richard king, richard, mueller nick, dykem, canode, high spot blue, carbide, diamond wheel, diamantschleifscheibe, flachschaber, tuschierfarbe

Id: QJXqHpSh3SE

Length: 30min 53sec (1853 seconds)

Published: Sun Jun 11 2017