How to flatten the back of a chisel or plane iron.

I've recently been commissioning two new benches for my students to work out normally we have a full set of hand tools on each bench and so commissioning the benches involved acquiring some new chisels now obviously as I mentioned in my sharpening video new chisels need the backs flattening or orbital lapping so I thought this would be a good opportunity to demonstrate how we go about lapping the back of a chisel so if you can be time to get prepared all well I'm look at that so this is a set of six narrator bevel edge tools which is standard set that used for more web inches at the moment they're 45 pounds a set from workshop heaven which i think is quite reasonable because they're pretty good chisels they hold their edge quite well and they don't take a lot of preparation some scissors some especially the cheaper end of the market they take a lot of preparation don't hold the vegetable well some of them you can't actually prepare them you can't actually get the backs of the chisels flat these ones look very good as we'll see in a minute so most chisels when you when you buy them unless they're very top of the market ones will have some sort of grinding marks on the back from left over from manufacturing now if we look at this one we can see some sort of stripes running across these are the lines left by the milling machine whenever cut you can also see a little blob of you can see that or not there's a blob of lacquer there where they've been dipped in lacquer after completion and manufacture and that's their really lacquered just to protect them in transit and if they're in storage for any lengthy time it's quite simple job team to get rid of that now one of the advantages of these narrow spaces is they are actually ground very slightly concave in in can I show you the direction in that direction so that that makes lapping them very easy and we'll see when we come to actually rub them on the abrasive we'll see we'll get an abrasion mark there and abrasion mark there and it won't be actually braiding to start with in the middle because of that slight concavity which is a good thing if the chisels curved in the other direction would ever hire a single high spot which would be a real pain in the backside because when we try to lap the chisel it will rock on that high spot and we won't go to get it flat it will just continue to rock so we could just continue to have that curve so this concavity is quite important so to remove that a little bit of lacquer off the end there it's quite a simple thing you can just see I'm just running a chisel underneath the blob and it should come away as just a lot away full of whatever it is so that just is now ready for us to give it a rub on the abrasive so what I'm using from initially from my lapping is I've got a sheet of little plate glass float glass and I've stuck on some wet and dry razor so I've got 80 grit there 120 grit 180 and 240 I've stuck it on using suckled spray round just like a spray contact adhesive often used by artists and things for mounting pictures and things are that anyway so we're going to grab the the flat of the chisel on starting off with the 80 grit and it's really important here that we keep nice and flat on the razor my business like that you see I'm holding it I've got all the intention on keeping it flat there so I've got me thumb and finger there and the other finger on there and I'm not holding the handle like that because there's a tendency to rock it up and down if you hold the handle so I've actually got to one or two fingers just sort of hooked around the blade there just to stabilize it I don't have them there it sort of rocks around and wobbles around but so I just hold those there just to stop it bobbing around all the intention is on keeping this really fast on the abrasive traicee important if we just have a look I've just done a bit of rubbing and it's looking pretty good already actually you can see yeah well it's done it actually just in that time it's very flat once it's gone what a warder is all rubbish slightly an angle because these machining marks are right angles to the blade yeah and I want to make sure I've got rid of all machining marks so if I rub it with the blade angled like that and all these razor marks I'm making will be diagonal I don't know if you can see that and any abrasion marks which are going that way we'll obviously be or any grooves markings are going that way will be from the original machining you'll want to do that that's looking pretty good I'm not sure whether the camera is picking that up but I can see sort of diagonal lines I can't see any lines running in that direction so I'm going to go on to the 123 and we've got it flat now all we do it is polishing it very so I'm now holding the chisel in the other direction so that any lines that are made by this clip will be he's at an angle to the previous clip so we're now looking to have all that all the grading lines going at this angle to get rid of the ones in previous angle and that's looking fairly good so I'm just going to go around to the 180 breasts okay so let's see what we got in our yeah this AXI a slight patch here which it's got the previous abrasion marks on it now not too concerned about that because we're really interested in the the front what 10 15 mil there doesn't matter if it's it's not quite flat and about CSAT front to 10 to 15 mil that's important so I'm going to go on to the final grip on this side and then we're going to turn it over again for some 5 degrees right that's looking quite good now that little patch there is because the as I said before in manufacture there's that very slight concavity in the in the blade and where we're looking really sort of get the abrasion there and there so it doesn't matter too much if we're not getting it spot on there when I'm getting the abrasion pattern right the way across as long as we've got a good flat at the end so I'm turning the plate over now we've got one last bit of right and dry here which is 400 grit and then we're going to go over to 3m laughing it's guru 3m lapping film which is an aluminium oxide impregnated what-what a sticky back plastic of Blue Peter fame so you can just peel the backing off and lay it carefully onto the the float glass yet be very careful that you don't have any impurities on the on the glass before you lay that the 3m stuff on because otherwise you get little dimples in the surface and it won't you won't get a flat cut and also what happen is that the lapping film will will tear where the dimple is so we're working on 40 microns here 30 and then 50 we go into microns this is grading microns rather than grit and I think 40 grit is more or less equivalent to 300 350 also grit and then we're working away down to 30 and then 50 so we're getting down to quite a polished edge and the reason I've gotta go to this is because otherwise I'd probably have to go on to me Waterstones and doing this sort of work on waterstones can kind of brave them quite bad for your end up the stones having to be resurfaced and it's particularly when I when we do it when we have a whole load of students all doing this on a on a course or something if they're all working on water stones then I'll be forever flattening the water stones are there that end up getting Moll away in no time so using this lapping film means that you can you you're not sort of affecting the water stones so yes I'm almost getting a mirror moving see that get enormous or getting towards a mirror finish now as I said before we did the flattening on the 80 grit or what we'll be doing now it's really polishing so that we get a nice good edge when we come to the whole thing and finally on 15 micron now who wanted I could actually go on and go on to the very fine stone that I've got I've got ten thousand grit stone which will give you a nice polished edge but I think we're okay there really that's looking quite nice I can see my reflection while we go all this trouble while he was well there's two reasons really one is if you watch my video on on honing you'll know that we sharpen a blade until we get a burr on the back then we go through the grits and then finally we turn the thing over and rub the bow off by rubbing the flat of the chisel onto the finest stone now the chisels very slightly curved convex so it's curving away like that when we rub the flatter the chisel on the fine stone we won't actually take the bow off because the very end of the chisel will be very slightly lifted by the curvature that fizzle so we won't actually get rid of the bone we won't have a perfectly sharp edge and the other reason is that again if we've got that sort of curvature in the wrong way then when you come to use the chisel for paring more like that what will happen is the chisel will ride up that curve so you wrote me here to get a nice horizontal cut and your paring which is quite an important skill in woodwork the ability to get a nice clean paring Cup which will be impeded by a curved back on you on your blade on your chisel so that's so that's lapping the back of a chisel one or two points I'd like to make I didn't make during the process one is that I didn't actually test this chisel to see whether it was flat or not because I knew that tools from Marik's usually have that sight concavity which I was telling you about so I didn't feel I needed to test it but other chisels you need to especially ones that you might buy from a car boot sale or second hand the ones from eBay you need to make sure that they are flat before you start if not flat than that they have you got that concavity in them if you if you have any of them convex which you're curving away from the flat then you've got your work cut out and it might be worth not actually bothering with them now the reason chisels can can end up like that one thing I forgot to mention this chisel we've been lapping here this is the 12 mil wide chisel 1/2 inch and we've been rubbing it in that direction with narrower chisels there's a danger that we've been very concerned about it being curved in that direction there's a danger when we rub it if we rub it sideways like that that we're going to actually round it over in that direction what cool dubbing over to avoid that I turn this this over to avoid that we would actually rub it in the opposite direction or right angle so with with it we do it in and out like that again making sure that we're keeping this front end as flat as possible on the on the abrasive we're not able to actually sort of do the rubbing in different directions on the diagonal to find the weather we've got rid of the abrasion from the previous from the previous of grit but it does mean we don't end up rounding over this we're doing it that way in which case we get that sort of effect which rounds over the face and what we're trying to do is get a flatter face as possible so we'd work this round all the way through the grits working in that direction rather than that direction and I'd say you probably need to do that with any chisel ten millimetres wide or below you need to be careful about its rounding anyway okay it's a if when you're holding a chisel if you don't keep absolutely perfectly flat on the stone when you turn it over to take the burr off if you lift the handle slightly or anything and over time you may create introduce a curve on the on the back and the other important element is if your flat stone isn't flat stones do aware oil stones water stones Diamond stones doing obviously and if when you try now over to again take the bow off and the stone isn't flat across the stone and you will that will end up with the back of the chisel being out of flat and you possibly have to lap it again I mean this should really be just the once in the lifetime which is what you do this but accidents do happen finally plane blades similar sort of process not hard to work because you've got a lot more wood wood lot more steel to remove so it can take a lot longer to lap a plane blade than it does a chisel blade anyway I hope you found that interesting and that you end up with nice flat chisels you

Channel: Chris Tribe

Views: 33,770

Rating: 4.8936877 out of 5

Keywords: Lapping a chisel, Lapping a plane iron, Lapping, Chisel sharpening, Plane iron sharpening, Sharpening, flatten chisel back

Id: xOMGWkKh2M4

Length: 16min 37sec (997 seconds)

Published: Tue Oct 28 2014