Basic Hand Scraping - A 12" Cast Iron Straightedge

i promised a fellow who was a friend that i would do a video scraping up one of his straight edges and i've gone back through a lot of my videos and i haven't actually done a real basic one as an introduction which is what i'll do now what do you need for scraping somewhat to scrape a reference surface some form of pigment ink or paint as a medium something to clean that off with some means of removing any burrs dusty brush a scraper and plenty of these i will cover each of those in turn starting off with the the bit that you're going to have in your hand most of time which is a scraper they come in all shapes and sizes um i'll be honest with you make the one that fits your hand and you aren't working with and you can't do that until you've done plenty for the simple reason you don't know what length you're gonna want and if you follow everybody else's length you'll end up finding it bloody uncomfortable traditionally they were made of high carbon steel and you can pick these up used on ebay i think that one i paid a five or four including postage i've just shaped the end of it for getting down into tightest box underneath dovetails as things developed tungsten carbide started being used and that is literally a piece of tungsten carbide and it's braised onto soldered onto a uh file which i've ground all the warm file which i've then ground all the teeth off and should handle on the end when you start going up market you can buy replaceable carbide blades um the only ones i've used are sandvik and they are that's a 30 ml wide blade and from memory it's about 35 quid and if you buy packs of 10 it works out a little bit less i've never bought a pack of 10. um they come in 35 25 and 20 mil widths and there are other alternatives out there but as i say i've not managed to get hold of any to try them out but what i can tell you is of all the different carbide blanks that i've used from different different grades the the sandvik one seems to hold its edge longest and to be brutally honest when you're doing a lot of scraping you don't want to be at the grinder all the time which is the only bit of kit i haven't shown on here you want some means of putting a new edge onto your tungsten carbide or your high speed carbide now if you're only doing a small area um high carbon steel or high speed steel for that matter gives you perfectly good edge which will last a reasonable length of time you've also got the benefit if you can grind it on a standard grinder without any worries if you're going to be doing a little bit more than a say a single straight edge or the lights i'd strongly recommend you go for a tungsten carbide edge just because it's hard enough learning how to scrape without wrestling with what a blunt blade is um so i'll cover the sharpening as we're going through um the next bit inexpensive paintbrush that's got a nice soft bristle and that's for sweeping off your area topman's hate me you want a piece of stone which is uh flat now i have the advantage of i used to do a lot of woodworking and i've got quite a few of these bench stones which were at the time expensive about 15 years ago you can now pick something similar up made in china for i think 10 to 12 and a inexpensive i mean mine's a teardrop shape and there are lots out there you want a fine grade carbohydrate stone or indian stone use the diamond stone to flat it off and you want it so that basically you can move it around and it's not got a hump in the middle i use a marking blue made by a company called stewart's which is readily available in the uk uh on the internet i think a tube of that is a from memory about seven quid so not far off for ten dollars and a tube of that will last me quite a few weeks of scraping i think i did the whole lathe with bed with one not even a full tube um i use mineral spirits which is white spirits to clean that off i apply it now basically with a rolled up cloth and that is literally a piece of um soft cotton cloth pure cotton no polyester or anything in it and you know you see that it's got a wrap of copper wire around twisted down like a tourniquet to make it nice and tight and no it's not lint free and yes it does drop tiny little bits but i've yet to come across any other medium application which doesn't drop little tiny bits as long as you're aware of it you can work with it my reference surface is actually a small surface plate and it's 12x8 this one appears to have been surface ground and then a rudimentary flaking over the top of it it's got next to no depth which means you need very little ink on it to fill it so you can ready you're ready to roll pretty quick why do i use that because that's the smallest surface i've got that will still fit that on it if i was working on a bigger longer uh straight edge or a bigger part i'd use a bigger plate so you want to try and keep things to the bare minimum not least because you gotta hump them about all the time first job before we do anything is make sure that our reference surface is good we've all got one of these uh quite helpful don't use any barrier cream on your hands when you're doing scraping because i think you'll find that a it makes your hands soft and b everything sticks to them so you never end up clean you're just going over the plate and you're making sure there's no dings burrs or anything you can feel and if there are you just take them down with your flat stone carefully once we've got that down we'll take our dubber this will piss a few people off so called experts now i used to use a roller and what i found was that the roller after a period of 20 or 30 hours of use it was dropping little tiny bits of plastic which are right hard and you've got to clean every one of those little tiny bits of plastic off and because this is small you could barely barely feel them let alone see them and when it finally fell apart i replaced it and the other one lasted about half as long um they weren't cheap in the 25 quid ink flying rollers uh my mentor used a piece of cloth as a show so i've started using that and it takes a little bit longer to get a coating but a lot less time picking stuff off now when you first start and you're prying your ink you want enough ink on there basically to give you a print but also just to provide a little bit of a film between the part you're trying to print which isn't perfectly smooth and certainly isn't flat when you start because it provides a little bit of protection again for this to make sure it doesn't get damaged now on a plate where you've got more that surface undulations or more depth to the scraping on it you need to apply more ink which means it does last longer because every time you're moving it over you're picking it out the troughs and depositing it on the high points with a plate that's effectively flat like this like a and smooth i will probably have to reapply ink several times and you're just basically putting it on to make sure that you've not got any dirty great big lumps all over it because the longer more wipes you get of it the more rubbing over the the part that'll progressively even itself out anyway once that's done shift it out the way don't keep it on the desk where you're doing your on the bench where you're doing your scraping because you don't want cast iron dust and grit getting onto it so otherwise you've got to clean it all off and re-ink it someone is over there uh word of caution try not to put it the other end of the workshop because it gets a long walk every time you go pay something down to it next job is to have a look at the strut at this straight edge and i'm going to clear the decks now and then we're going to have a good look at my friends straight edges on instagram i've been had an account on there for maybe two years uh there's a chap on there from the other end of this country uh landing down in essex called clive lamb and he got fed up with the fact that you couldn't buy a cast or a new cast straight edge in this country so he set about making his patterns and produced a range and he goes from this is his if you like a small sample one 12 inch i think he's gone up to 40 no 72 inches six foot something like that i'll put the details for the contacts anyway he was uh he's sent me a few comments on poster put on and then we had some dialogue and he said oh i'm gonna cast some do you wanna have a look so i said yeah fine let's have a look um and he does a range of these in different lengths and this one's a 12 inch one i think it's a 45 degree bevel so pretty much getting to anything you you're going to find clive only supplies these machined that way you can guarantee that the cast iron's got no porosity in it and uh the castings that they come when they come to him he then sends them out and they get heat treated so what you should end up with is a stable casting now this is as he's delivered to me so he's had his had a coat of primer on it he's tickled up the uh the faces and machined ready to go so the next thing you need to do is to basically you need some means of holding this because we're going to scrape the flat bottom first and then the second face will be that a normal camelback you'd have a curved top with maybe a couple of pads on these are a design he's come up with via autocad so the the size and the dimensions of the webbing is to optimize the rigidity of that face and give you better resistance against distortion from heat transfer in the lights right so i'm going to set up some kind of uh setup to hold this flat like that and then we'll um take a look at the bottom of it well i'm set up for work now so i'm off the fancy clean cloth um i've got a piece of mdf sat on it's actually sat on a saw table the straight edge is clamped against a vertical wooden face and the clamping is such that it won't move but there's not enough force going through it to actually distort anything i've seen guys do straight edges where they clamp them in a vise where they clamp stuff to it and it sits there's two things you want one don't distort it and two it's gotta be quick to set up because you're gonna be picking that up and putting it down a couple of dozen times at least as you're going through the scraping cycles and the last thing you want to be doing is fighting around moving bits left right and center um i usually find that after three or four passes i've got things sorted to how i want them and the other thing you need is you need to be able to scrape from one direction turn around and scrape from the other direction if you don't you run the risk of basically ending up with effectively original fur all the way down it because if you just turn the part round you're actually scraping the same direction all the time common fold easy easy to fall into the trap so uh the first thing we do once we've got it mounted up we're running our hands over it there's bits of over paint here cheers class i'm going to put a bit of a mineral spirit on it a bit of mineral spill spirit onto my diamond stone clean the bottom of my india stone and then i'm just deburring it the way that that's sucking down i know that it's a pretty good face let me take the first of what will probably be a couple of dozen rags clean that off put my fingers over it the end of your scraper and i'm going to be using this sandvik tip bomb uh the scraper i made you can buy them i think from memory 35 45 quid for a unit uh they are a bit long but you get away with it end of the end of the scrape has got a curve on it and people get really excited about what radius it's got to be um yeah to start off with you're just going to be removing metal you want it as flat as you can otherwise you end up digging troughs with it and it's got a slight bevel on that end so there's a cutting face there and a cutting face there and what you're actually producing is a negative face you're not digging into the cast iron you're effectively scraping it over if you look at turning tools for cast iron when they used to use just high speed steel negative rake on them so we're going to go over it and give it a single pass i'm just going to push push scraping to start off with because it's fairly quick and even um if if this was a pretty crappy surface i'll be just looking at a roughing pass what i'm actually going to do is do something about three quarter of an inch chomp chomp chomp chomp chomp chomp [Music] one pass take your tickly brush sweep the area off i'm just having a look because i can still see the tooling swirl so i could now do another pass that way basically yeah so instead of me working across at lines like that i turn those through 90 degrees and work across like that i'm not going to i'm just going to put a bit of a oil on it put mineral spirit on it now i can feel the burrs on that now and there's no there's no weight there you can feel as the birds get knocked off i'm just going until i stop feeling any bite from the stones which is where it's fighting on the a cloth give it a wipe off then run your hand over it so all we're doing there or started to do is remove the machining marks and we undo our clamp and we take it over and we do a print but a couple of things to remember when you use the white spirit it runs off the edge and over the part so then when you invert the piece onto this onto your surface plate all that white all that runny stuff runs down onto your surface plate and destroys your print so you've got to be a bit uh i used a lot then because i knew it was fairly rough surface you want to put the bare minimum on and then it's less to clean off you'll find the first few cycles you'll be picking up bits of fluff and bits of chips and all sorts bits of flakes paint although in fairness to clive these are pretty clean castings i cleaned up some old uh sort of 50 year old straight edges and they've still got sanding sun sanding the castings we're not hanging on to it for very long so we don't want any heat out of the hands distorting it lower it down at one end and then on the other and you're listening i can hear something under there and then i'll when i'm doing a rub i just move it from one end and i try and be consistent about which end i can tell you now it's not touching very many places i'm gonna get diagonally because it just gives me a little bit better area i'm gonna mark the ends the eyes holding yeah now if i'd grabbing it both hands and rubbing it vigorously like that i could get a lot more ink on that but it won't be a true rub so that's the end on memory that went down first the opposite end is basically touching along that edge now this is the bevel edge there's slightly less weight on that and we need to bear that in mind as we progress with the scraping because of the right slightly worth less weight on it it'll pick up slightly less ink as long as you're aware of it you can work with it so i started out with scraping going that way now i'm going that way i'm not looking at gouging big holes out because i don't think it needs that much off it a little bit less this time wipe it off with my hand i'm feeling for any burrs i'm doing the clamp wipe off the excess juice so basically it's rotating about that corner sorry that corner and that corner all right yeah and that corresponds with what we've got on the ink where we've got pick up there a tiny little pick up here and then there's a couple of blobs and we just keep going like that i said five cycles now so you can see that the uh the two corners which were touching here and here they're slowly spreading across so this is just this area is now light and i'm not leaning on the scraper i'm only taking off a small amount each time so the machining was pretty damn good the cast iron itself not buttery soft but it's uh it's easy enough to work uh it's certainly a lot softer than i found on my lathe bed or on some of the other straight edges i've done which makes it a bit more pleasurable to to work right i'm off to another few cycles and i'll bring you back in a minute that's seven cycles and you can see now that that area which was low here starting to pick up ink we've not got an even scrape over it yet barely touch this area so we just keep working it around what i'm actually doing now is picking off the blues because i know there's not a big difference in the if you like in the flat plane between these high points and the unprinted ones there's certainly less than half a thou that's a 10 roughing cycles and for all intents and purposes biggest holes probably there that's near enough there um it's pivoting and i'll bring you down in a second but it's pivoting there and there i'll show you why why with a close-up well you should be just be able to work out the the blue spots there are more of a gray on the inside yeah that's another high one there and the same at this end and that basically means that the the ink that was there has been squished even thinner so what you're actually looking at is the uh the cast iron with the thinnest of thin veneers on it i'm just trying to zoom out a bit so yeah uh ten cycles that's rough dim now normally what i would do would be then basically take the clamps off and just leave this sitting on top of the surface plate just to make sure that nothing's gonna relax move or otherwise what i'm going to do is give it another couple of cycles now just taking off the blues and i'll video it so you can actually see what i'm doing the key thing is once you start getting a reasonable spread if you remember when i started i was doing three-quarter inch long strokes i'm now down to about three-eighths of an inch sometimes down to a quarter as you reduce the length of the strokes the intensity the points per inch starts to increase now at the moment i'm still drawing intense purposes just scrubbing off the blue once these areas disappear and i start getting much more even it's a bit bit light on this area when i start getting a more even coverage i'll start spacing the scrapes out and uh we'll cover that in a move so i'm just removing the blues and i'm trying to keep the scrapes to sort of 3 8 of an inch or less and i'm not rushing but i am i'm not trying to separate scrapes i'm literally just skimming off the tops so there's no great pressure on that it's just the weight of my hand i've learned a long time back if you want to gouge out big holes you lean on it a lot [Music] but bear in mind every bit you take off if it's too deep you've got to take everything back down to that level so i came to the conclusion it's much better to take lots of shallow cuts until you've got a flat plane and then texture it that is to start out on the basis of digging through a foul deeper and taking everything down it's just a different approach i guess it's a damp site easier taking cuts which are half a thou deep than the third one off so so a few words about sharpening um as my friend clive will tell you folks in the north is generally tight i'm tighter than most uh tight meaning don't like spending more waste certainly don't like wasting money these things are expensive um the sooner you come up with a method of grinding them that is gives you a consistent result give me a bad result as long as it's consistent you can tweak it until you get a good result so the first first thing i did was um used to grind it on a green wheel on a standard bench grinder and yeah results were all over the shop it might be good one grind and next grind i can't take a scraping with it robin renzetti did a short video on a scraping that he did and he showed using a diamond hone wheel i think it was a 600 grit and he modified a relatively inexpensive slow grinder wet grinder so i'd look and found a very similar kind of thing uh it's a pile of crap uh i think that was 28 quid but it does the job just have to take the wet grinding wheel off make up a hub and put on a three pound 50 diamond flat wheel uh and i actually bought a set of them i think 20 quid and they go from 36 grit right the way up to a i think a 400 grit i use a 600 on it and basically i don't use any jigs for grinding the radius i do it all by hand as you've just seen because i am not particularly fussed on the exact radius and it's probably a compound radius on mine anyway um i know that certain guys who teach scraping specify a given radius for a given task and that's fine they have a system it works for them brilliant all i can tell you is a large relatively flat radius is great for leveling things out if you want to use something with a tighter radius and there's not a huge deal the difference between them so with a tighter radius you can produce a narrower width scrape or for the same width you can go deeper i use the the other one for getting into dovetails every now and again i will put on a narrow or a tight radius where i'm looking at just increasing the points per inch or splitting up an area which is a bit too solid it sometimes takes a bit of pressure off my arm that's about it so if you do if you do anything on scraping get your sharpening right because it makes life so much easier and as i mentioned earlier i don't believe in heaving on the scraper to take out a dirty great big gouge because you've got to do a dirty gate big gouge all the way across it and what you'll find is you're deeper at the start than you are at the end or you're deep in the middle than you are either end so when it comes to actually getting an even distribution of contact points um you've got a lot more work to do if you're not if you've not been consistent and you've not produced a consistent face and i think from the people i've spoken to and the people that i've seen scraping or trying to scrape that's the problem the inconsistency of their scrape and yeah practice improves right so i've got a bit more did to do on this um still taking down just taking down the blues it's pivoting around here and here so we're still a bit too far out we need to be about there and there but it's coming together each pass so now i've got one edge there and one edge there when those two are blunt i flip it over to this and turn it around so the stick is on the bottom and then i know that i've blunted both ends silly little thing but it saves re-sharpening a sharp edge so so a schematical representation of the scraped surface so you've got a high spot here slightly lower spot slightly lower again and it's let's call that a medium spot they're going to pick up transfer blue on the tip these aren't but in reality what happens is that little film which is microns thick gets squished down so you get basically a squished area and then a thin veneer so if you were looking at that if you're just looking at that you're gonna get a veneer there and then basically thicker blue around the outside and that thin veneer there in the extreme looks like dark dark grey almost black they caught us some guys call it bullseye surrounded by the pigment whatever you're using in my case blue but other guys use red so the reason you you you don't take it all off once you get past a certain number of or certain distribution if i went ahead and took it off to there all i've effectively done is made that point then lower than that one and end up you just end up chasing the same dots down um which you know will still result in you getting a flat surface it will just take a bit longer whereas if you just nick out the top of it with a shallow scrape that then brings that layer almost to that and then the next cycle you're going to take those two down and you'll pick that one up so then you've all straight away you've got three points of contact rather than one hard one slightly less hard a medium one and an almost contact that makes sense um another question got asked is do i ever check the depths of my scrapes i did what i started i used to do a lot of running over with the dti with a little finger gauge and i was looking for anything between our alpha thou and a thou and the net result of that was i got me a clip by my then mentor chris basically saying what are you pissing about doing that for is not necessary you only want the deep scrapes for shifting material once you've got a level plane your final pass will go over it and put your oil pockets in now he's not talking about what's regarded as flaking um the style of scraping that chris did and mine's a pretty poor imitation of it he would he would generate a plane which was for all intents and purposes not far off a ground finish you might get that and you'd get that as an area of contact that has an area of contact and that was an area of contact and his his scrape profiles were basically they were still let's call them half moons they were that that would be the deepest point the width there would be reduced as that length reduced so the actual shape of it stayed the same but it'd end up doing kills that sort of size so your deepest points were put and then in between you'd end up with almost a crisscross of contact points and then his final pass would be some something in approaching between those two and it'd just do an even coat all the way over it it looked fabulous sadly i never got the chance to see him finished uh put a finished coat on one of my straight edges he's he passed away before he could finish one for me but he did show me some examples so i only make my scrapes as deep as i could be bothered to push a scraper and then the final uh passover once i'm happy i've got an even plane will be basically to put in oil pockets and they're all around about half a thousand but they're spread a bit wider than when i'm doing the contact for bearing i hope that makes a bit of sense all right so we've got a print extending over the full extent a bit high density over that area and over that area hinging is good which is where you've got the high density areas so now it's a case of trying to pick out the higher of the highest of the highs and lower in the face down so we pick up more contact points along the bevel edge so i am going to go over it now with a a much shorter stroke something in the region of a quarter of an inch and fairly narrow maybe about an eighth of an inch and that'll start increasing the points per inch but also lowering the surface and i'll just be a little bit lighter on the cut over this front edge quick word on a common error which is basically down to a decision or a choice that you make as you're going along between going from sort of a roughing cycle to finishing cycles you quite often get it wrong so if we look at this you can see the contact areas if you look at the area to the right hand side so down here you've got much much much much much less contact and yet the rest of it's fine so i've got two options now i can either carry on scraping all the little blue bits off and eventually it will bring that into the same density or i can go back a step do two a couple more roughing cycles over this area taking that down so that then becomes the higher area it's a lot easier to work that then and the the way that that's happened is i've moved from thinking that i've got reasonable coverage i actually haven't i've got some low spots in there i'm sorry about the reflection of the light but you can see there are contact points but nowhere near as much as there should be and it's important that you recognize that otherwise you can spend an awful lot of time just keep taking these blues down and gradually and gradually you know you'll be talking about half a dozen cycles of just taking the bluff whereas if i do one rough cycle probably three lighter cycles it'll be there what's in all with me [Music] [Music] [Music] it's quite fairly even and what you'd expect after that is um you're basically going to be left with a lot less contact points but you should see more in that area and the reason you'll see less elsewhere is for the simple reason you can't guarantee that every high point you had before has come off so you might have a couple of cycles of just picking out the highest of the highs afterwards i need to re-bloom me re spread me around a bit more you

Channel: lookcreations

Views: 9,322

Rating: 4.9669423 out of 5

Keywords: Hand scraping, Cast Iron Straight Edge, camel Back Straight Edge, Bearing Scraping, Biax, Dapra, Machine Reconditioning, Vintage Machinery, Stuarts Micrometer Blue, Sandvic Carbide Scraper, Surface Plate Use, Dovetail Straight Edge, Lathe Rebuilding

Id: GlOwwqdX734

Length: 44min 43sec (2683 seconds)

Published: Wed Jun 24 2020